Auswahl der wissenschaftlichen Literatur zum Thema „Nano-Li2S“

Lithium sulfide (Li2S) is considered to be the best potential substitution for sulfur-based cathodes due to its high theoretical specific capacity (1166 mAh g−1) and good compatibility with lithium metal-free anodes. However, the electrical insulation nature of Li2S and severe shuttling of lithium polysulfides lead to poor rate capability and cycling stability. Confining Li2S into polar conductive porous carbon is regarded as a promising strategy to solve these problems. In this work, N-doped porous carbon microspheres (NPCMs) derived from yeasts are designed and synthesized as a host to confine Li2S. Nano Li2S is successfully entered into the NPCMs’ pores to form N-doped porous carbon microspheres–Li2S composite (NPCMs–Li2S) by a typical liquid infiltration–evaporation method. NPCMs–Li2S not only delivers a high initial discharge capacity of 1077 mAh g−1 at 0.2 A g−1, but also displays good rate capability of 198 mAh g−1 at 5.0 A g−1 and long-term lifespan over 500 cycles. The improved cycling and high-rate performance of NPCMs–Li2S can be attributed to the NPCMs’ host, realizing the strong fixation of LiPSs and enhancing the electron and charge conduction of Li2S in NPCMs–Li2S cathodes.

NASICON-type Li1.5Al0.5Ge1.5(PO4)3 (LAGP) is a remarkable solid-state electrolyte due to its high ionic conductivity and excellent air stability. However, the weak LAGP|Li interfacial compatibility (e.g., chemical instability of LAGP with Li metal and lithium dendrite growth) limits its practical application. Herein, an ultrathin CuS layer was fabricated on the surface of the LAGP electrolyte by magnetron sputtering (MS). Then, an in situ Li2S/Cu nano-layer formed via the conversion reaction between CuS and molten Li was constructed at the LAGP|Li interface. The Li2S/Cu nano-layer enables effective hindering of the reduction reactions of LAGP with Li metals and the suppression of lithium dendrite growth. The assembled Li symmetric battery with the Li2S/Cu@LAGP electrolyte shows a promising critical current density (CCD) of 0.6 mA cm−2 and a steady battery operation for over 700 h. Furthermore, the full LiFePO4 battery comprising the Li2S/Cu@LAGP electrolyte shows excellent capacity retention of 94.5% after 100 cycles, providing an appropriate interface modification strategy for all-solid-state Li metal batteries.

Abstract Lithium–sulfur (Li–S) batteries, regarded as one of the most promising alternatives to current state-of-the-art rechargeable Li-ion battery technologies, have received tremendous attention as potential candidates for next-generation portable electronics and the rapidly advancing electric vehicle market. However, substantial capacity decay, miserable cycle life, and meagre stability remain critical challenges. More specifically, shuttling of polysulfide (Li2S x (3 < x ⩽ 8)) species severely hinders the cycle performance resulting in capacity fade and cycling instability. In the present work, a highly conducting three-dimensional (3D) carbon nanofiber (CNF) foam has been synthesized using the lyophilization method followed by thermal pyrolysis. The highly porous foam materials have a bimodal porosity distribution in the nano and micro regime and were successfully investigated to serve as a potential host for sulfur species intended for Li–S battery application. 3D x-ray microtomography was employed to estimate the nature of sulfur impregnation and distribution in the 3D porous networks. On utilizing the final product as cathode material, sulfur impregnated carbonized CNF foam and modified the separator with functionalized multiwalled carbon nanotubes delivered a specific capacity of ∼845 mAh g−1 at 100 mA g−1.

Flow battery innovations should offer significant improvements in performance, without compromising the durability / lifetime, and be cost-effective and scalable. The presentation will review some of the progress that has been made to enhance flow battery performance, and will discuss a number of recent innovations that aim to deliver these characteristics. These will include: Magnetic flowable electrodes applied in a polysulfide-iodide flow battery. Using flow through the current feeder to enhance mass transport and enable dendrite free zinc deposition in the zinc-iodide flow battery. Graphene modified membrane for enhanced power density. Flowable electrodes have emerged as a novel concept for high energy density batteries. To date, in most cases the flowable solid phase includes a redox active energy storage material, for example in zinc-nickel, sodium-sulfur, and lithium-sulfur systems [1-3]. In contrast, we have demonstrated the use of a carbon – magnetite nanocomposite which acts as an electrocatalyst but is not redox active [4,5]. This nanomaterial can be dispersed in the electrolyte and circulated through the battery to enhance the performance of a conventional static electrode. The magnetic characteristics of the nanocomposite can also be exploited, by using a magnetic field to assemble a high surface area electrode comprising a percolating network of the nanomaterial on the current feeder. The electrode also can be removed by releasing the magnetic field at the current feeder, and after being washed out of the cell the nanocomposite can be separated in a magnetic field. This enables replacement of the active electrode without the need to dismantle the cell. Zinc-iodide flow batteries offer high energy density due to the high aqueous solubility of the ZnI2. However, the power density that can be achieved is limited by potential for the dendritic growth of zinc deposits, and as zinc metal builds up in the cell the areal capacity is limited. We have found that by drawing some of the electrolyte through the current feeder, improved performance can be obtained [6]. This enables operation at higher power density and the denser uniform deposit should enable increased areal capacity. We attempted to reduce crossover in the all-vanadium redox flow battery by using a graphene modified nafion membrane. However, we found that the addition of the graphene reduced the losses in the battery and enabling a significant increase in the power density and discharge capacity. Currently we are working to optimize and scale up the membrane modification process, and to explore the mechanism of performance enhancement. References G. Zhu et al. (2020) High-energy and high-power Zn–Ni flow batteries with semi-solid electrodes. Sustainable Energy Fuels, 4, 4076-4085. Yang et al. (2018) Sodium–Sulfur Flow Battery for Low-Cost Electrical Storage. Advanced Energy Materials, 11, 1711991. Suo et al. (2015) Carbon cage encapsulating nano-cluster Li2S by ionic liquid polymerization and pyrolysis for high performance Li–S batteries. Nano Energy, 13, 467-473. Rahimi, A.M. Dehkordi, E.P.L. Roberts (2021) Magnetic nanofluidic electrolyte for enhancing the performance of polysulfide/iodide redox flow batteries. Electrochimica Acta, 309, 137687. Rahimi, A.M. Dehkordi, H. Gharibi, E.P.L. Roberts (2021) Novel Magnetic Flowable Electrode for Redox Flow Batteries: A Polysulfide/Iodide Case Study. Ind. Eng. Chem. Res., 60, 824-841. F. ShakeriHosseinabad et al. (2021) Influence of Flow Field Design on Zinc Deposition and Performance in a Zinc-Iodide Flow Battery. ACS Applied Mat. & Interfa

Lithium-sulfur (Li-S) batteries are one of the promising alternatives to modern Lithium-ion Battery (LIB) technology due to their superior specific energy density, which can satisfy the emerging needs of advanced energy storage applications such as electric vehicles and grid-scale energy storage and delivery. However, achieving this high specific energy density is hampered by several challenges inherent to the properties of sulfur and its discharge products. One major issue is related to the insulating nature of S and its fully discharged product (Li2S), which often leads to low utilization of the active material and poor rate capability. The poor electronic conductivity of these species can be overcome by utilizing conductive hosts, though they are dilutive and decrease the energy density, meaning that their mass ratio to the active material should be as low as possible [1]. Another crucial issue relates to the undesired solubility of certain sulfur discharge products, so-called long-chain Li polysulfides (LiPSs), in the conventional ether-based liquid electrolyte. The solubility of long-chain LiPSs promotes their free back-and-forth transport between the positive and negative electrodes, which results in poor cyclability and capacity decay [2, 3]. Despite the efforts to engineer and control the undesired LiPSs shuttling effect, advances have been mostly limited to a small number of cycles (100-200), or the need for complex and often expensive synthesis that has limited the rational development of new sulfur cathodes. At present, a large majority of the sulfur cathode research has focused on nano-architectured electrodes using 2D and 3D host materials for sulfur, such as carbon nanotubes, graphene, conductive scaffolds, yolk-shell structures, and the like, to increase the conductivity and alleviate the LiPSs shuttling [4]. Although these approaches have helped to increase the achievable capacity, and sometimes the cyclability, their synthesis methods have been highly complex, meaning that their manufacturing cost will be high. Also, in operating cells, it is highly unlikely that these complex structures can be effectively reproduced upon many charge-discharge cycles – meaning that capacity loss is essentially inevitable. Thus, developing novel, yet affordable and scalable, cathode architectures that can enhance the rapid transport of Li-ions to active sites for electrode reactions, accommodate discharge-induced volume expansion, and minimize the shuttling mechanism by sulfur encapsulation are still in great need. In this work, we present a low-cost and scalable processing method for highly durable sulfur cathodes containing commercial sulfur, carbon black, and polyvinylidene fluoride (PVDF). The sulfur cathode slurry was prepared through a simple and scalable recipe where the degree of binder dissolution into the solvent was controlled before electrode deposition. Variables such as the solvent:binder ratio, dissolution time, and agitation will be discussed. The microstructure of the sulfur cathodes was characterized using scanning electron microscopy. Through controlled dissolution of binder, a porous, swollen network of binder was achieved that adhered the sulfur and carbon particles while providing a highly porous structure that can accommodate the sulfur volume expansion during discharge and impede dissolution of the discharge products into the electrolyte by physically trapping them. The cycling performance of the sulfur cathodes prepared through the present novel processing was tested at C/10 and compared with those prepared through the conventional production techniques. The sulfur cathodes prepared with this novel electrode processing offered impressive capacity retention of 80% after 1000 cycles suggesting a considerable improvement in the shuttling effect and active material preservation. These results are expected to help move the production and manufacturing of Li-S batteries forward. References -J. Lee, T.-H. Kang, H.-Y. Lee, J. S. Samdani, Y. Jung, C. Zhang, Z. Yu, G.-L. Xu, L. Cheng, S. Byun et al., Advanced Energy Materials, vol. 10, no. 22, p. 1903934, 2020. Yang, G. Zheng, and Y. Cui, Chemical Society Reviews, vol. 42, no. 7, pp. 3018–3032, 2013. She, Y. Sun, Q. Zhang, and Y. Cui., Chemical society reviews, vol. 45, no. 20, pp. 5605-5634, 2016. Zhou, D. L. Danilov, R.-A. Eichel, and P. H. L. Notten, Advanced Energy Materials, vol. 1, p. 2001304, 2020.

Les batteries Li-ion traditionnelles utilisent des électrolytes liquides organiques, qui sont sensibles aux températures élevées en raison de leur faible point d'éclair et de leur grande volatilité. Par conséquent, le remplacement des électrolytes liquides par des électrolytes solides devient l'un des points chauds de la recherche pour les batteries de stockage d'énergie chimique de la prochaine génération. Dans cette thèse, une méthode en phase liquide utilisant LiEt3BH ou Li-Naph comme matières premières est inventée pour synthétiser des sol précurseurs Li3PS4 et obtenir des nanoparticules Li3PS4 monodispersées. Cette thèse développe également un sol Li3PS4 présentant une excellente compatibilité avec les anodes de Li, de sorte qu'une couche protectrice Li3PS4 peut être déposée sur le Li par spin-coating du sol. En conséquence, les cellules symétriques au lithium avec des électrodes au lithium modifiées par Li3PS4 peuvent être cyclées de manière stable pendant 800 h à 1 mA cm-2. Pour améliorer encore la stabilité du cycle de l'anode Li sous une densité de courant extrêmement élevée, une structure à trois couches Ag/Li-LiF-PEO (alliage, inorganique et organique) est proposée. La structure Ag/Li-LiF-PEO améliore la stabilité de cyclage des anodes Li sous une densité de courant extrêmement élevée, ce qui est démontré dans les batteries symétriques au lithium et les batteries Li//LFP. À une densité de courant ultra-élevée de 20 mA cm-2, la cellule symétrique au lithium survit à un test de 1 450 cycles. Cette étude peut contribuer au développement de batteries Li métal à haute performance
Traditional Li-ion batteries use organic liquid electrolytes, which are susceptible to high temperatures due to their low flash point and high volatility. Therefore, it becomes one of the research hotspots for next generation chemical energy storage batteries to replace liquid electrolytes with solid electrolytes. In this thesis, a liquid-phase method using LiEt3BH or Li-Naph as raw materials is invented to synthesize Li3PS4 precursor sol and to obtain monodispersed Li3PS4 nanoparticles. This thesis also develops Li3PS4 sol exhibiting excellent compatibility with Li anodes, so that a Li3PS4 protective layer can be coated on Li by spin-coating of the sol. As a result, the lithium symmetrical cells with Li3PS4-modified lithium electrodes can be cycled stably for 800 h at 1 mA cm−2. To further improve the cycling stability of the Li anode under an extremely high current density, a Ag/Li-LiF-PEO (alloy, inorganic and organic) three-layer structure is proposed. The Ag/Li-LiF-PEO structure enhances the cycling stability of Li anodes under ultrahigh current density, which is demonstrated in lithium symmetrical batteries and Li//LFP batteries. At an ultrahigh current density of 20 mA cm-2, the lithium symmetrical cell survives a 1450-cycle test. This study may contribute to the development of high-performance Li metal batteries