A study of the interactive effect of cathode material loss, SEI formation and lithium plating in NMC-graphite battery modeling

Lithium-ion batteries (LIBs) with nickel-manganese-cobalt (NMC) cathode and graphite anode are widely used in electronic devices and electric vehicles. Understanding the degradation mechanisms of NMC-graphite LIBs is critical to estimating the battery life. However, there is a lack of research focusing on the interactions between different degradation mechanisms. In this work, an electrochemical-mechanical model is applied to estimate the cycling capacity loss of the NMC-graphite battery, with the SEI formation lithium plating and cathode material loss considered. Comparisons of voltage and capacity loss behavior between simulations and experiments are presented. The effects of interactions between cathode active material loss, SEI formation and lithium plating on battery capacity loss are quantified. The results demonstrate that the loss of cathode active material would affect capacity loss caused by SEI formation and lithium plating due to the change of local polarization on the anode. Therefore, simply adding up the capacity loss caused by each single degradation mechanism can be inaccurate in computing the overall capacity loss of LIBs. This paper represents an important step to learning the path dependence effect on battery capacity loss.