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

Official URL: http://dx.doi.org/10.1002/est2.154

One of the main problems of LiNi0.80Co0.15Al0.05O2(NCA) materials is the sidereactions occurring during battery cycling. These side reactions result in capac-ity 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. Apply-ing these layers may require additional complicated steps. To overcome thisproblem, we focused on coating the NCA electrode with a polymeric ion con-ductive layer that can easily be applied. For this purpose, using an ion-conductive polymer is a novel approach. We used Nafion as the protectivelayer on NCA electrodes. While the Nafion layer can protect the surfaceagainst the side reactions, it does not prevent the Li+ion flow. Following thispurpose, we synthesized NCA by a modified co-precipitation method followedby sintering at 750C. After the preparation of the NCA cathodes, we coatedthe surfaces with a more straightforward drip coating. The Nafion-coated elec-trodes delivered a superior electrochemical performance with 100% of dis-charge capacity retention even after 100 cycles at 0.1C. The electrochemicalimpedance spectroscopy revealed that the Nafion coating could effectively pre-vent passive layer formation, which causes capacity fading.