Method for manufacturing a secondary battery separator coating material, a separator containing said coating material, and a secondary battery comprising said separator

Separator with sustained-release additive coating using needle-shaped porous carriers

This technology improves long-term battery life and stability by incorporating needle-shaped carriers with internal pores (e.g., halloysite) into the separator coating layer. Functional additives for SEI formation or side-reaction suppression are loaded into these pores, allowing for the sustained release of additives during charge and discharge cycles.

Lithium-ion batteries have historically faced issues with capacity retention and performance degradation due to side reactions between electrodes and electrolytes during repeated cycling. Furthermore, limitations in separator reliability have persisted due to insufficient basic properties such as coatability, heat resistance, and wettability.

This technology creates a functional structure by loading functional additives into needle-shaped carriers with unidirectional pores using a vacuum method. By controlling the combined content of this structure and the binder to 15–25 wt% of the total coating material, it can be applied to separator coating processes for long-life EV and ESS cells using high-voltage cathodes. This ensures a continuous supply of electrolyte additives through the later stages of cycling while simultaneously enhancing the separator's heat resistance and wettability.

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Key Features:

• Functional structure consisting of a needle-shaped carrier with internal unidirectional pores and additives loaded within those pores
• Step of preparing a functional coating material for separators by mixing the needle-shaped carrier-based functional structure, binder, and solvent
• Functional coating material where the combined content of the functional structure and binder is controlled to be between 15 wt% and 25 wt% of the total weight
• Inlets provided at both ends of the unidirectional pores to regulate the release of the loaded additives

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This invention was developed with support from the Ministry of Science and ICT for energy storage and conversion systems based on sustained-release material control.

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