Evaluation of the sustainability of technologies to recycle spent lithium-ion batteries, based on embodied energy and carbon footprint

Battery demand is estimated to growth at a 25% annual rate, to reach a volume of 2600 GWh in 2030. Recovering critical raw materials from end-of-life batteries is now mandatory to limit the need of primary raw materials in the long-term. However, recycling of lithium-ion batteries (LIBs) is still in its early stage. Many technologies have been proposed, that consist of a combination of mechanical processing, often after thermal pre-treatment, ended up to hydrometallurgical or pyrometallurgical processing. All these methods have several pros and cons in terms of applicability, safety, environmental impact, eventual recovery efficiency of the components, and economic factors. In this frame, the evaluation of the sustainability of the proposed technologies plays a fundamental role in selecting the most suitable approaches able to support material supply for batteries, identifying the major solutions to optimize the end-of-life management strategies for LIBs, in the perspective of a circular economy context. However, LCA was developed to evaluate commercially mature technologies. This paper aims to propose and discuss, for the first time, the sustainability of 33 different technologies available in literature for LIBs recovery, even if developed only at laboratory level, by a screening approach, preliminary to LCA analysis. For this purpose, ESCAPE (standing for Evaluation of Sustainability of material substitution using CArbon footPrint by a simplified approach) tool based on the calculation of embodied energy and carbon footprint is used. Based on ESCAPE analysis results, this work shows and discusses the parameters that affect the technologies sustainability (thermal and mechanical treatments and chemicals and water use). The results, in accord with preliminary available LCA data, indicate that chemicals and ultrapure water consumption are the most energy-intensive processes drivers, showing that pyrometallurgy can limit carbon footprint and energy consumption in comparison to hydrometallurgy. Finally, by using the ESCAPE index, it is shown that some technologies may be improved for example by using industrial water instead of ultrapure water and/or by recycling the chemicals used for leaching steps. In summary it is shown that ESCAPE tool can be used in supporting eco-design strategies with the aim to facilitate the understanding of environmental implications of proposed LIBs recovery technologies and to focalize the research toward the more promising ones.