Resin Composition for Redox Flow Battery Electrodes
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Solution Overview
Problem
Electrically conductive resin films for redox flow batteries face challenges in achieving a balance between high electric conductivity, tensile elongation, durability to bending, and flexibility, as existing solutions either compromise on mechanical properties or result in high internal resistance due to the use of carbon nanotubes or costly noble metals.
Innovation Solution
A resin composition combining thermoplastic resin with carbon nanotubes and acetylene black, optionally including carbon fiber, which are melt-kneaded to create a film with optimized electric conductivity and mechanical properties, meeting the requirements for electrodes or protective coatings in secondary batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of electrically conductive carbon (such as ketjen black or carbon nanotubes) is added to achieve high electric conductivity, then the volume resistivity decreases, but the tensile elongation, durability to bending, and flexibility deteriorate significantly
Solution Approach 1:
The patent uses a composite material system consisting of thermoplastic resin, carbon nanotubes, and rubber particles. The rubber particles act as a matrix that disperses and supports the carbon nanotubes, creating a composite structure that maintains mechanical flexibility while achieving high electrical conductivity through the carbon nanotube network.
Solution Approach 2:
Rubber particles serve as an intermediary material between the thermoplastic resin and carbon nanotubes. These rubber particles improve the dispersion of carbon nanotubes and provide a flexible matrix that prevents the resin film from becoming brittle, thereby maintaining tensile elongation and flexibility while enabling high conductivity at lower carbon content.
2Stability of the object's composition
If high shearing stress is applied during spreading and dispersion to improve carbon nanotube distribution, then the dispersion quality improves, but the carbon nanotubes break and require even larger amounts to achieve satisfactory conductivity
Solution Approach 1:
Rubber particles act as a protective intermediary during the mixing process, providing a softer matrix that reduces mechanical stress on carbon nanotubes during dispersion. This prevents nanotube breakage while still achieving adequate distribution throughout the resin film.
Solution Approach 2:
The patent changes the physical parameters of the matrix material by incorporating rubber particles with different mechanical properties than pure thermoplastic resin. This modification allows for gentler processing conditions that preserve carbon nanotube integrity while achieving satisfactory dispersion.
3Reliability
If platinum plating is used to achieve high conductivity and chemical resistance, then both electric conductivity and chemical resistance improve, but the cost increases significantly due to noble metal usage
Solution Approach 1:
The patent replaces expensive noble metals with inexpensive carbon nanotubes as the conductive material. While carbon nanotubes may have shorter lifespan than platinum, the combination with rubber-enhanced resin provides adequate durability at a fraction of the cost, making the electrode material economically viable.
Data Source
Figure 1
AI summary
PURPOSE: The present invention provides a resin composition for an electrically conductive resin filmwhich is excellent in electric conductivity, tensile elongation, durability to bending and flexibility and is suitable as electrodes or protective coatings on the electrodes in redox flow batteries. CONSTITUTION: A resin composition comprising (A) 100 parts by weight of a thermoplastic resin, (B) 1 to 60 parts by weight of carbon nanotubes and (C) 1 to 100 parts by weight of at least one selected from the group consisting of acetylene black and graphite.