Graphite-Polymer Separator Molding to Suppress Flow Battery Swelling
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Solution Overview
Problem
The existing manufacturing methods for expansion graphite separators in flow batteries face issues such as swelling, increased electrical resistance, and poor chemical stability due to low density and high water content, leading to increased energy consumption and maintenance costs, as well as challenges in uniform mixing and drying.
Innovation Solution
The method involves pulverizing expansion graphite to increase its density, mixing it with a polymer, and performing high and low temperature heat treatments to enhance mechanical and chemical stability, while controlling sulfur content and optimizing the polymer content to suppress swelling and improve conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If expansion graphite is used as separator material, then chemical stability is improved, but density is low causing swelling and poor mechanical stability
Solution Approach 1:
The patent combines expansion graphite with graphite powder to create a composite separator material. This composite structure leverages the chemical stability of expansion graphite while using graphite powder to increase density and suppress swelling, thereby resolving the contradiction between chemical stability and density.
Solution Approach 2:
The patent modifies the physical parameters of expansion graphite by controlling particle size distribution (D10, D50, D90 values) and density through composite formation. These parameter changes enable the material to achieve both high chemical stability and sufficient density to prevent swelling.
2Manufacturing precision
If PTFE aqueous solution is sprayed for binder coating, then uniform mixing is achieved, but water content increases leading to high energy consumption
Solution Approach 1:
The patent removes water from the binder system by replacing the aqueous PTFE solution with organic solvent-based or powder PTFE binder. This extraction of water eliminates the need for high-energy drying processes while maintaining uniform mixing through alternative application methods.
Solution Approach 2:
The patent uses PTFE powder as a disposable binder material that can be directly mixed and molded without requiring solvent evaporation or high-temperature drying, thereby reducing energy consumption while achieving uniform distribution.
3Stability of the object's composition
If expansion graphite is used, then chemical stability is improved, but sulfur content causes deterioration of chemical stability
Solution Approach 1:
The patent removes sulfur from the expansion graphite structure through controlled oxidation treatment. This extraction of harmful sulfur components eliminates the chemical instability caused by sulfur while preserving the beneficial chemical stability of the graphite structure.
Solution Approach 2:
The patent applies strong oxidation treatment to convert sulfur compounds in expansion graphite into removable oxidized forms. This accelerated oxidation process effectively eliminates sulfur content that would otherwise deteriorate chemical stability.
4Ease of manufacture
If expansion graphite with large particle size is used, then manufacturing is simplified, but dry mixing becomes difficult
Solution Approach 1:
The patent segments the expansion graphite into controlled particle size ranges (D10, D50, D90 specifications) to optimize both manufacturability and mixing efficiency. This segmentation creates a balanced particle distribution that simplifies handling while enabling effective dry mixing.
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 resulting separator exhibits improved mechanical and chemical stability, reduced swelling, and increased conductivity, leading to enhanced performance and efficiency in flow batteries with increased tap density and reduced electrical resistance.
Implementation Method 1
pulverizing the expansion graphite
Implementation Method 2
drying and heat treatment
Implementation Method 3
mixing the expansion graphite and polymer
Data Source
AI summary
In one embodiment of the present invention, it is provided a method of manufacturing a separator comprising:preparing expansion graphite; pulverizing the expansion graphite; mixing the expansion graphite and polymer; and forming a separator by molding the mixture.