Owing to the high theoretical capacity, metal sulfides have emerged as promising anode materials for potassium-ion batteries (PIBs). However, sluggish kinetics, drastic volume expansion, and polysulfide dissolution during charge/discharge result in unsatisfactory electrochemical performance. Herein, we design a core-shell structure consisting of an active bismuth sulfide core and a highly conductive sulfur-doped carbon shell (Bi₂S₃@SC) as a novel anode material for PIBs. Benefiting from its unique core-shell structure, this Bi₂S₃@SC is endowed with outstanding potassium storage performance with high specific capacity (626 mAh·g⁻¹ under 50 mA·g⁻¹) and excellent rate capability (268.9 mAh·g⁻¹ at 1 A·g⁻¹). More importantly, a Bi₂S₃@SC//KFe[Fe(CN)₆] full cell is successfully fabricated, which achieves a high reversible capacity of 257 mAh·g⁻¹ at 50 mA·g⁻¹ over 50 cycles, holding great potentials in practical applications. Density functional theory (DFT) calculations reveal that potassium ions have a low diffusion barrier of 0.54 eV in Bi₂S₃ due to the weak van der Waals interactions between layers. This work heralds a promising strategy in the structural design of high-performance anode materials for PIBs.

由于理论容量高，金属硫化物已成为有前途的钾离子电池（PIBs）负极材料。然而，在充放电过程中缓慢的动力学、剧烈的体积膨胀和多硫化物溶解导致电化学性能不令人满意。在此，我们设计了一种由活性硫化铋核和高导电硫掺杂碳壳（Bi ₂ S ₃ @SC）组成的核壳结构，作为 PIB 的新型负极材料。得益于其独特的核壳结构，这种Bi ₂ S ₃ @SC 具有出色的储钾性能和高比容量（626 mAh·g ^-1 50 mA·g ^-1）和优异的倍率性能（268.9毫安·克^-1 1个A·克^-1）。更重要的是，成功制备了 Bi ₂ S ₃ @SC//KFe[Fe(CN) ₆ ] 全电池，在 50 mA·g ^-1 50 次循环下实现了 257 mAh·g ^-1的高可逆容量，在实际应用中潜力巨大。密度泛函理论 (DFT) 计算表明，由于层之间的弱范德华相互作用，钾离子在 Bi ₂ S _{3 中}具有 0.54 eV 的低扩散势垒。这项工作预示着一种用于 PIB 的高性能负极材料结构设计的有前景的策略。