Many countries have started their transition to a net-zero economy. Lithium-ion batteries (LIBs) play an ever-increasing role towards this transition as a rechargeable energy storage medium. Initially, LIBs were developed for consumer electronics and portable devices but have seen dramatic growth in their use in electric vehicles (EVs) and via the gradual uptake in battery energy storage systems (BESSs) over the last decade. As such, critical metals (Li, Co, Ni, and Mn) and chemicals (polymers, electrolytes, Cu, Al, PVDF, LiPF₆, LiBF₄, and graphite) needed for LIBs are currently in great demand and are susceptible to global supply shortages. Dramatic increases in raw material prices, coupled with predicted exponential growth in global demand (e.g., United States graphite demand from 2022 7000 t to ~145,000 t), means that LIBs will not be sustainable if only sourced from raw materials. LIBs degrade over time. When their performance can no longer meet the requirement of their intended application (e.g., EVs in the 8–12 year range), opportunities exist to extract and recover battery materials for re-use in new batteries or to supply other industrial chemical sectors. This paper compares the challenges, barriers, opportunities, and successes of the United States of America and Australia as they transition to renewable energy storage and develop a battery supply chain to support a circular economy around LIBs.

The number of plug-in electric vehicles sold in the U.S. has grown from 52,500 units in 2012 to over 160,000 vehicles sold in 2016; that is over a 300% increase in just four years. These vehicles’ batteries are going to reach auto dismantlers after approximately 10 years and require proper end-of-life processing, but the current solutions are not cost-effective. Argonne National Laboratory has developed a model that evaluates every stage of a battery’s life from material acquisition through recycling to provide a total cost and environmental impact. This allows for a direct comparison of virgin batteries to batteries with recycled content.

Direct recycling of lithium-ion battery (LIB) materials is a low-cost option for recovering critical materials due to the savings associated with the retention of the spent cathode’s crystal structure. In practice, end-of-life (EOL) recovered battery cathodes are usually isolated as a lithium deficient phase. The lithium deficiency was created by a variety of mechanisms, including electronic isolation of lithiated particles within the electrode, parasitic side reactions at low states of charge with the electrolyte, and solid electrolyte interphase (SEI) formation at the anode. In this overview, various lithium content restoration, or relithiation, methods will be discussed that have been used to return the lithium content and performance of EOL LiNi_0.6Mn_0.2Co_0.2O₂ (NMC622) cathodes to pristine NMC 622 conditions. The methods evaluated include solid-state thermal relithiation, hydrothermal relithiation, and ionothermal molten-salt relithiation. These processes were used to restore lithium content in 50 g batches of EOL NMC622 materials. After relithiation with each method, samples were annealed at elevated temperatures. The electrochemical performance of the restored NMC 622 material after each relithiation process compared favorably with the electrochemical performance of a commercial pristine NMC 622 material with ionothermal molten-salt relithiation demonstrating the highest specific capacity delivered with stable long-term cycling. SEM and XRD analysis showed no visible changes to the recycled material morphology and full recovery of the layered NMC 622 structure.