Hydrothermal synthesis of nano-SnO₂@SiO₂ composites for lithium-ion battery anodes

SnO₂-based lithium-ion batteries have low cost and high energy density, but their capacity fades rapidly during lithiation/delithiation due to phase aggregation and cracking. A modified hydrothermal method was developed to synthesize tin oxide doped with highly dispersed silicon oxide, sing SnCl₄·5H₂O and amounts of tetraethyl orthosilicate as the starting materials and NH₃·H₂O as PH regulator. Fine powders of tin oxide as active materials were doped with highly dispersed silicon oxide as inert materials in atomic or nano-meter scale. The microstructure, morphology and electrochemical performance of the mixtures were analyzed by X-ray diffraction, infra-red, scanning electron microscopy and electrochemical methods. Silicon oxide as matrix should be able to support the anode changes accompanied by the formation of lithium–tin alloys, thus an improvement of the cycle ability of the Li-ion battery would be expected. The electrochemical results showed that addition of silicon oxide reduces the irreversible capacity during the first discharge/charge cycle. The electrochemical performance indicates that amorphous silicon oxide is an appropriate matrix and these composites are good anode candidates for application in lithium-ion batteries.