储能用锰酸锂电池阻抗谱研究

Research on Impedance Spectroscopy of Manganese Acid Lithium Ion Battery for Energy Storage

对于储能用锰酸锂电池,除了需要准确把握其外特性,还应充分认识与电池外特性相对应的电池内特性。对储能用锰酸锂电池产品进行100%~0%荷电状态(SOC)的电化学交流阻抗测试,通过等效电路拟合,解析反映锰酸锂电池锂离子嵌入/脱出电化学反应和电荷扩散过程的电路元件参数值。结果表明锰酸锂电池的电化学反应电阻大于欧姆电阻,且随着电池SOC的降低而逐渐提高;锰酸锂电池电化学反应引起的电容效应弱于电荷扩散产生的电容效应,在20%SOC以下时锰酸锂电池扩散阻抗值随SOC的降低而逐渐提高;电池经历1 C高温(45℃)循环700次后电化学反应电阻明显提高,同时高温循环弱化了因电化学反应产生的电容效应。

For a better application of the manganese acid lithium ion battery in the field of energy storage,it is necessary to master not only output performance but also internal characteristics. A commercial manganese acid lithium ion battery was measured by electrochemical impedance spectrum(EIS) under the state of charge(SOC) ranging from 100% to 0%. By a supposed equivalent circuit and the afterwards fitting,parameters of every element in the circuit that represent Li+intercalation/deintercalation or charge transfer were obtained. As a new battery,the electrochemical reaction resistance is bigger than the ohmic resistance. It increases while SOC gradually lowers. In addition,the diffusion impedance also increases while SOC decreases less than 20%. The capacitive effect caused by electrochemical reactions is weaker than that caused by charge diffusion. However,after 700 cycles at 1 C at 45 ℃,the electrochemical reaction resistance increases obviously whereas the capacitive effect caused by electrochemical reaction is weakened.