锂离子电池 2 种内阻测试方法关联性的研究

文章基于锂离子全电池及半电池体系, 研究其在 $ 10\% \sim 90\% $ 荷电状态 (state of charge, SOC) 内直流阻抗 (direct current resistance, DCR) 与交流阻抗 (electrochemical impedance spectroscopy, EIS) 之间的关联性。结果表明: 在一定脉冲电流范围内, DCR 的大小仅与脉冲时间有关; 在 $ 1 \sim 100 \, mV $ 的扰动电压范围内, EIS 保持不变。当选取 EIS 谱图中交流阻抗处的时间常数 $ t_{R_{s} + R_{f} + R_{ct}} $ 作为 DCR 测试的脉冲时间时, 对于全电池体系, 2 种阻抗测试方法在所考察的 SOC 范围内均具有较好的关联性, 测得的阻抗值相对偏差小于 14.2%; 对于半电池体系, 2 种阻抗测试方法仅在 $ 40\% \sim 90\% $ SOC 内具有较好的关联性, 得到的阻抗值相对偏差小于 10.7%。该文将锂离子电池 2 种阻抗测试方法相关联, 对锂离子电池阻抗的测试及分析具有一定的意义。

The correlation between direct current resistance (DCR) measurement and electrochemical impedance spectroscopy (EIS) measurement in a state of charge (SOC) range from 10% to 90% for full-cell and half-cell lithium-ion batteries is studied. The results show that the DCR is only related to the pulse time within a certain pulse current range. The EIS remains unchanged in the disturbance voltage range of 1-100 mV. When taking the time constant $ t_{R_{s}+R_{t}+R_{ct}} $ at the electrochemical impedance in the EIS as the pulse time of the DCR, there is a good correlation between DCR and EIS at various SOC for the full cell and the relative deviation of impedance is less than 14.2%. And it is the same for the half cell only in 40%-90% SOC and the relative deviation of impedance is less than 10.7%. Two kinds of resistance measurement approaches are correlated in this paper, which is of significance for the impedance measurement and analysis of lithium-ion battery.