The improved study of thermal dependence equivalent circuit model for supercapacitor

Supercapacitor, because of its advantage of high specific power, quick charging or discharging with high current rates, and long cycle life, is an interesting energy storage for applications where high power is needed for only a few seconds, such as pulse-power supply systems and so on. With the widely using of supercapacitor all around the world, more and more attention has been focused on the temperature effect on its performance metrics such as capacitance, internal resistance and efficiency. In order to predict the terminal voltage of supercapacitor at different temperature, a three-branch RC equivalent circuit model is improved in this research, and it can predict the terminal voltage till to five to ten minutes after finish of charging or discharging. Firstly, a typical three-branch RC equivalent circuit model without temperature parameter is used to simulate the pulse charging and discharging behavior of a specific commercial type supercapacitor. Secondly, with the pulse charging and discharging experiment results under -40°C, -20°C, 0°C, 20°C, all parameters in circuit model are reset to a function of temperature, and the thermal dependence of parameters is discussed in detail and determined numerically. Finally, for the purpose of validating the correctness and the accuracy of the improved model, compared study of simulation results and experiment curves is done. Comparison results show that the fitting accuracy of the improved equivalent circuit model is satisfied in pulse charging and discharging at different temperature.