SnO2 nanocrystals on self-organized TiO2 nanotube array as three-dimensional electrode for lithium ion microbatteries

Three-dimensional (3D) anodes have been prepared for lithium ion microbatteries by depositing SnO2 nanocrystals into self-organized TiO2 nanotube arrays through the solvothermal method, with the SnO2 crystal size less than 5 nm. The 3D SnO2–TiO2 anodes exhibit excellent electrochemical performance with a good capacity retention of up to 70.8% over 100 cycles in the voltage range of 0.05–2.5 V. SnO2 enhances the capacity to more than double that of bare TiO2, while TiO2 nanotubes accommodate the volume changes of SnO2 during charge/discharge cycling. The amount of SnO2 loading can be controlled by varying the reaction time. The capacity of the 3D electrodes is controlled by the TiO2 tube length as well as by the amount of SnO2 loading. The maximum reversible capacity of the present samples can reach as high as about 300 µA h cm−2.