This technology features a separator structure in which cellulose nanofibers and inorganic particles are uniformly dispersed and coated onto a porous support using carboxymethyl cellulose (CMC) with specific degrees of polymerization and substitution, molecular weight, viscosity, and zeta potential as a dispersant.
Conventional separator coating processes have been complicated by the use of organic solvents, and the use of acrylic or rubber-based adhesives often leads to clogged pores, which reduces air permeability. Furthermore, there have been limitations regarding the uneven coating of inorganic particles and thermal shrinkage at high temperatures.
This technology utilizes a CMC dispersant that satisfies a degree of polymerization of 800–1500, a degree of substitution of 0.5–1.0, a molecular weight of 200,000–400,000 g/mol, and a zeta potential of -60 to -50 mV. The coating is formed by applying a slurry to a porous support, prepared by adding CMC, cellulose nanofibers, and inorganic particles to a solvent in that specific order. This technology can be applied to pouch cells for electric vehicles, where high-temperature safety is critical, and to separator coating lines transitioning to water-based processes. It enables the production of ceramic-coated separators that suppress thermal shrinkage while keeping pores open without the need for adhesives.
This invention was developed with support from the Korea Forest Service for the design and manufacturing technology of nanocellulose-coated separators.
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