A physical allocation method for comparative life cycle assessment: A case study of repurposing Australian electric vehicle batteries.

As the World's dependence on lithium battery technology continues its rapid growth, reserves of key manufacturing minerals are not forecast to keep pace with demand. Repurposed electric vehicle batteries offer a viable means to reduce the number of retired lithium-ion batteries proceeding directly to landfill and prolong their useful life while end of life solutions, including recycling, are developed and matured. This paper presents a novel physical allocation method based on the critical performance criteria: remaining capacity, module retention rate and repurposed electric vehicle battery lifetime (second life). To verify the allocation method, a case study directly compares the emissions generated by a repurposed electric vehicle battery and a virgin stationary storage battery of equivalent capacity in Australia. The repurposed battery has a smaller footprint across all eight environmental impact categories, provided it operates for a minimum of six years. A sensitivity analysis shows battery repurposing can achieve carbon reductions if the repurposed electric vehicle battery lifetime exceeds 4.25 years. The breakeven points for remaining capacity and module retention rate at the beginning of the second life occur at 66% and 75% respectively. In addition, a comprehensive repurposing life cycle inventory was developed for the repurposing phase which includes all added components and processes required to repurpose an electric vehicle battery to function as a stationary storage battery. Further analysis discusses the influence of increased production efficiencies over time when comparing product systems, and the need to account for these changes in allocation methodology. [Display omitted] [ABSTRACT FROM AUTHOR]