All Solid State Battery with Soft Carbon–TiSi ₂ Multilayer Structure for Optimized LiSi Anodes

Abstract Li metal and Si anodes are in urgent need for next‐generation all‐solid‐state batteries (ASSBs) due to their high energy density. However , short‐circuit caused by Li dendrite growth and rapid capacity fading due to severe volume expansion of Si still seriously limit their application. Herein , a Si‐TiSi 2 ‐LPSCl/soft carbon/Li (ST5‐SC‐Li) three‐layer structured anode is designed to overcome these challenges. Multi‐layer structure restricts the anisotropic expansion of Si by using the rigid support of TiSi 2 and the plastic deformation capability of LPSCl. The composite layer forms a continuous ionic channel through close contact between Si and sulfide electrolyte, and constructs an “ion‐electron dual network” in addition to the high electronic conductivity of the Si‐Ti alloy. The SC layer forms ion‐conductive LiC 6 , further absorbing expansion stress and inhibiting dendrite penetration. The Li metal layer dynamically compensates for the irreversible capacity loss of Si. The LCO/LPSCl/ST5‐SC‐Li SASSBs achieves an ultra‐long cycle of 64 000 cycles at a high rate of 10C (6.4 mA cm − 2 ) with a capacity retention rate >100%. Separately, a high reversible areal capacity of 19.6 mAh cm −2 is achieved at 0.1C under high loading.