On April 7, the reporter of Chongqing Daily learned from Chongqing University that in view of the problems with the existing lithium metal batteries, the research group of Professor Xu Chaohe from the School of Aerospace Engineering and Professor Wang Ronghua from the School of Materials Science and Engineering have recently designed and developed an ultra-thin, lightweight, multi-functional and high-temperature-resistant composite membrane. The composite membrane effectively regulates the deposition/dissolution behavior of lithium ions and catalyzes the conversion reaction of polysulfides, and by this way realizes the stable circulation of metal lithium cathode and lithium sulfur battery. Hopefully this membrane will be used in lithium metal batteries.
Lithium metal is believed to be an ideal cathode material for the next-generation high energy density battery devices. In the "14th Five-year Plan" of China, it was proposed to develop a subversive battery technology with an energy density of 600 Wh/kg (watt hour/kilogram) based on lithium metal anode.
"However, we have to tackle a number of challenges before we achieve the goal, particularly the performance degradation, short circuit and even thermal runaway caused by the formation of lithium dendrites and 'dead lithium'." Said Xu Chaohe frankly. For battery systems, high-specific-energy lithium sulfur battery is one of the important system options of high-energy chemical power supply in the future. However, in addition to the common challenges of the lithium cathode side, the sulfur anode side is also facing a number of complicated problems such as slow reaction kinetics, polysulfide shuttle and loss of active sulfur. As such, tackling these challenges with simple and practical solutions has become the frontier topic and key core technology of development of high-performance metal lithium batteries with metal lithium as cathode.
It is reported that the research group of Chongqing University used a simple coating process to evenly load the functional coatings of vanadium sulfide and tannic acid wrapped in graphene oxide nanosheets onto the commercial polyolefin membrane. The theoretical simulation results showed that the composite diaphragm could ensure uniform distribution of ions and electric field on the surface/interface of lithium cathode, realize uniform transportation and deposition of lithium ions, weaken the deposition amplification effect at the defects, and avoid the generation of lithium dendrites and dead lithium. At last, the metal lithium battery assembled based on the composite diaphragm realized stable circulation, and showed that the soft-packed lithium battery could be used to drive small electric robot.
According to Xu Chaohe, the research findings have been recently published in Nano Energy (Nano Energy, 2022, 95, 106982) and Advanced Science (Advanced Science, 2022, 2102215), and the research group has submitted applications for a number of national patents. The functional coating could also increase the heat resistance of the composite diaphragm, significantly improve the safety of metal lithium battery, and hopefully it will be applied extensively in the future.
Source: Chongqing Daily
