基于温度和SOC的退役电池电化学阻抗特性

Electrochemical impedance characteristics of retired battery based on temperature and SOC

以退役的电动汽车用磷酸铁锂(LiFePO_(4))正极锂离子电池为研究对象,分别在0℃、25℃、40℃和50℃下测得不同充放电荷电状态(SOC)的阻抗谱数据,基于锂离子电池内部电化学过程反应机理,建立退役磷酸铁锂电池的电化学阻抗模型LR[(RW)Q],并用ZSimDemo软件进行参数辨识。此模型在不同温度和SOC下都有较高的实测数据辨识精度,误差在0.01%以内,能较好地解析电池内部的动态传质过程。分析发现:退役电池的欧姆内阻、电荷传递阻抗与SOC的变化无关;欧姆内阻在0℃时较高,约为1.46 mΩ,电荷传递阻抗和扩散阻抗都与温度近似成反比关系;在40℃和50℃时,欧姆内阻、电荷传递阻抗和扩散阻抗的差别较小;在0℃时,退役电池内部的极化作用较强,使用时应注意欠压与过压保护。

The retired lithium iron phosphate(LiFePO_(4))cathode Li-ion battery of electric vehicle was taken as the research object,impedance spectrum data were measured under different state of charge(SOC)during charge-discharge at 0℃,25℃,40℃and 50℃.Then based on reaction mechanism of internal electrochemical process in Li-ion battery,a retired battery electrochemical impedance model[LR(RW)(Q)]was established,ZSimDemo software was used to identify the parameters.The model had a higher identification accuracy for the measured data under different temperature and SOC,the error was within 0.01%,which could well analyze dynamic mass transfer process inside the battery.It was found that the ohmic internal resistance and charge transfer impedance of retired battery were independent of SOC.The ohmic internal resistance at 0℃was higher,about 1.46 mΩ.Both the charge transfer impedance and diffusion impedance were approximately in inverse proportion to temperature.At 40℃and 50℃,the difference between ohmic impedance,charge transfer impedance and diffusion impedance was smaller.The internal polarization effect of retired batteries at 0℃was stronger,attention should be paid to under-voltage and over-voltage protection when using.