Separator Copolymer Coating for Heat-Resistant Li-Ion Batteries
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Solution Overview
Problem
Current polyolefin-based separators in lithium secondary batteries face issues with heat shrinkage and mechanical stability, leading to potential short circuits and explosions, necessitating improved heat resistance and adhesive strength.
Innovation Solution
A copolymer composition with specific monomer ratios of acrylonitrile, acrylate, acrylamide, and acrylic acid, combined with core-shell particles and inorganic particles, is used to create a slurry composition for coating the separators, enhancing adhesive strength and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polyolefin-based films are used as separators, then manufacturing ease and cost are improved, but heat resistance and mechanical stability deteriorate
Solution Approach 1:
The patent applies composite materials by combining polyolefin base material with a coating layer containing inorganic particles (such as alumina, silica, or boehmite) and a binder polymer. This composite structure allows the separator to maintain the manufacturing advantages of polyolefin while gaining enhanced heat resistance and mechanical stability from the inorganic coating layer, directly resolving the contradiction between ease of manufacture and reliability.
2Ease of manufacture
If polyolefin-based films are used as separators, then manufacturing ease is improved, but mechanical stability deteriorates
Solution Approach 1:
The coating layer comprising inorganic particles embedded in a binder polymer matrix creates a composite structure that significantly enhances the mechanical stability of the separator. The inorganic particles provide structural reinforcement while the binder ensures strong adhesion to the polyolefin substrate, allowing the separator to maintain its ease of manufacture while achieving improved mechanical strength and stability.
3Reliability
If inorganic particles and binder are coated on porous separator substrate, then heat resistance is improved, but adhesive strength deteriorates
Solution Approach 1:
The patent optimizes the molecular weight, composition, and structural parameters of the binder polymer to achieve optimal adhesive properties. By carefully selecting and adjusting these parameters, the coating layer maintains strong adhesion to the porous separator substrate while providing the desired heat resistance, thus resolving the contradiction between heat resistance improvement and adhesive strength maintenance.
4Reliability
If coating layer is applied to suppress shrinkage, then heat resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The coating layer is pre-formed with the appropriate composition and structure before being applied to the separator substrate. This preliminary preparation allows the coating to be applied in a straightforward coating process, reducing manufacturing complexity while ensuring the coating provides the necessary heat resistance and shrinkage suppression properties.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution improves the dispersion stability of the slurry, increases adhesive strength to the separator substrate and electrodes, and enhances the heat resistance of the separators, reducing manufacturing defects and achieving better battery performance and cycle characteristics.
Implementation Method 1
A copolymer of the present disclosure can improve the dispersion stability of a slurry composition
Implementation Method 2
increase adhesive strength to a polyolefin film, which is a separator substrate
Implementation Method 3
improve the heat resistance of a separator
Data Source
AI summary
The present invention relates to a copolymer and core-shell particles, a slurry composition, a separator and a secondary battery which comprise the copolymer, the copolymer comprising, with respect to 100 wt % of the total weight of the copolymer, greater than 5 wt % and less than or equal to 70 wt % of an acrylonitrile-based monomer unit, greater than or equal to 15 wt % and less than 90 wt % of an acrylate-based monomer unit, 1-20 wt % of an acrylamide-based monomer unit, and 1-10 wt % of an acrylic acid-based monomer unit.