Inner-Layer Indium Doping Achieved Highly Active and Stable Sulfur Vacancies in MoS₂ for Superior Sulfur Redox...

Defect engineering in MoS₂ via sulfur vacancies (Vs-MoS₂) has shown potential in enhancing lithium-sulfur battery (LSB) performance by mitigating the polysulfide shuttle effect. However, the high surface energy of Vs-MoS₂ impedes long-term catalyst stability. Herein, indium (In) doping is introduced into the inner layer of Vs-MoS₂ lattice (In-Vs-MoS₂), which effectively stabilizes the catalyst by reducing surface energy and enhancing sulfur redox kinetics. Theoretical calculations confirm that In doping, in conjunction with surface vacancies, optimizes charge distribution and generates unpaired electrons near the Fermi level, thus improving polysulfide adsorption and lowering Li₂S formation barriers. LSBs with In-Vs-MoS₂ separators deliver stable cycling at 0.5 C with a favorable capacity of 1042 mAh g^-1 retained after 100 cycles. Moreover, even at high current density (5 C) and high S loading (8.7 mg cm^-2) scenario, stable cycling is realized, demonstrating the strategy's effectiveness in advancing LSB electrocatalysis. This work offers a straightforward strategy for practical LSBs and deepens the understanding of vacancy-modulated electrocatalysts for sulfur redox.