Porous polyetherimide/aramid nanofibril composite membrane and secondary battery comprising the same

Dendrite-suppressing separator with self-assembled PEI particles on an aramid nanofibril framework

This technology creates a nanoporous structure by self-assembling polyetherimide (PEI) particles onto a robust aramid nanofibril (ANF) framework. It enhances ion affinity within the electrolyte to suppress lithium dendrite growth.

Conventional polyolefin separators are prone to lithium dendrite formation during charge/discharge cycles in lithium secondary batteries, leading to short circuits, fires, and reduced lifespan. It has also been difficult to simultaneously achieve high ionic conductivity and effective dendrite suppression.

This technology involves mixing an aramid nanoseed dispersion with a polyetherimide solution, coating the mixture, and then performing sequential solvent exchange using a protic solvent and water, followed by freeze-drying to produce a composite porous membrane with nanopores. This structure maximizes electrolyte wettability and ion transport rates while maintaining mechanical strength. Applicable to separators for lithium metal batteries and fast-charging EV cells, it blocks dendrite penetration paths, thereby reducing fire risks and extending cell life.

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Key Features:

• A polyaramid nanofibril framework defined by numerous irregular pores with nanometer-scale diameters
• Multiple polyetherimide particles located on the polyaramid nanofibril framework, merging on the surface to form a wavy sheath
• A step of immersing the mixed solution layer in an alcohol-containing protic solvent for primary solvent exchange to form an alcohol-gel membrane with self-assembled polyetherimide particles
• A step of performing secondary solvent exchange on the alcohol-gel membrane with water, followed by freeze-drying the resulting hydrogel membrane to form a composite porous membrane

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This invention was developed with support from the Carbon Neutral Water-Energy Integrated System Leading Research Center of the Ministry of Science and ICT.

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