Unlocking the Electrochemical Activation of Diatomaceous Earth SiO2 Anodes for Next-Generation Li-Ion Batteries

Silica (SiO₂) anodes are promising candidates for enhancing the energy density of next-generation Li-ion batteries, offering a compelling combination of high storage capacity, stable cycling performance, low cost, and sustainability. This performance stems from SiO₂ unique lithiation mechanism, which involves its conversion to electroactive silicon (Si) and electrochemically inactive species. However, widespread adoption of SiO₂ anodes is hindered by their slow initial lithiation. To address this, research has focused on developing electrochemical “activation protocols” that involve prolonged low-potential holding steps to promote SiO₂ conversion. Despite these efforts, the complex and multi-pathway nature of SiO₂ lithiation process remains poorly understood, impeding the rational design of effective activation strategies. By introducing a multi-probe characterization approach, this study reveals that, contrary to the previously proposed reaction mechanism of SiO₂ anodes, the lithiation process initiates at low potentials with the direct formation of Li₄SiO₄ and Li_xSi. Electrochemical activation potential was found to significantly influence the degree of conversion, with 10 mV identified as the optimal cut-off potential for maximizing SiO₂ utilization. These findings provide key enablers to unlock the full potential of SiO₂ anodes for battery technology.