Because of the disadvantages of commercial graphite anodes for high-power lithium-ion batteries, a kind of spinel nanolithium titanate (Li4Ti5O12)/graphene microsphere composite [denoted as LTO/reduced graphene oxide (rGO)] is successfully synthesized. The as-prepared composite is made up of curled graphene sheets which are anchored with nano-Li4Ti5O12 particles. These nano-Li4Ti5O12 particles are uniformly decorated on the conductive graphene framework and their sizes range from just 15 to 20 nm. In the as-prepared composite, the curled graphene sheets form a unique mesopore-oriented structure which provides plenty of three-dimensional channels for ion transportation. These structure characters greatly improve both the electron conductivity and Li+ diffusion ability. The ratio of pseudocapacitive capacity dramatically increases in the obtained LTO/rGO composite and generates excellent ultrahigh rate performances. The as-prepared LTO/rGO composite delivers a reversible capacity of 70.3 mA h g-1 at 200 C and a capacity retention of 84.7% after 1000 cycles at 50 C. As the current density varies from 30 to 100 C, the special capacity remains unchanged (about 112 mA h g-1). These results show that the graphene framework-supported nano-Li4Ti5O12 composite has potential application in high-power lithium-ion batteries.
Keywords: conductive framework; graphene; high power capability; mesopore-oriented; nano-Li4Ti5O12; pseudocapacitive capacity.