Aqueous Positive Electrode Slurry for Gel-Free Lithium Battery Coating
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Solution Overview
Problem
Traditional lithium-ion battery positive electrodes using polyvinylidene fluoride as a binder face issues with environmental pollution and high costs due to organic solvent volatilization, and the transition to aqueous systems struggles with gel formation, brittleness, and low cold-pressed density, affecting mechanical and electrochemical performance.
Innovation Solution
A positive electrode slurry comprising a conductive agent, an aqueous binder, and a functional additive with specific functional groups such as —NR3+, —SO32−, —PO43−, —CO—, —O—, and —NH2, which forms a coating layer on active material particles, improving dispersion and mechanical properties, and using water as a solvent to reduce environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyvinylidene fluoride as a binder is used with organic solvent, then bonding performance is improved, but environmental pollution and cost increase due to solvent volatilization
Solution Approach 1:
The patent changes the fundamental parameter of the solvent system from organic to aqueous-based, replacing volatile organic solvents with water as the continuous phase. This transformation maintains the binder's bonding functionality while eliminating the harmful volatilization effects, directly resolving the contradiction between bonding performance and environmental pollution.
Solution Approach 2:
The patent employs water-soluble binders that can be easily processed and removed or degraded, replacing expensive organic solvents that require complex recovery systems. The aqueous system allows for simpler, more economical processing without sacrificing adhesive performance.
2Object-generated harmful factors
If aqueous binder is used for positive electrode slurry, then environmental pollution is reduced, but gel formation occurs within 10 minutes making coating difficult
Solution Approach 1:
The patent introduces dispersants and protective colloids as intermediary substances that mediate between the aqueous binder and active material particles. These intermediaries prevent premature gel formation by maintaining stable dispersion during the critical coating window, enabling successful processing with aqueous systems.
Solution Approach 2:
The patent performs preliminary stabilization of the aqueous slurry through controlled mixing sequences and temperature management before coating. By preparing the slurry under optimized conditions beforehand, the coating process can be completed within the extended stability window, preventing gel formation during application.
3Quantity of substance
If aqueous positive electrode system is used, then cost is reduced, but coated electrode sheet becomes brittle and hard with low cold-pressed density
Solution Approach 1:
The patent creates a composite binder system combining aqueous-soluble polymers with flexible additives and plasticizers. This composite approach maintains the cost advantages of aqueous processing while restoring mechanical flexibility and improving cold-pressed density through synergistic material combinations.
Solution Approach 2:
The patent modifies the chemical composition parameters of the aqueous binder by incorporating flexible chain segments, plasticizers, and processing aids. These parameter changes transform the brittle characteristics of simple aqueous binders into flexible, mechanically robust electrode sheets suitable for battery manufacturing.
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 solution enhances the stability and toughness of the electrode sheet, reduces environmental pollution, and improves the mechanical and electrochemical performance of lithium-ion batteries by preventing gel formation and maintaining excellent bonding performance.
Implementation Method 1
the functional additive has at least one of —NR3+, —SO32−, —PO43−, —CO—, —O—, and —NH2, where R is an alkyl group
Data Source
AI summary
Provided is a positive electrode slurry, a positive electrode sheet, and a lithium battery. The positive electrode slurry includes a positive electrode active material, a conductive agent, an aqueous binder, and a functional additive, wherein the functional additive has at least one of —NR3+, —SO32−, —PO43−, —CO—, —O—, and —NH2, where R is an alkyl group.