Effects of temperature on electrochemical impedance spectroscopy of the LiFePO4 battery

Change in temperature affects cycle life and performance of the LiFePO 4 battery. Thus, different temperature (-20°C∼45°C) performance of the LiFePO 4 battery was investigated by electrochemical impedance spectroscopy (EIS). The prismatic 40 Ah batteries testing was utilized to show the effect of increasing temperature on ohmic impedance (RΩ) and charge transfer internal resistance (R ct ), and evaluate electrical performance consistency of a batch of batteries The results showed that the effect of increasing temperature on RΩ was very slight and on R ct was more obvious. The change was believed to result from ion moving speed, chemical reaction speed and ion charge transfer process at the electrode/electrolyte interface. At low-temperature (-20°C), the standard deviation of R was larger than other higher temperature, indicating that the electrical performance difference of the battery pack was large under low temperature condition.