Flow Battery Bipolar Plate Channel Design for Electrolyte Distribution

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Solution Overview

Problem

Flow batteries face a tradeoff between performance and pressure drop, with designs either providing poor performance with acceptable pressure drop using thick electrodes or good performance with high pressure drop and low durability due to steep concentration gradients and non-uniform diffusion.

Innovation Solution

The flow battery incorporates a bipolar plate with channel arrangements that create a pressure gradient to force liquid electrolytes into porous electrodes, combining forced convective flow with diffusion to achieve a balance between pressure drop and performance, using configurations such as interdigitated, serpentine, or tapered channels to optimize electrolyte flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If thick electrodes are used, then performance is poor but pressure drop is acceptable

Engineering Contradiction:
Improvepressure dropVSAvoidperformance
Core Design Contradiction:
Loss of energyVSProductivity

Solution Approach 1:

The patent changes the flow regime parameter from pure diffusion to forced convection by applying pressure gradient, enabling thin electrodes to achieve both low pressure drop and high performance simultaneously

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses hydraulic pressure gradient to force electrolyte flow through porous electrodes, replacing passive diffusion with active convective transport to improve mass transfer efficiency

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Productivity

If forced convective flow is used to improve performance, then pressure drop increases and durability decreases

Engineering Contradiction:
ImproveperformanceVSAvoiddurability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by creating non-uniform pressure distribution across the electrode surface, with higher pressure at inlet regions and lower pressure at outlet regions, optimizing flow distribution and reducing stress concentrations

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent introduces dynamic flow control through adjustable pressure gradient, allowing optimization of flow rate and velocity profiles to balance performance enhancement with mechanical durability

Inventive Principle:
Principle #15Dynamics

3Productivity

If steep concentration gradients are created, then performance improves but non-uniform diffusion occurs

Engineering Contradiction:
ImproveperformanceVSAvoiduniform diffusion
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent replaces passive molecular diffusion with forced convective flow driven by pressure gradient, achieving uniform mass transport and eliminating concentration gradient-related non-uniformity while maintaining high performance

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

This design allows for the use of thin electrodes with acceptable pressure drops, enhancing performance and durability by ensuring uniform diffusion and reduced parasitic loads, thereby improving the overall efficiency of the flow battery.

Implementation Method 1

channel arrangements that create a pressure gradient to force liquid electrolytes into porous electrodes

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

combining forced convective flow with diffusion to achieve a balance between pressure drop and performance

Methodology Applied
Scientific EffectForced convection: Forced Convection

Implementation Method 3

combining forced convective flow with diffusion to achieve a balance between pressure drop and performance

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 4

an electrolyte layer, which may include separator such as an ion-exchange membrane

Methodology Applied
Scientific EffectIon exchange: Ion Exchange

Data Source

PatentEP2795697B1Flow battery with mixed flow
Publication Date: 2020.11.04 RTX CORP
  • EP2795697B1 patent drawingFigure 1~2
  • EP2795697B1 patent drawingFigure 3A~8
  • EP2795697B1 patent drawingFigure 5A~7

AI summary

A flow battery includes a liquid electrolyte that has an electrochemically active specie and a bipolar plate that has channels for receiving flow of the liquid electrolyte. A porous electrode is arranged immediately adjacent the bipolar plate. The porous electrode is catalytically active with regard to the liquid electrolyte. The channels of the bipolar plate have at least one of a channel arrangement or a channel shape that is configured to positively force at least a portion of the flow of the liquid electrolyte into the porous electrode.