Evaluation of EV battery degradation under different charging strategies and V2G schemes

Electric vehicles (EVs) are key to cut down transport CO2 emissions, but the bottleneck lies in costly batteries. Vehicle-to-grid (V2G) can bring benefits to both the power grid and EV owners, but its implementation faces challenges due to the concern of battery degradation. In this paper, EV battery degradation under various charging strategies and V2G operational schemes is evaluated. Based on an empirical capacity fade model and real-world operational data, the capacity losses in lithium-ion batteries under each scenario are quantified. Delayed charging is found to be beneficial to reduce the ageing caused capacity loss of EV batteries. Analytical results also show that providing V2G services does not necessarily accelerate the battery degradation; in some cases, it even mitigates the ageing process. A case study undertaken shows that, compared to non-V2G scenario (no battery discharging to the grid), battery capacity loss under V2G is reduced by 13.51%. This work highlights the practices of implementing proper charging strategy and V2G scheme to reduce the negative impact on the batteries lifespan.