Amphoteric Resin Dispersant for Secondary Battery Electrode
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Solution Overview
Problem
Existing secondary battery electrode compositions face challenges in achieving uniform dispersion of active materials and conductive assistants, leading to inadequate electrode performance due to insufficient dispersibility, which results in increased internal resistance and potential partial heating during battery use.
Innovation Solution
The use of an amphoteric resin-type dispersant, obtained by neutralizing carboxyl groups in a copolymer formed from specific ethylenically unsaturated monomers, improves the dispersibility of active materials and carbon materials as conductive assistants, enhancing the flexibility and adhesion to current collectors and resulting in improved charge-discharge cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional dispersants are used in mixture ink, then some dispersion is achieved, but uniform dispersion of conductive assistant and active material is insufficient leading to inadequate electrode performance
Solution Approach 1:
The patent introduces a specific dispersant as an intermediary substance to mediate between the conductive assistant particles and the mixture ink medium. This dispersant contains hydrophilic groups that interact with the carbon particles and hydrophobic groups that interact with the organic solvent, creating a bridge that achieves uniform dispersion. The dispersant acts as a mediator that resolves the incompatibility between hydrophobic carbon particles and the mixture ink composition.
Solution Approach 2:
The patent changes the chemical parameters of the dispersant by selecting specific compounds with particular molecular weight ranges (500-5000) and specific functional group compositions. By adjusting these parameters - particularly the molecular weight and the ratio of hydrophilic to hydrophobic groups - the dispersant optimally balances particle separation and stability, resolving the dispersion uniformity issue while maintaining electrode performance.
2Reliability
If carbon material with large specific surface area is used as conductive assistant, then conductivity is improved, but cohesive force increases making uniform mixing and dispersion difficult
Solution Approach 1:
The dispersant serves as a mediator that adsorbs onto the surface of high-surface-area carbon particles through its hydrophobic groups, while its hydrophilic groups extend into the mixture ink medium. This creates a steric and electrostatic barrier that prevents particle aggregation, enabling uniform dispersion of high-surface-area conductive assistants that would otherwise be difficult to mix due to strong cohesive forces.
Solution Approach 2:
The patent creates a composite system consisting of the conductive assistant particles, dispersant molecules, and mixture ink components. This composite approach combines the high conductivity of carbon materials with the dispersing capability of the surfactant-like dispersant, achieving both excellent conductivity and ease of mixing by integrating multiple materials with complementary properties.
3Ease of manufacture
If mixture ink is applied onto current collector, then electrode formation is achieved, but flexibility and adhesion properties are insufficient leading to damage during cutting or peeling
Solution Approach 1:
The patent creates a composite electrode structure where the dispersant not only aids in mixing but also contributes to the mechanical properties of the final electrode. The dispersant molecules form a network that binds particles together and to the current collector, providing both adhesion strength and flexibility. This composite material approach resolves the contradiction between ease of formation and mechanical strength by integrating multiple functional components.
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 improved dispersibility of active materials and carbon materials leads to better electrode performance, including enhanced flexibility, adhesion, and charge-discharge cycle characteristics, reducing internal resistance and maintaining battery performance over cycles.
Implementation Method 1
an amphoteric resin-type dispersant (C) prepared by neutralizing at least some carboxyl groups in a copolymer obtained by copolymerizing the following monomers with a basic compound
Data Source
AI summary
The present invention addresses the problem of providing an electrode-forming composition, which is used for the purpose of producing a secondary battery that has excellent charge and discharge cycle characteristics, and which exhibits excellent dispersibility of an active material and a conductive assistant. The problem is solved by a composition for forming a secondary battery electrode, which contains (A) an electrode active material and/or (B) a carbon material that serves as a conductive assistant, (C) an amphoteric resin-type dispersant that is obtained by neutralizing at least some carboxyl groups in a copolymer containing aromatic rings, carboxyl groups and amino groups with a basic compound, and (D) an aqueous liquid medium.