Design of ZnSe-CoSe heterostructure decorated in hollow N-doped carbon nanocage with generous adsorption and catalysis sites for the reversibly fast kinetics of polysulfide conversion

Although lithium-sulfur batteries (LiSBs) are regarded as one of the most promising candidates for the next-generation energy storage system, the actual industrial application is hindered by the sluggish solid-liquid phase conversion kinetics, severe shuttle effect, and low sulfur loadings. Herein, a zeolitic imidazolate framework (ZIF) derived heterogeneous ZnSe-CoSe nanoparticles encapsulated in hollow N-doped carbon nanocage (ZnSe-CoSe-HNC) was designed by etching with tannic acid as a multifunc-tional electrocatalyst to boost the polysulfide conversion kinetics in LiSBs. The hollow structure in ZIF ensures large inner voids for sulfur and buffering volume expansions. Abundant exposed ZnSe-CoSe heterogeneous interfaces serve as bifunctional adsorption-catalytic centers to accelerate the conversion kinetics and alleviate the shuttle effect. Together with the highly conductive framework, the ZnSe-CoSe-HNC/S cathode exhibits a high initial reversible capacity of 1305.3 mA h g-1 at 0.2 C, high-rate capability, and reliable cycling stability under high sulfur loading and lean electrolyte (maintaining at 745 mA h g-1 after 200 cycles with a high sulfur loading of 6.4 mg cm-2 and a low electrolyte/sulfur ratio of 6 lL mg-1). Theoretical calculations have demonstrated the heterostructures of ZnSe-CoSe offer higher binding energy to lithium polysulfides than that of ZnSe or CoSe, facilitating the electron transfer to lithium poly-sulfides. This work provides a novel heterostructure with superior catalytic ability and hollow conductive architecture, paving the way for the practical application of functional sulfur electrodes.(c) 2023 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.