Polyolefin Porous Membrane Protrusions Prevent Separator Delamination
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Solution Overview
Problem
Conventional battery separators face challenges in ensuring safety due to partial delamination of modified porous layers during high-speed processing and assembly, particularly when the polyolefin resin porous membrane becomes thinner, leading to inadequate anchoring and increased risk of membrane puncture.
Innovation Solution
A polyolefin porous membrane with protrusions of specific size and height randomly disposed on its surface, combined with a modified porous layer comprising polyamideimide, polyimide, or fluorine-based resin, and inorganic particles, is used to enhance peel strength and prevent delamination during high-speed processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the polyolefin porous membrane is made thinner to increase battery capacity, then the area for electrode and separator can be increased, but the membrane may experience deformation and the modified porous layer may delaminate during processing
Solution Approach 1:
Protrusions are formed on the surface of the polyolefin porous membrane before laminating the modified porous layer. These pre-formed protrusions create mechanical interlocking structures that anchor the modified porous layer, preventing delamination during subsequent high-speed processing and assembly operations.
Solution Approach 2:
The surface of the polyolefin porous membrane is modified with protrusions that have specific dimensional characteristics (height of 1-10 μm and base diameter of 5-20 μm). These localized structural features provide enhanced anchoring capability at specific contact points with the modified porous layer, improving adhesion without affecting the overall thinness of the membrane.
2Strength
If resin is sufficiently permeated into the polyolefin porous membrane to improve contact and adhesion, then adhesion strength improves, but air permeation resistance increases significantly
Solution Approach 1:
Protrusions are pre-formed on the membrane surface before applying the modified porous layer. This preliminary structural preparation provides mechanical anchoring points that enable strong adhesion without requiring excessive resin permeation, thereby maintaining low air permeation resistance.
Solution Approach 2:
Instead of uniform resin permeation throughout the membrane, the protrusions provide localized anchoring zones. The modified porous layer adheres strongly at these discrete protrusion locations while leaving the bulk membrane structure open and permeable, thus maintaining low air permeation resistance.
3Ease of manufacture
If conventional smooth-surface porous membranes are used, then manufacturing is simpler, but peel strength with modified porous layer is insufficient leading to delamination during high-speed processing
Solution Approach 1:
Protrusions are incorporated into the membrane structure during the membrane formation process itself, before lamination. This approach integrates the anchoring feature creation into the existing manufacturing workflow without requiring separate complex post-processing steps, thus maintaining manufacturing simplicity while dramatically improving peel strength.
Solution Approach 2:
The protrusions create localized high-adhesion zones on the membrane surface. These discrete structural features provide strong mechanical interlocking with the modified porous layer at critical contact points, achieving high peel strength without requiring modification of the entire membrane structure or complex manufacturing processes.
Data Source
AI summary
A polyolefin porous membrane disclosed. The membrane includes a plurality of protrusions of polyolefin having a size (W) of 5 μm≤W≤50 μm and a height (H) of 0.5 μm≤H. The protrusions are disposed on one side of the polyolefin porous membrane with a density of at least 3/cm2 and at most 200/cm2, and the polyolefin porous membrane has a thickness of at most 20 μm. A battery separator including the membrane is also disclosed.