Synergistic Lithium Storage in Silica–Tin Composites Enables a Cycle-Stable and High-Capacity Anode for Lithium-Ion Batteries

Silica (SiO2) is considered as a promising candidate anode material for next-generation lithium-ion batteries (LIBs) owing to its low cost, abundant reserve on Earth, and relatively high theoretical specific capacity. However, the development of SiO2-based anode materials has been impeded by their poor electrical conductivity and sluggish charge-transfer kinetics. Herein, porous SiO2/tin (SiO2@Sn) composites with tunable SiO2 to Sn molar ratios are fabricated using a scalable, simple, and low-cost ball-milling and low-temperature thermal-melting combined method. It is found that the Sn phase can significantly improve the diffusion and migration kinetics of Li in the composites, whereas the SiO2 to Sn molar ratio plays a key role in the mechanical integrity and subsequent cycling behaviors of the composite electrodes. By optimizing the molar ratio of SiO2/Sn to 10:1, the synergistic effect of Li storage between SiO2 and Sn can lead to the simultaneous achievement of improved Li kinetics and ensured mechanical integrity, contributing to the excellent electrochemical performance of the composite with a large reversible capacity of 613 mAh g–1 at 100 mA g–1, a remarkable rate capability of 450 mAh g–1 retained at 1000 mA g–1, and long-term cycling durability with ∼95% capacity retention over 200 cycles.