Modification of VPO4 with carbon and 3DG for high performance lithium-ion battery anode

Lithium-ion batteries (LiBs) are one of the most promising energy storage devices. However, the large-scale application of LiBs is limited by their electrochemical properties. In this study, we built a three-dimensional (3D) conductive network structure with carbon and 3DG coating VPO4 (VPO4@C@3DG) via a one-pot hydrothermal method with subsequent high-temperature annealing. The effects of the content of three-dimensional porous graphene (3DG) on the crystal structure, morphology, and electrochemical properties of VPO4/C are investigated using characterization and electrochemical test techniques. The SEM images show that the size of sphere-like particles of VPO4@C@3DG composite with 20 wt.% of 3DG (VPO4@C@3DG-20) is the smallest in all samples. In addition, the electrochemical experimental results reveal that VPO4@C@3DG-20 exhibits the best cycling and rate performance compared to other VPO4@C@3DG composites. Specifically, VPO4@C@3DG-20 achieves an initial charge capacity of 601.2 mAh g(-1) at 0.2 C (110 mA g(-1)) and keeps at 354 mAh g(-1) at the 100th cycle. This is because the introduction of 20 wt.% 3DG graphene inhibits the growth and aggregation of the particles, thus shortening the diffusion path of Li+. In addition, the 3D conducting network structure boosts the conductivity of the materials and buffers the volume variation resulting from the charging/discharging process.