Application of the Jiles–Atherton model to construct the open-circuit voltage hysteresis model and determine the decommissioning of LiFePO4 batteries

Here, the Jiles–Atherton (J–A) hysteresis model is constructed based on the magnetic properties between the electrolyte and electrodes and is applied to the voltage hysteresis model of LiFePO4 batteries to evaluate the battery degradation degree. By constructing the voltage hysteresis model between the open-circuit voltage (OCV) and state of charge (SOC), the authors estimated the voltage hysteresis parameters of the J–A model using a differential algorithm and accurately described the OCV–SOC relationship of the battery. Finally, the battery degradation is evaluated according to changes in model parameters to determine whether the battery should be decommissioned. LiFePO4 batteries of identical specifications (ANR26650M1-B, 3.3 V, 2.5 Ah) were tested, including 30 brand-new batteries and 16 batteries that had been used for more than two years. The SOC–OCV curve data were measured under the 1C charge-discharge mode with fixed current and voltage, and the changes in voltage hysteresis curve model parameters were estimated as the basis for theoretical validation. Furthermore, the battery degradation degree was determined using the area under the voltage hysteresis curve. Results showed that the constructed model can accurately collect the battery degradation information and determine the battery degradation degree.