low-temperature behavior of li3v2(po 4)3/c as cathode material for lithium ion batteries

The electrochemical performance of Li 3 V 2 (PO 4 ) 3 /C was investigated at various low temperatures in the electrolyte 1.0 mol dm -3 LiPF 6 /ethyl carbonate (EC)+diethyl carbonate (DEC)+dimethyl carbonate (DMC) (volume ratio 1:1:1). The stable specific discharge capacity is 125.4, 122.6, 119.3, 116.6, 111.4, and 105.7 mAh g -1 at 26, 10, 0, -10, -20, and -30 °C, respectively, in the voltage range of 2.3-4.5 V at 0.2 C rate. When the temperature decreases from -30 to -40 °C, there is a rapid decline in the capacity from 105.7 to 69.5 mAh g -1 , implying that there is a nonlinear relationship between the performance and temperature. With temperature decreasing, R ct (corresponding to charge transfer resistance) increases rapidly, D (the lithium ion diffusion coefficients) decreases sharply, and the performance of electrolyte degenerates obviously, illustrating that the lowtemperature electrochemical performance of Li 3 V 2 (PO 4 ) 3 /C is mainly limited by R ct , D Li , and electrolyte.