High-performance multi-layers tubular nanostructure anode materials for lithium-ion batteries

In order to reduce the negative volume effect of Silicon (Si) and Silica (SiO2) as anode materials, CNTs@SiO2/Si@C is prepared by sol-gel method and magnesiothermic reduction process. SEM and TEM results show that the surface of Carbon nanotubes (CNTs) is uniformly coated with active materials including SiO2 and Si. Active materials (SiO2/Si) closely contact with the conductive network constructed by CNTs, which greatly improves the conductivity of the composite anode material. Moreover, the large specific surface area of the tubular structure provides more Li+ diffusion channel. The cushion space of the hollow tube structure effectively alleviates the volume effect of SiO2/Si and enables the anode material excellent electrochemical performance in the cycling test. The initial discharge capacity of CNTs@SiO2/Si@C is 1064 mAh/g at current density of 200 mA/g. The specific discharge capacity of CNTs@SiO2/Si@C is higher than 960 mAh/g after 100 cycles, and the coulomb efficiency maintains over 98% in the range from 30th to 100th cycle.