Bi 3+ Induced Crystal Growth of a Symbiotic Heterojunction Enables Long‐Lifespan Zn‐Ion Batteries

Abstract The MnO 2 /Mn 2 O 3 symbiotic heterojunction is considered to be a promising cathode material for aqueous zinc‐ion batteries (ZIBs) owing to the built‐in electric field generated from the heterojunction interface that can accelerate ion transporting. However, the structure collapse caused by the Mn 3+ dissolution, leading to a sharp capacity decline, is still one of the major issues. In this work, a Bi‐doped MnO 2 /Mn 2 O 3 symbiotic heterojunction with a uniform nanorod structure was formed due to the Bi‐induced crystal growth mechanism. In addition, Bi 3+ doped into the lattice effectively inhibited the dissolution of Mn 3+ and greatly enhanced charge transfer and reaction kinetics. Therefore, an impressive long‐term cycling performance over 6000 cycles at a current density of 2 A g −1 was obtained. Such a Bi 3+ induced symbiotic heterojunction crystal growth strategy may open new opportunities toward high‐performance aqueous ZIBs.