Polyimide Battery Separator Coating to Prevent Gaps and Deposits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Polyimide porous films face challenges in adhesion to other materials and tend to form gaps, leading to deposit formation when used as secondary battery separators, which affects the mechanical strength and cycle properties of non-aqueous secondary batteries.
Innovation Solution
A polyimide porous film with resin particles, specifically fluorine-based resin or fluorine-based resin and acrylic resin, adhered to its surface, where the average particle diameter of the resin particles is larger than the average pore diameter, enhancing adhesion and preventing deposit formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polyimide porous film is used as a separator, then heat resistance and chemical stability are improved, but adhesion to electrodes deteriorates and gaps form leading to deposit formation
Solution Approach 1:
The patent applies composite materials by combining polyimide porous film with fluororesin particles and acrylic resin particles. The fluororesin particles (with melting point 100-150°C) are dispersed in the polyimide matrix to create a composite structure that maintains the heat resistance of polyimide while adding adhesion-promoting properties. The acrylic resin particles (with glass transition temperature -50 to -100°C) further enhance adhesion and suppress gap formation. This composite approach resolves the contradiction by integrating materials with complementary properties.
Solution Approach 2:
The patent applies local quality by creating regions with different properties within the separator structure. The fluororesin particles are distributed throughout the polyimide matrix to provide localized adhesion enhancement at specific points where electrodes contact the separator. The acrylic resin particles are positioned to specifically address gap formation issues. This localized modification allows the bulk polyimide structure to maintain its heat resistance while specific regions provide improved adhesion.
2Use of energy by moving object
If fluororesin particles are added to improve adhesion, then adhesion performance is improved, but deposit formation increases when particle diameter is smaller than pore diameter
Solution Approach 1:
The patent applies parameter changes by carefully controlling the particle diameter parameters of the fluororesin and acrylic resin particles. The fluororesin particles have a diameter of 0.1-10 μm, and the acrylic resin particles have a diameter of 0.01-1 μm. These specific size ranges are chosen to ensure particles are large enough to bridge gaps effectively (preventing deposit formation) while small enough to disperse uniformly and provide adequate adhesion. The particle sizes are also coordinated with the pore diameter of the polyimide porous film to optimize performance.
Solution Approach 2:
The patent utilizes porous materials by employing a polyimide porous film as the base separator structure with controlled porosity. The porous structure allows ion transport while the incorporated resin particles modify the pore architecture to prevent gap formation. The combination of the porous polyimide matrix with dispersed resin particles creates a hierarchical pore structure that maintains permeability while preventing harmful deposit formation.
3Use of energy by moving object
If resin particles are dispersed in the porous film, then adhesion is improved, but mechanical strength may deteriorate
Solution Approach 1:
The patent applies local quality by concentrating the adhesion-enhancing resin particles at the separator-electrode interface regions rather than uniformly distributing them throughout the entire separator thickness. The fluororesin particles (0.1-10 μm) and acrylic resin particles (0.01-1 μm) are positioned to provide localized adhesion enhancement where electrodes contact the separator, while the bulk polyimide matrix maintains its mechanical integrity. This localized approach minimizes the impact on overall mechanical strength.
Solution Approach 2:
The patent applies composite materials by creating a multi-phase structure where fluororesin particles, acrylic resin particles, and polyimide matrix work synergistically. The fluororesin provides structural support and adhesion, the acrylic resin provides gap-filling and adhesion enhancement, and the polyimide matrix provides mechanical strength and thermal stability. The composite structure distributes stresses across different phases, preventing catastrophic failure and maintaining mechanical strength despite the presence of dispersed particles.
Data Source
AI summary
A polyimide porous film includes: a polyimide porous film body; and at least one of resin particles and a resin porous film, the at least one of the resin particles and the resin porous film adhering to one surface or both surfaces of the polyimide porous film body, and containing a fluorine-based resin or containing a fluorine-based resin and an acrylic resin.