Conductive Material Dispersion for Lithium-Ion Battery Electrodes
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Solution Overview
Problem
Existing methods for dispersing conductive materials in lithium-ion secondary batteries face challenges in achieving good dispersibility and stability, leading to poor conductivity and battery performance due to high viscosity and the presence of metallic foreign matter, which affects the cycle lifespan and safety of the batteries.
Innovation Solution
A conductive material dispersion using a copolymer with a nitrile group-containing structural unit and an amide-based organic solvent, with a pH of 9.0 or greater, and a complex elastic modulus less than 20 Pa, effectively disperses carbon fibers and improves the removal of metallic impurities, enhancing the formation of conductive networks and battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nanocarbons with large specific surface area are used as conductive material, then conductive network formation is improved, but dispersibility in slurry deteriorates
Solution Approach 1:
A dispersant comprising a copolymer with specific structural units (first structural unit with nitrile group, second structural unit with carboxyl group) is introduced as an intermediary substance. The dispersant adsorbs onto the nanocarbon surface through the nitrile group while the carboxyl group interacts with the slurry components, effectively mediating between the nanocarbon and the slurry to achieve both good dispersibility and conductive network formation.
Solution Approach 2:
The invention specifies precise compositional parameters of the dispersant copolymer (ratio of first to second structural units, molecular weight range) and processing parameters (pH range of 8.5-10.5, addition amount of dispersant) to optimize the balance between dispersibility and conductive network formation. By controlling these parameters, the contradiction between nanocarbon aggregation and poor dispersibility is resolved.
2Stability of the object's composition
If conductive material dispersion is prepared using conventional dispersants, then initial dispersibility is improved, but stability during electrode film formation deteriorates
Solution Approach 1:
The dispersant copolymer acts as a stable intermediary that maintains nanocarbon dispersion throughout the entire electrode film formation process. The specific copolymer structure with nitrile and carboxyl groups provides both initial dispersibility and long-term stability, preventing aggregation during slurry preparation, coating, and drying processes.
Solution Approach 2:
The invention creates a composite dispersion system combining nanocarbon, specifically designed copolymer dispersant, and slurry components. This composite approach ensures that the conductive material remains stably dispersed throughout the electrode film formation process, maintaining both initial dispersibility and conductivity stability.
3Quantity of substance
If filling amount of electrode active material is increased to improve capacity, then charging capacity is improved, but added amount of conductive material and binder resin must be reduced
Solution Approach 1:
The dispersant copolymer performs multiple functions simultaneously: it disperses nanocarbon, maintains dispersion stability, and contributes to conductive network formation. This self-service capability allows the system to achieve good conductivity with minimal added conductive material, as the dispersant itself facilitates network formation rather than requiring additional conductive additives.
Solution Approach 2:
The dispersant copolymer serves multiple functions: dispersion agent, stability maintainer, and conductive network promoter. This multi-functionality reduces the need for separate conductive material and binder resin additives, allowing higher electrode active material content while maintaining necessary conductivity and structural integrity.
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 achieves improved dispersibility and stability of conductive materials, leading to enhanced battery output and cycle lifespan, while reducing the risk of safety issues like short circuits and performance degradation.
Implementation Method 1
A conductive material dispersion using a copolymer with a nitrile group-containing structural unit and an amide-based organic solvent, with a pH of 9.0 or greater, and a complex elastic modulus less than 20 Pa, effectively disperses carbon fibers
Implementation Method 2
The solution achieves improved dispersibility and stability of conductive materials
Data Source
AI summary
A conductive material dispersion containing a conductive material containing carbon fibers, a dispersant, and an amide-based organic solvent, in which the dispersant contains a copolymer A containing a nitrile group-containing structural unit and satisfies following conditions.(I) A pH of the conductive material dispersion is 9.0 or greater.(II) A phase angle of the conductive material dispersion at a frequency of 1 Hz obtained by dynamic viscoelasticity measurement is 19° or greater, and a complex elastic modulus of the conductive material dispersion obtained by dynamic viscoelasticity measurement is less than 20 Pa.