Direct Recycling of End-of-Life Lithium-Ion Battery Cathode Materials through Redox Mediator Chemistry

Abstract

The surge of electric vehicle (EVs) adoption means imminent large amounts of lithium-ion battery waste will be generated. The need for recycled Li-ion batteries (LIBs) material is crucial for the sustainability of the renewable energy industry. The recycling process needs to be both economically and environmentally conscious. The 3 recycling methods being used today are pyrometallurgical, hydrometallurgical, and direct recycling. Pyrometallurgy is an expensive and energy-intensive process due to high energy requirements to reduce the End-Of-Life (EOL) Cathode materials. The component metal oxides are reduced to an alloy of Cobalt, Nickel, Manganese, Copper, and Aluminum. The hydrometallurgy process involves the use of aqueous solutions to leach the desired metals from EOL materials. This process is still expensive and has a considerable amount of waste generated from sintering, acid leaching, and chemical precipitation. Direct recycling on the other hand is cheaper and generates the least amounts of waste. Redox chemistry mechanism method for direct recycling is explored in this work to relithiate EOL NMC622 cathode material. Quinone-based redox mediators are used to restore lithium content in the EOL material. The redox mediator is reduced in the reaction and EOL is oxidized. These compounds can shuttle the charges very fast between lithium metal and the EOL. Analysis and characterization of the relithiated EOL NMC622 cathode material are carried out to compare with pristine baseline NMC622 cathode material. This approach will potentially pave way for quality material recovery at a low cost. This project is part of ReCell which is a collaborative effort to develop efficient and economical recycle and reuse methods for EOL battery cathodes. Figure 1