Effect of calendering and temperature on electrolyte wetting in lithium-ion battery electrodes

The formation process during which the liquid electrolyte wets into the porous electrode films usually takes several days or weeks at elevated temperatures, which poses a distinct bottleneck in the manufacturing line of lithium-ion batteries, especially for large-size batteries. However, despite the significance of achieving rapid and complete wetting, reliable scientific investigation on the wettability between the porous electrode and the liquid electrolyte has rarely been reported. In this study, a systematic study of the effect of different manufacturing factors on electrolyte wetting rate is conducted. The effect of calendering degree and wetting temperature on the electrodes obtained through both organic solvent-based processing and water-based processing are studied in detail. The results suggest that although increasing calendering degree increases volumetric energy density, it generally reduces electrolyte wetting rate. While switching anode manufacturing from conventional processing to aqueous processing retards the electrolyte wetting process, switching cathode processing from organic system to aqueous system can drastically influence the pore structure of the cathodes, resulting in irregularly shaped wetted regions. The results also show that while the electrolyte wetting rate of all the tested electrolytes increases with increasing temperature, the change is significant only for the electrolytes with relatively high salt concentrations.