Microporous Separator Surface Chemistry for Fast Electrolyte Injection
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Solution Overview
Problem
Conventional separators for power storage devices face a trade-off between adhesive force during pressing and electrolyte solution injection property, leading to poor injection times and inadequate molding state maintenance.
Innovation Solution
A polyolefin microporous membrane separator with specific water contact angle, porosity, and ATR-IR absorption peak ratio, combined with a coating layer, to enhance adhesive and injection properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thermoplastic polymer layer is provided as an adhesive layer on a polyolefin microporous membrane to improve adhesive property, then adhesive force during pressing is improved, but electrolyte solution injection property deteriorates (injection time increases)
Solution Approach 1:
The invention changes the chemical composition parameters of the microporous membrane by incorporating specific functional groups (carboxyl, hydroxyl, or amine groups) with controlled content ratios. This parameter change enables the membrane to achieve both adequate adhesive force and improved electrolyte solution injection property without requiring a separate adhesive layer, thus resolving the trade-off between adhesion and injection time.
2Loss of time
If conventional separators without adhesive layers are used to maintain short injection time, then electrolyte solution injection property is improved, but adhesive force during pressing deteriorates
Solution Approach 1:
The invention modifies the functional group composition parameters of the polyolefin microporous membrane to achieve optimal balance between injection property and adhesive force. By controlling the content ratios of carboxyl, hydroxyl, and amine groups, the membrane attains sufficient adhesive strength during pressing while maintaining short electrolyte solution injection time, eliminating the need for separate adhesive layers.
3Stability of the object's composition
If crimping is performed under conventional conditions (20°C to 40°C, 10 to 30 MPa, 3 to 10 seconds) to maintain molding state, then molding state is maintained, but both adhesive property and injection property are insufficient
Solution Approach 1:
The invention changes the functional group composition parameters of the microporous membrane to achieve optimal balance between molding state stability and adhesive property. By controlling the content ratios of carboxyl, hydroxyl, and amine groups, the membrane maintains adequate adhesive strength during conventional crimping while preserving molding state stability.
4Stability of the object's composition
If crimping is performed under conventional conditions to maintain molding state, then molding state is maintained, but electrolyte solution injection property deteriorates
Solution Approach 1:
The invention modifies the functional group composition parameters of the polyolefin microporous membrane to achieve optimal balance between molding state stability and electrolyte solution injection property. By controlling the content ratios of carboxyl, hydroxyl, and amine groups, the membrane maintains molding state during conventional crimping while achieving short electrolyte solution injection time.
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 achieves both adhesive strength during pressing and efficient electrolyte solution injection without using adhesives, improving device productivity and performance.
Implementation Method 1
allowing ions to pass through an electrolyte solution held in micropores
Implementation Method 2
preventing direct contact between the positive electrode and the negative electrode
Data Source
AI summary
Provided is a separator for a power storage device, the separator comprising a polyolefin microporous film that has a first principal surface and a second principal surface. The water contact angle of the first principal surface is 43°-118°, and when the absorbance of the first principal surface from 600 cm-1 to 4000 cm-1 is measured by ATR-IR measurement, the ratio of the absorption peak height at 1715 cm-1 and the absorption peak height at 1472 cm-1 is 0.0020-0.0280. The porosity of the polyolefin microporous film is 30%-65%.