Heterostructured MoO2@rGO facilitates enhanced kinetics in lithium-sulfur battery

Abstract

MoO₂ is heterogeneously grafted onto reduced graphene oxide (rGO) to create a MoO₂@rGO heterostructure, which acts as a host material for sulfur in lithium-sulfur batteries (LSBs). The transition metal compounds MoO₂ enhance the adsorption capacity for lithium polysulfides (LiPSs) and promote catalytic conversion processes. The MoO₂@rGO cathode exhibits high sulfur loading (70 wt%), elevated specific capacity (1136 mAh g⁻¹ at 0.3C, 9 mg cm⁻²), and excellent rate performance. Importantly, MoO₂@rGO/S (12 mg cm⁻²) demonstrates a localized capacity of 11.60 mAh in the first discharge. After 110 cycles under a current density of 2.01 mA cm⁻², it still retains residual capacity of 6.12 mAh, with a specific discharge capacity of 536 mAh g⁻¹, showcasing superior cycling competence. The MoO₂@rGO/S-100 mg pouch cell achieves an initial specific capacity of 1128 mAh g⁻¹. After 110 cycles at 0.2C, it retains a specific capacity of 738 mAh g⁻¹ (65.4 %), with a coulombic efficiency stabilizing around 99.2 %. Two series-connected MoO₂@rGO/S pouch cells-powered drone run continuously for 115 s. Hence, heterostructured MoO₂@rGO can serve as a LiPS catcher, accelerate the redox kinetics of sulfur, and hold promise for constructing next-generation LSBs with outstanding electrochemical performance.