Li-Si alloy pre-lithiated silicon suboxide anode constructing a stable multiphase lithium silicate layer promoting...

Enhancing the initial Coulombic efficiency (ICE) and cycling stability of silicon suboxide (SiO_x) anode is crucial for promoting its commercialization and practical implementation. Herein, we propose an economical and effective method for constructing pre-lithiated core-shell SiO_x anodes with high ICE and stable interface during cycling. The lithium silicon alloy (Li₁₃Si₄) is used to react with SiO_x in advance, allowing for improved ICE of SiO_x without compromising its reversible specific capacity. The pre-lithiated surface layer contains uniform multiphase lithium silicates (L₂SiO₃, Li₄SiO₄, and Li₂Si₂O₅) in the nanoscale. This multiphase lithium silicate layer exhibits mechanical robustness against variation of micro-stress, which can act as a buffer layer to relieve volume variation. In addition, analysis of dynamic electrochemical impedance spectroscopy (dEIS) and distribution of relaxation time (DRT) confirm that the multiphase lithium silicate layer enhances Li-ion diffusion kinetics and contributed to constructing stable SEI. As a result, the optimal L10-850 anode shows a high ICE of 85.3 %, together with a high specific capacity of 1771.5mAh mg^-1. This work gives a perspective strategy to modify SiO_x anodes by constructing a pre-lithiated surface layer with practical application potentials.