Viscous Acrylic Adhesive for Lithium-Ion Electrode Shape Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The electrode for lithium-ion batteries disclosed in existing patents requires separate addition of an adhesive material to retain shape, which is insufficient and decreases energy density when combined with a binder, leading to instability during charging and discharging.
Innovation Solution
A viscous adhesive with a glass transition temperature of 60° C. or lower, a solubility parameter of 8 to 13 (cal/cm3)1/2, and storage and loss shear moduli of 2.0×103 to 5.0×107 Pa, composed of an acrylic polymer with 50 wt % (meth)acrylic acid alkyl ester monomer and less than 3 wt % fluorine-containing monomer, is used to adhere active materials and form a shape-retaining electrode layer without a binder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If an adhesive material is added to retain electrode shape, then shape stability is improved, but energy density decreases due to the volume occupied by the adhesive
Solution Approach 1:
The patent changes the molecular weight parameter of the adhesive material to a specific range (10,000 to 1,000,000) to achieve optimal balance between shape retention and energy density. This parameter optimization allows the adhesive to provide sufficient binding force while minimizing volume occupation, thereby resolving the contradiction between shape stability and energy density
Solution Approach 2:
The patent uses a composite adhesive system consisting of multiple specific polymers (polyacrylic acid, polyacrylamide, polyvinyl alcohol, carboxymethyl cellulose, starch) in defined weight ratios. This composite approach creates a synergistic effect where the combination of materials provides superior shape retention at lower overall adhesive content compared to single-material systems, thus improving energy density while maintaining shape stability
2Shape
If a binder is combined with adhesive material to retain electrode shape, then shape stability is improved, but energy density decreases further due to additional component volumes
Solution Approach 1:
The patent extracts and eliminates the binder component from the electrode formulation, relying solely on the optimized adhesive material to provide both binding and shape retention functions. By removing the redundant binder, the total volume of non-active materials is reduced, thereby improving energy density while maintaining shape stability through the carefully selected adhesive system
3Quantity of substance
If adhesive material is used alone without binder, then energy density is improved, but shape retention becomes insufficient
Solution Approach 1:
The patent optimizes the molecular weight of the adhesive to a specific range (10,000 to 1,000,000) to enhance its binding capability and shape retention performance. This parameter adjustment allows the adhesive to function effectively as a standalone material, providing sufficient shape stability without requiring additional binder components, thus maintaining high energy density
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 electrode maintains shape stability and energy density, preventing destruction during charging and discharging, and exhibits excellent cycle characteristics.
Implementation Method 1
a viscous adhesive for a lithium-ion electrode which allows active materials to adhere to each other in a lithium-ion electrode
Implementation Method 2
the viscous adhesive is an acrylic polymer essentially containing a constituent unit derived from a (meth)acrylic acid alkyl ester monomer
Data Source
AI summary
The present invention provides a viscous adhesive capable of retaining the shape of an electrode and allowing for production of an electrode for a lithium-ion battery having a structure in which the energy density of the electrode does not decrease. The present invention relates to a viscous adhesive for a lithium-ion electrode which allows active materials to adhere to each other in a lithium-ion electrode, the viscous adhesive having a glass transition temperature of 60° C. or lower, a solubility parameter of 8 to 13 (cal/cm3)1/2, and a storage shear modulus and a loss shear modulus of 2.0×103 to 5.0×107 Pa as measured in a frequency range of 10−1 to 101 Hz at 20° C., wherein the viscous adhesive is an acrylic polymer essentially containing a constituent unit derived from a (meth)acrylic acid alkyl ester monomer, the proportion of the (meth)acrylic acid alkyl ester monomer in monomers constituting the viscous adhesive is 50 wt % or more based on the total monomer weight, and the proportion of a fluorine-containing monomer is less than 3 wt % based on the total monomer weight.