Copolymer Dispersant for Stable Electrode Slurry Conductive Networks
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Solution Overview
Problem
Existing methods for dispersing conductive materials in lithium-ion secondary battery electrodes face challenges in maintaining good dispersion states and forming efficient conductive networks, leading to poor battery performance and cycle life, particularly due to issues with dispersant robustness and fluidity.
Innovation Solution
A dispersant composition containing a copolymer with specific structural units, including an aliphatic hydrocarbon, nitrile, and unsubstituted carbamoyl groups, is used to achieve both excellent dispersibility and robustness, ensuring a stable conductive network in the electrode film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nanocarbon with large specific surface area is used as conductive material, then conductive network efficiency is improved, but dispersibility in slurry deteriorates
Solution Approach 1:
The patent uses a polymer dispersant as an intermediary substance between nanocarbon and the slurry medium. The dispersant molecules adsorb onto the nanocarbon surface through their hydrophobic groups while their hydrophilic groups interact with the slurry, effectively bridging the incompatible phases and enabling stable dispersion of high-surface-area nanocarbon without aggregation.
Solution Approach 2:
The patent modifies the chemical and physical parameters of the nanocarbon surface by controlling the adsorption of dispersant molecules. By adjusting dispersant concentration, molecular weight, and structural parameters, the surface properties of nanocarbon are changed to improve wettability and dispersibility while maintaining the high surface area necessary for conductive network efficiency.
2Ease of manufacture
If polymer dispersant is used to achieve good dispersion state, then dispersibility is improved, but robustness in electrode film formation deteriorates
Solution Approach 1:
The patent designs the polymer dispersant with local quality differentiation through its molecular structure - hydrophobic segments for binding to nanocarbon and hydrophilic segments for interaction with the slurry medium. This local quality differentiation enables the dispersant to perform different functions at different locations (nanocarbon surface vs. bulk slurry), achieving both good dispersion and robustness in electrode film formation.
Solution Approach 2:
The patent creates a composite system consisting of nanocarbon, polymer dispersant, and slurry components. The polymer dispersant acts as a composite material that combines the functions of adhesion promoter and lubricant, enabling the nanocarbon to maintain both dispersibility and robustness through the synergistic interaction of its multiple functional groups.
3Force
If hydrogenated nitrile rubber is used as dispersant, then viscosity is reduced, but dispersibility and conductive network formation deteriorate
Solution Approach 1:
The patent develops a composite polymer dispersant that combines the low-viscosity advantage of hydrogenated nitrile rubber with additional functional groups (carboxyl, hydroxyl, or amine groups) that provide enhanced dispersibility and conductive network formation capability. This composite structure allows the dispersant to simultaneously reduce viscosity while maintaining or improving dispersion quality.
Solution Approach 2:
The patent modifies the chemical composition parameters of the polymer dispersant by incorporating specific functional groups and adjusting the ratio of different monomer units. These parameter changes enable the dispersant to maintain low viscosity while introducing polar groups that enhance interaction with conductive materials and improve dispersibility and conductive network formation.
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 rate and cycle characteristics of lithium-ion secondary batteries by maintaining a good dispersion state and forming a robust conductive network, even with a small addition of conductive material, thereby improving battery output and cycle life.
Implementation Method 1
the dispersant comprises a copolymer including an aliphatic hydrocarbon structural unit, a nitrile group-containing structural unit, and an unsubstituted carbamoyl group-containing structural unit
Implementation Method 2
because the nanocarbon having a large specific surface area has a high cohesive force, it is difficult to favorably disperse the nanocarbon in the slurry for electrode film
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
Provided is a dispersant containing a copolymer that includes an aliphatic hydrocarbon structural unit, a nitrile group-containing structural unit, and a substituted or unsubstituted carbamoyl group-containing structural unit. The aliphatic hydrocarbon structural unit includes an alkylene structural unit. The content of the aliphatic hydrocarbon structural unit is 40 mass% or more and less than 85 mass% based on the mass of the copolymer, the content of the nitrile group-containing structural unit is 15 mass% or more and 50 mass% or less based on the mass of the copolymer, and the content of the substituted or unsubstituted carbamoyl group-containing structural unit is 10 mass% or less based on the mass of the copolymer. The weight-average molecular weight of the polymer is 5,000 or more and 400,000 or less.