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

Abstract

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.