Carbon coated TiO2–SiO2 nanocomposites with high grain boundary density as anode materials for lithium-ion batteries

Carbon coated TiO2–SiO2 nanocomposites (CTSO) with high grain boundary density fabricated by a simple hydrothermal approach have been investigated as anode materials for lithium-ion batteries. The CTSO anode exhibits superior high-rate capability and excellent cycling performance. The specific capacity of CTSO is much higher than that of pure TiO2 and silica-modified TiO2 without carbon nanocoating (TSO), indicating a positive synergistic effect of the material and structural hybridization on the enhancement of the electrochemical properties. The possible contributing factors include the formation of the Ti–O–Si bonding, which facilitates the reaction between SiO2 and Li; the presence of carbon layering on each nanocrystal; high grain boundary density among the nanoparticles and grain boundary interface areas embedded in a carbon matrix, where electronic and ionic transport properties are tuned by interfacial design and by varying the spacing of interfaces down to the nanoscale regime. The grain boundary interface embedded in the carbon matrix can also store electrolyte and allows more channels for the insertion/extraction reaction of Li ions. The composites exhibit strong potential as a promising anode for lithium-ion batteries.