Synthesis of Water-Resistant thin TiO_x Layer-Coated High-Capacity LiNi _a Co _b Al_1-a-B O₂ (a > 0.85) Cathode and Its Stable Charge/Discharge Cycle Cathode Performance to Apply a Water-Based Hybrid Polymer Binder to Li-Ion Batteries

Titanium oxide (TiOx) coating was treated on a surface of A LiNi a Co b Al1-a-b O2 (a > 0.85) cathode material, which exhibited high capacity of 200 mAhg-1 and however, the charge/discharge capacity with pristine LiNi a Co b Al1-a-b O2 degraded seriously after contacting with water. The formation of TiOx layer on the cathode material surface was characterized with field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The TiOx-coated LiNi a Co b Al1-a-b O2 cathode material did not form bubbles in the coating process when a water-based slurry was prepared with TiOx-coated LiNi a Co b Al1-a-b O2 particles and a water-based hybrid polymer binder, and then the slurry was coated on a aluminum current collector. Therefore, the cathode electrode fabricated with TiOx-coated LiNi a Co b Al1-a-b O2 exhibited comparable cycle and rate performance with the cathode which was composed of pristine LiNi a Co b Al1-a-b O2 particle and organic solvent-based PVdF binder even after it was exposed in the water-based slurry for 7 days.