Modeling the effects of state of charge and temperature on calendar capacity loss of nickel-manganese-cobalt lithium-ion batteries

Lithium-ion (Li-ion) batteries with nickel-manganese-cobalt (NMC) cathode and graphite anode are popularly used in portable electronic devices and electric vehicles. Calendar loss of the lithium-ion battery is a dominating factor in battery degradation during long-term usage. However, only a few physics-based modeling works were reported on studying the calendar capacity loss of NMC-graphite Li-ion batteries, while none of them can depict the complete voltage behavior during the storage period. In this work, a Pseudo-2D model for an NMC-graphite Li-ion battery was developed and applied to investigate its calendar loss behavior. Various factors affecting the calendar loss of the NMC-graphite batteries were systematically studied, with the results validated using experimental data of a Sanyo 18,650 cylindrical cell. It was found that at 25 °C working temperature and 100% state of charge (SOC), the capacity drops 6.3% of its original capacity after 10 months. Our simulation results demonstrate that a lower SOC and a proper cell working temperature could prolong the battery life during the storage period. This modeling work can help improve understanding of the calendar loss behavior of NMC-graphite Li-ion batteries and provide valuable guidance for battery performance optimization in the future.