Fluoropolymer Battery Vent Membrane for Gas-Moisture Selectivity
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Solution Overview
Problem
Existing batteries, such as lithium-ion batteries, face challenges in achieving an optimal balance between gas permeability and moisture permeability, which affects their performance and longevity.
Innovation Solution
The use of a fluoropolymer membrane with specific properties, including a crystallinity of 85% to 100% and a density of 2.0 g/cm3 to 2.2 g/cm3, is introduced to cover the openings of the battery housing. This membrane has a CO2 permeability to moisture permeability ratio of more than 0.5 and less than 1.5, enhancing the battery's performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional membranes are used to cover battery openings, then moisture permeability is reduced, but gas permeability is also reduced, affecting battery performance
Solution Approach 1:
The patent applies parameter changes by carefully controlling the crystallinity (85-100%) and density (2.0-2.2 g/cm³) of the fluoropolymer membrane to achieve optimal permeability characteristics. By adjusting these physical parameters, the membrane allows gas to pass through while blocking moisture, resolving the contradiction between gas permeability and moisture protection.
Solution Approach 2:
The patent uses fluoropolymer membranes (such as PTFE, FEP, or ETFE) as composite material solutions. These specialized polymers provide a balanced structure that inherently offers both gas permeability and moisture barrier properties, eliminating the need to choose between the two opposing requirements.
2Object-affected harmful factors
If membrane density is increased to block moisture, then moisture permeability decreases, but gas permeability is also reduced
Solution Approach 1:
The patent applies local quality by creating a membrane with heterogeneous structure where different regions have different densities and crystallinities. The membrane contains both crystalline regions (for moisture blocking) and amorphous regions (for gas permeability), allowing simultaneous achievement of moisture barrier and gas venting functions.
Solution Approach 2:
The patent optimizes the density parameter within a specific range (2.0-2.2 g/cm³) to achieve the desired balance. This parameter control ensures the membrane has sufficient density to block moisture while maintaining enough porosity and free volume to allow gas molecules to pass through.
3Object-affected harmful factors
If membrane crystallinity is increased to improve moisture barrier, then moisture permeability decreases, but gas permeability is also reduced
Solution Approach 1:
The patent applies parameter changes by optimizing crystallinity within the range of 85-100%. This high but controlled crystallinity provides excellent moisture barrier properties while the remaining amorphous regions and crystallite spacing maintain adequate gas permeability pathways.
Solution Approach 2:
The patent utilizes the porous nature of semi-crystalline fluoropolymer membranes where the crystalline regions form a dense barrier to moisture while the inter-crystalline spaces and amorphous regions create pathways for gas diffusion, simultaneously addressing both requirements.
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 implementation of the fluoropolymer membrane improves the battery's gas permeability to moisture permeability ratio, leading to enhanced performance and longevity by effectively managing gas release and moisture ingress.
Implementation Method 1
the at least one fluoropolymer membrane has a CO2 permeability to moisture permeability ratio of more than 0.5
Implementation Method 2
the at least one fluoropolymer membrane has a crystallinity of 85% to 100%
Data Source
AI summary
Some embodiments of the present disclosure relate to a battery comprising a housing. In some embodiments, the housing comprises an opening. In some embodiments, the battery comprises at least one fluoropolymer membrane. In some embodiments, the at least one fluoropolymer membrane covers the opening of the housing. In some embodiments, the at least one fluoropolymer membrane has a crystallinity of 85% to 100%. In some embodiments, the at least one fluoropolymer membrane has a density of 2.0 g/cm3 to 2.2 g/cm3. In some embodiments, the at least one fluoropolymer membrane has a CO2 permeability to moisture permeability ratio of more than 0.5. A polytetrafluoroethylene film for electronic components, characterized in that the polytetrafluoroethylene film can have a density of 1.40 g/cm3 or higher and an air impermeability of 3,000 seconds or higher.