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ABSTRACT

Purpose The purpose of this study was to analyze the environmental trade-offs of cascading reuse of electric vehicle (EV) lithium-ion batteries (LIBs) in stationary energy storage at automotive end-of-life. Methods Two systems were jointly analyzed to address the consideration of stakeholder groups corresponding to both first (EV) and second life (stationary energy storage) battery applications. The environmental feasibility criterion was defined by an equivalent-functionality lead-acid (PbA) battery. A critical methodological challenge addressed was the allocation of environmental impacts associated with producing LIBs across the EV and stationary use systems. The model also tested sensitivity to parameters such as the fraction of battery cells viable for reuse, service life of refurbished cells, and PbA battery efficiency. Results and discussion From the perspective of EV applications, cascading reuse of an LIB in stationary energy storage can reduce net cumulative energy demand and global warming potential by 15 % under conservative estimates and by as much as 70 % in ideal refurbishment and reuse conditions. When post-EV LIB cells were compared directly to a new PbA system for stationary energy storage, the reused cells generally had lower environmental impacts, except in scenarios where very few of the initial battery cells and modules could be reused and where reliability was low (e.g., life span of 1 year or less) in the secondary application. Conclusions These findings demonstrate that EV LIB reuse in stationary application has the potential for dual benefit-both from the perspective of offsetting initial manufacturing impacts by extending battery life span as well as avoiding production and use of a less-efficient PbA system. It is concluded that reuse decisions and diversion of EV LIBs toward suitable stationary applications can be based on life cycle centric studies. However, technical feasibility of these systems must still be evaluated, particularly with respect to the ability to rapidly analyze the reliability of EV LIB cells, modules, or packs for refurbishment and reuse in secondary applications.

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A circular economy (CE)-inspired waste management hierarchy was proposed for end-oflife (EOL) lithium-ion batteries (LIBs) from electric vehicles (EVs). Life cycle eco-efficiency metrics were then applied to evaluate potential environmental and economic trade-offs that may result from managing 1,000 end-of-life EV battery packs in the United States according to this CE hierarchy. Results indicate that if technology and markets support reuse of LIBs in used EVs, the net benefit would be 200,000 megajoules of recouped cumulative energy demand, which is equivalent to avoiding the production of 11 new EV battery packs (18 kilowatt-hours each). However, these benefits are magnified almost tenfold when retired EV LIBs are cascaded in a second use for stationary energy storage, thereby replacing the need to produce and use less-efficient lead-acid batteries. Reuse and cascaded use can also provide EV owners and the utility sector with cost savings, although the magnitude of future economic benefits is uncertain, given that future prices of battery systems are still unknown. In spite of these benefits, waste policies do not currently emphasize CE strategies like reuse and cascaded use for batteries. Though loop-closing LIB recycling provides valuable metal recovery, it can prove nonprofitable if high recycling costs persist. Although much attention has been placed on landfill disposal bans for batteries, results actually indicate that direct and cascaded reuse, followed by recycling, can together reduce eco-toxicity burdens to a much greater degree than landfill bans alone. Findings underscore the importance of life cycle and eco-efficiency analysis to understand at what point in a CE hierarchy the greatest environmental benefits are accrued and identify policies and mechanisms to increase feasibility of the proposed system. Keywords:circular economy eco-efficiency industrial ecology lithium-ion battery waste management hierarchy waste policy Supporting information is linked to this article on the JIE website Conflict of interest statement: The authors have no conflict to declare.