Ferrocene Organometallic Complexes for Multi-Electron Flow Batteries
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Solution Overview
Problem
Current Redox Flow Batteries (RFBs) face limitations due to low energy density, poor solubility, high cost, and instability of charge carriers, particularly in Vanadium-based systems, which restrict their ability to store multiple electrons effectively.
Innovation Solution
The development of Fc-substituted organometallic complexes, specifically those with Group 13 metals like Al, which enable multi-electron transfer events, enhancing energy density and stability, and are used as analytes in Non-Aqueous Redox Flow Batteries (NRFBs) to overcome these limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Vanadium-based charge carriers are used in RFBs, then the battery can store electrical energy, but the energy density remains low due to limited solubility and single electron transfer per charge carrier
Solution Approach 1:
The patent changes the fundamental parameters of the charge carrier by using Fc-substituted organometallic complexes instead of traditional Vanadium-based species. These complexes enable multi-electron transfer (n ≥ 2) per charge carrier, directly increasing the quantity of substance parameter (energy density) while eliminating the harmful limitation of single electron transfer.
Solution Approach 2:
The invention employs composite organometallic complexes containing ferrocene substituents combined with Group 13 metals (Al, Ga, In). This composite structure integrates the redox activity of ferrocene with the stability and multi-electron transfer capability of the metal center, achieving both high energy density and structural stability.
2Quantity of substance
If new RFB analytes with greater energy densities are developed by switching to nonaqueous media, then the solvent window increases and battery cell voltages increase, but the solubility and stability of charge carriers may be compromised
Solution Approach 1:
The patent uses composite organometallic complexes where the ferrocene-substituted organic ligands provide stability in nonaqueous media while the Group 13 metal center enables multi-electron transfer. This composite structure maintains both high energy density and charge carrier stability in nonaqueous solvents.
Solution Approach 2:
The invention introduces ferrocene substituents at specific positions on the organic ligands, creating local redox-active sites that enhance energy density without compromising the overall stability of the complex in nonaqueous media. The local ferrocene groups provide electron transfer capability while the rest of the complex structure maintains stability.
3Quantity of substance
If charge carriers that store multiple electrons are used, then the energy density increases, but poor solubility and high cost of certain metal ions become limiting factors
Solution Approach 1:
The patent changes the metal center parameter to Group 13 metals (Al, Ga, In) which are more abundant and less costly than traditional multi-electron transfer metals. These metals can still facilitate multi-electron transfer when combined with ferrocene-substituted ligands, achieving high energy density with improved ease of manufacture and lower cost.
4Reliability
If symmetric configuration RFBs are used with the same charge carrier at both electrodes, then the battery can operate with reversible redox couples, but species crossover leads to irreversible capacity loss and fade
Solution Approach 1:
The patent creates local differences between the two half-cells by using different Fc-substituted organometallic complexes with distinct redox potentials and chemical properties at each electrode. This local differentiation allows symmetric configuration operation while preventing harmful species crossover, as the different complexes have different solubilities and electrochemical behaviors that reduce cross-contamination effects.
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
These complexes allow for higher energy storage capacity, improved solubility, and extended cycle stability, maintaining 70% state of charge and 97% Coulombic efficiency for over 100 cycles, with potential for wider temperature operation and compatibility with renewable energy sources.
Implementation Method 1
Fc-substituted organometallic complexes of the present disclosure can be used as multi-electron charge carriers, to enhance, for example, the energy density of RFBs including non-aqueous RFBs (NRFBs)
Data Source
AI summary
Ferrocene (Fc)-substituted organometallic complexes are described. In one example, an Fc-substituted organometallic complex has a structure represented by formula IV:where M is a Group 13 metal, R1 is H or a substituted phenyl, and R2 is 4-ferrocenylphenyl. Non-aqueous redox flow batteries and electrical energy storage systems comprising the Fe-substituted organometallic complexes and methods of storing energy using the Fe-substituted organometallic complexes are provided.