Half-Cell Potential Measurement for Redox Flow Battery SOC

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing methods for monitoring the state-of-charge (SOC) of electrolytes in liquid systems are unreliable due to fouling and drifting over time, and they typically measure SOC for the entire battery rather than individual electrochemical half-cells.

Innovation Solution

The solution involves positioning electrodes in flow cells to detect the electric potential difference between inlet and outlet streams, which reflects the state-of-charge difference, and correlating this with control conditions to adjust operating parameters, allowing for precise SOC measurement and control of individual half-cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional SOC measurement methods are used in liquid systems, then SOC can be measured, but the measurements become unreliable over time due to fouling and drifting

Engineering Contradiction:
Improvemeasurement reliabilityVSAvoidSOC measurement accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The invention divides the battery measurement into separate half-cell measurements. By placing reference electrodes in individual half-cells (positive and negative sides), the system measures SOC independently for each half-cell rather than as a single battery measurement. This segmentation prevents cross-contamination and fouling effects that plague traditional single-point measurements, thereby improving reliability while maintaining precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention introduces reference electrodes as intermediary measurement points within each half-cell. These reference electrodes serve as stable intermediaries that establish reliable potential references without being affected by the dynamic electrolyte composition. This intermediary approach isolates the measurement system from direct exposure to fouling conditions while maintaining accurate SOC measurement capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If traditional SOC measurement methods are used, then battery SOC can be indicated, but they cannot measure SOC of individual electrochemical half-cells

Engineering Contradiction:
Improvemeasurement capabilityVSAvoidelectrode configuration
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The measurement system is segmented into independent half-cell measurement units. Each half-cell (positive and negative) receives its own reference electrode, enabling independent SOC measurement for each side. This segmentation provides versatile measurement capability that can monitor individual half-cell states, which is essential for understanding local electrochemical conditions and optimizing overall battery performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The reference electrode configuration serves multiple functions: it measures SOC for individual half-cells, provides stable potential references, and enables detection of local electrochemical conditions. This multi-functionality achieves high adaptability without proportionally increasing device complexity, as the same electrode structure serves multiple measurement purposes.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Productivity

If real-time SOC monitoring is implemented, then operation can be optimized, but fouling and drifting cause the measurements to become unreliable

Engineering Contradiction:
Improveoperational efficiencyVSAvoidmeasurement stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

By segmenting the measurement system into independent half-cell reference electrodes, the invention enables continuous real-time monitoring without the fouling and drifting problems that affect traditional single-point measurements. Each reference electrode operates independently in its own half-cell environment, maintaining measurement stability while providing the real-time data needed for operational optimization.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system implements continuous feedback through real-time SOC measurement of individual half-cells. The reference electrodes provide ongoing measurement data that feeds back to control systems, enabling dynamic optimization of operating parameters. This feedback mechanism maintains both productivity and reliability by continuously monitoring actual half-cell states and adjusting operations accordingly.

Inventive Principle:
Principle #23Feedback

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 provides reliable, real-time monitoring and control of SOC in flow cells and stacks, minimizing energy loss and optimizing operation by adjusting parameters such as flow rates and current densities based on measured potential differences.

Implementation Method 1

first and second electrodes positioned to contact and be in electrochemical communication with the inlet and outlet streams, respectively, and configured to allow detection of an electric potential difference between the two electrodes, said electrical potential difference reflective of the difference in the state-of-charge of the electrolyte in said inlet and outlet streams

Methodology Applied
Scientific EffectElectrochemical potential difference: Nernst Effect

Data Source

PatentEP3058608B1Method and apparatus for measuring transient state-of-charge using inlet/outlet potentials
Publication Date: 2019.12.25 LOCKHEED MARTIN ADVANCED ENERGY STORAGE LLC
  • EP3058608B1 patent drawingFigure 1
  • EP3058608B1 patent drawingFigure 2
  • EP3058608B1 patent drawingFigure 3

AI summary

The present invention relates to redox flow batteries and methods and apparatuses for monitoring the compositions of the electrolytes therein. In particular, the present invention relates to methods and configurations for monitoring the state-of-charge of an electrolyte stream of a flow cell or flow battery.