Evaluating the environmental impacts of self-sustaining batteries for electric vehicles: Influence of user charging behaviour

Abstract

Optimizing charging time has become essential with the increasing electrification of the vehicle fleet. However, fast charging can accelerate battery degradation, reducing the battery's lifespan. To address this challenge, batteries and cooling systems are being developed with enhanced capacities to support fast charging. This paper evaluates the environmental impacts of such improved systems using a comparative cradle-to-grave life cycle assessment. The performance of the enhanced system is compared to that of a reference system currently available on the market, under two scenarios: an overnight charging scenario and a fast-charging scenario. An additional scenario is modeled to reflect a limit on the number of fast charges per month to avoid battery replacement. While most existing studies that include battery degradation look at fast-charging effects, they often do not define scenarios based on individual user charging choices and therefore, potential switch between fast and slow charging. In this study, the functional unit is 1 km driven, and the need for battery replacement is calculated using results from ageing tests at the cell level. A sensitivity analysis is also conducted to evaluate the influence of a more decarbonized electricity mix. In the overnight charging scenario, for Ecotoxicity Freshwater, the reference system performs better. Under fast-charging scenario, the improved system outperforms the other across all impact categories. With a decarbonized electricity mix, the reference system performs better across more categories in the overnight charging scenario. Overall, the study demonstrates that the comparative environmental results of the two systems depend strongly on the charging scenario.