LiNi0.8Co0.15Al0.05O2 as both a trapper and accelerator of polysulfides for lithium-sulfur batteries

Achieving long-life is a crucial step for lithium-sulfur (Li-S) batteries as one of most promising next generation energy storage devices. Whereas, the severe shuttling and low redox reaction kinetics of polysulfides (LiPSs) cause the rapid loss of active material, poor rate performance and severe self-discharge. To address above issues, herein, for the first time, we reported the layered LiNi0.8Co0.15Al0.05O2 (NCA) particles as a host to trap LiPSs and accelerate LiPSs conversion simultaneously. We theoretically elucidate and experimentally verify the strong adsorption for Li2S6 through the NCA (104), (003) and (110) crystal planes by the formation of the strong Li-O and Co-S bonds to capture and immobilize LiPSs solidly. At the same time, the intrinsic catalytic effects of NCA with polar surface as an accelerator can propel the LiPSs redox reactions. In addition, NCA can effectively improve static stability of Li-S batteries and suppress their self-discharge behavior. Therefore, the LiS cells with NCA achieved a high discharge capacity of 755.4 mA h g(-1) with a low capacity decay rate of 0.02%/ cycle after 500 cycles at 1 C. This work opens up a convenient and effective way to substantially enhance the capability of Li-S batteries for their practical application.