LiNi0.33Co0.33Mn0.33O2 (NCM-111) is one of the most frequently applied cathode materials for lithium ion batteries in mobile applications. Changing the particle morphology from compact particles towards secondary particles with open pore structure and reduced primary particle size is one approach to improve the electrochemical performance (rate capability, cycle stability), as could be demonstrated in previous investigations .
To incorporate such a porous and nanostructured material into batteries which take full advantage of the modified morphology, the electrode processing has to be adapted correspondingly. The following aspects have to be considered:
• Porous particles increase the total porosity of the electrode. To avoid a reduction of the volumetric energy density, the calendaring step has to be enhanced – without destroying the integrity of the porous particles.
• Binder distribution within the electrode layer is affected by the additional particle porosity. The ability to adhere the electrode layer to the current collector foil is reduced as the binder partially infiltrates the pore network of the NCM-particles.
• Aqueous electrode processing is preferable to avoid usage of harmful organic solvents like NMP. Due to the substantially increased surface area, interactions between water and active material require higher attention; in particular, as conventional NCM powders typically reveal somewhat lower capacities when water-based binder systems are applied.
The presentation will demonstrate how processing affects the electrode microstructure and how this correlates with electrochemical characteristics measured on the basis of full-cell tests.