Layer by Layer: Improved Tortuosity in High Loading Aqueous NMC811 Electrodes

Thick electrode production is a key enabler for realizing high energy density Lithium-ion batteries. Therefore, the investigation of tortuosity as a crucial limiting parameter was conducted in this work. A thickness threshold (>150 mu m) for a drastic increase in tortuosity for aqueous processed LiNi0.8Mn0.1Co0.1O2 (NMC811) electrodes was determined. Symmetrical cells, under blocking conditions, were analyzed via electrochemical impedance spectroscopy. To counteract this phenomenon, multi-layer coated electrodes with varying binder concentrations were investigated. This novel coating method, combined with the reduction of binder material, leads to a tortuosity decrease of more than 80%, when compared to high-loading electrodes (>8.5 mAhcm(-2)) coated with the conventional doctor-blade technique. Additionally, a simplified transmission line model is opposed to a linear fitting method for analyzing the impedance data.