Redox Flow Battery Electrolyte Volume Equalization

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Solution Overview

Problem

Redox flow batteries experience efficiency and capacity degradation due to crossover between water molecules and electrolytes, self-discharge, and other side reactions, leading to imbalanced electrolyte volumes and densities, which degrade battery performance.

Innovation Solution

Discharge the redox flow battery when the volume difference between anode and cathode electrolytes is within 20% of the total volume, maintaining an open circuit voltage below 1.3 V/cell, and move electrolytes to equalize volumes, followed by recharging to restore performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the redox flow battery operates normally without intervention, then the battery continues to function, but the volume difference between anode and cathode electrolytes increases due to crossover, leading to performance degradation

Engineering Contradiction:

Improvebattery performanceVSAvoidelectrolyte volume balance

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback control mechanism by monitoring the volume difference between anode and cathode electrolytes and adjusting the discharge operation accordingly. When the volume difference exceeds a predetermined threshold (20% of total volume), the system automatically initiates a discharge process at controlled open circuit voltage (below 1.3V/cell) to restore volume balance, creating a closed-loop control system that maintains electrolyte composition stability

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes operational parameters (open circuit voltage threshold of 1.3V/cell and volume difference threshold of 20%) to trigger corrective discharge actions. By monitoring and responding to parameter changes in electrolyte volume balance, the system dynamically adjusts operation to prevent performance degradation while maintaining efficient energy storage

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the volume difference between anode and cathode electrolytes is large, then the battery may continue operating, but the charge retention rate decreases and performance degrades

Engineering Contradiction:

Improvecharge retention rateVSAvoidelectrolyte volume imbalance

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent takes preliminary action by establishing predetermined thresholds (20% volume difference, 1.3V/cell open circuit voltage) that trigger discharge operations before severe performance degradation occurs. This proactive approach prevents extreme volume imbalances by initiating corrective discharge when the volume difference first exceeds the threshold, thereby maintaining higher charge retention rates

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If the redox flow battery is discharged to equalize electrolyte volumes, then the volume balance is restored, but the open circuit voltage must be controlled to prevent excessive temperature increase

Engineering Contradiction:

Improveelectrolyte volume equalityVSAvoidtemperature increase during discharge

Core Design Contradiction:

Stability of the object's compositionVSTemperature

Solution Approach 1:

The patent carefully controls the discharge parameter (open circuit voltage threshold of 1.3V/cell) to balance two objectives: achieving sufficient volume equalization while preventing excessive temperature rise. This parameter optimization ensures that the discharge process restores electrolyte volume balance without generating harmful thermal effects

Inventive Principle:

Principle #35Parameter changes

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 method enables efficient and quick recovery of redox flow battery performance by equalizing electrolyte volumes, improving charge retention rates and reducing recovery time, while preventing excessive temperature increases.

Implementation Method 1

A redox flow battery is an oxidation/reduction cell capable of converting chemical energy of an active substance directly into electrical energy

Methodology Applied

Scientific EffectOxidation/reduction reaction: Redox Reactions

Implementation Method 2

During the process of charging and discharging, a hydrogen ion accompanied by water or vanadium ions may permeate the separation membrane, which is an ion crossover phenomenon, to generate a self-discharge

Methodology Applied

Scientific EffectIon crossover: Permeation

Data Source

PatentUS10014545B2Method for operating redox flow battery

Publication Date: 2018.07.03 LOTTE CHEM CORP

AI summary

The present disclosure relate to a method for operating a redox flow battery, which includes the steps of discharging the redox flow battery having an anode electrolyte and a cathode electrolyte when a volume difference between the anode electrolyte and the cathode electrolyte is within 20% of a total volume of the anode electrolyte and the cathode electrolyte, while maintaining an open circuit voltage of lower than 1.3 V/cell, and moving the anode electrolyte and/or the cathode electrolyte so that the volume difference is 2% or less between the anode electrolyte and the cathode electrolyte in the redox flow battery after the discharging.