In‐Situ Self‐Evolving µ‐Sn 10 Bi Cross‐Interlocked Structure and Three‐in‐One Kinetic Enhancement Mechanism: Superb Room/Low‐Temperature Sodium Storage Performance

ABSTRACT Sn with a high theoretical capacity and a low‐voltage plateau is considered a promising anode material for high‐energy‐density sodium ion batteries (HSIBs). However, the huge volume changes and poor conductivity of its sodiation products make it difficult to achieve long‐term stability and excellent rate performance. Herein, a remarkably simple structural reinforcement and three‐in‐one kinetic enhancement strategy is proposed for microsized Sn (µ‐Sn) electrode by introducing trace µ‐Bi. Interestingly, µ‐Bi spontaneously evolves into a 3D cross‐linked interlocked nanosheet network during cycling, ensuring long‐term structural stability of µ‐Sn. Meanwhile, the diametrically opposed patterns of electrical conductivity change in Bi and Sn during sodiation are utilized to achieve dynamic complementarity of their conductivity and reaction kinetics throughout the entire charge/discharge process. Additionally, the supercontinuous (104) crystal plane in the 3D Bi network and the Bi/Sn heterointerface in‐situ formed further accelerate e − /Na + transfer. As a result, the prepared µ‐Sn 10 Bi simultaneously exhibits high reversible capacity, excellent rate performance and ultralong cycle life in both half and full cell at room/low temperatures. Structural evolution/kinetic enhancement/sodium storage mechanism and structure‐activity relationship of µ‐Sn 10 Bi are revealed in detail, providing a constructive view for designing low‐cost, high‐capacity, structurally stable, fast‐charging anode with wide‐temperature adaptability for HSIBs.