Enable the Domino‐Like Structural Recovering in Bismuth Anode to Achieve Fast and Durable Na/K Storages

Abstract

AbstractAlloying‐type anodes show capacity and density advantages for sodium/potassium‐ion batteries (SIBs/PIBs), but they encounter serious structural degradation upon cycling, which cannot be resolved through conventional nanostructuring techniques. Herein, we present an in‐depth study to reveal the intrinsic reason for the pulverization of bismuth (Bi) materials upon (de)alloying, and report a novel particle‐in‐bulk architecture with Bi nanospheres inlaid in the bulk carbon (BiNC) to achieve durable Na/K storage. We simulate the volume‐expansion‐resistant mechanism of Bi during the (de)alloying reaction, and unveil that the irreversible phase transition upon (de)alloying underlies the fundamental origin for the structural degradation of Bi anode, while a proper compressive stress (~10 %) raised by the bulk carbon can trigger a “domino‐like” Bi crystal recovering. Consequently, the as obtained BiNC exhibits a record high volumetric capacity (823.1 mAh cm−3 for SIBs, 848.1 mAh cm−3 for PIBs) and initial coulombic efficiency (95.3 % for SIBs, 96.4 % for PIBs), and unprecedented cycling stability (15000 cycles for SIBs with only 0.0015 % degradation per cycle), outperforming the state‐of‐the‐art literature. This work provides new insights on the undesirable structural evolution, and proposes basic guidelines for design of the anti‐degradation structure for alloy‐type electrode materials.