Synergistic improvement of the overall performance of lithium-sulfur batteries

Abstract

<p indent="0mm">As one of the most promising next generation secondary battery systems, lithium-sulfur battery has the advantages of high energy density, low cost, and environmental friendliness. But its commercial application still faces several challenges, such as the intrinsic insulation of sulfur, the shuttle effect of the intermediate lithium polysulfide, and the growth of lithium dendrites. In recent years, our research group has systematically investigated the electrode materials, performance and mechanism for Li-S batteries. We have realized the solid-solid conversion of sulfur via micropore limitation, and rational cathode-electrolyte interface construction. Different from the conventional solid-liquid-solid cathode process, solid-solid conversion of sulfur can not only avoid the diffusion of the soluble intermediate lithium polysulfide and the “shuttle effect”, but also effectively reduce the electrolyte/sulfur ratio (E/S) and therefore enhance the energy density of battery. In addition, we have also realized high surface capacity of the Li-S battery through structural design, and effectively inhibited the shuttle effect of polysulfide by constructing a functional intermediate layer. For lithium metal anode protection, we have designed and constructed kinds of three-dimensional current collection, which can effectively inhibit the formation of lithium dendrite, and hence comprehensively improve the safety and cyclability. We have also improved the air stability and moisture resistance of lithium metal by artificial solid electrolyte interface construction and interface modification. In addition, due to the low room-temperature conductivity and weak mechanical strength of polymer electrolytes commonly used in solid state electrolytes, we have successfully improved the mechanical property and flame resistance of polymer electrolytes by modification. Finally, we put forward a prospect for promoting the practical application of Li-S batteries with the goal of high energy, high safety and long cycle life.