Flow Battery Electrode Structure with Vertical Tow Density Gradient
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Solution Overview
Problem
Flow battery stacks face issues with high contact resistance between traditional electrodes and adjacent components, leading to uneven electrolyte distribution, electrochemical reactions, and reduced energy efficiency due to inconsistent porosity after assembly.
Innovation Solution
The electrode structure consists of multiple continuous mesh-like porous layers with a higher density of vertical tows compared to parallel tows, optimized porosity, and specific material combinations to reduce contact resistance and ensure uniform porosity after compression, enhancing mechanical properties and energy output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional electrode structures with equal density of vertical and parallel tows are used, then the manufacturing process is simple, but the contact resistance between electrode and adjacent components is high
Solution Approach 1:
The patent applies local quality by creating different tow densities in different regions of the electrode. Specifically, the vertical tows (perpendicular to electrode surface) are arranged with higher density than parallel tows, and further, the vertical tow density increases from the center toward the edges. This localized variation in structure optimizes contact with adjacent components at the edges while maintaining overall performance.
2Manufacturing precision
If traditional electrode structures are compressed into stacks, then the stack assembly is achieved, but the porosity becomes uneven with lower porosity at sides and higher at center
Solution Approach 1:
The patent addresses porosity uniformity by implementing local quality through non-uniform vertical tow distribution. The vertical tows are arranged with increasing density from the center toward the edges of the electrode. During compression, this distribution pattern compensates for the differential compression forces, resulting in more uniform porosity throughout the electrode thickness and across the electrode surface.
Solution Approach 2:
The patent applies asymmetry by deliberately creating an asymmetric tow distribution pattern where vertical tows are not uniformly distributed but rather concentrated more toward the edges. This asymmetric arrangement counteracts the symmetric compression forces applied during stack assembly, leading to more uniform electrochemical performance across the electrode surface.
3Reliability
If carbon felt or graphite felt is used as electrode material, then the electrochemical performance is good, but the porosity varies in thickness direction after assembly leading to uneven electrolyte distribution
Solution Approach 1:
The patent applies local quality by creating different tow densities in different regions of the electrode. Specifically, the vertical tows (perpendicular to electrode surface) are arranged with higher density than parallel tows, and further, the vertical tow density increases from the center toward the edges. This localized variation in structure optimizes contact with adjacent components at the edges while maintaining overall performance.
Data Source
AI summary
An electrode structure of a flow battery. A density of the vertical tow in the electrode fiber is larger than the density of the parallel tow. In the electrode fiber per unit volume, the quantity ratio of the vertical tow to the parallel tow is at least 6:4. The electrode structure includes an odd number of layers of the electrode fibers, and the porosity of other layers is larger than that of the center layer. The electrode structure includes the vertical tows, so that, the contact area between the outer surface of the electrode and the adjacent component is increased and the contact resistance is reduced; the electrode has good mechanical properties; the contact resistance of such structure is reduced by 30%-50%; and the layers of the electrode have different thickness depending on the porosity. After compression, the layers with optimized thickness have a consistent porosity.