Porous Membrane Strength via Organic Particle Shape Control
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Solution Overview
Problem
Lithium ion secondary batteries face challenges with porous membranes containing organic fine particles, including low strength, difficulty in achieving uniform membrane thickness and strength distribution, leading to potential short circuits and reduced battery performance due to moisture and metal ion contamination.
Innovation Solution
The use of organic fine particles with specific shape factors and size distributions, closer to spherical shapes, to enhance the strength and uniformity of the porous membrane, while minimizing contamination and preventing short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If inorganic fine particles are used in the porous membrane, then thermal resistance and strength are improved, but moisture and metal ion contamination increases
Solution Approach 1:
The invention changes the material parameter from inorganic fine particles to organic fine particles with specific properties (polystyrene, polyacrylic acid, or polyacrylonitrile). This material substitution fundamentally alters the contamination profile while maintaining the porous membrane's structural integrity and strength requirements.
2Object-affected harmful factors
If organic fine particles are used in the porous membrane, then moisture and metal ion contamination is reduced, but strength and short circuit prevention ability decreases
Solution Approach 1:
The invention optimizes specific parameters of organic fine particles including particle size (0.1-10 μm), shape factor (0.7-1.3), and chemical composition (polystyrene, polyacrylic acid, or polyacrylonitrile). These parameter adjustments enable the organic particles to achieve both low contamination and sufficient mechanical strength.
Solution Approach 2:
The porous membrane is formulated as a composite material system containing organic fine particles dispersed in a binder matrix. This composite structure combines the low-contamination benefits of organic particles with the mechanical strength provided by the binder, resolving the contradiction between contamination reduction and strength maintenance.
3Object-affected harmful factors
If organic fine particles are used in the porous membrane, then moisture and metal ion contamination is reduced, but uniform distribution of membrane thickness and strength becomes difficult to achieve
Solution Approach 1:
The invention specifies a shape factor range (0.7-1.3) for the organic fine particles, which represents particles that are nearly spherical. This geometric parameter control ensures uniform packing behavior and consistent distribution throughout the membrane, achieving both low contamination and uniform thickness/strength distribution.
Data Source
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AI summary
A porous membrane for a secondary battery including non-electroconductive particles and a binder for a porous membrane, wherein the non-electroconductive particles are particles of a polymer, an arithmetic mean value of a shape factor of the non-electroconductive particles is 1.05 to 1.60, a variation coefficient of the shape factor is 16% or less, and a variation coefficient of a particle diameter of the non-electroconductive particles is 26% or less; manufacturing method thereof; and an electrode, a separator and a battery having the same.