Building Interconnected Architectures with Silicon‐Based Nanospheres and TiN Ionic Fence Enables Ultrahigh Electrochemical Stability

Abstract

AbstractSilicon oxide (SiOx) material is gradually developing as a promising alternative to silicon due to a better trade‐off in terms of volume expansion and theoretical capacity. However, the low conductivity and the instability of the electrode–electrolyte interface caused by the penetration of the fluorine anion (F−) severely affect the stability of the solid electrolyte interphase (SEI), ultimately leading to capacity loss and cycling instability. In this work, an “ionic fence” idea is proposed, which effectively inhibits the shuttle of F− and promotes the stability of the SEI. Based on this, a dense and orderly silicon‐based interconnected assembly covered by a TiN protective ionic fence is designed using melt‐assembly technique and nitridation strategy. After 1000 deep cycles, the capacity can be maintained at 431.7 mA h g−1, the average Coulombic efficiency can reach 99.69% throughout the cycling process, and even a steady state after 2000 cycles, showing excellent electrochemical stability. Finite element analysis reveals that the TiN fence, as a stress management layer, effectively constrains the volume expansion of materials and improves the mechanical structural stability of the particles in the fully lithiated state, thus ensuring long‐term cycling stability. Selective fence design for material interface has great universality and development potential in building stable electrode materials.