Dimethoxydimethylsilane-coated cathode active material for lithium-ion batteries and manufacturing method thereof

High-Nickel NCM Cathode Materials with Enhanced High-Temperature Lifespan via Dimethoxydimethylsilane Coating

This technology involves a cathode active material for lithium secondary batteries and its manufacturing method, where the surface of an NCM cathode active material with a nickel content of 60–90% is coated with 1–10 wt% of dimethoxydimethylsilane (DODSi) and heat-treated at 400–800℃ to form an artificial CEI layer containing Si-O functional groups.

While Ni-rich NCM cathodes with increased nickel ratios offer high specific capacity and energy density, they suffer from poor surface stability due to electrolyte decomposition at the electrode-electrolyte interface and nickel leaching caused by fluoride species. This leads to a significant limitation in charge-discharge cycle life, particularly at high temperatures.

This technology utilizes a one-step wet coating process, mixing DODSi with the cathode material in an NMP solvent to create a nanometer-thick Si-O functionalized protective layer. This layer suppresses interfacial electrolyte decomposition and scavenges F- species to reduce nickel leaching. Applicable to high-energy-density cells for electric vehicle batteries and energy storage systems, it achieves significantly improved capacity retention at 55℃ compared to untreated NCM811.

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Key Features:

• Cathode active material for lithium secondary batteries with dimethoxydimethylsilane coated on the surface of a cathode active material represented by LiNiaCobMncO2 (0.6≤a≤0.9, a+b+c=1)
• Coating composition containing 1–10 wt% of dimethoxydimethylsilane relative to 100 wt% of the cathode active material, heat-treated at 400–800℃
• Lithium secondary battery comprising a cathode containing the dimethoxydimethylsilane-coated cathode active material, an electrolyte containing 1.0 M LiPF6 in a 1:2 EC/EMC mixed solvent, and an anode
• Step of mixing dimethoxydimethylsilane with the cathode active material in an N-methyl-2-pyrrolidone solvent to coat the surface, followed by heat treatment at 400–800℃, such as 600℃

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This invention was developed with support from the Ministry of Education for the development of blue carbon biomass-based source materials and the establishment of a marine resource recycling platform.

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