Enhanced rate performance of nanosized Li₄Ti₅O₁₂/graphene composites as anode material by a solid state-assembly method

Nanosized Li₄Ti₅O₁₂/graphene materials have been successfully synthesized by a solid state-assembly method. As the anode materials for lithium ion batteries, nanosized Li₄Ti₅O₁₂/graphene exhibits higher specific capacity, much improved rate capability, and better cycle stability than the pure Li₄Ti₅O₁₂. In the potential range of 1.0-2.0 V at room temperature, Li₄Ti₅O₁₂/graphene with weight ratio of LTO:GO to 1000:5 shows discharge capacities of more than 144 and 96.2 mAh g^-1 after 100 cycles at 1C and 3C charge-discharge rates, while the correspond discharge capacities of pure Li₄Ti₅O₁₂ are only 108 and 75.4 mAh g^-1, respectively. The resulting Li₄Ti₅O₁₅/graphene (1000:5) sample demonstrates remarkable rate capability in that it delivers a reversible capacity of 53.4 mAh g^-1 in the 1000th cycle at 10C charge-discharge rate, about 240% that of pristine Li₄Ti₅O₁₂ particles (22.2 mAh g^-1). The low charge-transfer resistance and large lithium ion diffusion coefficients confirmed that Li₄Ti₅O₁₂/graphene materials possessed better electronic conductivity and lithium ion mobility. The present work demonstrates that Li₄Ti₅O₁₂/graphene composite is a promising anode material for high-rate and long life lithium ion batteries and this simple preparation method makes its production on a large scale.