A facile one-step solid-state synthesis of a Li4Ti5O12/graphene composite as an anode material for high-power lithium-ion batteries

摘要

Li4Ti5O12/graphene composites with different graphene additives (0.47 wt%, 0.93 wt%, 1.99 wt%) were prepared by a facile one-step solid-state reaction with sand milling followed by sintering at 800 degrees C. The electro-chemical performance of the Li4Ti5O12/graphene composites is influenced significantly by the graphene proportion. The Li4Ti5O12/graphene composite with 0.93 wt% graphene (denoted GLTO-2) exhibits an excellent rate performance with specific charge capacities of 175.2, 175.8, 171.9, 167.9, 166.4, 164.1, 161.4159.4 and 150.8 mAh g(-1) at 0.2, 0.5, 1, 3, 5, 10, 15, 20 and 30 C (1 C = 160 mAh g(-1)), respectively. GLTO-2 also shows a remarkable long-term cycling stability with a charge-capacity retention of 80.2% after 2000 cycles at a rate of 5 C, which is higher than that of pure Li4Ti5O12 (57.0%). The significant enhancement in electrochemical properties of GLTO-2 could be attributed to the smallest polarization and charge-transfer resistance (47.3 Omega), and the highest Li+ diffusion coefficient (1.04 x 10(-9) cm(2) s(-1)) demonstrated by the cyclic-voltammetry and electrochemical-impedance spectra tests. Our study provides a facile strategy for preparing Li4Ti5O12/graphene composites with an outstanding rate capability for high-power lithium-ion batteries, which is desirable for large-scale applications.