Electro-thermal cycle life model for lithium iron phosphate battery

An electro-thermal cycle life model is developed by incorporating the dominant capacity fading mechanism to account for the capacity fading effect on the lithium ion battery performance. This model is comprehensively validated in three different aspects: (1) Electrochemical performance with different discharge C_rates (C/10, 1C, 3C) and different ambient temperature (0 °C, 25 °C, 45 °C, 60 °C); (2) battery surface temperature and center temperature during 6 C_rate constant current charge–constant voltage charge–constant current discharge (CC–CV–CC); (3) the amount of capacity fade indicated by the discharge potential curves of different cycle conditions. The feasibility of using the dominant factor only to represent the overall capacity fading in model is verified, and the model is used to predict OCV–SOC curves of cycled battery. To recover the capacity fade of cycled battery, either charging the negative electrode of fully discharged battery or charging the positive electrode of fully charged battery, could be an effective method, and possible capacity recovering design is presented. The decreasing trend of thermodynamic parameter Ea with increasing C_rate in the capacity fading function is deduced with increasing battery temperature when increasing discharge C_rate.