Aqueous Cathode Binder Composition for Adhesion and Stability
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Solution Overview
Problem
Existing lithium-ion battery binders, such as PVDF and aqueous alternatives like CMC and SBR, face issues with adhesion capability, electrochemical stability, and environmental hazards, particularly in cathodes, leading to high production costs and environmental pollution.
Innovation Solution
A binder composition comprising a copolymer with structural units from carboxylic acid, amide, and nitrile group-containing monomers, along with an anionic reactive emulsifier, is used in an aqueous dispersion medium to enhance adhesion and electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PVDF binder is used, then electrochemical stability is improved, but environmental pollution and handling complexity increase due to NMP solvent requirements
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 used with water-based solvents instead of NMP, eliminating environmental pollution while maintaining electrochemical stability through the synergistic effect of the functional groups in the copolymer structure.
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 material approach allows the binder to simultaneously provide adhesion, electrochemical stability, and compatibility with water-based solvents, resolving the contradiction between performance and environmental impact.
2Strength
If PVDF binder with NMP solvent is used, then binding capability is improved, but manufacturing cost increases due to NMP recovery system requirements
Solution Approach 1:
The invention changes the solvent parameter from NMP to water-based solvents, eliminating the need for expensive NMP recovery systems. The copolymer binder structure is specifically designed to maintain strong binding capability through its functional groups while being compatible with the cheaper, easier-to-handle water-based solvent system, thereby reducing manufacturing costs.
3Object-affected harmful factors
If aqueous binders like CMC and 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 that integrates multiple functional groups (carboxylic acid for chelation and adhesion, amide for polarity and bonding, and nitrile for electrochemical stability) into a single molecular structure. This composite approach enables the aqueous binder to achieve adhesion capability and cycle life comparable to PVDF while maintaining environmental friendliness through water-based formulation.
Solution Approach 2:
The invention optimizes the chemical composition parameters of the aqueous binder by incorporating specific ratios of carboxylic acid, amide, and nitrile groups in the copolymer structure. This parameter optimization enhances adhesion capability through improved interaction with electrode materials while maintaining compatibility with water-based solvents, thereby achieving both environmental friendliness and high performance.
4Adaptability or versatility
If SBR binder is used, then water solubility is improved, but performance deteriorates due to high expandability and agglomeration
Solution Approach 1:
The invention develops a composite copolymer binder that combines hydrophilic segments (providing water solubility) with functional segments containing carboxylic acid, amide, and nitrile groups (providing structural stability and electrochemical performance). This composite structure maintains water solubility while preventing the high expandability and agglomeration issues associated with conventional SBR, thereby achieving both adaptability and reliability.
Data Source
AI summary
Provided is an aqueous binder composition for a secondary battery electrode, 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, a structural unit (c) derived from a nitrile group-containing monomer, and at least one anionic reactive emulsifier, with an improved binding capability. In addition, battery cells comprising the cathode prepared using the binder composition disclosed herein exhibits exceptional electrochemical performance.