Lithium secondary battery cathode with a polymer-treated surface

NCM Cathode with High-Voltage Degradation Prevention via Cross-Linked PVP Polymer Post-Coating

This technology is a surface modification method that applies a poly(4-vinylphenol) (PVP) organic polymer layer onto the surface of a finished NCM-613 cathode via spin coating and cross-linking, preventing crystal structure degradation and suppressing side reactions with the electrolyte.

Operating Ni-rich layered NCM-613 cathode materials at high voltages above 4.3V has historically led to irreversible crystal structure collapse. Furthermore, electrolyte decomposition causes severe surface polarization, limiting long-term cycle life and rate performance.

This technology involves spin-coating a PVP solution mixed with a cross-linking agent (HMBG) onto the finished cathode surface to create a protective layer 0.05–10㎛ thick, which is then cured at 130℃. Since it adds only one post-processing step to existing electrode coating lines, it can be applied to high-voltage small electronic cells and high-energy-density EV cells, boosting lifespan at the electrode level without changing the active material synthesis recipe.

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Key Features:

• A cathode material formed on a current collector for a lithium secondary battery, comprising a cathode active material, a conductive agent, and a binder.
• A poly(4-vinylphenol) (PVP) coating layer that uniformly covers the surface of the cathode material via post-treatment and forms cross-links.
• A layered lithium nickel-cobalt-manganese oxide cathode active material included in the cathode material, consisting of LiNi0.6Co0.1Mn0.3O2 (NCM-613).
• A PVP protective layer formed on the cathode material surface with a weight of 0.01–5 wt% relative to the cathode active material and a thickness of 0.05–10 ㎛.

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