Electrode Dispersant Composition for CNT Dispersion in Polar Solvents
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Solution Overview
Problem
Existing dispersants for electrode power storage devices face challenges in achieving good solubility in polar solvents at room temperature and ensuring high dispersibility of carbon material-based conductive materials, particularly carbon nanotubes with high aspect ratios.
Innovation Solution
A dispersant composition containing a repeating unit with a long chain alkyl group (16-22 carbon atoms) and a spacer group (1-12 carbon atoms) is used, which enhances solubility in organic solvents and improves the dispersibility of carbon material-based conductive materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a dispersant with short-chain alkyl group is used to improve solubility in polar solvents, then solubility is improved, but dispersibility of carbon nanotubes deteriorates
Solution Approach 1:
The dispersant molecule is designed with different functional groups having different properties: a long-chain alkyl group (16-22 carbon atoms) for adsorbing carbon nanotubes and a spacer group (1-12 carbon atoms) for solubility in polar solvents. This local differentiation of molecular segments resolves the contradiction between solubility and dispersibility.
Solution Approach 2:
The dispersant is constructed as a composite molecular structure combining a polyolefin backbone with amidated long-chain alkyl groups and spacer groups. This composite structure integrates the functions of both hydrophobic interaction (for CNT dispersibility) and polar solvent compatibility.
2Reliability
If a dispersant with long chain alkyl group is used to improve dispersibility of carbon materials, then dispersibility is improved, but solubility in polar solvents deteriorates
Solution Approach 1:
The dispersant molecule is designed with different functional groups having different properties: a long-chain alkyl group (16-22 carbon atoms) for adsorbing carbon nanotubes and a spacer group (1-12 carbon atoms) for solubility in polar solvents. This local differentiation of molecular segments resolves the contradiction between solubility and dispersibility.
3Power
If carbon material is used as conductive material in positive electrode, then electron transfer rate is improved, but viscosity of slurry increases
Solution Approach 1:
The dispersant acts as an intermediary substance between carbon materials and the slurry medium. It adsorbs onto carbon material surfaces, providing steric hindrance and electrostatic repulsion that prevent aggregation, thereby maintaining low slurry viscosity while preserving the high electron transfer rate of carbon materials.
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 composition achieves high solubility in organic solvents at room temperature and improves the dispersibility of carbon material-based conductive materials, leading to the production of low-resistance positive electrodes and power storage devices with high productivity.
Implementation Method 1
R3 represents an alkyl group with 16 to 22 carbon atoms... the dispersant having a long chain alkyl group is particularly effective for dispersion in a nonpolar solvent
Implementation Method 2
R4 represents an alkyl group with 1 to 12 carbon atoms... the dispersant having a short chain alkyl group is particularly effective for dispersion in a polar solvent
Data Source
AI summary
An aspect of the present disclosure relates to a dispersant for an electrode of a power storage device. The dispersant contains a repeating unit represented by the following general formula (1), where a, b, and c each represent a mole fraction, provided that a+b+c=1, and b and c satisfy the relationship expressed by 0.50<b+c≤1.00 and 0.50≤b/b+c)≤0.95. R4 is preferably a branched alkyl group. R5 is preferably an alkyl group with 1 to 12 carbon atoms, a saturated hydrocarbon group with 1 to 12 carbon atoms that includes an alicyclic hydrocarbon group, or a saturated hydrocarbon group with 1 to 12 carbon atoms that has a hydroxyl group.