Water-based Pickering emulsion for concurrent washing and CNT coating of high-nickel layered lithium-ion cathodes

This study presents a novel water-based Pickering emulsion method for high-nickel cathodes, addressing two key challenges: removing surface residual lithium and enhancing cycle retention through CNT coating. This scalable and cost-effective approach combines lithium washing and CNT coating in a single process, minimizing water usage and preventing over-washing, while significantly improving the electrochemical cycle life. [Display omitted] •A water-based Pickering emulsion for one-step coating & residual Li (RL) removal.•Lab-scale test handles 50 g in 20 min., demonstrating efficiency & processability.•Preventing over-washing while removing RL more efficiently than other methods.•Achieving uniform CNT coating enhances electrochemical cycle life remarkably.•This method simplifies production & scalability for high-energy cathode materials. High-nickel layered oxide cathodes have gained prominence in lithium-ion battery systems due to their exceptional energy density. However, their unstable surface chemistry and the need for excess lithium precursor during synthesis result in residual lithium (RL), causing issues such as slurry gelation in electrode fabrication and gas evolution in battery operation. Furthermore, severe anisotropic lattice volume changes during cycling lead to chemo-mechanical degradation, which limits the cycle life of the cathode. In this study, we introduce a water-based Pickering emulsion method for conformal carbon nanotube (CNT) coating that simultaneously addresses RL while significantly enhancing cycle retention. Notably, we successfully scaled up the Pickering emulsion method to produce 50 g of CNT-coated NCA at the lab. This scalable process not only prevents over-washing to minimize active surface degradation but also achieves superior RL removal compared to conventional washing methods. The combined effects of RL removal and CNT coating result in a 12% improvement in capacity retention after 200 cycles, outperforming conventionally washed high-nickel cathodes. This integrated washing and coating approach offers a cost-effective and environmentally friendly solution, applicable to high-nickel cathodes and other battery materials that benefit from enhanced electrochemical performance.