Sustainable Biorecovery of Critical Materials From Lithium-Ion Batteries: Techno-Economic Analysis, Life Cycle Assessment, Supply Chain Optimization

Abstract

The demand for lithium-ion batteries (LIBs) has surged in recent years, owing to their excellent electrochemical performance and increasing adoption in electric vehicles and renewable energy storage. As a result, the expectation is that the primary supply of LIB materials (e.g., lithium, cobalt, and nickel) will be insufficient to satisfy the demand in the next five years, creating a significant supply risk. The number of LIBs reaching their end-of-life (EOL) is expected to grow substantially in the next decade. These EOL LIBs represent a significant secondary source of materials that can be recovered and reused in LIBs or other products.Bioleaching has received substantial attention in recent years for its potential to recover metals in a more environmentally sustainable manner than conventional hydrometallurgical and or pyrometallurgical methods. Developing a cost-effective LIB bioleaching process could be a promising alternative to traditional energy-intensive technologies. The purpose of this study is to increase the bioleaching technology’s readiness for industrial adoption to recycle and recover value from spent LIBs in the United States by evaluating economic and environmental feasibility of the process, optimizing the process, and identifying the optimal supply chain configuration for the LIB bioleaching. First, techno-economic analysis (TEA) and life cycle assessment (LCA) evaluated economic viability and environmental sustainability of a novel bioleaching technology for value recovery from EOL LIB black mass, i.e., cathode-containing powder, under industrially relevant conditions. Black mass was leached using a biolixiviant produced from corn stover by Gluconobacter oxydans bacteria. Iron(II) was used as a reducing agent to promote metal dissolution. TEA estimated a potential average profit margin of 21% for processing 10,000 tons of black mass per year, which represents approximately 30% of the available black mass in the US in 2020. LCA demonstrated that bioleaching of spent LIBs could be more environmentally sustainable than alternative hydrometallurgical recovery methods such as hydrochloric acid leaching (16−19 kg vs. 43−91 kg CO2 equivalent global warming potential per kg of recovered cobalt). The TEA results are highly dependent on the cost of black mass production, which varies by EOL LIB collection and transportation costs. Emerging technologies for deactivating used LIBs for fire safety at collection centers will allow the transport of EOL LIBs as non-hazardous materials, lower the cost of preparing black mass and thereby increase economic prospects for EOL LIBs recycling using this approach. Second, another study described the process optimization of the bioleaching conditions for maximum economic competitiveness through design of experiments using iterative response surface methodology (RSM). After two iterations of RSM, i.e., (1) fractional factorial design and steepest ascent (2) central composite design and ridge analysis, the optimal condition for leaching black mass was identified as 2.5% pulp density in 75 mM gluconic acid biolixiviant at 55°C for 30 h. This condition recovered 57% to 84% of the nickel, 71% to 86% of the cobalt, 100% of the lithium, and 100% of the manganese, yielding an estimated positive net profit margin of 17%–26%. Third study evaluated the potential of bioleaching technology as a sustainable solution for recycling spent LIBs to help inform decision-making processes for stakeholders involved in LIB recycling supply chains. A supply chain model has been developed to include required upstream processes with the objective of maximize economic feasibility of LIB recycling through the technology. The model has been applied for the United States and optimal supply chain configuration was identified, considering the main affecting factors on the economic viability of the technology. The net present value of the supply chain is estimated to be $9.9 billion for operating over 10 years, achieving the maximum processing capacity of 900,000 tons of black mass per year. The economic viability of the technology was identified to be highly sensitive to the cost associated with purchasing black mass, which accounts for more than 40% of the total supply chain cost. The supply chain could tolerate a black mass price increase of $2.6/kg without a reduction in processing capacity, but prices higher than $3.6/kg significantly decrease the processing capacity of the supply chain, jeopardizing its economic sustainability. The study also examined the non-cooperative scenarios where each tier tries to maximize its own profit to demonstrate how the overall profitability of the supply chain changes with different pricing strategies of sortation facilities and acid producers. The study estimated that the maximum increase in non-recyclable paper and acid prices that the supply chain can tolerate are 400% and 250%, respectively, beyond which the supply chain is no longer sustainable.