Novel design of silicon-based lithium-ion battery anode for highly stable cycling at elevated temperature

Abstract

Despite Si being one of the most promising anode materials in lithium-ion batteries, significant challenges remain, including a large volume change, low electrical conductivity and high temperature operation for practical use. Herein, we demonstrate a facile synthesis of Si particles with double-shell coating layers, in which aluminum trifluoride (AlF₃) acts as an artificial defensive matrix, and carbon layers enhance electrical conductivity and compatibility with carbon black. Our study reveals that Si anodes with double shell layers composed of AlF₃ exhibit excellent electrochemical properties at 25 °C and 60 °C, owing to the formation of a stable solid electrolyte interface layer on the Si surface, and the good mechanical strength and chemical nature of AlF₃ layers. The Si@AlF₃@C anode shows a significantly improved cycling performance (capacity retention of 75.8% after 125 cycles at 25 °C and 73.7% at 60 °C after 150 cycles, compared to the specific capacity in the first cycle) and excellent rate capability of >1600 mA h g⁻¹, even at a 5C rate (at 25 °C). Furthermore, the AlF₃ assisted Si electrode exhibits remarkably reduced volume expansion (thickness change of 71% after 125 cycles at 25 °C and 128% after 150 cycles at 60 °C).