Stereochemically Active Lone Pairs Promoted High Rate Potassium-Ion Storage in Bismuth Sulfide

Bismuth sulfide (Bi₂S₃) is a promising potassium-ion battery anode candidate due to its high theoretical capacity and cost-effectiveness. However, it experiences severe volume variation and structure collapse during potassiation/depotassiation, leading to inferior cycling stability and rate performance. Herein, a novel stereochemically active lone pairs (SCALP)-oriented strategy integrated with structural engineering is proposed. Guided by density functional theory calculations predicting that controlled lattice distortion can tune SCALP behavior, a rationally designed Bi₂S₃ anchored within hollow carbon spheres (HCS@Bi₂S₃) is synthesized via controlling sulfidation time. SCALP-oriented approach narrows band gap and strengthens K⁺ adsorption, improving redox reaction kinetics coupled with efficient ion-transport pathways in well-crystallized regions; HCS alleviates volumetric expansion and suppresses potassium-polysulfide dissolution and shuttling. HCS@Bi₂S₃-3 delivers high reversible capacity (471.5 mAh g^-1 at 200 mA g^-1), good high-rate long-term cycling stability (147.3 mAh g^-1 after 1000 cycles at 10 A g^-1), and excellent rate capability (128.4 mAh g^-1 at 12 A g^-1). Full cell paired with 3,4,9,10-perylenetetracarboxylic dianhydride cathode delivers exciting cycling stability, indicating the practical applications potential of HCS@Bi₂S₃-3. This work highlights SCALP-modulation as a fundamental strategy optimizing electronic properties, while HCS mitigates volume changes, offering a new pathway for developing fast and stable potassium storage anodes using metal chalcogenides.