Cathode active material, method for manufacturing the same, and lithium secondary battery comprising the same

Nickel-based cathode material with a surface cubic protective phase formed by trace tungsten doping

This technology involves doping nickel-based cathode active materials with less than 2 mol% of additive metals, such as tungsten. By adjusting the ratio of the rhombohedral crystal structure inside the particles to the cubic crystal structure on the surface, it improves structural stability, thermal stability, and cycle life.

Conventional nickel-based cathode active materials suffer from structural instability and particle degradation during high-voltage charging and discharging. They also face performance limitations due to gas generation from residual lithium and fluorine (F) penetration from the electrolyte.

This technology dopes additive metals like tungsten from the precursor stage to ensure uniform distribution throughout the particles and controls the crystal structure by increasing the calcination temperature in proportion to the additive concentration. Specifically, it increases the cubic crystal ratio on the particle surface to act as a protective layer, preventing side reactions with the electrolyte and stabilizing lithium-ion transport paths. Applicable to electric vehicle and plug-in hybrid batteries that require high-voltage charging, it achieves both surface stabilization and reduced gas generation through doping alone, without the need for additional coating processes.

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Key Features:

• Cathode active material containing lithium, at least one of nickel, cobalt, manganese, or aluminum, and less than 2 mol% of additive metal on average
• Cubic first crystal structure and rhombohedral second crystal structure with ratios adjusted based on additive metal content
• Cubic crystal structure that is more prevalent at the surface than the center and increases with higher additive metal content
• Step of preparing a metal hydroxide precursor doped with additive metals by supplying a base aqueous solution and an additive aqueous solution to a reactor

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