Electrochemical performance of low concentration Al doped-lithium titanate anode synthesized via sol-gel for lithium ion capacitor applications

In spite of its high potential, the electrochemical performance of lithium titanate (LTO) has rarely been investigated as an anode material in lithium ion capacitor (LIC). This study is aimed to probe the effect of low concentration Al doping on the properties of LTO as well as its electrochemical performance for lithium ion capacitor application. In this work, a facile sol gel reaction is employed to synthesize Li₄Ti_5-xO₁₂Al_x (x = 0, 0.025, 0.05, and 0.075). The starting materials were stoichiometrically dissolved in ethanol and mixed, followed by calcination at 800 °C for three hours. XRD pattern of the samples demonstrate the peak shifting of LTO structure, as Al content increases to some extent. The LTOA 0.025 sample has smaller and more uniform particles than that of pristine LTO. The half-cell performance shows that LTOA 0.025 has higher current peak and capacity, 154.5 mAh.g⁻¹ than that of pristine LTO. Meanwhile, the performance of full-cell LIC also demonstrate the increase of its specific capacitance at various scan rate and the excellent retention stability, which can sustain 83.9% of its initial performance after 800 cycles.