Valence Electron: A Descriptor of Spinel Sulfides for Sulfur Reduction Catalysis

Catalysts are essential for achieving high-performance lithium–sulfur batteries. The precise design and regulation of catalytic sites to strengthen their efficiency and robustness remains challenging. In this study, spinel sulfides and catalyst design principles through element doping are investigated. This research highlights the distinct role of lattice sulfur sites in lithium polysulfide conversion and emphasizes the differences in catalytic activity between metal and anion sites. The valence electron model as a descriptor can characterize catalytic performance, guiding the design of a (FeCo)₃(PS)₄ catalyst co-doped with cation and anion. The (FeCo)₃(PS)₄ exhibits the highest catalytic performance among spinel catalysts to data, particularly under high sulfur loading conditions. It achieves an initial specific capacity of 1205.9 mAh g⁻¹ (6.1 mAh cm⁻²) at a sulfur loading of 5 mg cm⁻² and 1192.7 mAh g⁻¹ (11.9 mAh cm⁻²) at 10 mg cm⁻², demonstrating excellent electrocatalytic performance.