Powder Water-Soluble Binder for Low-Swelling Battery Electrodes
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Solution Overview
Problem
Existing lithium-ion battery binders face challenges with insufficient adhesive strength, flexibility, and swelling inhibition, leading to poor cycling performance, particularly with silicon-based negative electrodes, and are limited by high transportation and packaging costs due to low solid content in aqueous solutions.
Innovation Solution
A water-soluble binder composed of a copolymer formed by specific monomers, optimized for high molecular weight and controlled molecular weight distribution, is developed in powder form, enhancing adhesive strength and swelling inhibition while reducing transportation and packaging costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PAA binders are used in aqueous solution form to maintain good suspension and dispersion capability, then adhesive strength and swelling inhibition are improved, but solid content becomes low leading to increased transportation and packaging costs
Solution Approach 1:
The patent changes the physical state parameter of the binder from aqueous solution to powder form. This parameter change increases the solid content from typically 5-15% in solutions to nearly 100% in powder form, dramatically reducing transportation and packaging costs while maintaining the adhesive strength and swelling inhibition properties through controlled molecular weight and composition of the copolymer
Solution Approach 2:
The patent extracts the binder material from the aqueous solution medium and presents it in pure powder form. This extraction eliminates the need for large volumes of water or solvent, concentrating the active binder material and thereby increasing solid content while reducing transportation costs
2Ease of manufacture
If SBR binders are used in negative electrodes, then ease of manufacture is improved, but adhesive strength and swelling inhibition are insufficient leading to poor cycling performance
Solution Approach 1:
The patent uses a copolymer composed of multiple monomer units (acrylic acid, acrylonitrile, and optionally other functional monomers) to create a composite binder material that combines the advantages of different polymer components, achieving both ease of manufacture through aqueous processing and superior adhesive strength and swelling inhibition for improved cycling performance
Solution Approach 2:
The patent changes the chemical composition parameters of the binder by using a copolymer with specific monomer ratios rather than homopolymers. This compositional parameter change enables the binder to maintain ease of manufacture while achieving the adhesive strength and swelling inhibition necessary for good cycling performance
3Strength
If high molecular weight PAA is used to maintain good suspension and dispersion capability, then adhesive strength is improved, but solid content becomes low increasing transportation costs
Solution Approach 1:
The patent changes the physical state parameter from aqueous solution to powder form, which allows the high molecular weight polymer to be presented in concentrated powder form with near 100% solid content. This eliminates the volume expansion caused by water or solvent, reducing transportation costs while maintaining the adhesive strength provided by the high molecular weight structure
Data Source
AI summary
A water-soluble binder, a battery electrode sheet and the use thereof. The water-soluble binder comprises a copolymer. Polymeric monomers of the copolymer comprise a combination of a double-bond-containing nitrile monomer, a double-bond-containing amide monomer, a double-bond-containing carboxylic acid monomer, optionally a double-bond-containing sulfonic acid monomer and optionally a fifth monomer. The water-soluble binder is in the form of powder, and the mass percentage content of the copolymer in the water-soluble binder is greater than or equal to 92%. By means of the design of the polymeric monomers and the copolymer and the combination of the copolymer and the powder form, the water-soluble binder has excellent binding power, and can effectively inhibit the volume expansion of an electrode sheet during charge and discharge cycles, thereby improving the cycling performance of the electrode sheet and a lithium-ion battery.