MXene-Ce-BTC heterostructure derived from Ce metal-organic framework for enhancing adsorption and catalytic capabilities of lithium-sulfur battery

Abstract

The performance of lithium-sulfur batteries (LSBs) is constrained by the shuttle effect of lithium polysulfides (LiPSs), the sluggish conversion kinetics of LiPSs, and high reaction barrier during Li₂S deposition/dissolution. In this study, MXene is innovatively incorporated into the synthesis of Ce Metal-organic framework (Ce-BTC) for heterogeneous modification, resulting in a novel nanorod-shaped MXene-Ce-BTC materia. This material possesses more metal sites and functional groups, which not only facilitate the formation of surface defects and increase oxygen vacancies but also enhance the adsorption of LiPSs, thereby promoting their rapid conversion. Finally, MXene-Ce-BTC is incorporated into the prepared paper-based self-supporting cathode and subsequently assembled into LSBs, demonstrating remarkable electrochemical performance: it achieves an initial discharge specific capacity of 1195 mA h g⁻¹ at a sulfur loading of 3.5 mg cm⁻² and a current density of 0.2C. After 200 cycles, the capacity is 1148 mA h g⁻¹, with a retention rate of 96.1 %. Even at a high sulfur loading of 8.5 mg cm⁻², it delivers an initial specific capacity of 532 mA h g⁻¹, with a retention rate of 90.7 % after 100 cycles. This study develops a simple yet efficient MXene-Ce-BTC cathode material, offering novel insights into the design of cathode catalysts.