Copper incorporated in Li3V2(PO4)3/C cathode materials and its effects on high-rate Li-ion batteries

Abstract

Copper incorporated in Li3V2(PO4)3/C cathode materials for high-rate Li-ion batteries were prepared by a self-catalysed sol-gel approach followed by a sintering process. The effect of copper incorporating amounts on the crystal structure, morphology and related electrochemical properties of Li3V2(PO4)3/C was investigated. It is noteworthy that the impurity Li3PO4 phase can be effectively affected by copper-incorporating without any significant influence on the surface morphology and crystal structure; moreover, the carbon layer coated onto Li3V2(PO4)3-Cu0.05/C can be separated into the porous inner layer and the graphene-type outer layer. Benefiting from above two factors, copper-incorporated Li3V2(PO4)3/C composite with improved electrochemical properties has been achieved. In comparison with pure Li3V2(PO4)3/C, the Li3V2(PO4)3-Cu0.05/C composite delivers a reversible specific capacity of 123.3 mAh g−1 after 50 cycles at a current rate of 1C and 116.2 mAh g−1 at 10C, maintaining 98.2% and 89.5% of capacity retention, respectively, and even cycled at 20C rate, it still possesses 105.4 mAh g−1 of discharge capacity, demonstrating an excellent rate capability and cycling stability.