Fibrillar PVDF Separator for Battery Adhesion and Cycling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing non-aqueous secondary battery separators face issues with adhesiveness to electrodes, handling ability, and liquid shortage prevention, particularly with high-capacity electrode materials that undergo significant volume changes during charging and discharging, leading to decreased battery cycling characteristics.
Innovation Solution
A non-aqueous secondary battery separator featuring a microporous membrane with an adhesive porous layer made of fibrillar polyvinylidene fluoride resin, with specific average hole diameters and fibrillar diameters that enhance peeling strength and ionic permeability, ensuring excellent adhesiveness and preventing liquid shortage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a porous layer is formed on the polyolefin microporous membrane to improve adhesiveness, then the adhesiveness between separator and electrode is improved, but the porous layer is easily detached and handling ability deteriorates
Solution Approach 1:
The patent changes the physical and chemical parameters of the porous layer by controlling the molecular weight of polyvinylidene fluoride (600,000 to 3,000,000) and the porosity (30% to 60%), which optimizes both adhesiveness and handling properties simultaneously
Solution Approach 2:
The patent creates a composite structure by forming a porous layer of polyvinylidene fluoride on the polyolefin microporous membrane, combining the advantages of both materials to achieve excellent adhesiveness while maintaining structural integrity and handling ability
2Strength
If hot pressing is applied to improve adhesiveness, then the adhesive strength is improved, but holes are collapsed and ionic permeability decreases
Solution Approach 1:
The patent optimizes the porosity parameter of the porous layer to be within 30% to 60%, which allows the layer to maintain sufficient holes for ion permeation while achieving adequate adhesive strength through molecular weight control of the polyvinylidene fluoride
Solution Approach 2:
The patent utilizes a porous layer with controlled porosity (30% to 60%) that maintains open hole structures, ensuring ionic permeability is not compromised while still providing the necessary adhesive function
3Stability of the object's composition
If the separator does not follow volume change of high-capacity electrodes, then the separator structure is maintained, but liquid shortage occurs and cycling characteristics deteriorate
Solution Approach 1:
The patent adjusts the porosity parameter of the porous layer to be within 30% to 60%, enabling the separator to accommodate electrode volume changes during charging and discharging while maintaining sufficient liquid electrolyte retention and preventing liquid shortage
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 separator ensures sufficient ionic permeability, handling ability, and adhesiveness with electrodes, improving battery cycling characteristics and manufacturing yield while preventing liquid shortage, thus enhancing the overall performance and longevity of non-aqueous secondary batteries.
Implementation Method 1
peeling strength between the microporous membrane and the adhesive porous layer is equal to or greater than 0.10 N/cm
Implementation Method 2
an average hole diameter acquired from the specific surface area of the microporous membrane is greater than 90 nm and equal to or smaller than 250 nm
Data Source
AI summary
Provided is a non-aqueous-secondary-battery separator including: a microporous membrane; and an adhesive porous layer which is provided on one or both surfaces of the microporous membrane and includes a fibrillar polyvinylidene fluoride resin, in which an average hole diameter acquired from the specific surface area of the microporous membrane is greater than 90 nm and equal to or smaller than 250 nm, peeling strength between the microporous membrane and the adhesive porous layer is equal to or greater than 0.10 N/cm, and a fibrillar diameter acquired from the specific surface area of the adhesive porous layer is from 50 nm to 70 nm.