A Porous Hexagonal Prism Shaped C-In2–xCoxO3 Electrocatalyst to Expedite Bidirectional Polysulfide Redox in Li–S Batteries

The shuttling behavior of soluble lithium polysulfides (LPSs) extremely restricts the practical application of lithium sulfur batteries (Li-S batteries). Herein, the hollow porous hexagonal prism shaped C-In2-xCoxO3 composite is synthesized to restrain the shuttle effect and accelerate reaction kinetics of LPSs. The novel hexagonal prism porous carbon skeleton not only provides a stable physical framework for sulfur active materials but also facilitates efficient electron transferring and lithium ion diffusion. Meanwhile, the polar In2-xCoxO3 is equipped with strong adsorption capacity for LPSs, which is confirmed by density functional theory (DFT) calculations, helping to anchor LPSs. More importantly, the doping of Co regulates the electronic structure environment of In2O3, expedites the electron transmission, and bidirectionally improves the catalytic conversion ability of LPSs and nucleation-decomposition of Li2S. Benefiting from the above advantages, the electrochemical performance of Li-S batteries has been greatly enhanced. Therefore, the C-In2-xCoxO3 cathode presents a good rate performance, which exhibits a low-capacity fading rate of 0.052% per cycle over 800 cycles at 5 C. Especially, even under a high sulfur loading of 4.8 mg cm-2, the initial specific capacity is as high as 903 mAh g-1, together with a superior capacity retention of 85.6% after 600 cycles at 0.5 C.