Dissertations / Theses: 'Composite Polymet Electrolytes'

1

Denney, Jacob Michael. "The Thermal and Mechanical Characteristics of Lithiated PEO LAGP Composite Electrolytes." Wright State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=wright1609971094548742.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Treptow, Florian. "Polyaniline as electrolyte in polymer electrolyte membrane fuel cells." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/11086.

Full text

Abstract:

The applications of polyaniline (PAni) for use as electrolyte in Polymer-Electrolyte-Membrane Fuel Cells (PEMFC) were investigated. P Ani was dissolved in N-methyl pyrrolidone (NMP), cast as Emeraldine Base membranes (EB) and then doped with halide acids. The proton conductivity was measured according to Hittorf. The chloride ion distribution within the membrane was evaluated using energy-dispersive-X-ray analysis (EDX) and photometric analysers and the diffusion coefficient was calculated. The specific resistance was determined using conventional 4-point measurement. Halide doped membranes were found to be proton conducting, however, during cell operation halide removal occurred causing a rapid decline in the cell performance. The maximum power density achieved was O.3m W·cm-2 for a 70J.1m thick membrane saturate with chloride between 3,5 and 4,5mgchloride per gPAni. Composite membranes with phosphotungstic acid (PWA), antimonic acid (AA) and zirconium phosphate (ZP) were developed and also tested in a standard measuring fuel cell. While membranes produced via ion exchange (ZP) showed the same result like halide doped ones, AA composite membranes showed a stable voltage and current results. The highest measured outcome of 373.3mW·cm-2 was found with a PWA membrane, produced through dispersing 3g of phosphotungstic acid in 300ml of a 1% polyanilinelNMP solution. It was also observed, that the higher power density was obtained from the fuel cell which uses the lower-loaded membrane. It is clear that a positive effect on the cell performance is given by the addition of phosphotungstic acid to the polyaniline membrane. Therefore, the saturation of PW A have to be taken into account to not lower the power density.

APA, Harvard, Vancouver, ISO, and other styles

3

Inaba, Minoru. "Electrochemical Reactions on Polymer Electrolyte Membrane/Electrode Composites." Kyoto University, 1994. http://hdl.handle.net/2433/74664.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Kashyap, Aditya Jagannath. "Conducting Polymer Based Gel Electrolytes for pH Sensitivity." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7824.

Full text

Abstract:

The evaluation of concentration of ions and molecules with the help of biosensors have been regarded as an emerging technology. Bio and chemical sensors have a variety of applications in the field of medicine, military, environmental and food industries alike. With an estimated investment growth of over 4.31% in the development of pH sensors in the next five year, the objective of a developing a robust measurement system is all the more required. The scope of this research is to evaluate the ability of conducting polymer-based gel electrolytes for pH sensitivity, as a function of the transistor characteristics using an Extended Gate Field Effect Transistor or a conducting film in an electrochemical cell. Polymer gels were prepared by dissolving a suitable conducting polymer in an acidic media. The interaction of the gel with a buffer solution of known pH was collected as electric signals using a glassy carbon as an electrode. The electrochemical cell was further connected to the gate of a Metal-Oxide-Semiconductor Field Effect transistor (MOS-FET). The drain current was measured under two conditions; a) voltage across the gate (VGS) was kept constant, with varying voltage across the drain (VDS) and b) voltage across drain was fixed, while gate voltage changed. The drain current versus voltage of the transistor was plotted as a function of the ion interaction between the gel and the buffer. Different plots were recorded for different values of pH solutions. Final results were plotted to calculate the change in threshold voltage, for every change in pH of the observed solution. pH sensitivity of the gels was further tested through the Electrochemical Impedance Spectroscopy method, using a potentiostat and a three-electrode electrochemical cell. With a small excitation, the AC current flowing through the circuit at different frequencies were recorded and the plots discussed, to evaluate sensitivity to pH.

APA, Harvard, Vancouver, ISO, and other styles

5

Zhao, Fangtong. "A SOLID-STATE COMPOSITE ELECTROLYTE FOR LITHIUM-ION BATTERIES WITH 3D-PRINTING FABRICATION." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1619814091802231.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Yarmolenko, O. V., S. A. Baskakov, Y. M. Shulga, P. I. Vengrus, and O. N. Efimov. "Supercapacitors Based on Composite Polyaniline / Reduced Graphene Oxide with Network Nanocomposite Polymer Electrolyte." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35510.

Full text

Abstract:

The paper describes investigation on new types of supercapacitors based on composite polyani-line/reduced graphene oxide with network nanocomposite polymer electrolyte. Its prototypes are all solid state. The new network polymer electrolytes based on polyethylene glycol diacrylate and nanoparticle SiO2 was synthesized by reaction of radical polymerization in the environment of liquid organic electrolyte. The work is aimed to obtain a polymer electrolyte that is compatible with the electrode materials of superca-pacitors. For these purposes the method of FTIR spectroscopy, a.c. electrochemical impedance and gal-vanostatic cycling were used. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35510

APA, Harvard, Vancouver, ISO, and other styles

7

Yin, Yijing. "An Experimental Study on PEO Polymer Electrolyte Based All-Solid-State Supercapacitor." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/440.

Full text

Abstract:

Supercapacitors are one of the most important electrochemical energy storage and conversion devices, however low ionic conductivity of solid state polymer electrolytes and the poor accessibility of the ions to the active sites in the porous electrode will cause low performance for all-solid-state supercapacitors and will limit their application. The objective of the dissertation is to improve the performance of all-solid-state supercapactor by improving electrolyte conductivity and solving accessibility problem of the ions to the active sites. The low ionic conductivity (10-8 S/cm) of poly(ethylene oxide) (PEO) limits its application as an electrolyte. Since PEO is a semicrystal polymer and the ion conduction take place mainly in the amorphous regions of the PEO/Lithium salt complex, improvements in the percentage of amorphous phase in PEO or increasing the charge carrier concentration and mobility could increase the ionic conductivity of PEO electrolyte. Hot pressing along with the additions of different lithium salts, inorganic fillers and plasticizers were applied to improve the ionic conductivity of PEO polymer electrolytes. Four electrode methods were used to evaluate the conductivity of PEO based polymer electrolytes. Results show that adding certain lithium salts, inorganic fillers, and plasticizers could improve the ionic conductivity of PEO electrolytes up 10-4 S/cm. Further hot pressing treatment could improve the ionic conductivity of PEO electrolytes up to 10-3 S/cm. The conductivity improvement after hot pressing treatment is elucidated as that the spherulite crystal phase is convert into the fringed micelle crystal phase or the amorphous phase of PEO electrolytes. PEO electrolytes were added into active carbon as a binder and an ion conductor, so as to provide electrodes with not only ion conduction, but also the accessibility of ion to the active sites of electrodes. The NaI/I2 mediator was added to improve the conductivity of PEO electrolyte and provide pseudocapacitance for all-solid-state supercapacitors. Impedance, cyclic voltammetry, and gavalnostatic charge/discharge measurements were conducted to evaluate the electrochemical performance of PEO polymer electrolytes based all-solid-state supercapacitors. Results demonstrate that the conductivity of PEO electrolyte could be improved to 0.1 S/cm with a mediator concentration of 50wt%. A high conductivity in the PEO electrolyte with mediator is an indication of a high electron exchange rate between the mediator and mediator. The high electron exchange rates at mediator carbon interface and between mediator and mediator are essential in order to obtain a high response rate and high power. This automatically solves the accessibility problem. With the addition of NaI/I2 mediator, the specific capacitance increased more than 30 folds, specific power increased almost 20 folds, and specific energy increased around 10 folds. Further addition of filler to the electrodes along with the mediator could double the specific capacitor and specific power of the all-solid-state supercapacitor. The stability of the corresponded supercapacitor is good within 2000 cycles.

APA, Harvard, Vancouver, ISO, and other styles

8

Kannan, R. "Functionalized carbon nanotube based polymer composites as electrolytes in proton exchange membrane fuel cells." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2010. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3752.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Kumar, Ravi. "An investigation of the composite polymer electrolytes and electrocatalysts for the proton exchange membrane fuel cell." Thesis, University of Newcastle upon Tyne, 2014. http://hdl.handle.net/10443/2417.

Full text

Abstract:

Durability is one of the major issues for the successful commercialisation of polymer electrolyte membrane fuel cells (PEMFCs) and it mainly depends on the stability of the individual cell components. In order to minimise the durability issues, the development of new materials or modification to replace the existing fuel cell components is required. The typically used proton exchange membrane (PEM) is the perfluorosulfonated polymer such as Nafion® and electrocatalysts for PEMFC is high surface area carbon supported platinum electrocatalyst (Pt/C). A higher temperature of operation (>80 oC) of PEMFC would boost their performance by enhancing the electrochemical kinetics and also improve the carbon monoxide tolerance of platinum catalysts. A Nafion® type membrane is not suitable for higher temperature operation as its proton conductivity mainly depends on the hydration level. An approach to improve the proton conductivity of Nafion® based membranes is the incorporation of hydrophilic inorganic oxide materials into the Nafion® polymer matrix. A composite membrane based on graphite oxide (GO) has been developed and demonstrated as an alternative PEM for high temperature operation up to 120 oC. GO is an insulator and hydrophilic in nature. GO exhibits proton conductivity due to the presence of acidic functional groups like, carboxylic acid, hydroxyl groups and epoxy groups. Further functionalisation of GO with sulfonic acid (called SGO) improves the proton transport properties of GO which in turn improves the composite membrane proton conductivity. Free standing GO and SGO papers were fabricated and evaluated to understand their proton transport mechanism. The in-plane and through-plane proton conductivities of GO paper were 0.008 and 0.004 S.cm-1 at 30 oC and 25% RH respectively. The in-plane and through-plane proton conductivities of SGO paper were 0.04 and 0.012 S.cm-1 at 30 oC and 25% RH respectively. The fuel cell performance of a membrane electrode assembly made with SGO paper gave a maximum power density of 113 mW cm-2. GO/Nafion composite membranes were fabricated with different GO content. The composite membranes with an optimum of 4 wt% GO showed better mechanical strength (tensile strength of 8.17 MPa) and water uptake (37.2%) compared to recast Nafion. A GO (4 wt%) /Nafion composite membrane gave a high ion exchange capacity (IEC) value of 1.38 meq g-1. The proton conductivity of GO (4 wt%) /Nafion was 0.026 S.cm-1 at 120 oC. SGO/Nafion composite membrane showed improved proton ii conductivity (0.029 S.cm-1). The SGO/Nafion composite membrane gave peak power density of 240 mW cm-2, whereas GO/Nafion composite membrane gave a power density of 200 mW cm-2 at 120 oC and 25% RH. The stability and durability of GO and SGO/Nafion composite membranes was investigated under fuel cell operating conditions and compared with recast Nafion. A non fluorinated proton exchange membrane based sulfonated poly ether-ether ketone (SPEEK) was used to develop a composite membrane with SGO. SGO (4 wt%) /SPEEK composite membrane showed high IEC of 2.3 meq g-1 and proton conductivity of 0.055 S.cm-1 at 80 oC and 30% RH. SGO (4 wt%) /SPEEK composite membrane gave a power density of 378 mW cm-2 at 80 oC and 30% RH, which was higher than that of recast SPEEK (254 mW cm-2). Transition metal nitride based electrocatalyst support such as titanium nitride (TiN), has been used to replace carbon to support Pt and Pt-Co alloy for PEMFC cathode. Nafion® stabilised Pt nanoparticles supported on TiN (Pt/TiN) were prepared and evaluated as cathode electrocatalyst for PEMFC. Pt/TiN showed better electrocatalytic activity, stability and durability under fuel cell operating conditions compared to commercial Pt/C. Pt/TiN retained 66% of electrochemical active surface area (ECSA) after 1000 potential cycles (cycled between the potential range of +0.6 to +1.20 V vs. RHE) under fuel cell operating conditions. The ECSA of the Pt/C catalyst fell by 75%. Pt/TiN was also evaluated for its suitability in phosphoric acid based PEMFCs. Pt/TiN showed better durability than Pt/C under fuel cell operating conditions. Pt/TiN showed a two-fold increase in mass and specific activities than Pt/C as calculated from oxygen reduction reaction data at 0.9 V. An improved durability of Pt/TiN resulted from a Nafion® layer surrounding the Pt protecting from phosphate ion adsorption. Alloying of Pt with 3d transition metals changes the electronic structure of Pt (Pt becomes e- deficient) and enhances the electrocatalytic activity of PtM alloy compared to Pt. 3d transition metals such as Fe, Co and Ni are reported to be more active than other metals. Pt-Co alloy supported on TiN was prepared and evaluated. Pt-Co/TiN showed about +21 and +32 mV positive shifts in half-wave potential compare to Pt/TiN and conventional Pt/C respectively. After 5000 potential cycles, the ECSA of Pt-Co/TiN had decayed by about 55%, whereas Pt/TiN and Pt/C showed a greater loss in ECSA of 70%.

APA, Harvard, Vancouver, ISO, and other styles

10

Crisanti, Samuel Nathan Crisanti. "Effect of Alumina and LAGP Fillers on the Ionic Conductivity of Printed Composite Poly(Ethylene Oxide) Electrolytes for Lithium-Ion Batteries." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1522756200308156.

Full text

APA, Harvard, Vancouver, ISO, and other styles

11

Jalani, Nikhil H. "Development of nanocomposite polymer electrolyte membranes for higher temperature PEM fuel cells." Link to electronic dissertation, 2006. https://www.wpi.edu/ETD-db/ETD-catalog/view%5Fetd?URN=etd-032706-165027.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Chamaani, Amir. "Hybrid Polymer Electrolyte for Lithium-Oxygen Battery Application." FIU Digital Commons, 2017. https://digitalcommons.fiu.edu/etd/3562.

Full text

Abstract:

The transition from fossil fuels to renewable resources has created more demand for energy storage devices. Lithium-oxygen (Li-O2) batteries have attracted much attention due to their high theoretical energy densities. They, however, are still in their infancy and several fundamental challenges remain to be addressed. Advanced analytical techniques have revealed that all components of a Li-O2 battery undergo undesirable degradation during discharge/charge cycling, contributing to reduced cyclability. Despite many attempts to minimize the anode and cathode degradation, the electrolyte remains as the leading cause for rapid capacity fading and poor cyclability in Li-O2 batteries. In this dissertation, composite gel polymer electrolytes (cGPEs) consisting of a UV-curable polymer, tetragylme based electrolyte, and glass microfibers with a diameter of ~1 µm and an aspect ratio of >100 have been developed for their use in Li-O2 battery application. The Li-O2 batteries containing cGPEs showed superior charge/discharge cycling for 500 mAh.g-1 cycle capacity with as high as 400% increase in cycles for cGPE over gel polymer electrolytes (GPEs). Results using in-situ electrochemical impedance spectroscopy (EIS), Raman spectroscopy, and scanning electron microscopy revealed that the source of the improvement was the reduction of the rate of lithium carbonates formation on the surface of the cathode. This decrease in formation rate afforded by cGPE-containing batteries was possible due to the decrease of the rate of electrolyte decomposition. The increase in solvated to the paired Li+ ratio at the cathode, afforded by increased lithium transference number, helped lessen the probability of superoxide radicals reacting with the tetraglyme solvent. This stabilization during cycling helped prolong the cycling life of the batteries. The effect of ion complexes on the stability of liquid glyme based electrolytes with various lithium salt concentrations has also been investigated for Li-O2 batteries. Charge/discharge cycling with a cycle capacity of 500 mAh·g-1 showed an improvement as high as 300% for electrolytes containing higher lithium salt concentrations. Analysis of the Raman spectroscopy data of the electrolytes suggested that the increase in lithium salt concentration afforded the formation of cation-solvent complexes, which in turn, mitigated the tetragylme degradation.

APA, Harvard, Vancouver, ISO, and other styles

13

Junior, Antonio Carlos Bloise. "Estudo em nanocompósitos e eletrólitos poliméricos por ressonância magnética." Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-14112007-091237/.

Full text

Abstract:

Foram realizadas pesquisas em uma série de condutores iônicos que apresentam aplicações na área dos dispositivos eletroquímicos de estado sólido, utilizando-se basicamente a técnica de Ressonância Magnética Nuclear (RMN). A primeira parte deste trabalho é dedicada aos compostos de intercalação baseados na matriz de dissulfeto de molibdênio (MoS2) onde as espécies intercalantes (íons de lítio e moléculas de aminas) são inseridas num espaço de dimensionalidade reduzida gerado pela matriz. Já a segunda parte envolve os condutores iônicos poliméricos do tipo compósitos, nos quais foram utilizadas nanopartículas de carbono (Carbon Black) e titânio (TiO2) no eletrólito formado pelo poli(óxido de etileno) (POE) e o perclorato de lítio (LiClO4). Todos estes sistemas apresentam, em geral, uma considerável complexidade estrutural, o que significa que os movimentos moleculares e de difusão iônica se produzem num meio semicristalino (caso dos compósitos) ou num meio de dimensionalidade reduzida (caso dos intercalados). A espectroscopia de RMN dos núcleos de 7Li e 1H é uma técnica conveniente para o estudo destes materiais, pois é possível avaliar, através dos resultados obtidos das medidas dos tempos de relaxação e formas de linha, os efeitos provocados pela baixa dimensionalidade dos movimentos em estruturas laminares (caso dos intercalados), bem como identificar e aferir as interações e os mecanismos de relaxação resultantes dos diferentes graus de liberdade dos movimentos (iônicos e moleculares), fornecer parâmetros estruturais (distâncias interatômicas) que auxiliam na proposta de possíveis modelos estruturais e caracterizar completamente a escala temporal dos movimentos iônicos e moleculares.
Nuclear Magnetic Resonance (RMN) techniques were used to study a series of ionic conductor materials, which present applications in the area of the solid-state electrochemical devices. The first part of this work is dedicated to the study of intercalation compounds based on the molybdenum disulfide matrix (MoS2), where the intercalated species (lithium ion and amine molecule) are inserted in the low-dimensionality space generated by the matrix. The second part involves the study of a composite polymer electrolyte, employing fillers like Carbon Black and titanium dioxide (Tio2) nano particles in the electrolyte formed by the poly(ethy1ene oxide) and a lithium salt (LiClO4). In general, these systems present a considerable structural complexity, meaning that the molecular movements and ionic diffusion are produced in a semicrystalline environment (case of the composites) or in an environment of reduced dimensionality (case of intercalates). The 7Li and 1H NMR spectroscopy is a convenient technique for the study of these materials. Relaxation time and line shape measurements may provide a tool to investigate the effects provoked by the low-dimensionality of the movements in laminate structures (case of intercalate), to identify the interactions and relaxation mechanisms of the ionic and molecular motions, to supply structural parameters (interatomic distances) that would help the proposal of possible structural models, and finally, to characterize the time scale of the ionic and molecular movements completely.

APA, Harvard, Vancouver, ISO, and other styles

14

Flynn, Dara S. "Mechanical behavior analysis of a carbon-carbon composite for use in a polymer electrolyte fuel cell." Worcester, Mass.: Worcester Polytechnic Institute, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0302104-163107/.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Flynn, Dara S. "Mechanical Behavior Analysis of a Carbon-Carbon Composite for Use in a Polymer Electrolyte Fuel Cell." Digital WPI, 2004. https://digitalcommons.wpi.edu/etd-theses/172.

Full text

Abstract:

While there is a substantial amount of information regarding the electrochemical behavior of fuel cells and there components little to no information is available regarding the mechanical properties of fuel cell materials in stack setups. This set of experiments was set up to test mechanical properties of gas diffusion layer and bipolar plate materials in a one cell setup. Samples were clamped to specified pressures and deformation properties were observed and measured. Measurements were taken of impingements of the gas diffusion layers into the gas flow channels. A limit for compression of cell configurations was found to be approximately 300psi. Upon reaching the compression limit bipolar plates collapse and materials between plates show signs of breakage. Under compression diffusion media showed impingement into the gas flow channels as well as substantial compression of the three layer stack.

APA, Harvard, Vancouver, ISO, and other styles

16

Raut, Prasad S. "Towards Development Of Polymeric Compounds For Energy Storage Devices And For Low Energy Loss Tires." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1493947416353888.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Wang, Yuhua. "Conductive Thermoplastic Composite Blends for Flow Field Plates for Use in Polymer Electrolyte Membrane Fuel Cells (PEMFC)." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/2893.

Full text

Abstract:

This project is aimed at developing and demonstrating highly conductive, lightweight, and low-cost thermoplastic blends to be used as flow field bipolar plates for polymer electrolyte membrane (PEM) fuel cells.

The research is focused on designing, prototyping, and testing carbon-filled thermoplastic composites with high electrical conductivity, as well as suitable mechanical and process properties.

The impact of different types of fillers on the composite blend properties was evaluated, as well as the synergetic effect of mixtures of fill types within a thermoplastic polymer matrix. A number of blends were produced by varying the filler percentages. Composites with loadings up to 65% by weight of graphite, conductive carbon black, and carbon fibers were investigated. Research results show that three-filler composites exhibit better performance than single or two-filler composites.

Injection and compression molding of the conductive carbon filled polypropylene blend was used to fabricate the bipolar plates. A Thermal Gravimetric Analysis (TGA) was used to determine the actual filler loading of composites. A Scanning Electron Microscope (SEM) technique was use as an effective way to view the microstructure of composite for properties such as edge effects, porosity, and fiber alignment. Density and mechanical properties of conductive thermoplastic composites were also investigated. During this study, it was found that 1:1:1 SG-4012/VCB/CF composites showed better performance than other blends. The highest conductivity, 1900 S/m in in-plane and 156 S/m in through plane conductivity, is obtained with the 65% composite. Mechanical properties such as tensile modulus, tensile strength, flexural modulus and flexural strength for 65% 1:1:1 SG-4012/VCB/CF composite were found to be 584. 3 MPa, 9. 50 MPa, 6. 82 GPa and 47. 7 MPa, respectively, and these mechanical properties were found to meet minimum mechanical property requirements for bipolar plates. The highest density for bipolar plate developed in this project is 1. 33 g/cm³ and is far less than that of graphite bipolar plate.

A novel technique for metal insert bipolar plate construction was also developed for this project. With a copper sheet insert, the in-plane conductivity of bipolar plate was found to be significantly improved. The performance of composite and copper sheet insert bipolar plates was investigated in a single cell fuel cell. All the composites bipolar plates showed lower performance than the graphite bipolar plate on current-voltage (I-V) polarization curve testing. Although the copper sheet insert bipolar plates were very conductive in in-plane conductivity, there was little improvement in single cell performance compared with the composite bipolar plates.

This work also investigated the factors affecting bipolar plate resistance measurement, which is important for fuel cell bipolar plate design and material selection. Bipolar plate surface area (S) and surface area over thickness (S/T) ratio was showed to have significant effects on the significance of interfacial contact resistances. At high S/T ratio, the contact resistance was found to be most significant for thermoplastic blends. Other factors such as thickness, material properties, surface geometry and clamping pressure were also found to affect the bipolar plate resistance measurements significantly.

APA, Harvard, Vancouver, ISO, and other styles

18

Safa, Meer N. "Poly (Ionic Liquid) Based Electrolyte for Lithium Battery Application." FIU Digital Commons, 2018. https://digitalcommons.fiu.edu/etd/3746.

Full text

Abstract:

The demand for electric vehicles is increasing rapidly as the world is preparing for a fossil fuel-free future in the automotive field. Lithium battery technologies are the most effective options to replace fossil fuels due to their higher energy densities. However, safety remains a major concern in using lithium as the anode, and the development of non-volatile, non-flammable, high conductivity electrolytes is of great importance. In this dissertation, a gel polymer electrolyte (GPE) consisting of ionic liquid, lithium salt, and a polymer has been developed for their application in lithium batteries. A comparative study between GPE and ionic liquid electrolyte (ILE) containing batteries shows a superior cyclic performance up to 5C rate and a better rate capability for 40 cycles for cells with GPE at room temperature. The improvement is attributed to GPE’s improved stability voltage window against lithium as well as higher lithium transference number. The performance of the GPE in lithium-sulfur battery system using sulfur-CNT cathodes shows superior rate capability for the GPE versus ILE for up to 1C rates. Also, GPE containing batteries had higher capacity retention versus ILE when cycled for 500 cycles vii at C/2 rate. Electrochemical impedance spectroscopy (EIS) studies reveal interfacial impedances for ILE containing batteries grew faster than in GPE batteries. The accumulation of insoluble Li2S2/Li2S on the electrodes decreases the active material thus contributes to capacity fading. SEM imaging of cycled cathodes reveals cracks on the surface of cathode recovered from ILE batteries. On the other hand, the improved electrochemical performance of GPE batteries indicates better and more stable passivation layer formation on the surface of the electrodes. Composite GPE (cGPE) containing micro glass fillers were studied to determine their electrochemical performance in Li batteries. GPE with 1 wt% micro fillers show superior rate capability for up to 7C and also cyclic stability for 300 cycles at C/2 rate. In situ, EIS also reveals a rapid increase in charge transfer resistance in GPE batteries, responsible for lowering the capacity during cycling. Improved ion transport properties due to ion-complex formations in the presence of the micro fillers, is evidenced by improved lithium transference number, ionic conduction, and ion-pair dissociation detected using Raman spectroscopy.

APA, Harvard, Vancouver, ISO, and other styles

19

Langer, Frederieke [Verfasser], Robert [Akademischer Betreuer] Kun, Robert [Gutachter] Kun, and Matthias [Gutachter] Busse. "Synthesis and electrochemical investigation of garnet-polymer composite electrolytes for solid state batteries / Frederieke Langer ; Gutachter: Robert Kun, Matthias Busse ; Betreuer: Robert Kun." Bremen : Staats- und Universitätsbibliothek Bremen, 2017. http://d-nb.info/1154925854/34.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Anderson, Jordan. "Electrochemical Studies of Nanoscale Composite Materials as Electrodes in Direct Alcohol Fuel Cells." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5104.

Full text

Abstract:

Polymer electrolyte membrane fuel cells (PEMFCs) have recently acquired much attention as alternatives to combustion engines for power conversion. The primary interest in fuel cell technology is the possibility of 60% power conversion efficiency as compared to the 30% maximum theoretical efficiency limited to combustion engines and turbines. Although originally conceived to work with hydrogen as a fuel, difficulties relating to hydrogen storage have prompted much effort in using other fuels. Small organic molecules such as alcohols and formic acid have shown promise as alternatives to hydrogen in PEMFCs due to their higher stability at ambient conditions. The drawbacks for using these fuels in PEMFCs are related to their incomplete oxidation mechanisms, which lead to the production of carbon monoxide (CO). When carbon monoxide is released in fuel cells it binds strongly to the platinum anode thus limiting the adsorption and subsequent oxidation of more fuel. In order to promote the complete oxidation of fuels and limit poisoning due to CO, various metal and metal oxide catalysts have been used. Motivated by promising results seen in fuel cell catalysis, this research project is focused on the design and fabrication of novel platinum-composite catalysts for the electrooxidation of methanol, ethanol and formic acid. Various Pt-composites were fabricated including Pt-Au, Pt-Ru, Pt-Pd and Pt-CeO2 catalysts. Electrochemical techniques were used to determine the catalytic ability of each novel composite toward the electrooxidation of methanol, ethanol and formic acid. This study indicates that the novel composites all have higher catalytic ability than bare Pt electrodes. The increase in catalytic ability is mostly attributed to the increase in CO poison tolerance and promotion of the complete oxidation mechanism of methanol, ethanol and formic acid. Formulations including bi- and tri-composite catalysts were fabricated and in many cases show the highest catalytic oxidation, suggesting tertiary catalytic effects. The combination of bi-metallic composites with ceria also showed highly increased catalytic oxidation ability. The following dissertation expounds on the relationship between composite material and the electrooxidation of methanol, ethanol and formic acid. The full electrochemical and material characterization of each composite electrode is provided.
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry

APA, Harvard, Vancouver, ISO, and other styles

21

Tambelli, Cassio de Campos. "Ressonância magnética nuclear (1H e 7Li) dos compósitos formados por POE: LiCl04 e aluminas." Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-13122013-103359/.

Full text

Abstract:

Os eletrólitos poliméricos formados com base de poli(óxido de etileno) POE e um sal alcalino, vem sendo motivo de grande interesse científico devido ao seu potencial de aplicações em dispositivos eletroquímicos. A condutividade iônica nestes sistemas resulta do fato que a macromolecula atua como solvente para o sal, deixando-o parcialmente dissociado. Neste trabalho, foi utilizada a técnica de Ressonância Magnética Nuclear (RMN) para caracterizar as dinâmicas do spin nuclear do 1H e do 7Li findando investigar os mecanismos de transporte iônico dos compósitos de eletrólitos poliméricos baseados no POE8:LiC104 e partículas de &3945; e γ-alumina. Foram feitas medidas da forma da linha de ressonância e da relaxação spin-rede nas frequências de 36 MHz (1H) e 155,4 MHz (7Li) em função da temperatura no intervalo de 170-350 K. Caracterizações fisicas das partículas foram realizadas através das medidas de tamanho de partícula, porosidade e área superficial. Nos compósitos foram feitas medidas de análise témica por DSC e de condutividade elétrica ac por impedância complexa. Os resultados de RMN do 1H mostraram uma maior mobilidade das cadeias poliméricas para o compósito preparado com a dispersão de 20% de α-Al203 em massa, em relação ao eletrólito polimérico sem partículas. Nenhuma alteração foi observada nas medidas de largura de linha e relaxação spin-rede para os compósitos preparado com 5% de α ou γ-alumina. A mobilidade dos íons Li+ apresenta um aumento quando é disperso 20% de α-alumina no complexo polimérico. Em contrapartida, a adição de 20% de γ-alumina não altera os valores da taxa de relaxação (1/T1), porém um estreitamento da linha de ressonância em baixas temperaturas, em relação ao complexo polimérico, é observado. Os resultados serão discutido com base nas interações de ácido-base de Lewis
Polymeric electrolytes based on poly(ethylene oxide) (PEO) and alkaline salts has been subject of scientific and technological interest due to its potential applications as solid electrolytes in electrochemical devices. The ionic conductivity of such electrolytes results from the fact that the macromolecule acts as a solvent for the salt, leaving it partially dissociated. Nuclear magnetic resonance (NMR) techniques were used to characterize the 1H and 7Li nuclear spin dynamics in order to investigate the transport properties associated to the ionic conduction mechanisms of polymeric composites based on PEO8:LiC1O4 and particles of α and γ-alumina. NMR lineshapes and spin-lattice relaxation were measured at 36 MHz (1 H) and 155.4 MHz (7Li) as a function of temperature in the range of 170-350 K. Physical characterization of the particles was realized by measuring the particle size distribution, porosity and superficial area. Differential scanning calorimetry (DSC) and ac electric conductivity of the composites were measured. 1H NMR results show that the polymeric chains of the composite prepared with 20 wt.% of α-alumina has a greater mobility if compared with the unfilled polymeric material. No changes in linewidth and relaxation rates were observed following the addition of 5 wt.% of α or γ-alumina. The 7Li mobility increases when 20 wt.% of &3945;-alumina is added to the starting polymeric material. On the other hand, addition of 20 wt.% of γ-alumina do not alter the relaxation rates but produces a small change in linewidth. Results are discussed in accordance with the Lewis acid-base interaction

APA, Harvard, Vancouver, ISO, and other styles

22

Subbaraman, Ramachandran. "A multi-scale hierarchical approach for understanding the structure of the polymer electrolyte membrane fuel cell (PEMFC) electrodes - from nanoparticales to composites." online version, 2008. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=case1205852564.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Subbaraman, Ramachandran. "A MULTI-SCALE HIERARCHICAL APPROACH FOR UNDERSTANDING THE STRUCTURE OF THE POLYMER ELECTROLYTE MEMBRANE FUEL CELL (PEMFC) ELECTRODES - FROM NANOPARTICLES TO COMPOSITES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=case1205852564.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Li, Shuai. "Preparation and characterization of perovskite structure lanthanum gallate and lanthanum aluminate based oxides." Doctoral thesis, Stockholm : Skolan för industriell teknik och management, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10588.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

Gao, Hongrong. "Stabilisation des Membranes Perfluorosulfoniques par Réticulation et Développement de Membranes Composites Inorganique-organique. Application aux Piles à Combustible à Moyenne Température." Thesis, Montpellier 2, 2010. http://www.theses.fr/2010MON20236.

Full text

Abstract:

Ce travail décrit le développement de membranes réticulées et de membranes composites inorganique-organique basées sur des polymères perfluorosulfoniques (PFSA) à chaîne longue (LSC) et courte (SSC) et à faible masse équivalente, pour application dans une pile à combustible fonctionnant à moyenne température et à faible humidité relative. Des membranes (LSC-PFSA) réticulées par des groupements sulfonimide ont été préparées à partir de membranes fonctionnalisées par des groupements fluorure de sulfonyle. Les membranes réticulées de type SSC-PFSA ont été préparées à partir d'un polymère à chaînes 2-bromo-1,1,2,2-tetrafluoroéthoxy pendantes et réticulables, par traitement thermique pour former des ponts perfluoro. Les membranes préparées ont été caractérisées par spectroscopies IR, Raman, RMN et XPS, par MEB-EDX et ATG. Les membranes de LSC-PFSA et SSC-PFSA réticulées présentent une stabilité dimensionnelle accrue et une meilleure performance en pile à combustible hydrogène-oxygène jusqu'à 110°C que celles des membranes de PFSA non modifiées. Une procédure d'échange ionique/précipitation a été utilisée pour la préparation de systèmes composites à partir de membranes de LSC-PFSA et SSC-PFSA. Plusieurs techniques ont été utilisées pour caractériser les matériaux préparés. Les membranes de type SSC-PFSA-ZrP présentent une morphologie distincte, et différente de celle des membranes LSC-PFSA-ZrP. En pile à combustible, ces membranes composites autorisent une température de fonctionnement plus élevée et une humidité relative plus faible, que les membranes non modifiées
The objective of this research was to develop cross-linked and composite inorganic-organic membranes based on long and short side chain (LSC, SSC) perfluorosulfonic acid (PFSA) polymers with low equivalent weight/high ion exchange capacity for operation at medium temperature and low relative humidity in proton exchange membrane fuel cells. Covalently cross-linked LSC-PFSA membranes were prepared from sulfonyl fluoride form membranes by reaction with an ammonium base followed by thermal processing to give cross-linking through sulfonimide groups. Covalently cross-linked SSC-PFSA membranes were prepared by formation of perfluoro-cross-links under thermal treatment of solution cast polymers containing cross-linkable 2-bromo-1,1,2,2-tetrafluoroethoxy side chains. Evidence for cross-linking was provided by IR, Raman, NMR and XPS spectroscopies, SEM-EDX, tensile testing and TGA. Cross-linked LSC and SSC-PFSA membranes have increased dimensional stability and improved performance in a single hydrogen-oxygen cell fuel up to 110°C compared with the corresponding non-cross-linked membranes. Composite PFSA-zirconium phosphate membranes, based on LSC and SSC PFSA (or cross-linked PFSA) membranes were prepared using an ion exchange/precipitation procedure. The physical properties of LSC-PFSA-ZrP and SSC-PFSA-ZrP have been compared and the morphology of the composite membranes shown to differ in SSC and LSC membranes. Composite membranes enabled fuel cell operation at higher temperature/lower RH than non-composite PFSA. Preliminary results indicated that association of cross-linking and composite membrane formation is a clear future perspective of this work

APA, Harvard, Vancouver, ISO, and other styles

26

Michalak, Franck. "Étude d'électrodes composites polymères/oxydes colloidaux : application aux systèmes électrochromes sur supports souples." Grenoble INPG, 1995. http://www.theses.fr/1995INPG0091.

Full text

Abstract:

Au cours de ce travail, nous avons etudie des electrodes composites polymeres/oxydes colloidaux en vue d'application aux systemes electrochromes sur supports souples. Ces composites sont constitues d'un materiau electrochrome colloidal (wo#3, iro#2) et d'un polymere ionique (nafion) ou neutre (polyacrylamide, polymethylmetacrylate, polyvinylbutyral). Nous avons etudie la synthese de ces oxydes dans le but d'obtenir un materiau colloidal stable de taille inferieure a 100 nm. Nous avons obtenu des sols de wo#3 stables contenant des particules ayant un diametre moyen de 10 nm. Les composites wo#3 - polymere contiennent jusqu'a 90% en poids de wo#3 et restent transparents. Ils constituent l'electrode electrochrome de nos systemes. Les particules d'iro#2 obtenues sont trop grosses pour les applications visees (100nm). Nous avons alors utilise la polyaniline comme materiau de contre electrode. La polyaniline a ete deposee sous forme d'un film mince par polymerisation galvanostatique sur un substrat en polyethylene terephtalate recouvert d'une fine couche d'or. Le systeme electrochrome complet comprenant l'electrode composite wo#3/polymethylmetacrylate, la contre electrode en polyaniline et l'electrolyte polymere (bpei-1. 5 h#3po#4) a un contraste de 35% a 700 nm

APA, Harvard, Vancouver, ISO, and other styles

27

DESTRO, MATTEO. "Towards Realization of an Innovative Li-Ion Battery: Materials Optimization and System Up-Scalable Solutions." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2506270.

Full text

Abstract:

The optimisation of existing chemistries by the introduction of environmentally friendly materials and the simplification of the device production process are intriguing challenges to promote the future widespread diffusion of LIBs. Moreover, the recent development of the next-generation electronic devices promoted a new research field for the modification of the current systems into light, flexible and/or micro-sized device. The enhancement of mechanical properties through the introduction of flexible electrodes will enable LIBs to be embedded into various functional systems in a wide range of innovative products such as smart cards, displays and implantable medical devices. Moreover, the optimisation of the electrolyte by moving towards an all-solid-state configuration will offer adaptability to various designs and stressful mechanical handling, as well as enhance cell safety and reliability. During the three years of the Ph.D. course, the attention was focused on the optimisation of innovative materials for Li-ion batteries as well as the development of easily up-scalable procedures for the production of electrodes and polymer electrolytes. The basic idea was to start from eco-friendly materials to develop simple, low-cost and easily adaptable processes in order to propose innovative solutions for LIBs with a wide range of possible applications. Moreover, during my experimental activities, I considered the performances and the cycling stability of Li-ion batteries, by studying the mechanisms related to the capacity fade of lab-scale batteries and also by analysing commercial Li-ion batteries for automotive application. The results of the research work are presented in this thesis (Chapters 4-7) following an introductory section that provides the general information needed to follow the discussions (Chapters 1-3). The experimental research work presented in Chapter IV was carried out in collaboration with the Laboratory of Pulp and Paper Science and Graphic Arts (LGP2) in Grenoble (France). A well-known natural material such as cellulose was exploited for the production of innovative low-cost and easily recyclable electrodes for Li-ion batteries. A simple aqueous filtration process, based on a well-known industrialised paper-making technology, was developed and the electrodes (graphite-based anodes and LiFePO4-based cathodes) produced and partly characterized in Grenoble by Dr. Lara Jabbour were electrochemically studied in our Labs in Politecnico di Torino. In particular, cellulose fibres (FBs) were used as natural binder for the production of paper-like electrodes obtained without addition of any synthetic binder and/or solvent and showing electrochemical performance comparable to those produced with the same active materials by a standard process. In Chapter V, results are reported regarding a newly developed procedure where a methacrylic-based polymer electrolyte is directly formed in situ at the interface with the electrodes. Exploiting the versatile nature of UV-induced free-radical photo-polymerisation, novel ready-to-use multiphase electrode/electrolyte composites (MEEC) were developed in which the electrode is conformally coated by the polymer electrolyte. This “one-shot” process was successfully applied to enhance the cycling performances of two nanostructured materials conceived for microbattery application, such as Cu2O (in collaboration with CSHR@Polito IIT research institute in Torino) and V2O5 (in collaboration with Prof. Mustarelli’s group in University of Pavia), prepared in the form of thin films and proposed respectively as anode and cathode. The proposed one-shot process, thanks to the intimate interfacial contact between electrodes surface and electrolyte obtained by in situ process, induced a huge effect of stabilization thus improving the cycling stability of both the nanostructures. All along Chapter VI, the problems related to the assembling of complete Li-ion cells, starting from two well performing electrodes, are progressively discussed and valuable solutions are proposed. A strong capacity fade was initially found, thus the possible causes were studied also considering the failure mechanisms proposed in the literature. Several measures were adopted to improve the cycling stability, considering the effect of all the different cell components as well as the effects of both charging protocol and cell apparatus. Moreover, due the knowhow progressively achieved on the intimate characteristics of complete Li-ion cells and their assembly, even thanks to a three months stage at ENEA Casaccia Research Centre of Rome, the installation of a 10 m2 dry room was personally followed at our Electrochemistry Research Group Labs in Politecnico di Torino and the results obtained are presented in the same Chapter VI. These results include the realisation of an all-paper Li-ion battery with the cellulose-based electrodes and paper hand-sheets as separator. Finally, the cycling stability and the failure prediction issue was studied for a 53 Ah commercial battery. The results obtained, by means of different standard reference tests, are reported in Chapter VII. The commercial battery was also disassembled in the controlled atmosphere of an Ar-filled dry box in order to study the system structure and characterise the various components. A testing protocol was personally developed and the results obtained allowed to evaluate the commercial battery based on the performances requested for HEV and EV application. In particular, an easy measure of the internal resistance was developed, by opportunely modulating the measured parameters, and the obtained results were found to be very useful in directly predicting the cell failure which is fundamental in practical application.

APA, Harvard, Vancouver, ISO, and other styles

28

Baissac, Lucas. "Compréhension des mécanismes d’élaboration de revêtements de zinc électrolytiques composites (nano et microparticules) pour la protection vis-à-vis de la corrosion de l’acier et les propriétés d’adhésion." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD005.

Full text

Abstract:

Les revêtements électrodéposés d’alliages zinc-nickel, sont très utilisés pour protéger l’acier de la corrosion et dans la production de pièces d’assemblage avec des caoutchoucs adhérisés. Cependant, ils présentent l’inconvénient de coûts élevés et sont par visés l’évolution des normes européennes qui cherchent à restreindre l’usage des sels de nickel. Ce travail propose d’incorporer des particules de silices et/ou de PMMA à une matrice de zinc, de dimensions respectivement nano et submicrométriques. Si la disponibilité commerciale des particules de silice n’est pas un problème, ce n’est pas le cas des particules polymères. Une méthodologie originale de synthèse des particules a donc été développée. Elle est basée sur l’émulsification du monomère dans l’eau par irradiation ultrasonore en exposant le mélange à plusieurs sonication de fréquences croissantes, permettant de maitriser la taille des particules dans une gamme de 100 à 300 nm, et le signe de leur charge de surface. L’influence de ce dernier paramètre a pu être vérifié lors d’une étude préliminaire de leur incorporation dans une matrice organique. Les particules sont ensuite dispersées dans des électrolytes qui sont caractérisés par voie électrochimique. Ceci a permis de mettre en évidence une interaction entre les particules de PMMA et le substrat d’acier lors de sa polarisation cathodique. Ensuite, les revêtements composites sont réalisés sous agitation mécanique ou sous irradiation ultrasonore. La convection au niveau de la cathode est au préalable calibrée de manière à pouvoir comparer la contribution du type d’agitation, grâce au concept de vitesse équivalente. L’impact de l’incorporation des particules sur la morphologie et la microstructure des revêtements est alors évalué suivant les conditions hydrodynamiques et le type de particule incorporé. L’incorporation de particules entraine un affinement de la morphologie des revêtements par modification de l’orientation de leur structure cristalline. Les ultrasons, comme le signe de la charge de surface des particules de PMMA, permettent de moduler la morphologie et la structure des revêtements. La transposition du procédé de revêtement est ensuite opérée dans une cellule pilote d’une capacité de 50L. Une exposition en brouillard salin permet de constater que les meilleures performances anticorrosion sont obtenues pour les revêtements composites Zn/PMMA. Les meilleures propriétés d’adhérence sont obtenues pour le revêtement composite Zn/SiO2
Electrodeposited zinc nickel alloy coatings are widely used for steel protection against corrosion and for assembly by rubber to metal bonding. However, ZnNi technologies cost and the possible restriction for its use due to European legislation strengthening are serious drawbacks. This work proposes particles codeposition of silica and polymethyl methacrylate together with zinc, of respectively nanometric and submicronic size. If silica particles are available on the market, polymer particles are not in a reasonable cost. Thus, a synthesis protocol had been developed. It consists in emulsifying monomer into water by sonication of the mixture with successive sonications of increasing frequencies. After polymerization, monodisperse PMMA spherical particles of 100 to 300 nm in diameter are obtained. Moreover, the proposed synthesis allows the choice of particles charge signs. This parameter is a key one in particles codeposition in electrodeposited matrix. After a preliminary study with conductive polymers, particles are dispersed into the electrolytes and then characterized by electrochemistry. It appears that PMMA particles interact with the steel substrate if polarized as a cathode. Composite coatings are elaborated, under mechanical steering or ultrasound irradiation, with convection intensity near the cathode previously homogenized to compare the contribution of the different kinds of convection, thanks to the concept of equivalent velocity. The influence off the particles’ incorporation on the morphology and the microstructure off the coatings are evaluated, related to the hydrodynamic conditions and the type of particle incorporated. PMMA particles incorporation leads to the refinement of the coating, the opposite being observed for silica particles. Ultrasound as well as the surface charge sign of PMMA particles influenced significantly morphology and microstructure off the coatings. The scale up off the plating process is led in a pilot cell of 50L. An exposure to Neutral Salt Spray test showed that Zn/PMMA composite coatings exhibit the best corrosion properties, while the better adhesion results are obtained with Zn/SiO2 composite

APA, Harvard, Vancouver, ISO, and other styles

29

Zhan, Chi. "Towards Development of Porous Polymeric Materials for Oil Absorption and Energy Storage Devices." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1525712548230523.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Ressam, Ibitissam. "Élaboration et caractérisation de nouvelles membranes composites à conduction protonique pour les piles à combustible." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066732.

Full text

Abstract:

Le Nafion a été considéré comme électrolyte modèle pour les piles à combustible (PAC), grâce à sa stabilité thermique et chimique ainsi que sa bonne conductivité protonique. Cependant, la conductivité protonique du Nafion se détériore à des taux d’humidité < 50% et à des températures >80°C. Pour cette raison de nouvelles membranes hybrides ont été élaborées afin d’en améliorer les performances. Plusieurs pistes ont été envisagées comme par exemple i) Membranes à base de chitosane, considéré comme le second polysaccharide le plus abondant après la cellulose. Ce polymère naturel permet d’assurer la stabilité physique et chimique de la membrane en présence d’eau, sans oublier son coût de revient qui reste moins cher en comparaison avec celui du Nafion et ii) Membranes à base de Nafion et d'argiles fibreuses (HNT), ces dernières confèrent à la membrane une conductivité protonique élevée en construisant des voies de transfert larges et continues. Cela permet aussi d'améliorer les propriétés thermiques et mécaniques des PEM. Notre étude est basée sur l'élaboration de membranes composites, nafion, chitosane et HNT. Des mesures de conductivité ont été entreprises et les valeurs obtenues comparées à celles du nafion. Des mesures d'ac-électrogravimétrie ont aussi été entreprises afin de mieux aborder les mécanismes de conduction
The perfluoro-sulfonated ionomer membranes are employed as separators in many industrialapplications such as fuel cells, chloro-alkali industry, electrodialysis and gaining inclininginterest in aqueous rechargeable or redox-flow batteries where the knowledge of their ionictransport and transfer properties is fundamental.Particularly, Nafion is adopted as a referencemembrane for polymer electrolyte membrane (PEM) fuel cells due to its thermal stability andgood proton conductivity. However, Nafion membranes have several disadvantages such as a decrease in the proton conductivity at low relative humidity (<50%) and high temperatures(>80°C), and excessive dimensional changes due to the swelling/deswelling, leading tomechanical instabilities.To circumvent these problems, novel proton conducting membraneshave been developed, either by completely replacing or by using organic and/or inorganiccomponents to Nafion.3 In this regard, a large spectrum of membranes have been elaboratedconsidering many attributes such as high proton conductivity, physical separation between theanode and the cathode and fuel barrier characteristics, good chemical and physical stability andlow elaboration cost of the membrane. Two types of additives were examined to improve the performances, particularly : Membranes based on Nafion with Chitosan biopolymer. This naturel polymer is consideredas the second most abundant polysaccharide after cellulose.6 Chitosan improves the physical andchemical stability of the membrane in the presence of water, and it is considered as a less costlyadditive to Nafion7.The improvement of the proton conductivity with pristine chitosan isessentially challenging. Previous studies demonstrated that vehicularandGrotthuss mechanismjointly govern the proton transfer in chitosan membranes.In the vehicular mechanism, the protons diffuse together with solvent molecules in the form of hydronium ions byforming acomplex such as H5O2+ and H9O4+. In the Grotthuss mechanism, however, the protons jump fromone solvent molecule or functional group to the next by the continuous formation and breakingof hydrogen bonds. Membranes based on Nafion with Halloysite nanotubes (HNT). These clays confer to themembrane high proton conductivity by constructing large and continuous conductionpathways.These inorganic additives also improve the thermal and mechanical properties of PEM. Composite membranes of Nafion/Chitosan- SO3H and Nafion/HNT-SO3H are prepared. Theresulting composite membranes were studied by various conventional structural characterizationtechniques. H+ conductivity measurements were performed and the values obtained are higherthan those of pristine Nafion at various relative humidity (RH%) levels and temperatures (30°C-80°C). Our results highlight the beneficial character of functionalized chitosan biopolymer andHalloysite nanotube clays as additives to improve PEM performances

APA, Harvard, Vancouver, ISO, and other styles

31

Géniès, Sylvie. "Étude de la passivation de l'électrode carbone-lithium." Grenoble INPG, 1998. http://www.theses.fr/1998INPG0008.

Full text

Abstract:

Le phenomene de la passivation de l'electrode carbone-lithium utilisee comme pole negatif dans la batterie lithium-ion est d'une importance cruciale dans les caracteristiques du fonctionnement de cette electrode. Il en fixe la capacite reversible (ou utile), la duree de vie et le taux d'autodecharge. Ce travail est une contribution a la comprehension des processus chimiques et electrochimiques survenant a la surface de l'electrode au cours de l'echange du lithium avec une solution electrolytique a base d'un ou plusieurs solvant(s) organique(s) et d'un sel de lithium et conduisant a la formation d'un film de passivation. Apres une presentation bibliographique qui situe l'etude dans son contexte national et international, le travail experimental s'adresse dans un premier temps au role des parametres qui influent sur le processus de passivation tels que la nature de l'anion du sel de lithium et celle du materiau carbone ainsi que la composition de l'electrolyte. La caracterisation de ce film obtenu par des methodes chimiques ou electrochimiques utilise une large gamme de techniques : drx, meb, met, microscopie a champ proche (afm), ir-tf, rmn, esca, atg et dsc. Les techniques electrochimiques sont aussi variees : chronoamperometrie, chronopotentiometrie, impedance complexe et voltamperometrie cyclique. Les resultats obtenus sont pour la plupart originaux. Ainsi, les analyses de la composition chimique du film par esca et par ir-tf sont non seulement completes et nouvelles mais mettent en evidence pour la premiere fois le caractere polymere du film. Ce resultat devrait avoir des repercutions importantes sur l'elaboration ex situ du film pour une etude plus approfondie. L'observation du film forme sur un graphite hautement oriente par afm a permis d'obtenir les images les plus precises et les plus claires jamais publiees. L'etude electrochimique est completee par une synthese chimique du film par une methode originale. L'utilisation de ce film comme electrolyte de type plastifie a ete demontree.

APA, Harvard, Vancouver, ISO, and other styles

32

Blackmore, Paul David. "Degradation of polymeric outdoor high voltage insulation : surface discharge phenomena and condition assessment techniques." Thesis, Queensland University of Technology, 1997.

Find full text

APA, Harvard, Vancouver, ISO, and other styles

33

Seck, Serigne. "Elaboration de matériaux hybrides organiques / inorganiques par extrusion réactive : Application en pile à combustible." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0027.

Full text

Abstract:

A l’heure actuelle, les piles à combustible à membrane échangeuse de protons (PEMFC) les plus avancées, qu’elles soient disponibles commercialement ou intégrées dans des démonstrateurs, sont réalisées avec des électrolytes polymères perfluorosulfonés de types Nafion®. En effet, ce type de polymère est celui qui présente à la fois les meilleures performances et la plus grande durée de vie sans pour autant qu’elles soient suffisantes, et ce, quelles que soient les applications (portable, stationnaire, transport). En effet ce polymère présente toutefois trois inconvénients majeurs : son prix, sa perméation au méthanol et sa perte de performance (et surtout de conductivité) dès 80-85 °C. Selon les projections avec les technologies actuelles (source DOE), le prix de vente du Nafion® serait de 80 $/m2 pour une production de 1 Mm2. Il existe un réel besoin de développer de nouveaux matériaux pour membranes échangeuses de protons présentant d’excellentes performances (propriétés mécaniques, imperméabilité maximale au méthanol et H2, conduction protonique..) sur une large gamme de températures, typiquement entre 25 et 150°C (selon l’application visée), mais présentant également un coût de fabrication réduit. Or aujourd’hui, ces différentes fonctions sont assurées par un seul polymère perfluorosulfoné ce qui est le problème principal. Ainsi, l’intérêt du projet est de combiner les avantages d’un matériau hybride obtenu par génération in situ de la phase inorganique (Sol-Gel) nanométrique avec l’utilisation d’un procédé en continu de mise en œuvre par extrusion (voie fondu), exempt de tout solvant et facilement transférable industriellement. La conduction protonique sera assurée par des fonctions sulfoniques générées grâce à l'oxydation des sites fonctionnels apportés par le précurseur fonctionnel
Fuel cells technologies are electrochemical energy conversion devices and have a real potential to revolutionize the way to produce energy, offering cleaner, more-efficient alternatives to combustion of gasoline and other fossil fuels. In that way, the Proton Exchange Membrane Fuel Cells (PEMFC) are probably the most studied. Those fuel cells are mainly based on perfluorosulfonic acid membranes, such as Nafion®. However, Nafion® membranes, present some limitations such as dehydration at high temperatures or at low relative humidity rate leading to a decrease of proton conductivity and thus poor PEMFC performance. Consequently, PEMFC require significant improvements prior to be largely used in the automobile field. Research efforts have been oriented on the development of new materials for the PEMFC membrane as it is the main limitative component for high temperature fuel cell. In the present contribution, we wish to report the validation of a new concept of hybrid materials for the realization of proton exchange membranes. The originality of this hybrid concept is based on the contribution of both phases’ specific properties. We investigated the preparation of hybrid materials based on an inert polymer matrix (low cost) providing the mechanical stability embedding inorganic phase providing the necessary properties of proton-conduction and water retention. Hybrid nanocomposite membranes were synthesized using evaporation and recasting technique from solution containing dispersion of inorganic particles in the adequate polymer. Scanning electron microscopy (SEM) images for membrane morphology and proton conductivity results using impedance measurements from hybrid membranes will be presented. The performance of the membrane-electrode assembly (MEA) using the hybrid membrane was also evaluated by a fuel cell test. Finally, we wish to present a promising way of research based on Sol-Gel approach to generate a proton-conducting inorganic phase into the polymer matrix

APA, Harvard, Vancouver, ISO, and other styles

34

Po-HanLi and 李柏翰. "Polymer-Eutectic Salt Composite Electrolytes." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/vt48f6.

Full text

APA, Harvard, Vancouver, ISO, and other styles

35

Dam, Tapabrata. "Study of Relaxation Dynamics and Ion Conduction Mechanism of Composite Polymer Electrolyte and Gel Polymer Electrolyte." Thesis, 2017. http://ethesis.nitrkl.ac.in/8736/1/2017_PhD_511PH103_TDam.pdf.

Full text

Abstract:

The increasing demand for miniaturized portable electrical energy sources has led towards intensive research on developing efficient electrochemical energy storage/conversion devices. Based on the capability of delivering continuous energy for a longer period of time or quick charge-discharge capabilities, these devices can be divided into energy and current sourcing devices. Among these devices, batteries show intermediate power density along with energy density. At present in most of the commercially available devices, liquid organic carbonate electrolytes having conductivity values close to 10􀀀3 Scm􀀀1 are being used. Although liquid electrolyte shows a high conductivity value, they possess a serious safety concern. Therefore, prior importance is given to developing a polymer electrolyte with comparable ionic conductivity at ambient temperature. Polymer electrolyte has the prospect to improve various key properties of lithium based batteries when used as the electrolyte. These properties include design flexibility, safety, cyclability, energy and power density etc. However, polymer electrolytes are having a serious drawback of low ionic conductivity limiting its potential application. Therefore primary interest is given in the preparation of polymer electrolytes with high ionic conductivity at room temperature. Achievement of the desired level of ambient temperature ionic conductivity (_ 10􀀀3 Scm􀀀1) is still an open problem. Literature suggests that to improve the ionic conductivity of polymer electrolytes several strategies such as plasticization, copolymerization, fabrication of composite/nano-composite etc. have been studied extensively. These techniques mainly concentrate on increasing the amorphous content of polymer electrolytes in order to favour ion mobility to increase the ionic conductivity. In this regard, optimization of ionic conductivity of polymer electrolytes is carried out in the present investigation for composite polymer electrolytes and gel polymer electrolytes. In addition to the process of optimization, prior importance is also given on the understanding the ion conduction mechanism in these two class of polymer electrolytes. In this study three different series of polymer composite electrolytes are prepared using polyethylene oxide as the host polymer, lithium triflate as salt and nanocrystalline zirconia, titania and organo-modified hydrophobic montmorillonite clay as fillers. In addition to this a series of gel polymer electrolyte is also prepared by blending polymer host and 1 molar lithium triflate electrolyte solution consisting of a mixture of ethylene carbonate and diethyl carbonate as solvent. Phase formation of the filler materials, composite nature of polymer composite electrolytes and blended polymer host matrix prepared for gel polymer electrolytes are studied using X-ray diffraction technique. Surface morphology of all these materials is studied using FE-SEM. Polymer salt interactions are investigated using FTIR. Ionic conductivity is measured over a wide range of temperature for getting proper idea about its temperature dependent behaviour. In all these electrolytes, we have achieved room temperature ionic conductivity up to the order of 10􀀀5 S cm􀀀1. This is nearly two order higher in magnitude than conventional polymer-salt complexes at room temperature. Though we are successful in increasing the ionic conductivity by almost two orders in magnitude at room temperature, there exist a huge scope for further improvement in terms of the magnitude of the ionic conductivity. For this reason, a proper understanding of ion conduction mechanism is necessary. Ionic transport mechanism is probed using broadband dielectric spectroscopy over a wide range of frequency and temperature. Relaxation dynamics at different length and time scale is analyzed using broadband dielectric spectroscopy in order to get a proper idea about the ion conduction processes taking place at the microscopic level. The physical parameters that aids in increasing the ionic conductivity of these materials are also studied with observations made from broadband dielectric spectroscopy. An in-depth step by step analysis of the data obtained from electrical characterizations are carried out. The temperature-dependent ionic conductivity for polymer composite electrolytes are found to follow VTF behaviour, indicating there exist coupling between ionic conductivity and polymer segmental motion. Segmental relaxation time also follow similar behaviour. To explain and investigate the coupled nature of ion conduction mechanism, ion diffusivity analysis is carried out by employing Trukhan model. The outcome of these analysis also supports the coupled nature of ion conduction process. Empirical laws like Jonscher power law, double power law and different models like RFEBM, Ngai coupling model, MIGRATION model are used to describe the frequency and temperature dependent ionic conductivity of polymer electrolytes. Havriliak -Negami expression is used to analyze the relaxation phenomenon present in polymer electrolytes. Study of ion conduction mechanism in polymer nanocomposite electrolyte suggest ionic conduction and segmental relaxation are coupled physical process. In the case of polymer gel electrolytes, polymer host does not play any significant role in ionic conduction but only provide the mechanical stability to the absorbed liquid electrolytes. Proper understanding of ion conduction mechanism will help us for preparing good quality polymer electrolytes with high room temperature ionic conductivity, excellent mechanical, thermal and electrochemical stability. By achieving the aforementioned desired properties, the solid polymer electrolytes can replace the organic carbonate liquid based electrolytes commonly used in most of the portable energy storage/conversion devices.

APA, Harvard, Vancouver, ISO, and other styles

36

Chiang, Chin-Yeh, and 江菁燁. "Investigate of nano-particle/tube TiO2 composite polymer electrolyte." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/09965377798185218068.

Full text

Abstract:

碩士
國立中央大學
化學研究所
91
Nano composite polymer electrolytes are one of the effective approaches to enhance ionic conductivity, mechanical stability and better interfacial contact with electrodes ( i.e., Li metal ) in secondary batteries and other ionic devices. Ion conduction enhancement is higher when filler nano particles in smaller dimensions with high specific surface area. The strong Lewis base characteristics of nano inorganic oxide particles facilitate salt disassociation and physical cross-link with polymer chain improves the mechanical strength. The formation of TiO2 nano-particle and nano-tube were confirmed with XRD、TEM、XPS、TGA. The XPS results are consistent with structure that the fluorine atoms in PVDF and oxygen atoms in inorganic oxide TiO2 are coordinate with the dissociated Li+ ions through acid-base reactions. As evident from SEM micrograph, contents of lithium salt and TiO2 with different scale will affect polymer crystallinity. When polymer electrolyte is swollen with organic solvent, the overall ion conductivity would be governed by the dissociation of salt, and ion mobility governed by the polymer and the plasticizer dielectric constant and the viscosity. On a separate studies of PEO, nano-tube TiO2 surface groups provide cross-link centers for the PEO segments and also for the anions, which reduces the polymer reorganization with higher degree of amorphous in composite electrolytes. Nano-tube TiO2 surface groups also facilitated more complete salt dissociation. Conduction path is established on the nano-tube TiO2 where the charge transport achieved by replacing the nearby vacancy ( the “hole” ) hopping in sequential manner.

APA, Harvard, Vancouver, ISO, and other styles

37

Wang, Yao-Lin, and 王耀琳. "Preparation and characterization of PEO/LiClO4/mesoporous silica composite polymer electrolytes." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/07141186150120600586.

Full text

Abstract:

碩士
中原大學
化學研究所
94
In this study, a series of totally amorphous PEO/LiClO4/mesoporous silica nanocomposite polymer electrolytes were prepared with high molecule weight polyethylene oxide, high concentration lithium perchlorate and low content of a homemade mesoporous silica. The SEM/EDS images of the nanocomposite polymer electrolytes indicated that 2wt.% of the mesoporous silica was well dispersed in the PEO polymer electrolyte matrix. The interactions in the system and possible conduction mechanism were studied by DSC, XRD, FT-IR, and 7Li-NMR analysis. It was found that conductivity was significantly improved by the addition of the as-prepared mesoporous silica. A maximum ambient conductivity value of 7.09×10-5 S/cm was obtained for the nanocomposite polymer electrolyte O6A2. The AC-DC polarization results showed that the lithium ion transference number(t+) of O6A2 was about 0.67, which is the highest value reported in PEO/LiClO4/SiO2 system up to now. The high ionic conductivity and lithium ion transference number suggested that it can be used as a potential candidate of the electrolyte material for lithium polymer batteries.

APA, Harvard, Vancouver, ISO, and other styles

38

Chiou, Bor-Ning, and 邱伯寧. "In Situ Synthesis Of PEO-Based Composite Solid Polymer Electrolyte." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/00307978419789010611.

Full text

Abstract:

碩士
國立中央大學
化學研究所
92
The major challenge of Solid Polymer Electrolytes (SPE) is to achieve fair ionic conductivities at ambient temperature, while maintaining film-forming property. Present study disclosed a unique network structured polymer electrolyte by in-situ polymerize phenolic in PEO solution which is subsequently cross-linked by HMTA to form a mechanical stable freestanding and homogenous film.The structure and PEO crystalline before and after cross-linking、thermal stability、surface morphology、molecular motion ability and state、structure and ion transport are characterized. by DSC、TGA、XRD、SEM、FT-IR、NMR、AC-impedance experiments, respectively. These results show the present in situ composite Solid Polymer electrolytes (in situ CSPE) establish a fair interpenetrating network (IPN) structure with good mechanical properties suitable for general electrolyte applications. The CSPE exhibits lower Tm and Tc than that obtained from blending, which implies the PEO crystallite is well-dispersed and large crystallite is hindered in the confined polymer matrix which results in lowering crystalline of polymer. Due to the unique microstructure, re-crystallization of PEO polymer is not occurring after cross-linking phenolic.

APA, Harvard, Vancouver, ISO, and other styles

39

Mitra, Sagar. "Sol-Gel Derived Ionically Conducting Composites : Preparation, Characterization And Electrochemical Capacitor Studies." Thesis, 2004. https://etd.iisc.ac.in/handle/2005/1226.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Mitra, Sagar. "Sol-Gel Derived Ionically Conducting Composites : Preparation, Characterization And Electrochemical Capacitor Studies." Thesis, 2004. http://etd.iisc.ernet.in/handle/2005/1226.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Lian, Zuo-Yu, and 連佐育. "Preparation and analysis of composite polymer electrolyte membranes and application on lithium polymer batteries." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/m26am3.

Full text

Abstract:

碩士
明志科技大學
化學工程研究所
101
This study reports on the preparation of a composite polymer electrolyte for rechargeable lithium polymer battery. Poly(vinylidiene fluoride-hexafluoropropylene) (P(VDF-HFP)/SBA-15 was prepared by solution cast method, which is composed of SBA-15 (silica) filler as the additive for the polymer matrix. The P(VDF-HFP) copolymer has excellent chemical and mechanical properties, it is due to –VDF part; moreover, it also shows high electronegativity and lower crystallinity due to –HFP soft segment part. In addition, the –HFP segment is capable of trapping large amounts of liquid electrolyte. The SBA-15 (silica) molecular sieve has a mesoporous structure with a high specific surface area over 1000 m2 g-1. It may help to reduce the crystallinity of P(VDF-HFP) copolymer and augment to trap more liquid electrolyte and enhance the ionic conductivity. The mechanical properties, thermal stability and electrochemical stability of composite polymer electrolyte are also markedly improved. SEM images show several macro and micropores distributed structure on the polymer membrane and it also exhibits a high porosity, when m-SBA-15 powders dispersed efficiently in the matrix. However, the high porosity structure may enhance the liquid electrolyte uptake to increase the ionic conductivity capacity. The experimental results indicate that the dimensional stability and liquid uptake swelling were increased with the addition of SBA-15 fillers into the solid polymer electrolyte (SPE). The AC impedance method was used to study the ionic conductivity of the as-prepared SPE. It was found that the ionic conductivity of PE separator was 4.5010-4 S cm-1 at 30℃ and pure P(VDF-HFP) polymer film was 1.6010-3 S cm-1. The highest ionic conductivity for P(VDF-HFP)/3wt.%m-SBA-15 SPE was around 3.2310-3 S cm-1. It was found that the ionic conductivity are highly dependent on the contents of m-SBA-15 ceramic fillers and electrolyte concentrations. XRD patterns for pure P(VDF-HFP) film and P(VDF-HFP)/SBA-15 composite polymer membranes show that the added m-SBA-15 fillers can reduce the crystallinity of SPE and augment the amorphous domains of the polymer membranes. TGA results indicate that the thermal degradation temperature of P(VDF-HFP)/3wt.%m-SBA-15 composite polymer membranes was around 476.7℃ to 497.3℃. LiNi0.5Co0.2Mn0.3O2 (denoted as LNCMO) cathode material, Li metal and composite polymer electrolyte were used to assemble Li/SPE/LNCMO polymer battery. The discharge capacity of lithium polymer battery based on LNCMO material with PE separator at 0.1C/0.1 rate was 146 mAh g-1, in contrast to pure P(VDF-HFP) polymer membrane was 145 mAh g-1. However, the P(VDF-HFP)/3wt.%m-SBA-15 composite polymer membranes was achieved as much as 155 mAh g-1. LiFePO4 (denoted as LFP) cathode material, Li metal, and the as-prepared composite polymer electrolyte were also used to assemble Li/SPE/LFP polymer battery. The discharge capacity of lithium polymer battery based on LFP cathode with PE separator at 0.1C/0.1 rate was 148 mAh g-1. By comparison, the lithium LFP polymer battery using P(VDF-HFP)/3wt.%m-SBA-15 composite polymer membranes was as high as 162.24 mAh g-1. Moreover, at 0.2C/1C rate, the discharge capacity with PE separator was only 129.96 mAh g-1, and battery with P(VDF-HFP)/3 wt.%m-SBA-15 composite polymer membranes was 140.0 mAh g-1. It shows that the P(VDF-HFP) composite polymer electrolytes exhibit the much better electrochemical performance than that of PE separator. From the application and analysis of lithium polymer batteries based on two kinds of cathode materials were performed. The as-prepared P(VDF-HFP)/SBA-15 composite polymer electrolyte not only on LNCMO cathode material（3.0~4.3 V vs. Li+/Li）, but also on LFP/C cathode material（2.0~3.8 V vs. Li+/Li）. It demonstrats that the discharge capacity of lithium polymer batteries can be markedly increased by using SPE.

APA, Harvard, Vancouver, ISO, and other styles

42

CheongKou and 高翔. "Reducing interfacial resistance with composite polymer electrolytes for solid-state lithium batteries." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/4ew87p.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Wen, Chih-yu, and 溫治宇. "Study of supercapacitor fabricated with composite electrodes and gel polymer electrolyte." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/nc72b5.

Full text

Abstract:

博士
國立中山大學
電機工程學系研究所
106
This study separately mixed Ni(CH3COO)2 and H2O4W solutions with mesocarbon microbeads (MCMBs), filtered the resulting solution, and then subjected the carbon paste to heat treatments to give rise to composite carbon powder. The powder was then mixed with an adhesive and then applied to a conductive carbon (CC)/ITO glass substrate, which completed the fabrication of a composite electrode for supercapacitors. Gel polymer electrolytes (GPEs) were made using lithium salts LiClO4 and LiBOB in propylene carbonate (PC) solvent. The resulting electrolytes were tested using AC impedance spectroscopy and galvanostatic charge-discharge efficiency tests to determine the influence of the lithium salt used on the capacitance properties of the GPE. Finally, charge-discharge efficiency tests, ambient temperature tests, and lifetime tests were conducted on the supercapacitor. The results show that a 0.75-M H2O4W solution paired with a 100C heat treatment to produce a composite-structured carbon powder in addition to 25 wt.% carbon black and 2 wt.% adhesive results in a composite electrode with the best capacitance properties. Its specific capacitance in a electrolyte (1 M LiClO4) was 249 F∙g-1. The GPE (Sample 4) made with 8 wt.% LiClO4 and 30 wt.% Ionic liquid (IL) presented lower bulk impedance, lower electrolyte-electrode interface impedance, a lower device decline rate, and a higher specific capacitance. The charge-discharge tests revealed that within the voltage range of 0 V to 2.5 V and a charge/discharge current density of 0.3 A∙g-1, the WO3/MCMB presented the optimal specific capacitance of 234.22 F∙g-1. From this results, It could be calculated that the energy density was 293 Wh∙kg-1, and the power density was 105.4 kW∙kg-1 (discharge current @0.03 A). The results therefore demonstrate that the composite electrode fabricated in this study exist good performance capacitance. Furthermore, the composite electrode presented near-100% charge-discharge efficiency and good adhesion between the electrode materials and the substrate after 1,000 charge-discharge cycles in the galvanostatic charge-discharge efficiency tests and service-life tests.

APA, Harvard, Vancouver, ISO, and other styles

44

Mali, Taylor J. "Thermoplastic Composites for Polymer Electrolyte Membrane Fuel Cell Bipolar Plates." Thesis, 2006. http://hdl.handle.net/10012/2679.

Full text

Abstract:

Polymer electrolyte membrane fuel cells (PEMFCs) exhibit encouraging potential as an enabling technology for the Hydrogen Economy. Currently an important barrier to commercialization is the cost associated with existing PEMFC materials; this project’s goal was to investigate alternative materials for PEMFC bipolar plates. Conductive thermoplastic materials offer the promise of low density, low cost processing, and inexpensive resins, and were the focus of material development for PEMFC bipolar plate applications. In order to develop a thermoplastic bipolar plate this study utilized the combination of a low cost injection moldable commodity polymer resin, and low cost carbon materials as conductive fillers. The materials selected and tested included; a polypropylene copolymer; acetylene carbon black; Vulcan carbon black; and short carbon fiber. The components were combined in a twin screw extruder and injection molded into samples for testing. The result was a spectrum of composite samples with a range of filler loadings from 0 to 60 wt% and varying filler type ratios. Synergy between the different carbon types was achieved which led to better physical properties, specifically conductivity. The novel blends produced were tested for electrical conductivity, mechanical properties, rheology, microscopy, and actual plates were made and tested in a single cell PEMFC. These trials enabled discussion around the feasibility of the materials with respect to processability, cost, and performance (both in the fuel cell and in potential applications). The most significant results were measured using a composite blend with 54 wt% filler loading and a 1:1:1 filler ratio. Mechanical results achieved 68% and 100% of the industry targets for tensile and flexural strength, respectively. Tensile strength attained 27.7 MPa and flexural strength measured 82.8 MPa. Electrical conductivity results for the same samples varied between the two methods of measurement used. Using a fuel cell industry recommended procedure 2.2 S/cm was achieved and using a four point ASTM measurement technique 12.0 S/cm was reported. These values represent 3% to 12% of the industry target. Actual 16 cm2 fuel cell plates were produced, fuel cell hardware constructed and assembled, and the power output was found to be 51% relative to graphite plates. Thermoplastic bipolar plates for PEMFCs made of composite materials is promising, but optimum filler loading that balances all properties is still required in order to achieve conductivity targets. Nevertheless this study has demonstrated that conductive thermoplastic bipolar plates can be produced via injection molding.

APA, Harvard, Vancouver, ISO, and other styles

45

Chen, Jian-Yu, and 陳建宇. "Nonwoven Fabric/ Gel Polymer Electrolyte Composites Prepared by Epoxy Resins." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/d94848.

Full text

Abstract:

碩士
國立臺北科技大學
化學工程與生物科技系化學工程碩士班
106
Gel polymer electrolyte (GPE)/nonwoven separators were prepared by impregnation of various epoxy resins and curing agent, such as polyetheramine and diethylenetriamine, into the nonwoven PP. The cured epoxy composites were soaked with LiClO4 in the liquid electrolyte of ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC). The thermal shrinkage, electrolyte uptake, and ionic conductivity of the epoxy composites dependent on the composition and morphologies of the epoxy gels have been further analyzed and discussed. It was found that thermal shrinkage of the nonwoven PE/PP was 21.5%, which was reduced to 1.4% by impregnating the epoxy gel in to the nonwoven fabric. The ionic conductivity of the nonwoven fabric/gel polymer electrolyte composite was approximately 0.1 mS/cm at 30oC.

APA, Harvard, Vancouver, ISO, and other styles

46

Tsai, Yi-Yuan, and 蔡亦媛. "Cross-linked composite polymer electrolyte using surface modified mesoporous silica MCM-41." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/54116249824954020621.

Full text

Abstract:

碩士
國立中央大學
化學研究所
91
The thesis divided into two parts. First, we are interested that the effect of addition of Mesoporous silica MCM-41 with surface modification of (3-glycidyloxypropyl)trimethoxysilane (GLYMO) to poly(ethylene oxide) (PEO) complexed with LiClO4 has been explored by alternating current (AC) impedance, powder X-ray diffraction (XRD) , differential scanning calorimeter (DSC), and multinuclear solid-state NMR measurements. The presence of small quantity of GLYMO modified MCM-41 enhances the ionic conductivity of the resulting composite electrolyte as compared to present PEO/LiClO4 electrolyte. The enhancement in conductivity is directly correlated with the improved compatibility between PEO and surface modified MCM-41 as a result of blending PEO with GLYMO group. Addition of high concentration of surface modified MCM-41 leads to a decrease in the conductivity of the composite electrolyte, mainly because MCM-41 filler acts an insulator that impedes the lithium ion transport. DSC results show that both the polymer segmental motion and the proportion of amorphous PEO phase are affected by addition of MCM-41 filler. The change of portion of crystalline PEO phase can be explained by Lewis acid-base interactions between PEO chain, MCM-41 surface, and lithium cation. Solid-state 7Li NMR measurements show that the 7Li linethwidth narrowing begins at temperature much lower than the glass transition temperature of PEO chains, indicative of the presence of an additional conduction mechanism with lithium ions moving along (both interior and exterior) the mesoporous channels of MCM-41.The additional mechanism is unique for the composite electrolytes doped with mesoporous silica MCM-41, and is absent in the case of other spherical fillers such as Al2O3 and SiO2 particles in PEO-based electrolytes. Variable temperature proton decoupled 7Li MAS (magic angle spinning) NMR spectra reveal that at least two different lithium environments are present in the composite electrolyte, serving as an evidence for the existence of interaction between lithium cation and MCM-41 surface. In the second part of my thesis, the effect of addition of uncalcined or calcined mesoporous silica MCM-41 to poly(ethylene oxide) (PEO) complexed with LiClO4 has been explored by alternating current (AC) impedance, powder X-ray diffraction (XRD) , differential scanning calorimeter (DSC), and multinuclear solid-state NMR measurements. The present of small quantity of uncalcined MCM-41 do not enhance the ionic conductivity of the resulting composite electrolyte as compared to present PEO/LiClO4 electrolyte. However, the present of small quantity of calcined MCM-41 enhances the ionic conductivity of the resulting composite electrolyte as compared to present PEO/LiClO4 electrolyte. The enhancement in conductivity is directly correlated with Lewis acid-base interactions between PEO chain, MCM-41 surface, and lithium cation. Addition of high concentration of uncalcined or calcined MCM-41 leads to a decrease in the conductivity of the composite electrolyte, mainly because uncalcined or calcined MCM-41 filler acts an insulator that impedes the lithium ion transport. Variable temperature proton decoupled 7Li MAS (magic angle spinning) NMR spectra reveal that at least two different lithium environments are present in the composite electrolyte, serving as an evidence for the existence of interaction between lithium cation and MCM-41 surface.

APA, Harvard, Vancouver, ISO, and other styles

47

Jhang, Jian-Fong, and 張建豐. "Preparation and characterization of electrospun polymer electrolyte nanofibers and their composites." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/05655393285873458331.

Full text

Abstract:

碩士
國立雲林科技大學
化學工程與材料工程系碩士班
100
In this study, Nafion / polyaniline (PANI) composite fibers were fabricated by electrospinning process for the modification of Nafion membrane,and tested for their application as proton exchange membranes in direct methanol fuel cells (DMFC). Nafion solution is difficult to separate electrospinning method is made, this small addition of polyethylene oxide (polyethylene oxide, the PEO) obtained continuous fibers. At first, investigate the following factors, including the PEO concentration, voltage, solution flow rate, needle to the collector plate distance and relative humidity. The results showed that Nafion solution add a solution of 0.045 wt% of PEO, the voltage of 12 KV, the distance is 12 cm, the volumetric flow rate of 1 ml / h and a relative humidity of 40% under the conditions of uniform Nafion fiber. After that, explore the hydrochloric acid-doped polyaniline nanofibers added to the Nafion solution and reference using previously prepared by electrospinning parameters Nafion / PANI composite fibers. By scanning electron microscopy showed the same concentration of Nafion in the electrospinning solution, the amount of 10 wt% polyaniline can still Preparation of a complete fiber, and Fourier transform infrared absorption spectrometer, UV - visible light spectrometer, thermal gravimetric analysis and transmission electron microscopy confirmed that the Nafion / PANI composite fibers. After that, Nafion / PANI fiber mat to hot pressing as the layer of Nafion surface modification, and modified membrane to contain 1.5 wt% polyaniline has the better of the methanol selectivity, and its proton conductivity of 2.46 × 10-2 S / cm,slightly lower than Nafion115 (2.86 × 10-2 S / cm), while the methanol permeability of the membrane was 1.03 × 10-6 cm2 / s, better than Nafion115 (1.71 × 10-6 cm2 / s). Modified membrane assembled into a single cell in the performance of direct methanol fuel cell test ,the results show the modified membrane at high methanol concentration operation has obvious advantages, 4M, 6M and 8M concentration of methanol, its performance is superior to the unmodified filmand the degree of improvement was also superior to situ synthesis of polyaniline at the surface of the Nafion membrane.

APA, Harvard, Vancouver, ISO, and other styles

48

Lai, Yen-Chieh, and 賴彥榤. "Application of PVDF-HFP/mesoporous silica composite polymer electrolytes on dye-sensitized solar cell." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/5c6y6d.

Full text

Abstract:

碩士
中原大學
化學研究所
98
In this study, poly(vinylidenefluoride-co-hexafluoropropylene)(P(VDF-HFP)) were introduced into to liquid electrolyte to formed the gel electrolyte, and commercials silica (CS) and mesoporous silica (MS) powders were used, separately, as a filler to induced into the gel electrolyet. It is discussed that the properties of composite gel electrolyte and application of dye-sensitized solar cells. The morphologies and porosity of the silicas were characterized by SEM,TEM and BET measurements. The composite polymer electrolytes wrer investigated by morphologies, crystallinity, ionic conductivity, diffusion coefficient of tri-iodide and light-to-electrical-energy conversion efficiencies. It was found that presence of the CS were increased, the porosity of composite gel electrolytes were decreased, but P10MSx composite electrolytes were not changed obviously. And MS were disdrdered pore structure, electrolytes would penetrated into pores and increased ionic conductivity, diffusion coefficient of I3－. It exhibited an overall light-to-electrical-energy conversion efficiencies of 4.08 %, which is 37 % higher than the corresponding values of the DSSC fabricated with the electrolyte without MS additive, more then 9% higher than electrolyte under the same condition.

APA, Harvard, Vancouver, ISO, and other styles

49

Chen, Chien-Liang, and 陳建良. "Study of Organic-Inorganic Composite Polymer Electrolyte Based on Triblock copolymer and Alkoxysilanes." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/85046100758408196684.

Full text

Abstract:

碩士
國立中央大學
化學研究所
91
The objective of this study is to investigate the effect of the mesoporous molecular sieve SBA-15 on the ionic conductivity behavior, and investigate into a inorganic-organic hybrid electrolyte derived from the self-assembly of poly(ethylene oxide)—poly(propylene oxide)—poly(ethylene oxide) triblock copolymer by co-condensation of an epoxy silane and tetraethoxysilane (TEOS) in the presence of LiClO4. In the first part of this thesis, solid polymer electrolytes based on poly (ethylene oxide) (PEO) have been characterized by solid-state NMR, scanning electron microscopy (SEM), X-ray diffraction Spectrometer (XRD), differential scanning calorimemeter (DSC), and AC impedance measures. The present of small quantity of uncalcined SBA-15 do not enhance the resulting composite electrolyte as compared to present PEO/LiClO4 electrolyte, mainly because uncalcined SBA-15 filler acts an insulator that impedes the lithium ion transport. However, the present of small quantity of calcined SBA-15 enhances the resulting composite electrolyte as compared to present PEO/LiClO4 electrolyte. The hybrid with 10 wt% LiClO4 and 10 wt% calcined SBA-15 reaches conductivity up to 3.85 × 10-5 S/cm at 30 oC. In the second part of this thesis, a new inorganic-organic hybrid electrolyte has been prepared and characterized. The block copolymer acts as a structure-directing surfactant to organize polymerizing XRD results show the formation of stabilized mesophases with long-range ordering has been built by the self-assembly of triblock copolymer and alkali metal salts, particularly for [O]/[Li] = 16. A combination of XRD and conductivity results allows us to presume that the drastically enhanced conductivity for the hybrid with high long-range ordering is closely related to the formation of mesophase, which might improve the arrangement of Li+ conducting pathways. The hybrid with [O] / [Li] = 16 reaches conductivity up to 10-5 S/cm at 30 oC

APA, Harvard, Vancouver, ISO, and other styles

50

Sun, Chih Hung, and 孫誌鴻. "Studies on Composite Polymer Electrolyte and It''s Application in Lithium Secondary Battery." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/68325949839253479038.

Full text

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Composite Polymet Electrolytes'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles