Carbon Conductive Dispersion Copolymer for Low-Viscosity Battery Electrodes
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Solution Overview
Problem
Conductive material dispersion liquids with high carbon-based conductive material content exhibit increased viscosity and poor storage stability due to the limitations of existing dispersants, hindering the uniform distribution and conductivity of carbon nanotubes in electrode active material layers.
Innovation Solution
A conductive material dispersion liquid using a copolymer dispersant with specific repeating units, including a styrene-derived unit for stability, an acrylonitrile-derived unit for polarity, and an alkyl (meth)acrylate-derived unit for low polarity, which maintains dispersibility and forms bonds with carbon-based conductive materials, combined with a non-aqueous solvent, to achieve low viscosity and enhanced storage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of carbon-based conductive material is increased to enhance electrical conductivity, then the electrical conductivity is improved, but the viscosity of the dispersion liquid is rapidly increased
Solution Approach 1:
The invention changes the chemical structure parameters of the dispersant by using a copolymer with specific repeating units (styrene, acrylonitrile, and alkyl (meth)acrylate in specific ratios) instead of conventional dispersants. This parameter change in the dispersant structure enables it to effectively disperse carbon-based conductive materials at high concentrations without causing rapid viscosity increase, thus resolving the contradiction between improving electrical conductivity and maintaining low viscosity.
2Ease of operation
If a dispersant with low weight-average molecular weight is used to lower viscosity, then the viscosity is reduced, but the dispersant becomes gelated and storage stability is rapidly degraded
Solution Approach 1:
The invention optimizes the molecular weight parameters of the dispersant by selecting a copolymer with a weight-average molecular weight within a specific range (10,000 to 100,000). This parameter optimization prevents gelation while maintaining low viscosity, thereby resolving the contradiction between reducing viscosity and ensuring storage stability.
Solution Approach 2:
The invention uses a copolymer dispersant composed of multiple types of repeating units (styrene, acrylonitrile, and alkyl (meth)acrylate) rather than a homopolymer. This composite structure combines the benefits of different monomer units: styrene provides structural stability, acrylonitrile provides polarity for good dispersion, and alkyl (meth)acrylate provides low polarity for compatibility. This composite material approach enables the dispersant to maintain both low viscosity and high storage stability without gelation.
3Stability of the object's composition
If conventional dispersants are used to disperse carbon nanotubes, then dispersibility is achieved, but coatability and processability are degraded due to bundle type or entangled type growth
Solution Approach 1:
The invention changes the dispersant structure parameters by using a copolymer with specific repeating units (styrene, acrylonitrile, and alkyl (meth)acrylate in controlled ratios) instead of conventional dispersants like PVP or acrylonitrile-butadiene rubber. This structural parameter change enables effective dispersion of carbon nanotubes at the molecular level, preventing bundle and entangled type growth, thus simultaneously improving both dispersibility and coatability/processability.
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 allows for a high content of carbon-based conductive materials with low viscosity and excellent storage stability, enabling improved electrical conductivity and processability in lithium secondary batteries.
Implementation Method 1
the dispersant is a copolymer including a first repeating unit represented by Chemical Formula 1 below, a second repeating unit represented by Chemical Formula 2 below, and a third repeating unit represented by Chemical Formula 3 below
Implementation Method 2
which maintains dispersibility and forms bonds with carbon-based conductive materials
Implementation Method 3
A conductive material dispersion liquid using a copolymer dispersant with specific repeating units... which maintains dispersibility and forms bonds with carbon-based conductive materials, combined with a non-aqueous solvent, to achieve low viscosity and enhanced storage stability
Data Source
AI summary
Provided are a conductive material dispersion liquid, and an electrode and a lithium secondary battery manufactured using the same. The conductive material dispersion liquid according to the present invention includes a carbon-based conductive material, a dispersant, and a dispersion medium, wherein the dispersant is a copolymer including a first repeating unit represented by Chemical Formula 1, a second repeating unit represented by Chemical Formula 2, and a third repeating unit represented by Chemical Formula 3, and the dispersion medium is a non-aqueous solvent.