Effect of reduction agent on the performance of Li3V2(PO4)3/C positive material by one-step solid-state reaction

The effects of reduction agent on the electrochemical properties of Li3V2(PO4)3/C positive materials were studied. An one-step solid-state reaction route was applied to synthesize Li3V2(PO4)3/C samples. The humic acid, glucose and carbon were used as reduction agent. SEM images show that the particles of sample with humic acid as reduction agent merge with each other and form a porous structure, and yet the particles of sample synthesized using carbon as reduction agent are wrapped with small carbon particles and separate each other. Electrochemical tests show that the samples using humic acid and glucose as reduction agents have better cyclic performance than the one using carbon as reduction agent. At the 200th cycle, the sample using humic acid as reduction agent still keeps 145.2 mAh g−1 at 1 C charge and discharge rates. However, the sample using carbon as reduction agent shows a fast decline in capacity during cycling and has 54.5% capacity loss of the initial value after 200 cycles. The results indicate that different reduction agents can obviously affect the morphologies and electrochemical properties of the products.