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 gas-solid 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 mA h 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.