Drying of Compact and Porous NCM Cathode Electrodes in Different Multilayer Architectures: Influence of Layer Configuration and Drying Rate on Electrode Properties

Porous, nanostructured particles ensure the wetting of electrolyte up to the particle core and shortened diffusion paths, which is relevant not only for lithium-ion batteries but also for postlithium systems like sodium-ion batteries. The porous structure leads to a high C-rate capability. However, compared to conventional compact NCM, porous NCM shows a reduced adhesion force but no or only slight negative influence on C-rate capability by binder migration at higher drying rates. Herein, a multilayer concept is used to increase the adhesion force with equal or better electrochemical performance compared to single-layer electrodes. Compact particles of high volumetric energy density and porous particles with high C-rate capability are combined in a simultaneously coated multilayer electrode. Multilayers with compact NCM toward the current collector and porous NCM with reduced binder content toward the separator side show an about 16-times higher adhesion force at lower drying rate and an about ten-times higher adhesion force at increased drying rate compared to electrodes produced of porous NCM only. The specific discharge capacity of the multilayers is increased by 88% at the lower and 67% at the higher drying rate for a discharge rate of 3C compared to a single layer with compact NCM.