Sandwiched cathodes kinetically boosted by few-layered catalytic 1T-MoSe₂ nanosheets for high-rate and long-cycling lithium-sulfur batteries

An advanced electrocatalyst to accelerate the sluggish kinetics of multistep redox reactions and suppress the severe shuttle effects is desirable in Li-S batteries (LSBs). Phase engineering can provide a fascinating way to modulate electronic structures and boost catalytic activity of electrocatalysts. In this study, few-layered 1T-MoSe₂ nanosheets grown on carbon cloth (1T-MoSe₂/CC) are synthesized and employed as a multifunctional interlayer as well as a catalytic 3D current collector in LSBs to promote both physiochemical confinement and catalytic conversion toward lithium polysulfides (LiPSs). Density functional theory (DFT) calculations reveal that 1T-MoSe₂ has metallic properties beneficial for rapid electronic transport and exhibits a superior catalytic activity to reduce the Gibbs free energy barriers toward LiPS conversion. Significant improvements in chemisorption toward LiPSs, diffusion coefficients of Li ions, and Li₂S deposition/decomposition reaction kinetics are realized by the 1T-MoSe₂/CC film. Consequently, the Al@S/AB@1T-MoSe₂/CC LSB, where 1T-MoSe₂/CC is used an interlayer, presents high rate capability of 1253 (1C), 1052 (2C) and 882 (4C) mAh g⁻¹ and excellent long-term cycling stability at a high rate (2000 cycles at 4C) with a low capacity fading rate (0.017% per cycle). Moreover, with a sandwiched cathode of 1T-MoSe₂/CC@S/AB@1T-MoSe₂/CC, where 1T-MoSe₂/CC works as both a catalytic 3D current collector and a multifunctional interlayer, the LSB at high S loading of 5.7 mg cm⁻² and low electrolyte/sulfur ratio of 7.8 μL mg⁻¹ exhibits a high initial areal capacity of 5.43 mAh cm⁻² and remarkable rate-cycling performance (200 cycles). © 2023 The Authors. EcoMat published by The Hong Kong Polytechnic University and John Wiley & Sons Australia, Ltd.