To ensure an extensive market penetration of electric vehicles, among others, lithium ion batteries (LIBs) need to achieve a further reduction of the environmental impact and costs of the electrode manufacturing process. Aqueous processing of LIB cathode electrodes has become a vital strategy to substitute state-of-the-art teratogenic N-Methyl-2-pyrrolidone (NMP) solvent and the fluorinated polymer polyvinylidene difluoride (PVDF) binder with more sustainable materials, corresponding to 2 % of battery costs. Additionally, benefits like savings in investments and processes, e.g., via circumventing solvent recovery and a faster recycling can be expected.
Aqueous processing of Ni-rich layered oxide (NCM) cathodes is investigated and demonstrated, though obvious issues require further investigations, i.e., Li-leaching, aluminium dissolution/corrosion as well as moisture-sensitive CAM degradation. Individual and issue-targeted solutions are established in literature, while their relevance for individual processing step including meaningfulness of strategy combinations are less investigated and discussed. Therefore, the protection and stabilization of the NCM particle is considered in a bottom-up approach. In general, a coating is suitable to protect the initial NCM surface while other approaches including additives and binder are reasonable to protect fresh formed surfaces during cathode processing and cycling.
In this study, selected surface protection opportunities are investigated and rated considering ecological impact with an outlook towards competitiveness of aqueous processing in the future.