Study on xLiVPO(4)F·yLi(3)V(2)(PO(4))(3)/C Composite for High-Performance Cathode Material for Lithium-Ion Batteries

Cathode materials made of xLiVPO(4)F·yLi(3)V(2)(PO(4))(3)/C (x:y = 1:0, 2:1, 0:1) are synthesized via a feasible sol-gel method for high-performance lithium-ion batteries. The structures, morphology, and electrochemical properties of the composites are thoroughly investigated. The results show that LiVPO(4)F/C, Li(3)V(2)(PO(4))(3)/C, and 2LiVPO(4)F·Li(3)V(2)(PO(4))(3)/C can be synthesized under 750°C without the formation of impurities. Meanwhile, the unique morphology of the 2LiVPO(4)F·Li(3)V(2)(PO(4))(3)/C composite, which is porous, with nanoflakes adhering to the surface, is revealed. This composite integrates the advantages of LiVPO(4)F and Li(3)V(2)(PO(4))(3). There are four discharge plateaus near 4.2, 4.1, 3.7, and 3.6 V, and the cathode material delivers high capacities of 143.4, 141.6, 133.2, 124.1, and 117.6 mAh g(−1) at rates of 0.1, 0.2, 0.5, 1, and 2 C, respectively. More importantly, the discharge capacity can be almost fully recovered when the discharge rate returns to 0.1 C. The study is highly promising for the development of cathode material for LIBs.