Preparation of Water-Resistant Surface Coated High-Voltage LiNi0.5Mn1.5O4 Cathode and Its Cathode Performance to Apply a Water-Based Hybrid Polymer Binder to Li-Ion Batteries

Water-resistant LiNi0.5Mn1.5O2 spinel cathode was prepared by surface coating with carbon, Al2O3 and Nb2O5 to use a water-based hybrid polymer (TRD202A, JSR, Japan) as a binder and to form the cathode film on an Al current collector. The surface composition and degree of the surface coverage of carbon, Al2O3 and Nb2O5 were characterized with field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The coated LiNi0.5Mn1.5O2 particles not only exhibited water-resistant property but also showed no decrease in discharge capacity and only a small degradation of discharge rate performance. In addition, the coated LiNi0.5Mn1.5O2 particles, that were exposed to water-based binder solution for one week, exhibited the same charge discharge cycle performance as observed for the cathode of the pristine LiNi0.5Mn1.5O4 particles, suggesting that the coated particles are promising as cathode materials with a water-resistant property and therefore water can be used as solvent for preparing the cathode slurry solution in the place of e.g., carcinogenic N-methyl-2-pyrrolidone which is used actually. (C) 2016 Elsevier Ltd. All rights reserved.