UC San Diego

As demand for electric vehicles and other electronic devices advances in the realm of possibilities, the demand for better-performing batteries with higher energy densities, fast charging capability, longer lifetime, etc… rises. One solution out of the many is to increase the cathode active material(CAM) percentage of the electrode, reducing the inactive material of the electrode. This solution theoretically results in lower parasitic side reactions and increased volumetric energy density. However, with the widely used solvent-based slurry casting processes, it is difficult to achieve high CAM electrodes as electrodes become more prone to cracking. In this study, by utilizing a dry electrode coating process, we fabricate a variety of high NCM percentage electrodes, up to 99.5%, and demonstrate stable full cell cycling of 95%-NCM and 97%-NCM cell with capacity retention of 86.3% and 83% after 100 cycles, respectively. However, 99%-NCM showed lower cycling performance, indicating the existence of an active material to inactive material ratio threshold in the cathode composition. The phenomenon is studied through SEM, 4-point probe test, and EIS data. These results open up possibilities for increasing the active material ratio in electrode fabrication to achieve higher energy density, thus reducing the thickness of the layer and the battery.