Small-sized microcrystalline SiO2 catalyzed Na2S2-to-Na2S conversion for high-performance room-temperature sodium–sulfur batteries

Abstract

Biomass-derived carbon materials are widely employed as cathode carriers for RT-Na/S batteries. However, their limited surface activity and scarcity of catalytic sites hinder stable long-term cycling performance, particularly under high current densities. In this work, we successfully synthesized large-sized, microcrystalline, and amorphous SiO₂ structures via in situ growth on carbon substrates, utilizing the natural silicate components inherent to the biomass precursors. The designed C/M-SiO₂@S cathode demonstrates remarkable electrochemical performance, retaining a specific capacity of 1021 mAh g⁻¹ after 5000 cycles at a high current density of 5 A g⁻¹. The microcrystalline SiO₂ exhibits pronounced catalytic activity, significantly facilitating the conversion kinetics from Na₂S₂ to Na₂S and enabling a shortened sodium-ion diffusion pathway. This study provides valuable insights for engineering catalytic architectures within biomass-derived carbon.