Identifying the origin of porous evolution of microsized bismuth in potassium-ion batteries

Microsized bismuth (Bi) with in-situ constructed three-dimensional (3D) porous network has been considered as a promising anode for high-performance potassium-ion batteries (PIBs). However, the mechanism of the in-situ porous evolution of microsized Bi during the charge/discharge process is still mysterious. Herein, various electrolytes are employed to disclose the origin of porous evolution of microsized Bi in PIBs. Experimentally and theoretically, the 3D porous network originates from the uniform interfacial charge distribution on the Bi surface in the linear ether-based electrolyte. In addition, the universality of the interfacial charge distribution mechanism was verified by microsized Sn and Sb. The in-situ constructed 3D porous network of Bi enables a superior potassium storage performance in a wide temperature range from −40 to 40 °C. More importantly, the K_0.9Mn_0.7Ni_0.3O₂∥Bi full cell delivers excellent cycling stability (a high capacity retention of 88.44% even after 2,000 cycles) and good temperature tolerance. This work gives a distinct clarification of the origin of the porous evolution of microsized Bi during cycling, which is critical for developing high-performance PIBs. (Figure presented.)