This technology improves electrode structural stability and enhances electrochemical performance and cycle life in high-voltage environments by forming a fluoride coating layer (AlaNibFc) with a specific composition containing aluminum (Al) and nickel (Ni) on the surface of lithium secondary battery composite oxide cathode active materials.
While lithium-cobalt, nickel, and manganese-based cathode active materials allow for high capacity, they suffer from structural instability at high voltages. They also face limitations such as capacity degradation and shortened cycle life due to side reactions with the electrolyte.
This technology involves coating composite oxide particles with 0.1–10 wt% of an AlaNibFc fluoride that satisfies 0.15≤a≤1.05, 0.05≤b≤0.35, 2≤a/b≤4, and c=3(a+b). The process consists of dispersing the active material in an aqueous solution of Al and Ni compounds, adding an aqueous fluorine compound solution, stirring at 70–100°C, and heat-treating at 400–600°C. Applicable to cathodes for flagship mobile devices and high-energy electric vehicle cells that utilize 4.5V-class high-voltage charging, it provides design headroom that prevents surface degradation from accumulating even when the upper charging voltage limit is increased.
WO2014-115973A1
