Environmental Impacts of Graphite Recycling from Spent Lithium-Ion Batteries Based on Life Cycle Assessment

Abstract

With the emergence of portable electronics and electric vehicle adoption, the last decade has witnessed an increasing fabrication of lithium-ion batteries (LIBs). The future development of LIBs is threatened by the limited reserves of virgin materials, while the inadequate management of spent batteries endangers environmental and human health. According to the Circular Economy principles aiming at reintroducing end-of-life materials back into the economic cycle, further attention should be directed to the development and implementation of battery recycling processes. To enable sustainable paths for graphite recovery, the environmental footprint of state-of-the-art graphite recycling through life cycle assessment is analyzed quantifying the contribution of nine recycling methods combining pyrometallurgical and hydrometallurgical approaches to indicators such as global warming, ozone layer depletion potential, ecotoxicity, eutrophication, or acidification. Laboratory-scale recycling is scaled up into pilot-scale processes able to treat 100 kg of spent graphite. With values ranging from 0.53 to 9.76 kg·CO2 equiv. per 1 kg of graphite, energy consumption and waste acid generation are the main environmental drivers. A sensitivity analysis demonstrates a 20-73% impact reduction by limiting to one-fourth the amount of H2SO4. Combined processes involving hydrometallurgy and pyrometallurgy give environmentally preferable results. The electrochemical performance of regenerated graphite is also compared with virgin battery-grade graphite. This work provides cues boosting the environmentally sustainable recycling of spent graphite from lithium-ion batteries, strengthening the implementation of circular approaches in the battery industry.