Manganese Redox Flow Battery Suppressing Precipitation
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Solution Overview
Problem
Conventional redox flow batteries, such as iron-chromium and vanadium-based batteries, do not generate a sufficiently high electromotive force, which is necessary for meeting future global energy demands and require a stable, cost-effective metal ion for active materials.
Innovation Solution
A redox flow battery using manganese ions as the positive electrode active material, combined with titanium, vanadium, chromium, zinc, or tin ions in the negative electrode electrolyte, to achieve a higher electromotive force by suppressing manganese dioxide precipitation through specific operating conditions and electrolyte compositions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If manganese ion concentration in electrolyte is increased to improve energy density, then energy density is improved, but manganese dioxide precipitation occurs
Solution Approach 1:
The patent introduces a complexing agent as an intermediary substance that binds to Mn3+ ions, forming stable complexes that prevent MnO2 precipitation. This mediator allows the battery to operate at higher manganese ion concentrations without the harmful precipitation effect, thus resolving the contradiction between energy density and precipitation.
Solution Approach 2:
The patent changes the chemical environment parameters by adding complexing agents and adjusting pH levels, which alters the stability characteristics of manganese ions in solution. This parameter change prevents the disproportionation reaction that leads to MnO2 precipitation, enabling higher manganese concentrations for improved energy density.
2Object-generated harmful factors
If acid concentration is increased to suppress manganese dioxide precipitation, then precipitation is suppressed, but manganese ion solubility decreases
Solution Approach 1:
The complexing agent acts as a mediator that provides an alternative stabilization mechanism for Mn3+ ions, replacing the need for high acid concentrations. This allows the system to maintain low acid levels while preventing precipitation, thereby preserving manganese ion solubility and energy density.
Solution Approach 2:
The patent changes the chemical parameters by introducing complexing agents that alter the solubility characteristics of manganese ions. This parameter change enables the system to achieve precipitation suppression without relying on high acid concentrations, thus maintaining high manganese ion solubility.
3Reliability
If conventional metal ions (Fe2+/Fe3+ or V4+/V5+) are used to ensure stable supply and low cost, then stability and cost are improved, but electromotive force is insufficient
Solution Approach 1:
The patent changes the key parameter of standard oxidation-reduction potential by selecting Mn2+/Mn3+ redox couple instead of conventional Fe2+/Fe3+ or V4+/V5+. This parameter change increases the electromotive force from approximately 0.77V or 1.0V to 1.51V, while maintaining reliability through the use of complexing agents that stabilize the manganese ions.
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 battery achieves a high electromotive force while maintaining stable operation and energy density, preventing manganese dioxide precipitation and ensuring long-term battery capacity and manufacturability.
Implementation Method 1
a redox flow battery containing, as a metal ion for a positive electrode active material, manganese (Mn) which is a water-soluble metal ion, has a standard oxidation-reduction potential higher than those of conventional metal ions
Implementation Method 2
Mn3+ is unstable, and produces Mn2+ (divalent) and MnO2 (tetravalent) through the following disproportionation reaction in a manganese ion aqueous solution
Data Source
AI summary
Provided are a redox flow battery (RF battery) in which a positive electrode electrolyte and a negative electrode electrolyte are supplied to a battery cell including a positive electrode, a negative electrode, and a membrane, to charge and discharge the battery, and a method of operating the RF battery. The positive electrode electrolyte contains a manganese ion, or both of a manganese ion and a titanium ion. The negative electrode electrolyte contains at least one type of metal ion selected from a titanium ion, a vanadium ion, a chromium ion, a zinc ion, and a tin ion. The RF battery can have a high electromotive force and can suppress generation of a precipitation of MnO2 by containing a titanium ion in the positive electrode electrolyte, or by being operated such that the positive electrode electrolyte has an SOC of not more than 90%.