All Solid State Battery with Soft Carbon–TiSi2 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-TiSi₂-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 TiSi₂ 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 LiC₆, 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.