The low and high temperature electrochemical performances of Li 3V 2(PO 4) 3/C cathode material for Li-ion batteries

Abstract

Li 3V 2(PO 4) 3/C cathode material is synthesized by a carbon-thermal reduction method using polyvinyl alcohol as carbon source at 700 °C. The Li 3V 2(PO 4) 3/C electrode presents a high initial discharge capacity of 84.3, 111.1, 128.7, 129.2 and 132.1 mAh g −1 at −20, 0, 25, 40 and 65 °C between 3.0 and 4.3 V, and 118.9, 132.1, 187.6, 180.3 and 172.2 mAh g −1 between 3.0 and 4.8 V at 0.1 C, respectively. However, the electrode only delivers small discharge capacities at −20 °C at 10 C rate. The capacity fade at low temperatures is mainly attributed to the reduced ionic and electronic conductivity of the electrolyte, the increased impendence of solid electrolyte interface (SEI) and charge-transfer resistance on the electrolyte–electrode interfaces. At higher temperatures, the capacity increases with increasing temperature between 3.0 and 4.3 V, but decreases between 3.0 and 4.8 V. In the potential range of 3.0–4.8 V, the larger crystal structural distortion and non-uniformity of SEI layer at high temperatures may be the main reasons for the capacity loss.