Insights into a crystallization-like activation mechanism of diatom biosilica as an anode for next-generation Li-ion batteries

Abstract

Silica is a promising anode material due to its high theoretical specific capacity and natural abundance. The design of a hollow porous structure and preparation of composite materials can effectively inhibit the volume strain and improve the poor conductivity of SiO₂. Diatom biosilica (DBS) has such natural advantages in structure and composition. The prepared carbon-coated diatom-based biosilica (DBS@C) anode shows good cycle stability at different current densities and a stable capacity of ∼900 mA h g⁻¹ at 1 A g⁻¹ after 400 cycles. The tested electrode material is prepared by embedding slices and characterized by transmission electron microscopy (TEM), and the establishment of the conductive path is observed. According to previous research and combining the lattice stripes by high-resolution TEM (HRTEM) with the standard PDF card, the reduction products and paths of SiO₂ are analysed. Furthermore, a crystallization-like activation mechanism is proposed, and the electrochemical phenomenon of the DBS@C anode is reasonably explained.