Flexible Electrode Slurry Using pH-Controlled Aqueous Emulsion
Solution Overview
Problem
Existing flexible electrodes face challenges in maintaining conductivity and flexibility while avoiding breakage during extension, with previous solutions using carbon nanotubes posing health risks and organic solvents increasing the risk of ignition, and existing conductive compositions failing to suppress resistance value changes effectively.
Innovation Solution
A slurry comprising an aqueous emulsion of specific polymer components, carbon black, and optional carbon nanotubes or graphene, with carefully controlled mass ratios and pH, to create a uniform conductive path that maintains conductivity and flexibility without breaking during extension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filling amount of conductive agent is increased to improve conductivity, then the conductivity at natural length is improved, but the electrode may break during extension and the viscosity of slurry increases making coating difficult
Solution Approach 1:
The patent changes the physical and chemical parameters of the conductive agent by using carbon black with specific DBP absorption amounts (150-300 mL/100g) and BET specific surface areas (35-140 m²/g), along with controlling the pH of the aqueous emulsion (6.5-8.0), to achieve optimal conductivity and flexibility balance without increasing filling amount excessively
Solution Approach 2:
The patent creates a composite material system combining carbon black particles with specific surface properties and an aqueous polymer emulsion, forming a synergistic composition where the emulsion matrix and conductive agent work together to provide both conductivity and flexibility simultaneously
2Ease of operation
If the filling amount of conductive agent is reduced to ensure flexibility and coatability, then the viscosity of slurry is reduced and flexibility is improved, but the conductivity is lowered and electric charge cannot be supplied to the dielectric layer sufficiently
Solution Approach 1:
The patent optimizes the surface area to volume ratio parameters of the carbon black particles by selecting materials with specific BET specific surface areas (35-140 m²/g) and DBP absorption amounts, which increases the effective surface area for conductivity per unit volume, allowing reduced filling amounts while maintaining conductivity
Solution Approach 2:
The patent creates an efficient conductive network structure where carbon black particles are uniformly distributed and connected through the aqueous emulsion matrix, forming a percolating pathway that replicates effective conductivity with minimal material content
3Reliability
If carbon nanotubes are used to improve conductivity and flexibility, then the conductive path is improved, but there is a risk of health influence from nanomaterials and organic solvents may be heated and ignite
Solution Approach 1:
The patent replaces expensive and potentially hazardous carbon nanotubes with carbon black, a more economical and safer alternative that achieves comparable conductive performance without the health risks associated with nanomaterial handling and organic solvent usage
Solution Approach 2:
The patent converts the typically undesirable property of carbon black (aggregation tendency) into a benefit by carefully controlling particle surface area and using pH-adjusted aqueous emulsions to prevent aggregation, thereby achieving uniform dispersion and reliable conductivity without health hazards
4Length of moving object
If the electrode is greatly extended together with the dielectric layer, then the displacement is increased, but the distance between the conductive agents is increased so that the conductive path is cut and the electric resistance is increased
Solution Approach 1:
The patent creates a dynamic conductive network using carbon black particles embedded in an elastic aqueous polymer emulsion matrix that can dynamically reconfigure and maintain conductive pathways during extension, allowing the electrode to adapt its structure while preserving electrical connectivity
Solution Approach 2:
The patent forms a composite structure where carbon black particles are dispersed in an elastic polymer matrix, creating a synergistic material that combines the electrical conductivity of carbon black with the extensibility of the polymer, enabling large displacements without breaking conductive paths
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 effectively suppresses the increase in electric resistance during extension, producing flexible electrodes with resistance values below 80 Ω·cm at 150% strain and 500 Ω·cm at 200% strain, ensuring the electrodes do not break, while ensuring safe and efficient production.
Implementation Method 1
a conductive path that maintains conductivity and flexibility without breaking during extension
Implementation Method 2
dispersed in the aqueous emulsion
Data Source
Figure 1~2
AI summary
According to one of various aspects of the present invention, a slurry for a flexible electrode contains a component (a) dispersed in an aqueous emulsion. The emulsion includes one or more polymer components selected from the group consisting of acrylic polymers, urethane polymers, fluorine polymers, urea polymers, chloroprene polymers, and butadiene polymers. The emulsion has a pH of 6.5 to 8.0. In the slurry, the total of the polymer component(s) and the component (a) is 20 to 30% by mass. Of the total of the polymer component(s) and the component (a) in the slurry, the polymer component(s) is 60 to 85% by mass, and the component (a) is 15 to 40% by mass. Component (a) is carbon black having a DBP absorption amount under uncompressed conditions of 150 to 300 mL/100 g and a BET specific surface area of 35 to 140 m2/g.