SiO2@C hollow sphere anodes for lithium-ion batteries

As anode materials for lithium-ion batteries, SiO2 is of great interest because of its high capacity, low cost and environmental affinity. A facile approach has been developed to fabricate SiO2@C hollow spheres by hydrolysis of tetraethyl orthosilicate (TEOS) to form SiO2 shells on organic sphere templates followed by calcinations in air to remove the templates, and then the SiO2 shells are covered by carbon layers. Electron microscopy investigations confirm hollow structure of the SiO2@C. The SiO2@C hollow spheres with different SiO2 contents display gradual increase in specific capacity with discharge/charge cycling, among which the SiO2@C with SiO2 content of 67 wt% exhibits discharge/charge capacities of 653.4/649.6 mA h g−1 over 160 cycles at current density of 0.11 mA cm−2. The impedance fitting of the electrochemical impedance spectroscopy shows that the SiO2@C with SiO2 content of 67 wt% has the lowest charge transfer resistance, which indicates that the SiO2@C hollow spheres is promising anode candidate for lithium-ion batteries.