Cobalt-free cathode active material and lithium secondary battery containing the same

Cobalt-free nickel-manganese cathode material with surface cation ordering and high-voltage phase transition control

This technology enhances structural stability and electrochemical performance in cobalt-free, nickel-manganese-based layered cathode materials by introducing cation ordering at the particle surface and controlling the H2-H3 phase transition in the 4.12V–4.6V range.

Conventional nickel-rich cathode materials rely on expensive cobalt, leading to high production costs. Furthermore, irreversible phase transitions during high-voltage charging cause micro-cracks within the particles and structural instability, which degrades long-term cycle performance.

This technology utilizes a cobalt-free LiaNixMnyO2 (0.5≤x≤0.99, 0.01≤y≤0.5) composition and forms a cation-ordered structure within 2㎛ of the secondary particle surface, where lithium and transition metals are regularly swapped. By optimizing the H2-H3 phase transition under charging conditions above 4.4V and increasing particle strength to 120–250MPa, it ensures superior rate capability and thermal stability. It is ideal for mass-producing EV cathode materials and developing high-voltage cells, enabling both cost reduction and stable operation at voltages above 4.4V.

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Key Features:

• A layered structure in which lithium layers containing only lithium and transition metal layers containing only transition metals are arranged in a regular, alternating pattern
• A cathode active material for lithium secondary batteries represented by the composition Lia1Nix1Mny1O2, with a nickel ratio between 0.5 and 0.99 and containing no cobalt
• A cation-ordered structure formed within 2㎛ from the outermost surface toward the center of the cathode active material, where lithium and transition metals are substituted for each other
• A secondary particle formed by the aggregation of multiple primary particles, possessing a particle strength of 120MPa to 250MPa

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