Dry-Process Microporous Battery Separators With High Puncture Strength
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Solution Overview
Problem
Existing microporous membranes used as battery separators often face issues with low puncture strength, thickness uniformity, and poor runnability, making them unsuitable for modern batteries and equipment, particularly those requiring thin separators with high energy density.
Innovation Solution
Development of improved strength microporous membranes with specific properties such as puncture strength, tensile strength, surface roughness, and porosity, made through a dry process using polyolefin materials, which can be used as battery separators or components in energy storage devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If separator thickness is reduced to increase energy density, then energy density is improved, but puncture strength and thickness uniformity deteriorate
Solution Approach 1:
The patent employs composite material structures combining different polymer layers (e.g., polyethylene/polypropylene blends, cross-linked polyolefin layers) to achieve high strength-to-thickness ratios. The composite structure allows thin separators to maintain puncture strength through synergistic material properties, resolving the contradiction between reduced thickness and maintained strength.
Solution Approach 2:
The patent utilizes parameter changes in material composition (crystallinity, molecular weight, cross-linking degree) and processing conditions (stretching ratios, annealing temperature) to optimize the balance between thickness and puncture strength. By adjusting these parameters, thin separators achieve enhanced mechanical properties without sacrificing energy density.
2Quantity of substance
If separator thickness is reduced to increase energy density, then energy density is improved, but thickness uniformity deteriorates
Solution Approach 1:
The patent divides the separator into multiple functional layers, each with specific thickness control mechanisms. This segmentation allows independent optimization of each layer's thickness uniformity during manufacturing, while the combined structure achieves overall thinness for high energy density.
Solution Approach 2:
The patent adjusts processing parameters (extrusion speed, stretching temperature, cooling rate) to improve thickness uniformity in thin separators. By optimizing these parameters, the manufacturing process maintains consistent thickness across the separator surface, preventing defects while achieving reduced overall thickness.
3Reliability
If porosity is increased to improve ionic conductivity, then ion flow is improved, but mechanical strength deteriorates
Solution Approach 1:
The patent employs controlled porous structures with optimized pore size distribution and connectivity. The porous design ensures sufficient ionic conductivity pathways while the pore architecture (size, shape, distribution) is engineered to maintain mechanical integrity, resolving the contradiction between ion flow and strength.
Solution Approach 2:
The patent uses composite material systems where one component provides porosity for ionic conductivity while another component reinforces mechanical strength. The synergistic combination allows the separator to achieve both high ion flow and adequate tensile strength that neither material could provide alone.
Data Source
AI summary
An improved strength microporous membrane is described herein. The microporous membrane may be useful as a battery separator, separator membrane, base film, or membrane with a variety of uses thereof. The improved microporous membranes described herein may be dry process polyolefin membranes and may be used as battery separators or as a component of a composite or battery separator. The battery separators or composites may be used in energy storage devices including primary batteries, secondary batteries, fuel cells, capacitors, or super capacitors.