Integration of capacity fading in an electrochemical model of Li-ion batteries

We have developed a new method to describe a fading model integrated with a parasitic reaction of rechargeable Li-ion batteries in the present work. In our work, the Li-ion battery reactions and the parasitic reaction are incorporated into one model. A new governing equation and a new field variable are presented in the new model to characterize the parasitic reaction and the relationship to the battery fading. Due to the new variations, the parameters that are changed with the battery’s aging are able to be calculated and updated automatically in the model. The parasitic reaction is assumed to obey a Tafel equation. The simulating results show that the distribution of overpotential of the parasitic reaction as function of x shapes, a figure close to a “V,” suggests the nonuniform distribution of the parasitic current. The parasitic reaction’s equilibrium potential is proved to be one of most important factors that determine the rate of the reaction. In addition, the cutoff charging state of charge (SOC) has a large influence on the parameters related to the rate of the parasitic reaction. Therefore, controlling the charging SOC can be seen as an effective method to protect the battery from aging.