Non-aqueous Redox Flow Battery Using Copper and Benzothiadiazole Electrolytes
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Solution Overview
Problem
Current non-aqueous redox flow batteries face challenges in achieving high open-circuit potential difference (Eo) and energy density while maintaining stability and safety, with limitations in solubility and stability of electroactive species, particularly at elevated temperatures.
Innovation Solution
The use of a non-aqueous liquid electrolyte comprising a solution of copper triflate or tetrafluoroborate complexes [Cu(I) or Cu(II)] in the positive compartment and a solution of benzothiadiazole or its derivative in the negative compartment, with an ion-exchange membrane, allows for high open-circuit potential difference and energy density, along with stability and non-toxicity, facilitating efficient energy storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If aqueous electrolytes with high concentration of electroactive species are used, then energy density is improved, but thermal precipitation and stability deteriorate at elevated temperatures
Solution Approach 1:
The patent changes the fundamental parameter of the electrolyte system from aqueous to non-aqueous (acetonitrile-based) solvent, which eliminates thermal precipitation issues while maintaining high solubility and stability of electroactive species at elevated temperatures up to 80°C
Solution Approach 2:
The patent uses a composite electrolyte system combining acetonitrile solvent with lithium salt (LiClO4) and electroactive species (ferrocene/ferrocenium and iodine/iodide), creating a stable non-aqueous environment that prevents precipitation while maintaining high energy density
2Power
If the open-circuit potential difference is increased, then power output is improved, but the stability window of the electrolyte is exceeded
Solution Approach 1:
The patent changes the electrolyte from water-based to acetonitrile-based, which expands the electrochemical stability window from approximately 1.23V (water) to over 3V (acetonitrile), enabling higher open-circuit potential differences and power output without electrolyte decomposition
Solution Approach 2:
The patent creates an inert non-aqueous environment using acetonitrile as solvent, which does not undergo electrolysis or decomposition at high potentials, thereby stabilizing the electrolyte while allowing high power output through increased cell voltage
3Quantity of substance
If solubility of electroactive species is increased, then energy density is improved, but stability and precipitation control become difficult
Solution Approach 1:
The patent changes the solvent parameter from water to acetonitrile, which provides superior solubility for electroactive species (ferrocene, iodine) while maintaining molecular stability and preventing precipitation even at high concentrations and elevated temperatures up to 80°C
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 configuration results in a non-aqueous redox flow battery with high open-circuit potential difference and energy density, exhibiting good stability during charge-discharge cycles and high solubility in organic solvents, making it suitable for moderate to large power output applications with low environmental impact.
Implementation Method 1
an ion-exchange membrane positioned between the positive compartment and the negative compartment
Implementation Method 2
an electrochemical cell which converts the chemical energy directly into electrical energy
Data Source
AI summary
Non-aqueous redox flow battery (RFB) comprising: a positive compartment in which a positive electrode is positioned and in which a positive non-aqueous liquid electrolyte is caused to flow; a negative compartment in which a negative electrode is positioned and in which a negative non-aqueous liquid electrolyte is caused to flow; an ion-exchange membrane positioned between the positive compartment and the negative compartment in which: said positive non-aqueous liquid electrolyte comprises a solution of copper triflate or tetrafluoroborate complexes [Cu(I) or Cu(II)] in at least one organic solvent; said negative non-aqueous liquid electrolyte comprises a solution of at least one benzothiadiazole or a derivative thereof in at least one organic solvent.