Surface coating of a LiNi(x)Co(y)Al(1−x−y)O(2) (x > 0.85) cathode with Li(3)PO(4) for applying a water-based hybrid polymer binder during Li-ion battery preparation

To produce water-stable Ni-rich lithium nickel cobalt aluminum oxides (LiNi(x)Co(y)Al(1−x−y)O(2), x > 0.85, NCAs), the formation of trilithium phosphate (Li(3)PO(4))-coated layers on the NCA surfaces was attempted through the use of a surface reaction in a mixture of ethanol and water and a post-heat treatment at 350 and 400 °C. Based on the results of X-ray photoelectron spectroscopy (XPS), the coated layers consisted of nickel phosphate (Ni(3)(PO(4))(2)) and Li(3)PO(4). The coated NCA surface could have sufficient water stability to maintain the cathode performance in a water slurry for 1 day. In addition, the coated layers formed on the NCA surfaces did not block Li(+)-ion transfer through the Ni(3)(PO(4))(2)/Li(3)PO(4)-coating layers and enhanced the high-rate discharge performance.