Aqueous Cathode Binder Composition for Adhesion and Cycle Stability
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Solution Overview
Problem
Current lithium-ion battery binders, such as PVDF, are insoluble in water and require toxic organic solvents like NMP, leading to environmental and health risks, while aqueous binders like CMC and SBR offer poor adhesion and cycle life, limiting their application in cathodes.
Innovation Solution
A binder composition comprising a copolymer derived from a carboxylic acid group-containing monomer, an amide group-containing monomer, and a nitrile group-containing monomer, which forms a stable and adhesive film in an aqueous medium, enhancing electrochemical performance and adhesion capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVDF binder is used, then electrochemical stability and adhesion are improved, but environmental pollution and health risks increase due to toxic organic solvents
Solution Approach 1:
The invention changes the chemical composition parameters of the binder from conventional PVDF to a copolymer containing carboxylic acid groups, amide groups, and nitrile groups. This parameter change enables the binder to be soluble in water instead of requiring toxic organic solvents like NMP, thus eliminating environmental pollution while maintaining electrochemical stability and adhesion properties
Solution Approach 2:
The invention uses a composite copolymer structure combining multiple functional groups (carboxylic acid, amide, and nitrile groups) within a single binder molecule. This composite structure integrates the advantages of different functional groups to achieve both water solubility and excellent electrochemical performance, resolving the contradiction between environmental friendliness and reliability
2Object-affected harmful factors
If aqueous binders like CMC or SBR are used, then environmental friendliness is improved, but adhesion capability and cycle life deteriorate
Solution Approach 1:
The invention creates a composite copolymer binder integrating carboxylic acid groups (for adhesion), amide groups (for flexibility and stability), and nitrile groups (for electrochemical performance). This multi-functional composite structure overcomes the limitations of single-function aqueous binders like CMC or SBR, achieving both environmental friendliness and superior adhesion capability
Solution Approach 2:
The invention assigns different functional groups to specific locations within the copolymer structure, where carboxylic acid groups provide localized adhesion to the current collector, while amide and nitrile groups provide localized electrochemical stability. This local quality differentiation enables the binder to simultaneously achieve good adhesion and long cycle life in aqueous environments
3Ease of operation
If SBR binder is used, then water solubility is improved, but dispersion homogeneity and electrode resistance worsen due to agglomeration
Solution Approach 1:
The invention changes the molecular structure parameters of the binder by incorporating carboxylic acid groups that provide excellent water solubility and electrostatic repulsion, preventing particle agglomeration. This parameter change enables homogeneous dispersion in aqueous media while maintaining good adhesion and electrochemical performance
Data Source
AI summary
An aqueous binder composition for a secondary battery electrode is provided, comprising a copolymer and a dispersion medium, wherein the copolymer comprises a structural unit (a) derived from a carboxylic acid group-containing monomer, a structural unit (b) derived from an amide group-containing monomer and a structural unit (c) derived from a nitrile group-containing monomer, with an improved binding capability. In addition, battery cells comprising the cathode prepared using the binder composition disclosed herein exhibits exceptional electrochemical performance.