Synthesis and electrochemical performance of TiNb2O7 nanoparticles grown on electrochemically prepared graphene as anode materials for Li-ion batteries

In this study, the electrochemically exfoliated graphene nanosheets are used as conductive networks to enhance the electrochemical performance of titanium niobium oxide (TNO) nanoparticles as anode for Li-ion batteries (LIBs). The morphological analyses show that without using graphene, the TNO porous microspheres are formed through the self-assembly mechanism. However, by adding different contents of graphene (1, 3, and 5 wt%), the TNO nanoparticles are distributed on the graphene nanosheets. The distribution of the TNO nanoparticles on graphene nanosheets decreases due to the increase in the number of the graphene layer. Accordingly, the effectiveness of graphene nanosheets in enhancing the electrochemical performance of TNO depends on their content. The TNO/3 wt% graphene has the best electrochemical performance among all samples. At 20C, the capacity value of pure TNO is improved by two orders via the addition of 3.0 wt% graphene nanosheets. The capacity retention of the pure TNO at 1C and after 200 cycles is improved by about 25% by the addition of 3.0 wt% graphene nanosheets due to the buffering effect of graphene. However, the higher contents of graphene nanosheets (5.0 wt%) not only cannot improve the properties of TNO but also reduce its capacity.