Positive Electrode Dispersant Composite for Low-Viscosity Slurry
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Solution Overview
Problem
The preparation of positive electrode slurry for secondary batteries faces challenges due to poor dispersion of active material powder and high viscosity, leading to defects such as cracking, film peeling, uneven weight, particle scratching, or pinholes in the electrode plate.
Innovation Solution
A dispersant composite is introduced, comprising a polymer with specific monomer units and a wetting agent, which improves the dispersion and viscosity of the slurry, comprising a hydrogenated nitrile rubber as the dispersant and a low molecular weight polymer or small-molecule organic solvent as the wetting agent, optimizing the mass ratios and molecular weights to enhance the slurry's fluidity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If positive electrode active substance powder is used directly in slurry preparation, then the electrode plate can be formed, but poor dispersion and high viscosity occur leading to defects
Solution Approach 1:
The patent introduces a dispersant composite as an intermediary substance between the positive electrode active substance powder and the dispersion medium. This dispersant composite includes a polymer with specific monomer units (acrylonitrile, butadiene, styrene) in controlled ratios, along with a wetting agent. The dispersant composite acts as a mediator that facilitates uniform distribution of powder particles in the slurry, reduces viscosity, and prevents aggregation, thereby improving both electrode plate quality and slurry processability without requiring extreme processing conditions.
2Quantity of substance
If high solid content is achieved in slurry, then energy density improves, but viscosity increases making coating difficult
Solution Approach 1:
The patent employs parameter changes by carefully controlling the composition ratios of monomer units in the polymer (acrylonitrile 25-55%, butadiene 40-70%, styrene 0.1-5%) and adjusting the molecular weight (50,000-500,000). These parameter adjustments optimize the dispersant's effectiveness in reducing slurry viscosity while maintaining high solid content. The wetting agent with specific surface tension (20-40 mN/m) further modifies the liquid phase properties to enable high solid content slurries to remain coatable.
3Reliability
If powder dispersion is improved by reducing particle size, then surface area increases enhancing reactivity, but viscosity increases making handling difficult
Solution Approach 1:
The patent creates a composite dispersant system combining a polymer with specific monomer composition (acrylonitrile-butadiene-styrene copolymer) and a wetting agent. This composite material approach allows the dispersant to effectively manage fine powder particles with high specific surface area. The polymer provides structural framework while the wetting agent reduces surface tension, together enabling good dispersion of fine particles without excessive viscosity increase, thus maintaining both electrode performance and handling ease.
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 dispersant composite significantly improves the processability and performance of the positive electrode slurry, reducing viscosity and enhancing filtration performance, thereby improving the overall performance and stability of the secondary battery.
Implementation Method 1
surface tension of the wetting agent is 20 mN/m-40 mN/m
Implementation Method 2
a dispersant composite including a dispersant and a wetting agent
Implementation Method 3
the dispersant includes a polymer, the polymer including: a first monomer unit represented by formula 1; a second monomer unit being at least one selected from a group consisting of a monomer unit represented by formula 2 and a monomer unit represented by formula 3
Data Source
AI summary
This application provides a dispersant composite, a positive electrode plate, a secondary battery, a battery module, a battery pack, and an electric apparatus. In particular, this application provides a dispersant composite including a dispersant and a wetting agent. The dispersant composite of this application can alleviate the problems of poor dispersion of positive electrode active material powder and high slurry viscosity during preparation of a positive electrode slurry, and further, can improve flexibility of the positive electrode plate.