Redox Flow Battery Mediators for Higher Energy Density
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Solution Overview
Problem
Redox flow batteries (RFBs) face low energy density due to solubility limitations of redox species in non-aqueous solvents, hindering their practical application in large-scale energy storage for intermittent renewable sources.
Innovation Solution
Incorporating a bio-inspired redox active material, vanadium(IV/V)bis-hydroxyiminodiacetate (VBH), coupled with cobalt hexacyanoferrate (CoHCF) as solid charge storage materials, which enhances energy density by overcoming solubility limitations through targeted redox reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If non-aqueous solvents are used in redox flow batteries, then thermal stability is improved, but energy density deteriorates due to solubility limitations
Solution Approach 1:
The patent introduces solid charge storage materials (CoHCF, NiHCF, CuHCF) as intermediaries that enable redox reactions without requiring high solubility of redox species in the non-aqueous electrolyte. The solid materials are deposited on electrode surfaces and undergo redox reactions with the electrolyte, allowing the system to maintain thermal stability while achieving high energy density through surface-based reactions rather than solution-based reactions.
2Quantity of substance
If solubility of redox species is increased to improve energy density, then thermal stability deteriorates due to potential decomposition
Solution Approach 1:
The patent replaces the traditional solution-based redox mechanism with a surface-based mechanism. Instead of relying on dissolved redox species that require high concentration (and thus risk decomposition), the system uses solid charge storage materials deposited on electrodes that undergo redox reactions at the solid-liquid interface. This substitution of the reaction mechanism allows high energy density without compromising thermal stability.
3Ease of operation
If conventional redox flow battery design is used, then ease of operation is maintained, but productivity deteriorates due to low energy capacity
Solution Approach 1:
The patent applies preliminary action by pre-depositing charge storage materials (CoHCF, NiHCF, CuHCF) onto the electrode surfaces before operation. This pre-preparation of the electrode surfaces with high-capacity materials allows the battery to achieve high energy density from the start without requiring complex operational procedures. The electrodes are prepared in advance with the active materials, maintaining ease of operation while dramatically improving energy capacity.
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 integration of VBH and CoHCF increases energy capacity by approximately 5 times, with up to 70% utilization of theoretical capacity, significantly improving the energy density of RFBs.
Implementation Method 1
CAT is a cation having the metal in a first oxidation state when the complex is dispersed in the anode and the metal is in a second oxidation state when the complex is dispersed in the cathode
Implementation Method 2
solid charge storage materials, which are reversibly oxidized or reduced in the electrolyte tanks upon interaction with the redox active species (mediators) dissolved in electrolyte
Data Source
AI summary
Various aspects disclosed relate to a redox flow battery that includes an anode in communication with a current collector and comprising a first solid charge storage medium disposed within the anode. The redox flow battery further includes a cathode in communication with the current collector and comprising a second solid charge storage medium disposed within the cathode. At least one of the anode, current collector, or cathode includes a complex having a structure according to Formula I:[ML2]m−2[CAT]n+2 (I),wherein,M is metal;L is a ligand.