Rapid mechanochemical synthesis of Li2SiO3 from recycled silicon via reactive SiO2 intermediates

Abstract

A rapid mechanochemical route for Li2SiO3 synthesis from recycled silicon is demonstrated, achieving an estimated yield of 97.15% at 900 °C within 21 min. Phase evolution analysis reveals the formation of SiO2 polymorphs (quartz and cristobalite) at ~700 °C, which act as reactive intermediates and are progressively consumed during lithium silicate formation. Mechanochemical activation enhances solid-state reactivity by increasing interfacial contact, enabling Li2SiO3 formation under non-equilibrium conditions. Quantitative phase analysis confirms Li2SiO3 as the dominant phase (~94 wt%), in agreement with thermogravimetric estimation. These results are consistent with an apparent diffusion-assisted process occurring under non-equilibrium conditions, where LiCl is suggested to contribute to phase transformation and interfacial reactions. This approach provides one of the fastest reported routes for lithium silicate production from secondary raw materials.