DC Resistance Analysis Based on Discharge Curve Analysis for Life Prediction of Lithium-Ion Batteries

摘要

The non-destructive DC internal resistance analysis technique was developed. This analysis is based on a physical model and can evaluate the resistance of the positive electrode, the negative electrode, and the residual ohmic resistance. Previously, the authors developed the discharge curve analysis technique that can evaluate the factors of capacity fade. These factors are (1) usable mass of the active materials of the positive and negative electrodes and (2) lithium-loss by side reactions. Also, the authors proposed the capacity-fading prediction based on this analysis, which showed more accurate predictions than the conventional "square root time rule". In this work, the authors improved the analysis technique to deal with both capacity-fade and resistance rise. It consists of 3 steps. Step 1 is to measure the specific discharge curves and resistance curves of the positive and negative electrodes with the half-cells. Here, the resistance curve means the relation between discharged capacity and internal resistance. Step 2 is to reproduce experimental discharge curves of the full-cells based on the previously proposed discharge curve analysis. Step 3 is to reproduce experimental resistance curves of the full-cells base on the model equations, and fixed parameters of (3) charge-transfer resistance ratio on the unit reaction area and (4) residual ohmic resistance.