This technology is a cathode material for lithium secondary batteries that modifies the surface of high-nickel NCM811 cathode active material by coating it with lithium trimethylsiloxide (LiOTMS)—composed of silicon, oxygen, and lithium—followed by heat treatment. By utilizing LiOTMS as a coating material rather than an electrolyte additive, it forms an interfacial layer that removes hydrogen fluoride within the battery.
NCM811 cathodes with a nickel content of 80% or higher have faced issues where unstable Ni4+ increases at the interface during charging, accelerating electrolyte decomposition and increasing interfacial resistance, which leads to a sharp decline in battery life. Furthermore, hydrogen fluoride generated by electrolyte side reactions causes transition metal dissolution and damage to the anode SEI. Additionally, using LiOTMS as an electrolyte additive has been limited by a significant drop in initial coulombic efficiency due to reactions with carbonate solvents.
This technology involves mixing LiOTMS with the cathode active material in an NMP solvent, coating it, and then heat-treating it at approximately 700°C to form a stable inorganic coating layer. This reduces overpotential during high-temperature charging and achieves a discharge capacity retention rate of 63.1% after 100 charge-discharge cycles. It can be applied to the production of high-energy-density lithium secondary battery cathode materials for electric vehicles and energy storage systems, allowing for the mitigation of high-temperature degradation in high-nickel materials through a simple surface treatment.
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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