Protective Flow Channels for Redox Battery Stack Homogeneity

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Solution Overview

Problem

Redox flow batteries (RFBs) face inhomogeneous electrical performance due to higher work loads and uneven electrolyte flow distribution at the ends of electrochemical cell stacks, leading to reduced reliability and shorter lifespan.

Innovation Solution

Incorporating protective channels or cells at the ends of the stack that allow electrolyte flow without undergoing electrochemical reactions, ensuring uniform temperature and flow distribution across all cells, thereby reducing the workload on end cells and enhancing stack homogeneity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If electrochemical cells are assembled in a stack to increase storage capacity, then the energy storage capacity of the RFB system is improved, but inhomogeneous voltage distribution and uneven electrolyte flow occur at the end cells, reducing reliability

Engineering Contradiction:

Improveenergy storage capacityVSAvoidvoltage distribution uniformity

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent divides the electrochemical cell stack into functional segments: active electrochemical cells for energy storage and inactive protective cells at the ends. This segmentation isolates the problematic end cells from electrochemical reactions, preventing them from contributing to voltage inhomogeneity while preserving the energy storage capacity of the central active cells.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces protective cells as intermediary elements between the electrolyte flow system and the active electrochemical cells. These protective cells act as mediators that guide electrolyte flow uniformly across the stack without undergoing electrochemical reactions, thereby eliminating their contribution to voltage distribution problems while maintaining system capacity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If electrolyte flows through all cells in the stack, then the electrochemical reactions occur in all cells, but the end cells experience higher work loads and shorter lifespan

Engineering Contradiction:

Improveelectrochemical reaction rateVSAvoidcell lifespan

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent extracts the electrochemical reaction function from the end cells by converting them into protective cells that do not undergo electrochemical reactions. This removes the source of premature failure at the stack ends while preserving the productive electrochemical reactions in the central active cells, thereby extending overall system lifespan.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies beforehand cushioning by placing protective cells at the vulnerable end positions of the stack before operation begins. These protective cells preemptively absorb the mechanical and hydraulic stresses that would otherwise cause end cell failure, cushioning the active cells from harmful flow distribution effects.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If protective cells are added at the ends of the stack, then the voltage distribution uniformity and cell lifespan are improved, but the device complexity increases

Engineering Contradiction:

Improvevoltage distribution uniformityVSAvoidstack structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies universality by designing protective cells with the same basic structure as active electrochemical cells, allowing them to be integrated into the existing stack architecture. This multi-functional approach enables the same cell design to serve either as active energy storage units or as protective flow-guiding elements, minimizing structural complexity changes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the protective cell function into the existing electrochemical cell structure, combining flow distribution and structural support functions into the same physical components. This integration avoids adding separate protective structures and maintains the modular stack design, thereby limiting increases in device complexity.

Inventive Principle:

Principle #5Merging (Combining)

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 implementation of protective channels or cells improves the uniformity of voltage distribution and extends the lifetime of the cell stack, leading to more consistent and reliable operation of RFBs.

Implementation Method 1

each of the plurality of electrochemical cells comprises a positive portion separated from a negative portion by an ion transfer membrane

Methodology Applied

Scientific EffectIon transfer: Ion Exchange

Implementation Method 2

the first protective cell anolyte channel is in liquid communication with at least one electrochemical cell anolyte channel... and wherein the first protective cell anolyte channel is not in ionic communication with the first protective cell catholyte channel

Methodology Applied

Scientific EffectLiquid flow:

Data Source

PatentUS9153832B2Electrochemical cell stack having a protective flow channel

Publication Date: 2015.10.06 VENTURE LENDING & LEASING VII INC AKA WTI

AI summary

Disclosed herein are improved electrochemical cell stacks having at least one protective channel on an end of the stack. Redox flow batteries (RFBs) containing the “protected” electrochemical cell stacks, and methods of operating such RFBs, are also provided.