Sinuous Channel Back Plate for Redox Flow Cell Electrolyte Distribution
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Solution Overview
Problem
Redox flow storage systems face challenges with non-homogeneous permeability of compressed carbon felt electrodes and excessive passive power requirements for electrolyte irrigation, leading to inefficient energy storage and potential electrode starvation, especially at high current densities.
Innovation Solution
A novel conductive back plate - electrode - membrane assembly featuring spaced parallel sinuous open channels for uniform electrolyte distribution and drainage, preventing sagging of the carbon felt and maintaining low contact resistance, while reducing internal cell resistance and passive power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If forced flow of electrolyte solutions is increased to enhance reaction dynamics at electrodes, then mass transport to electrodes is improved, but passive power consumption significantly increases
Solution Approach 1:
The back plate is segmented into multiple flow channels that distribute electrolyte flow across different regions of the electrode. This segmentation creates multiple parallel flow paths, reducing the pressure drop and power consumption required for each individual channel while maintaining overall mass transport efficiency to the electrode surface.
Solution Approach 2:
The flow channel design provides locally optimized flow distribution, with channels positioned to deliver electrolyte to regions of the electrode where mass transport is most needed. The channel geometry and spacing are tailored to create appropriate local flow velocities and pressure gradients, enhancing mass transport where required while minimizing overall power consumption.
2Power
If current density is increased to improve power output, then energy storage capacity is enhanced, but internal voltage drop and cell resistance steeply increase
Solution Approach 1:
The back plate is divided into multiple flow channels that distribute current and electrolyte flow across parallel paths. This segmentation reduces the current density and voltage drop in each individual channel, allowing the system to operate at higher overall power levels without experiencing excessive internal resistance losses in any single region.
Solution Approach 2:
The invention transitions from a single-plane flow distribution to a multi-dimensional channel network within the back plate. This three-dimensional arrangement of flow channels creates additional pathways for both electrolyte flow and current transport, reducing resistance by distributing the load across multiple spatial dimensions rather than relying on a single flat electrode surface.
3Reliability
If compressed carbon felt electrode is used to ensure electrical contact, then conductivity is improved, but non-homogeneous permeability causes flow distribution issues and electrode starvation
Solution Approach 1:
The flow channel network segments the electrolyte flow into multiple controlled pathways, ensuring that each region of the compressed carbon felt electrode receives adequate electrolyte supply. This segmentation prevents any single region from becoming starved of electrolyte, maintaining homogeneous mass transport across the entire electrode area despite compression-induced permeability variations.
Solution Approach 2:
The channel placement and geometry are optimized to provide locally appropriate flow rates to different regions of the electrode. Areas with lower permeability due to compression receive higher local flow velocities, while more permeable regions receive proportionally lower flows, creating a locally balanced mass transport system that compensates for non-uniform electrode properties.
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 ensures consistent and uniform electrolyte distribution across the electrode area, reducing internal cell resistance and passive power requirements, thereby enhancing energy efficiency and maintaining electrode activity at maximum current densities without sacrificing active surface area or electrical contact quality.
Implementation Method 1
Mass transport to the electrodes must be assisted by a forced flow of the two electrolyte solutions through the respective porous electrode compartments
Implementation Method 2
identical porous and fluid permeable carbon felt electrodes on both sides of the membrane separator in electrical contact with respective carbon base electrically conductive back plates
Implementation Method 3
a fluid impervious perm-ionic membrane cell separator
Implementation Method 4
These conditions make mass transport of the redox process supporting ions to active electrode sites a most critical parameter
Implementation Method 5
Mass transport to the electrodes must be assisted by a forced flow of the two electrolyte solutions through the respective porous electrode compartments
Implementation Method 6
electrochemical reactors for conducting reduction and oxidation reactions in respective positive and negative liquid electrolytes
Data Source
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AI summary
Effects of non homogeneity of elastically compressed carbon felt electrodes (2) in terms of permeability to a forced liquid flow and of excessive passive power requirement for adequately irrigating the porous electrodes (2) with fresh electrolyte solution, without detracting from the ability to ensure a good electrical contact between the felt electrode and a conductive back plate (1) are alleviated by providing a first plurality of spaced parallel sinuous open channels (sc1) that originate from an inlet manifolding flow space (4min) extending along one side of the assembly into which the electrolyte solution enters the cell compartment through one or more inlet ports (4h). The sinuous channels (sc1) terminate short of reaching an outlet manifolding flow space (4mout) extending along the opposite side of the channeled area, from which the electrolyte solution exits the cell compartment through one or more outlet ports. Vice versa, a second plurality of spaced parallel sinuous open channels (sc2), interleaved to the channels (sc1) of the first plurality, originate from the outlet manifolding flow space (4mout) and terminate short of reaching the inlet manifolding flow space (4min). Preferably, through holes (2h) with diameter equal to or larger than the width of the channels (sc1, sc2) of the interleaved sinuous channel-works in the contact area of the conductive back plate (1) and spaced along a sinuous track lines in the carbon felt electrode, coincide with either a underlying electrolyte solution distribution channel (sc1) or with an underlying electrolyte solution drainage channel (sc2), respectively.