Substituted Catecholate Coordination Compounds for Flow Battery Electrolytes
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Solution Overview
Problem
Existing flow batteries face challenges with high cell resistance and active material crossover, leading to diminished energy storage performance and poor cycle life, despite significant development efforts, no commercially viable technologies have achieved a desirable combination of properties.
Innovation Solution
The use of aqueous electrolyte solutions containing coordination compounds with substituted catecholate ligands, which provide high solubility and improved operating characteristics for flow batteries, enhancing energy density and cycle life by modifying the active materials in the positive and negative electrolyte solutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional battery chemistries and cell designs are used, then flow batteries can decouple power density and energy density, but high cell resistance and active material crossover occur, leading to diminished energy storage performance and poor cycle life
Solution Approach 1:
The patent changes the chemical parameters of the electrolyte solutions by using coordination compounds with substituted catecholate ligands instead of conventional battery chemistries. This parameter change resolves the contradiction by achieving both low cell resistance (improved energy storage performance) and minimal active material crossover (improved cycle life) simultaneously
Solution Approach 2:
The patent employs composite coordination compounds formed by combining metal centers with substituted catecholate ligands. These composite materials provide both high solubility in aqueous electrolytes and stable redox behavior, resolving the contradiction between maintaining reliable cycle life and preventing energy loss through crossover
2Duration of action of stationary object
If conventional active materials are used, then flow batteries can operate with separate electrolyte solutions, but active materials cross over the membrane and mix with opposing electrolyte solution, resulting in poor cycle life
Solution Approach 1:
The patent applies local quality by designing catecholate ligands with specific substituent groups that create localized chemical environments. These local modifications to the ligand structure enhance the stability of the coordination compounds and prevent their crossover through the membrane, thereby extending cycle life while maintaining composition stability
Solution Approach 2:
The coordination compounds act as intermediaries between the metal centers and the aqueous electrolyte environment. The substituted catecholate ligands serve as mediators that provide both solubility in water and stability against membrane crossover, resolving the contradiction between duration of operation and compositional stability
3Quantity of substance
If high-concentration electrolyte solutions are used, then energy density is improved, but solubility limitations of conventional materials are reached
Solution Approach 1:
The patent changes the solubility parameters by introducing substituted catecholate ligands with appropriate hydrophilic groups. This allows the coordination compounds to maintain high solubility in aqueous electrolytes, enabling the preparation of high-concentration electrolyte solutions that improve energy density without sacrificing compositional stability
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 substituted catecholate ligands and their coordination compounds offer high-concentration electrolyte solutions that improve energy density and operating characteristics of flow batteries, achieving higher open circuit voltages and sustained charge/discharge cycles, suitable for large-scale energy storage applications.
Implementation Method 1
The battery is charged or discharged through electrochemical reactions of the active materials that occur inside the cell
Implementation Method 2
aqueous electrolyte solutions containing coordination compounds with substituted catecholate ligands
Data Source
Figure 1~2
AI summary
Active materials for flow batteries can include various coordination compounds formed from transition metals. Some compositions containing coordination compounds can include a substituted catecholate ligand having a structure of in a neutral form or a salt form, in which Z is a heteroatom functional group bound to the substituted catecholate ligand at an open aromatic ring position and n is an integer ranging between 1 and 4. When more than one Z is present, each Z can be the same or different. Electrolyte solutions can include such coordination compounds, and such electrolyte solutions can be incorporated within a flow battery.