Structure and electrochemical properties of surface-activated C/SiO₂ composite derived from rice husks as a high-performance anode for sodium-ion batteries

Sodium-ion batteries (SIB) have been becoming a promising candidate for future energy storage and conversion owing to the abundant sodium sources and availability of their featured materials for solving the planet's sustainability issues, which is recently a global overriding concern. The development of low-cost, sustainable, compatible, and stable anode materials should be parallel driven in coherent with the great efforts dedicated to the cathode materials research. Through the process of surface activation and subsequent heat treatment, herein, we explored a facile and effective in combining both silica and organic components contained rice husks (RH) to synthesize a high-performance C/SiO₂ anode promising for SIB applications. SiO₂ nanoparticles with KOH activation embedded in a carbon scaffold with a high surface area were highly activated to sodiation reaction, enabling a high-rate capability and long cycling performance, especially after the second cycle. The composite anode C/SiO₂ could deliver a good initial capacity of 450 mAh g⁻¹ at a current density of 0.05 A g⁻¹. Moreover, full-cell Na₃V₂(PO₄)₃ /C/SiO₂ showed the first discharge capacity of 125 mAh g⁻¹ at C/10. In detail, EIS and SEM ex situ methods were used to study the effect of SEI layer formation in the initial cycle and explore the electrochemical reactions in the cell system.