Boosting catalytic activity by using the interfacial electric field of VN–V2O3 heterogeneous nanoparticles for efficient lithium polysulfide conversion

Abstract

The capacity loss and reduced cycling performance caused by the shuttle effect of lithium polysulfides (LiPSs) present significant challenges for the practical application of lithium-sulfur (Li–S) batteries. In this study, innovative VN–V₂O₃ heterogeneous nanoparticles supported on a porous carbon framework (VN–V₂O₃/C) were synthesized as efficient catalysts. Through comprehensive experimental characterization, VN–V₂O₃/C was found to exhibit a balance of moderate polysulfide adsorption capability and high electrochemical activity. Theoretical calculations revealed that the superior electrochemical performance of VN–V₂O₃ nanoparticles arises from an interfacial electric field generated by charge redistribution at the VN/V₂O₃ interface. This electric field facilitates electron transfer, accelerating the conversion of LiPSs. Li–S batteries equipped with VN–V₂O₃/C@S cathodes demonstrated an outstanding initial discharge capacity of 1191.96 mA h g⁻¹, excellent rate performance (641.69 mA h g⁻¹ at 5C), and an extremely low capacity decay rate of 0.026% over 1000 cycles at 2C. Additionally, the assembled pouch cell achieved an initial energy density of 351.1 W h kg⁻¹. This work offers new insights into the catalytic mechanisms of vanadium-based heterostructure catalysts in enhancing the redox kinetics of polysulfide conversion.