Coherent Interface Growth of PCuAg‐Si Anode for Long‐Term Cycling Stability in All‐Solid‐State Batteries

Abstract Sulfide all solid‐state batteries (ASSBs) with Si‐based anode offers a promising route to high energy density of Energy Storage Devices. Nevertheless, the unstable interface of ASSBs remains a critical challenge, especially causing issues such as decomposition of sulfide solid electrolyte (SSE). Thus, a composite porous CuAg‐Si (PCuAg‐Si) anode with a coherent interface of multi‐phase (Ag, Cu and Cu 15 Si 4 ) is designed. The Si epitaxial grown Cu and Ag form a coherent interface with the sulfide electrolyte, which provides enhanced Li + diffusion pathways. Furthermore, this coherent interface creates an “electron shielding effect” that lowers the rate of reduction reactions in the SSE, further stabilizing the interface and reducing unnecessary degradation of the electrolyte. Additionally, the porous structure can effectively inhibit volume expansion during Li + insertion/disinsertion, ensuring stable interfacial stress and further reducing the electron leakage path caused by mechanical cracks in the SSE. Consequently, the PCuAg‐Si anode exhibits a reversible specific capacity of 420 mAh g −1 after 1500 cycles at 1 A g −1 (capacity degradation rate per cycle is as low as 0.02%). Meanwhile, PCuAg‐Si || LNO@NCM811 demonstrates a high specific capacity of 77 mAh g −1 after 720 cycles at 1C. Engineering coherent interfaces charts a compelling pathway toward next‑generation, high‑performance ASSBs.