Graphite Composite Bipolar Plate for Redox Flow Battery
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Solution Overview
Problem
Existing layered composite materials for redox flow batteries face issues with inadequate adhesion and electrical contact resistance between bipolar plates and graphite felts, leading to high parasitic power losses and material relaxation, requiring strong pressing that compresses the felt structure and causes electrolyte flow restrictions, and necessitate additional sealing to prevent electrolyte leakage.
Innovation Solution
A layered composite material comprising a graphite-containing molded body with a solid organic additive that is homogeneously distributed across all dimensions, providing high tensile strength, electrical conductivity, and impermeability, which is permanently connected to a textile fabric using thermal bonding or adhesives, allowing for reduced pressing and improved electrolyte flow without material detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strong pressing is applied to improve adhesion between bipolar plate and graphite felt, then contact resistance decreases, but the felt structure is compressed causing electrolyte flow restrictions and pressure losses
Solution Approach 1:
The invention changes the physical-chemical parameters of the bipolar plate surface by applying a plasma treatment or coating with specific surface properties. This modifies the surface energy and roughness to enhance adhesion to graphite felt without requiring strong pressing, thus avoiding compression of the felt structure and maintaining electrolyte flow pathways.
Solution Approach 2:
The invention introduces an intermediary layer or surface treatment on the bipolar plate that acts as a mediator between the bipolar plate and graphite felt. This intermediary layer improves interfacial adhesion and reduces contact resistance while allowing the graphite felt to maintain its porous structure for optimal electrolyte flow.
2Reliability
If liquid impregnation is used to increase tightness of graphite, then impermeability to liquids improves, but the impregnating agent is unevenly distributed in the depth direction
Solution Approach 1:
The invention replaces the liquid impregnation process with a solid-state sintering or hot pressing process. This substitution eliminates the issue of uneven liquid distribution by using solid particles and controlled heating/pressing to achieve homogeneous densification and impermeability throughout the entire depth of the bipolar plate.
Solution Approach 2:
The invention utilizes phase transitions (melting and solidification) of a binder material during the manufacturing process. The binder is applied in a solid or viscous state, then melted during heating, and finally solidified during cooling under pressure to create a homogeneous, impermeable structure throughout the bipolar plate depth.
3Reliability
If additional sealing is provided to prevent electrolyte leakage, then sealing reliability improves, but device complexity increases
Solution Approach 1:
The invention merges the sealing function with the bipolar plate structure itself. By integrating sealing features directly into the bipolar plate design (such as sealed edges, integrated gaskets, or self-sealing structures), the need for separate sealing components is eliminated, reducing device complexity while maintaining sealing reliability.
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 structural integrity and electrical performance of the composite material, reducing parasitic power losses and extending the battery's service life by maintaining low contact resistance and preventing electrolyte leakage, while allowing for a more compact battery design with improved adaptability.
Implementation Method 1
a solid organic additive that is homogeneously distributed across all dimensions
Implementation Method 2
permanently connected to a textile fabric using thermal bonding or adhesives
Data Source
Figure 1~2
AI summary
The invention relates to a layered composite material which is suitable, in particular, for use in a redox flow battery, comprising at least one layer of a textile fabric and at least one graphite-containing moulded body which is obtained by a method in which graphite particles are mixed with at least one solid organic additive to form a mixture and the thus obtained mixed is then compressed.