Nafion‐coated LiNi0.80Co0.15Al0.05O2 (NCA) cathode preparation and its influence on the Li‐ion battery cycle performance

Abstract One of the main problems of LiNi 0.80 Co 0.15 Al 0.05 O 2 (NCA) materials is the side reactions occurring during battery cycling. These side reactions result in capacity fading, which in turn decreases the life span of the battery. Conventionally, for nickel‐rich cathodes, an inorganic layer is used as a protective layer. Applying these layers may require additional complicated steps. To overcome this problem, we focused on coating the NCA electrode with a polymeric ion conductive layer that can easily be applied. For this purpose, using an ion‐conductive polymer is a novel approach. We used Nafion as the protective layer on NCA electrodes. While the Nafion layer can protect the surface against the side reactions, it does not prevent the Li + ion flow. Following this purpose, we synthesized NCA by a modified co‐precipitation method followed by sintering at 750°C. After the preparation of the NCA cathodes, we coated the surfaces with a more straightforward drip coating. The Nafion‐coated electrodes delivered a superior electrochemical performance with 100% of discharge capacity retention even after 100 cycles at 0.1C. The electrochemical impedance spectroscopy revealed that the Nafion coating could effectively prevent passive layer formation, which causes capacity fading.