Three-Stage Aqueous Binder for pH-Stable Lithium-Ion Slurries
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Solution Overview
Problem
Existing aqueous binders for lithium-ion battery ternary materials fail to stabilize the pH of the slurry during storage, leading to viscosity fluctuations and corrosion of the aluminum current collector due to reactions in highly alkaline environments.
Innovation Solution
A three-stage copolymer aqueous binder is developed through stage I and II polymerization, using carboxyl-containing functional monomers, vinyl acetate, and acrylate monomers, with specific mass ratios and reaction conditions to form a protective gel, which can adjust and stabilize the pH of the slurry, suitable for pulping and coating processes in lithium-ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing aqueous binders are used for ternary materials in lithium-ion batteries, then the binder can be applied to the positive electrode material, but the pH of the slurry cannot be stabilized during storage, leading to viscosity fluctuations and corrosion of the aluminum current collector
Solution Approach 1:
The patent modifies the chemical composition parameters of the aqueous binder by incorporating specific carboxyl-containing functional monomers (such as acrylic acid, methacrylic acid, itaconic acid) in controlled amounts (0.1-10% by mass). This parameter change enables the binder to buffer pH variations in the slurry, stabilizing the alkaline environment and preventing aluminum foil corrosion while maintaining coating consistency during storage
Solution Approach 2:
The patent creates a composite aqueous binder system by combining multiple functional components: carboxyl-containing functional monomers for pH buffering, vinyl acetate monomers for adhesion, and acrylate monomers for film formation. This composite structure provides both pH stabilization capability and effective corrosion protection for the aluminum current collector in highly alkaline ternary material slurries
2Ease of operation
If existing aqueous binders are used for ternary materials, then the binder can facilitate pulping and coating processes, but the viscosity of the slurry fluctuates with pH changes, affecting coating consistency
Solution Approach 1:
The patent adjusts the pH-sensitive parameters of the slurry by incorporating carboxyl-containing functional monomers that act as buffers. These monomers maintain the slurry pH within a stable range (12-14) during storage and processing, thereby stabilizing the viscosity and ensuring consistent coating quality while remaining adaptable to pulping and coating operations
3Reliability
If aluminum foil is used as the current collector for the positive plate, then the current collector provides good electrical conductivity, but the aluminum foil reacts under highly alkaline conditions, emitting gas and corroding the cathode current collector
Solution Approach 1:
The patent introduces the aqueous binder containing carboxyl-containing functional monomers as an intermediary protective layer between the aluminum foil current collector and the highly alkaline slurry environment. This binder layer acts as a buffer that neutralizes excessive alkalinity and prevents direct contact between the aluminum foil and corrosive hydroxide ions, thereby eliminating gas emission and corrosion while preserving the electrical conductivity of the aluminum current collector
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 effectively stabilizes the pH and viscosity of the ternary material slurry, preventing corrosion of the aluminum current collector and ensuring consistent coating, thereby enhancing the performance and stability of lithium-ion batteries with different nickel-cobalt-aluminum ratios.
Implementation Method 1
carboxyl-containing functional monomers, vinyl acetate monomers and acrylate monomers are mixed to perform stage I polymerization to form a stage I binder
Data Source
AI summary
The present invention discloses an aqueous binder, which is prepared by the following methods: (1) under the action of protective gel, carboxyl-containing functional monomers, vinyl acetate monomers and acrylate monomers are mixed to perform stage I polymerization to form a stage I binder; (2) after the stage I polymerization is completed, vinyl acetate monomers are added to perform stage II polymerization to form a stage II binder; (3) after the stage II polymerization is completed, a pre-emulsion, which is formed in advance of carboxyl-containing functional monomers, vinyl acetate monomers and acrylate monomers, is added dropwise to react completely to form a stage III binder. The binder can adapt to the pulping and coating process in highly alkaline environments, can be applied to ternary materials of lithium-ion batteries, and can stabilize or adjust the pH value of the ternary material slurry of lithium-ion batteries, and has a wide market application value.