Unlocking sustainable power: advances in aqueous processing and water-soluble binders for NMC cathodes in high-voltage Li-ion batteries

Abstract

Current cathode electrode processing of lithium-ion batteries relies on the conventional use of polyvinylidene fluoride (PVDF) as a binder, accompanied by the toxic solvent N-methylpyrrolidone (NMP). Within cathode materials, the LiNi_xMn_1−x−yCo_yO₂ (NMC) families stand out as most promising candidates for the next generation of lithium-ion batteries, boasting high energy density and capacity. This review extensively compares traditional battery manufacturing methods with the use of emerging waterborne binders, highlighting the benefits in terms of cost-effectiveness, environmental sustainability, and enhanced processing conditions. The transition to sustainable aqueous processing encounters challenges, including pH elevation, aluminium collector corrosion, and lithium leaching from the NMC materials. The exploration extends to tailored binder selection and additives, crucial in optimizing electrochemical properties for distinct NMC compositions, such as LiNi_0.33Mn_0.33Co_0.33O₂ (NMC 111), LiNi_0.5Mn_0.3Co_0.2O₂ (NMC 532), LiNi_0.6Mn_0.2Co_0.2O₂ (NMC 622) and LiNi_0.8Mn_0.1Co_0.1O₂ (NMC 811), and addressing challenges inherent in their aqueous processing. The integration of aqueous binders promises advancements and also shapes a strategic outlook for future research, contributing significantly to the sustainability of lithium-ion batteries.