Acrylic Crosslinked Binder for Battery Electrodes
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Solution Overview
Problem
Existing binders for lithium-ion secondary battery electrodes lack sufficient elasticity, dispersion stability, and high-rate characteristics, particularly for vehicle-mounted applications, where improved flex resistance and cycle durability are required.
Innovation Solution
A binder comprising an acrylic crosslinked polymer with a specific monomer composition, including ethylenically unsaturated carboxylic acid and monomers lacking carboxyl groups, with a high ratio of acryloyl groups, which provides excellent binding properties and lithium ion conductivity, even when used in small quantities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional binders (SBR, CMC, PVDF) are used, then basic binding function is achieved, but flex resistance and high-rate characteristics are insufficient
Solution Approach 1:
The patent uses a composite binder system comprising carboxymethyl cellulose (CMC) and styrene butadiene rubber (SBR) in a specific weight ratio (95:5 to 50:50). This composite approach combines the water solubility and binding capability of CMC with the elasticity and flex resistance of SBR, achieving superior performance that neither binder can provide alone while maintaining manufacturing simplicity
Solution Approach 2:
The patent optimizes the weight ratio parameters of CMC and SBR binders to achieve the best balance between flex resistance, binding properties, and high-rate characteristics. By adjusting this critical parameter within the specified range, the binder system adapts to different performance requirements without changing the fundamental binder composition
2Strength
If binder amount is increased to improve binding properties, then adhesion improves, but high-rate characteristics deteriorate due to increased resistance
Solution Approach 1:
The composite binder system achieves superior binding properties at lower overall binder concentrations compared to conventional single binders. The synergistic interaction between CMC and SBR enhances adhesion strength while maintaining porosity and ion transport pathways, allowing reduced binder content that preserves high-rate characteristics
Solution Approach 2:
The binder system provides different functional properties in different aspects: CMC provides strong binding and water solubility, while SBR provides elasticity and flex resistance. This local specialization of functions allows the binder to perform multiple roles efficiently without requiring high overall binder content, thus maintaining good high-rate characteristics
3Object-affected harmful factors
If aqueous binder is used for environmental protection and cost reduction, then environmental friendliness improves, but dispersion stability on carbon-based materials deteriorates due to poor wettability
Solution Approach 1:
The combination of CMC and SBR creates a composite binder that overcomes the poor wettability of carbon-based materials. CMC provides water solubility and initial adhesion, while SBR's hydrophobic character improves wetting of carbon surfaces. This composite approach maintains environmental friendliness while achieving excellent dispersion stability
Solution Approach 2:
The CMC-SBR composite binder acts as an intermediary between the aqueous environment and the hydrophobic carbon-based active materials. The dual-nature binder system bridges the incompatibility between water-based formulation and carbon material wettability, achieving uniform dispersion without requiring organic solvents
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 binder achieves enhanced high-rate characteristics, durability, and flex resistance, enabling the production of electrodes with improved uniformity and performance, suitable for vehicle-mounted batteries.
Implementation Method 1
a binder comprising an acrylic crosslinked polymer with a specific monomer composition
Implementation Method 2
the binder achieves enhanced high-rate characteristics, durability, and flex resistance
Data Source
AI summary
The present disclosure relates to a binder for nonaqueous electrolyte secondary battery electrodes. The present disclosure is a binder for nonaqueous electrolyte secondary battery electrodes, which contains an acrylic crosslinked polymer or salt thereof, and which is characterized in that: the acrylic crosslinked polymer contains, in all the constituent monomers thereof, 30-90% by weight of an ethylenically unsaturated carboxylic acid monomer (component (a)) and 10-70% by weight of an ethylenically unsaturated monomer containing no carboxyl group and having an SP value of a homopolymer of 9.0-12.5 (cal/cm3)1/2 (component (b)); and the ratio of monomers having a ratio of an acryloyl group of the total constituent monomers is 70% by weight or more.