Aqueous Flow Battery Electrolytes with Tunable Redox Potentials
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Solution Overview
Problem
Existing flow battery technologies face limitations in energy storage due to poor electrode kinetics, flammable gases, and dendrite growth, leading to inefficiencies and high costs, which have hindered widespread commercial adoption.
Innovation Solution
The use of aqueous, benign electrolytes with redox-active moieties that exhibit reversible electrochemistry and tunable redox potentials, combined with specific electrode compositions, to create efficient flow batteries operating at high voltages, decoupling energy and power storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional flow battery systems use simple transition metal salts and halogen ions in acidic or caustic electrolytes, then the system structure is simple and manufacturing is easier, but the electrode kinetics are poor, leading to low energy storage efficiency and high costs
Solution Approach 1:
The patent changes the chemical parameters of the electrolyte by using aqueous solutions with pH between 8-13 instead of traditional acidic or caustic electrolytes. This parameter change enables the use of redox-active moieties like metal-ligand coordination compounds and organic molecules that exhibit reversible electrochemistry, thereby improving electrode kinetics and energy storage efficiency while maintaining system feasibility
Solution Approach 2:
The patent employs composite redox-active materials including metal-ligand coordination compounds (e.g., Fe(catecholate)3 2-/3-), organic molecules (e.g., quinones, hydroquinones, viologens), and their combinations. These composite materials provide both reversible electrochemistry and tunable redox potentials, resolving the contradiction between manufacturing simplicity and energy storage efficiency
2Reliability
If flow batteries operate with traditional active materials, then the system cost is lower, but dendrite growth and flammable gases are generated, reducing safety and reliability
Solution Approach 1:
By changing the operating pH parameter to 8-13 and using aqueous electrolytes, the patent eliminates the generation of flammable gases and dendrite growth associated with traditional systems. The benign aqueous environment with controlled pH prevents harmful side reactions while maintaining electrochemical activity, thereby improving safety and reliability
Solution Approach 2:
The patent uses cost-effective redox-active materials such as iron-based metal-ligand coordination compounds and organic molecules that can be synthesized from abundant precursors. These materials replace expensive traditional active materials while providing comparable or superior performance, reducing system cost without compromising safety
3Reliability
If flow batteries use redox-active moieties with fixed redox potentials, then the system design is simpler, but the energy storage efficiency and voltage are limited
Solution Approach 1:
The patent introduces tunability in redox potentials through the selection of different redox-active moieties and their combinations. The system can dynamically adjust its electrochemical properties by selecting appropriate metal-ligand coordination compounds or organic molecules with specific redox characteristics, thereby optimizing energy storage efficiency and voltage for different applications
Solution Approach 2:
The patent employs a universal platform using aqueous electrolytes with pH 8-13 that can accommodate multiple types of redox-active moieties including metal-ligand coordination compounds, organic molecules, and their combinations. This universal approach allows the same system architecture to achieve high energy storage efficiency through diverse redox couples with tunable potentials
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 enhances energy storage efficiency, reduces costs, and improves the reliability of flow batteries by addressing the limitations of traditional systems, enabling more effective energy storage and utilization.
Implementation Method 1
redox-active moieties that exhibit reversible electrochemistry and tunable redox potentials
Implementation Method 2
aqueous, benign electrolytes with redox-active moieties
Data Source
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AI summary
The invention concerns flow batteries comprising: a first half-cell comprising: (i) a first aqueous electrolyte comprising a first redox active material; and a first carbon electrode in contact with the first aqueous electrolyte; (ii) a second half-cell comprising: a second aqueous electrolyte comprising a second redox active material; and a second carbon electrode in contact with the second aqueous electrolyte; and (iii) a separator disposed between the first half-cell and the second half-cell; the first half-cell having a half-cell potential equal to or more negative than about -0.3 V with respect to a reversible hydrogen electrode; and the first aqueous electrolyte having a pH in a range of from about 8 to about 13, wherein the flow battery is capable of operating or is operating at a current density at least about 25 mA/cm2 .