Influence of the Mixing and Dispersing Process on the Slurry Properties and the Microstructure and Performance of Ultrathick Cathodes for Lithium-Ion Batteries

The influence of industrial-suited mixing and dispersing processes on the processability, structure, and properties of suspensions and electrodes for lithium-ion batteries is investigated for the case of ultrathick NCM 622 cathodes (50 mg cm(-)(2)). Performed with a 10 dm(3) planetary mixer, two different process strategies for the preparation of the suspensions are compared in which 1) all powders are mixed initially and the solvent is added stepwise so that the process starts with very high shear stress or 2) the powders are added stepwise to a binder solution so that lower shear stress is exerted. It is shown that the process strategy and within this, the level of solid content throughout the process as a measure of shear stress strongly affects the properties of the suspensions and the microstructure, mechanical quality, and electrochemical performance of the resulting electrodes. Compared with the more unfavorable processes following strategy: 1) the most beneficial process following strategy 2) leads to a strongly enhanced elasticity of ultrathick electrodes making them suitable for roll-to-roll processing and furthermore to a drastic increase of their rate capability expanding their range of outperforming state-of-the-art electrodes regarding energy density to higher current densities.