Enhanced high rate capability of dual-phase Li_4Ti_5O_(12)-TiO_2 induced by pseudocapacitive effect

摘要

The dual-phase Li_4Ti_5O_(12)-TiO_2 nanocomposite is successfully synthesized by a hydrothermal route with adding thiourea. The electrochemical performance of the dual-phase nanocomposite as anode for lithium-ion batteries is investigated by the galvanostatic method, cyclic voltammetry and electrochemical impedance spectra. It is demonstrated that the dual-phase Li_4Ti_5O_(12)-TiO_2 nanocomposite presents the improved electrochemical performance over individual single phase Li_4Ti_5O_(12) and anatase TiO_2 samples. After 300 cycles at 1 C, the dual-phase Li_4Ti_5O_(12)-TiO_2 nanocomposite can still maintain the large discharge capacity of 116 mAh g~(-1). It indicates that the as-prepared nanocomposite can endure great changes of various discharge current densities to retain a good stability. The large discharge capacity of 132 mAh g~(-1) is also obtained at the large current density of 1600mAg~(-1) upon cycling. In particular, as verified by the cyclic voltammetry, the pseudocapacitive effect is induced due to the presence of abundant phase interfaces in the dual-phase Li_4Ti_5O_(12)-TiO_2 nanocomposite, which is beneficial to the enhanced high rate capability and good cycle stability.