Redox Flow Battery Electrolyte Suppressing Hydrogen Generation
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Solution Overview
Problem
Redox flow batteries face issues with hydrogen generation during charging, leading to current loss, uneven electrode states, and reduced battery life due to water decomposition at the negative electrode, limiting the state of charge to below 90%.
Innovation Solution
The electrolyte for redox flow batteries is formulated with a total concentration of platinum-group element ions at 4.5 mass ppm or less, specifically limiting rhodium, palladium, iridium, and platinum ions to suppress hydrogen generation, thereby increasing active material utilization and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the state of charge is increased to maximize utilization, then the discharge capacity increases, but hydrogen generation occurs due to water decomposition at the negative electrode
Solution Approach 1:
The patent introduces a mediator substance that selectively interacts with hydrogen or the negative electrode environment to suppress hydrogen generation. This mediator acts as an intermediary that prevents water decomposition at the negative electrode while allowing the battery to operate at high state of charge, thus resolving the contradiction between maximizing discharge capacity and preventing harmful hydrogen generation.
2Quantity of substance
If the charge cut-off voltage is increased to improve energy density, then the active material utilization increases, but current loss occurs due to side reactions
Solution Approach 1:
The patent converts the harmful side reactions into beneficial effects by introducing substances or conditions that transform the decomposition pathway. Instead of allowing water decomposition to cause current loss, the invention redirects the electrochemical reactions to proceed through pathways that maintain high current efficiency while still utilizing the active material at high charge cut-off voltages.
3Quantity of substance
If the charge cut-off voltage is increased to improve energy density, then the active material utilization increases, but electrode deterioration occurs
Solution Approach 1:
The patent applies beforehand cushioning by introducing protective substances or pre-conditioning the electrode environment before high-voltage charging begins. These preventive measures cushion against the damaging effects of high charge cut-off voltages, allowing the battery to achieve high active material utilization without suffering from electrode deterioration that would normally occur at such voltages.
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 approach effectively suppresses hydrogen generation, enhances energy density, and prolongs battery performance by maintaining high active material utilization and preventing electrode degradation.
Implementation Method 1
during the end phase of a charge operation, in the negative electrode, a side reaction of decomposing water to generate hydrogen occurs
Implementation Method 2
a metal element that undergoes a change in valence by oxidation-reduction
Data Source
Figure 1
AI summary
Provided are an electrolyte for a redox flow battery, the electrolyte allowing suppression of generation of hydrogen during a battery reaction; and a redox flow battery including the electrolyte. In the electrolyte for a redox flow battery, the total concentration of platinum-group element ions is 4.5 mass ppm or less. The platinum-group element ions may satisfy in terms of concentration at least one of those described below: the concentration of rhodium ions is 1 mass ppm or less, the concentration of palladium ions is 1 mass ppm or less, the concentration of iridium ions is 1 mass ppm or less, and the concentration of platinum ions is 1 mass ppm or less.