Fe-Cr Electrolyte Composition for Low-Cost Redox Flow Batteries
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Solution Overview
Problem
There is a need for an affordable and reliable energy storage system to store power generated by intermittent renewable power sources like solar, hydroelectric, and wind, and provide power when these sources are insufficient.
Innovation Solution
A method to produce an Fe—Cr electrolyte by oxidizing a carbon-containing Fe—Cr alloy with Fe2O3 or FeO, treating with FeCl3 or HCl, and adjusting the iron to chromium molar ratio, followed by evaporation and crystallization to create a FeCl2—CrCl3 electrolyte for use in redox flow batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional methods are used to produce Fe-Cr electrolyte, then the electrolyte can be produced, but the production cost is high and the process is complex
Solution Approach 1:
The production process is divided into distinct sequential steps: (a) oxidizing carbon-containing Fe-Cr alloy with Fe2O3 or FeO, (b) treating with FeCl3 or HCl, (c) removing excess FeCl2, and (d) oxidizing removed FeCl2 to FeCl3 for reuse. This segmentation allows each step to be optimized independently and simplifies the overall manufacturing complexity.
Solution Approach 2:
The method recovers and reuses FeCl3 by oxidizing the removed FeCl2 portion. This circular approach reduces material waste and production costs while maintaining electrolyte quality, directly addressing the high cost issue of conventional methods.
2Reliability
If renewable power sources are used, then clean energy is generated, but the intermittent nature causes mismatch with user load patterns
Solution Approach 1:
The patent extracts and stores energy in the form of chemical potential energy within the Fe-Cr electrolyte system. By separating energy storage from generation, the system can accumulate excess renewable energy during high-generation periods and release it during low-generation periods, solving the intermittency problem.
Solution Approach 2:
The redox flow battery changes the chemical state parameters of the electrolyte (Fe2+/Fe3+ and Cr2+/Cr3+ ratios) to store and release energy. This allows the system to maintain reliable power output regardless of the intermittent input from renewable sources by adjusting the oxidation states of the electrolyte components.
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 method enables the production of a cost-effective Fe—Cr electrolyte suitable for redox flow batteries, providing long-life, reusable energy storage with tunable power and storage capacity.
Implementation Method 1
oxidizing a carbon-containing Fe—Cr alloy with Fe2O3 or FeO
Implementation Method 2
treating the oxidized carbon-containing Fe—Cr alloy with FeCl3 or HCl
Implementation Method 3
using evaporation to remove the portion of the FeCl2
Implementation Method 4
oxidizing at least part of the removed portion of the FeCl2 to produce FeCl3
Data Source
AI summary
A method of making an Fe—Cr electrolyte includes a) oxidizing a carbon-containing Fe—Cr alloy with Fe2O3 or FeO; and b) treating the oxidized carbon-containing Fe—Cr alloy with FeCl3 or HCl or any combination thereof to produce a FeCl2—CrCl3 electrolyte. The method may also include treating, under reducing conditions, a starting material, such as chromite ore, with a carbon source to produce the carbon-containing Fe—Cr alloy. Additionally or alternatively, the method may include removing a portion of the FeCl2 from the FeCl2—CrCl3 electrolyte to obtain a selected iron to chromium molar ratio for the Fe—Cr electrolyte.