This technology provides a cathode active material for secondary batteries, featuring a tannic acid coating layer on the surface of transition metal-containing particulate cathode active materials, along with its manufacturing method. The phenolic hydroxyl groups of the tannic acid form a complex through coordination bonding with the transition metals on the active material surface, thereby modifying the surface.
In layered cathode active materials such as high-nickel types, transition metals like nickel and manganese tend to leach into the electrolyte during battery operation. The leached metals deposit on the anode, thickening the SEI layer and consuming lithium ions, which leads to reduced cycle life and compromised thermal stability.
This technology creates a coating layer simply by mixing the cathode active material with tannic acid in a weight ratio of 1:0.005 to 1:0.3. The tannic acid in this layer acts as a physical and chemical protective barrier through coordination bonding with transition metals. It is compatible with lithium transition metal oxides such as NCM and NCA, as well as manganese oxides like MnO2. Applicable to high-nickel cathodes for EVs, batteries for power tools and ESS in high-temperature environments, and manganese-based aqueous battery cathodes, this low-cost, simple mixing process using natural polyphenol (tannic acid) effectively prevents transition metal leaching, thereby improving both cycle life and thermal stability.
This invention was developed with support from the Ministry of Science and ICT for the development of high-performance aqueous zinc secondary battery systems.
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