The low and high temperature electrochemical performances of Li3V2(PO4)3/C cathode material for Li-ion batteries

Li3V2(PO4)(3)/C cathode material is synthesized by a carbon-thermal reduction method using polyvinyl alcohol as carbon source at 700 degrees C. The Li3V2(PO4)(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 Vat 0.1 C, respectively. However, the electrode only delivers small discharge capacities at -20 degrees 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. (C) 2011 Elsevier B.V. All rights reserved.