High rate cycling performance of nanosized Li4Ti5O12/graphene composites for lithium ion batteries

Nanosized Li4Ti5O12/graphene(LTO/graphene) materials have been successfully synthesized by a sol-gel method. The LTO/graphene composites exhibit a well-defined cubic spinel structure with an average particle size of approximately 200-500 nm. Compared with pure Li4Ti5O12, LTO/graphene composites show higher specific capacity, much improved rate capability and better cycle stability when used as anode materials for lithium ion batteries. The initial capacity of the LTO/graphene composite(0.5 wt%) reaches 170.7 mAh g−1 at 1C, which slightly decreases to 168.5 mAh g−1 after 100 cycles with a capacity loss of 1.3%. More importantly, the resulting LTO/graphene (0.5 wt%) sample demonstrates remarkable rate capability in that it delivers a reversible capacity of 108.4 mAh g−1 in the 1000th cycle at 10C charge-discharge rate, about 2.5 times that of pristine Li4Ti5O12 particles (44.1 mAh g−1). The improved high-rate capability, cycling stability, fast charge-discharge performance of LTO/graphene composites can be ascribed to the improvement of lithium ion diffusion and ionic conductivity by graphene-coating.