Development and Upscaling of a Waterborne Formulation for High‐Energy Density NMC811 Cathodes

Abstract

The pursuit of high‐energy lithium‐ion cells has led to an increase in the fraction of nickel in the LiNixMnyCozO2 (NMC, with x+y+z=1) layered oxide, a state‐of‐the‐art cathode material in electric vehicles. NMC is usually processed using organic solvents that are non‐sustainable. Nevertheless, increasing the Ni fraction entails a decrease in the electrode stability and the processability of this material in water. In this work, high‐nickel NMC materials have been subjected to water processing. In an initial stage, water sensitivity of the materials has been studied. Then, the formulation has been adapted to enhance the NMC fraction without penalizations in the electrochemical performance and compared to an organic solvent‐based formulation. The recipe developed, consisting of 93% of NMC, has been successfully upscaled to a semi‐industrial coating line. The pH buffering has been observed as a critical step to mitigate lithium leaching and implement this process in an industrial environment. The obtained electrodes have been tested in single‐layer pouch cells using silicon‐based negative electrodes, also processable in water‐based slurries. The resulting cells provide limited cycling life due to the low cyclability of the negative electrode but evidence that it is industrially viable to manufacture high‐energy cells consisting only of water‐processed electrodes.