This technology involves constructing a lithium-ion battery with a nickel-rich cathode containing 50–70 wt% nickel by using a boron compound of Formula 1, such as triphenyl borate, as an electrolyte additive. During charge and discharge cycles, the additive forms a cathode-electrolyte interphase (CEI) protective layer on the cathode surface and removes residual lithium species.
While nickel-rich NCM cathodes offer high specific capacity, their low surface stability has historically led to the continuous accumulation of electrolyte decomposition byproducts on the cathode surface and increased cell resistance. Furthermore, residual lithium hydroxide and lithium carbonate from the calcination process decompose at voltages above 4.0V, generating oxygen, hydrogen, and carbon dioxide gases, which cause rapid cell expansion.
This technology uses boron compound additives to remove residual lithium, thereby suppressing gas generation and internal cell pressure buildup, while the CEI protective layer prevents electrolyte decomposition to extend cycle life. Designed to function with a combination of EC/EMC mixed solvents and LiPF6 electrolyte salt, it can be implemented by simply adding the additive to existing electrolyte processes. Applicable to high-energy-density batteries for electric vehicles, energy storage systems, and communication devices, it reduces safety issues caused by cell swelling and accelerates the adoption of nickel-rich cathodes, which are advantageous for increasing driving range.
This invention was developed with support from the Ministry of Science, ICT and Future Planning for the development of residual lithium reduction technology for high-capacity lithium secondary battery cathode materials.
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