Low-Temperature De-alloying and Unique Self-filling Interface Optimization Mechanism of Layered Silicon for Enhanced Lithium Storage

Abstract

Layered silicon (L-Si) anodes are celebrated for their high theoretical capacity but face significant challenges regarding safety and material purity during preparation. This study addresses these challenges by employing NH4Cl-CaSi2 as the raw material in a steam de-alloying process, which enhances both safety and purity compared to traditional methods. The L-Si anodes produced demonstrate outstanding electrochemical performance, delivering a high reversible lithium storage capacity of 1497.7 mAh g⁻¹ at a current density of 0.5 A g⁻¹, and exhibiting stable performance over 1200 charge-discharge cycles. In-situ and ex-situ characterizations reveal that electrolyte decomposition products effectively fill the voids within the electrode, while the gradual disintegration of the L-Si structure contributes to the formation of a dense, conductive network. This process enhances lithium ion transport and exploits the capacitive storage benefits of layered silicon. The insights from this study provide valuable guidance for the development and optimization of other silicon-based anode materials, paving the way for high-performance lithium-ion batteries.