Battery Porous Membrane Binder Composition for Stable High-Shear Slurry
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Solution Overview
Problem
Existing binder compositions for non-aqueous secondary battery porous membranes face issues with high water content and instability at high shear rates, which affect the performance and durability of the membranes.
Innovation Solution
A binder composition comprising a particulate polymer with a surface acid amount of 0.05 to 0.50 mmol/g and a liquid phase acid amount to surface acid ratio of 0.1 to 0.2, along with sulfosuccinic acid ester and/or its salt, is used to enhance slurry stability and reduce water content in the membranes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the amount of acidic group-containing monomer unit in the particulate polymer is increased to improve slurry stability at high shear rates, then the stability at high shear rates is improved, but the water content in the resulting porous membrane increases
Solution Approach 1:
The invention changes the parameter of surface acid amount to a specific range (0.05 mmol/g or more and 0.50 mmol/g or less) to achieve optimal balance between slurry stability and water content control. This parameter optimization allows the binder to provide sufficient stability at high shear rates while limiting excessive water absorption in the porous membrane.
Solution Approach 2:
The invention uses a composite binder composition comprising both a particulate polymer with controlled surface acid amount and a water-soluble polymer with specific carboxylic acid content. This composite approach allows the two materials to work synergistically, where the particulate polymer provides structural stability and the water-soluble polymer enhances adhesion while controlling overall water content.
2Strength
If a binder with higher surface acid amount is used to improve adhesion and slurry stability, then the binding performance is improved, but the water content in the porous membrane increases excessively
Solution Approach 1:
The invention optimizes the surface acid amount parameter to a specific range (0.05-0.50 mmol/g) that provides sufficient adhesion strength without causing excessive water content. This precise parameter control ensures the binder maintains strong bonding while limiting water absorption to acceptable levels.
Solution Approach 2:
The water-soluble polymer acts as an intermediary that enhances the binding performance and adhesion strength while simultaneously controlling the water content. This intermediary material bridges the gap between the particulate polymer and the porous membrane, providing improved adhesion without the excessive water content associated with high-surface-acid polymers alone.
Data Source
Figure 1
AI summary
Disclosed is a binder composition for a non-aqueous secondary battery porous membrane which comprises: a particulate polymer; a sulfosuccinic acid ester and/or a salt thereof; and water, wherein the particulate polymer has a surface acid amount S of 0.05 mmol/g or more and 0.50 mmol/g or less, and a ratio L/S which is a ratio of an acid amount L in a liquid phase of the binder composition to the surface acid amount S is 0.1 or more and 0.2 or less.