Combined modification by LiAl_(11)O_(17) and NaAl_(11)O_(17) to enhance the electrochemical performance of Li_4Ti_5O_(12)

摘要

The intrinsically moderate Li-ion diffusion coefficient and poor electronic conductivity of Li4Ti5O12 ( LTO) restricts the practical application in Li-ion batteries. In view of the rapid two-dimensional diffusion channels in ionic conductor of LiNaAl22O34 for Li-ions, the LTO modified by combining equivalent molar ratio of LiAl11O17 with NaAl11O17 (LNAO) was fabricated by a simple reaction between LiNO3, Na2CO3, Al (NO3)(3)center dot 9H(2)O and LTO at various sintering temperatures. The product with a LNAO/LTO mass ratio of 0.0106 and calcined at 600 degrees C achieved reversible capacities of 163.8, 160.6, 156.5, 150.9, 132.9 and 163.4 mAh g(-1) at the current rates of 100, 200, 400, 800, 1600 and 100 mA g(-1), respectively. Even cycled 800 times at 500 mA g(-1), a capacity of 147.9 mAh g(-1) was retained. The outstanding cycling and rate performance is attributable to the simultaneously formed LNAO coating on the LTO particles and superficial Al3+ doping in the LTO, achieving combined improvement in the ionic and electronic conductivities of LTO and thus boosting the comprehensive electrochemical performance of LTO. (C) 2018 Elsevier B.V. All rights reserved.