Fe-Cr Battery Electrolyte Preparation With Impurity Removal
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Solution Overview
Problem
Current redox flow battery systems face challenges in maintaining long-term storage capacity and avoiding hydrogen evolution, particularly in iron-chromium (Fe—Cr) systems, where materials like lithium and vanadium are scarce, and hydrogen generation is undesirable.
Innovation Solution
The development of an iron-chromium redox flow battery system using Fe3+/Fe2+ and Cr3+/Cr2+ redox chemistry, with chromium complexes and nitrogen-containing ligands to stabilize chromium ions, and a method to manage chromium utilization and impurity removal through electrode design and cleaning solutions, reducing hydrogen generation and maintaining storage capacity over many charge/discharge cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If iron-chromium redox flow battery systems are used to store renewable energy, then storage capacity and duration are improved, but hydrogen evolution occurs which reduces efficiency and creates safety concerns
Solution Approach 1:
The patent converts the harmful hydrogen evolution into a beneficial process by using the evolved hydrogen to reduce chromium(VI) to chromium(III) in situ. This prevents the accumulation of harmful chromium(VI) while utilizing the hydrogen that would otherwise be a waste product or safety hazard, thereby extending storage duration without the negative effects of hydrogen gas accumulation.
Solution Approach 2:
The patent changes the oxidation state parameter of chromium from Cr(VI) to Cr(III) through in situ reduction by hydrogen. This parameter change transforms the toxic, unstable chromium(VI) into the safe, stable chromium(III) form, enabling long-term energy storage without the harmful effects associated with chromium(VI) while maintaining system safety.
2Ease of manufacture
If chromium ore is used directly to prepare electrolyte, then material costs are reduced, but metal impurities accumulate which degrade battery performance
Solution Approach 1:
The patent extracts and removes metal impurities from the electrolyte through a filtration system that separates particulate matter from the electrolyte solution. This extraction process eliminates impurities that would otherwise accumulate and degrade battery performance, while still allowing the use of cost-effective chromium ore as the starting material.
Solution Approach 2:
The patent implements a self-cleaning system where the filtration apparatus automatically removes impurities from the electrolyte during normal operation. This self-service approach maintains battery performance stability without requiring manual intervention or complex external purification systems, balancing cost-effectiveness with reliability.
3Quantity of substance
If chromium(VI) is used in the electrolyte to increase capacity, then energy storage capacity is improved, but chromium(VI) reduces to chromium(III) which limits further capacity utilization
Solution Approach 1:
The patent converts the reduction of chromium(VI) to chromium(III), which would normally limit capacity utilization, into a beneficial process. By using in situ hydrogen reduction, the system prevents chromium(VI) accumulation and maintains stable chromium(III) levels, enabling sustained energy storage capacity without the limitations imposed by chromium reduction.
Solution Approach 2:
The patent ensures continuous energy storage capacity by maintaining chromium in the stable Cr(III) state through controlled in situ reduction. This continuous process prevents the intermittent capacity loss that would occur if chromium cycled between oxidation states, allowing for sustained and reliable energy storage operation.
4Ease of manufacture
If conventional electrolyte preparation methods are used, then manufacturing simplicity is maintained, but chromium contamination and impurity removal require additional complex steps
Solution Approach 1:
The patent merges the electrolyte preparation process with the impurity removal process by integrating the filtration system directly into the electrolyte circulation loop. This combination allows for continuous impurity removal during normal battery operation, eliminating the need for separate, complex purification steps while maintaining manufacturing simplicity.
Solution Approach 2:
The patent implements a self-cleaning electrolyte system where the filtration apparatus automatically removes impurities during normal operation without requiring external intervention. This self-service approach maintains electrolyte purity and removes contaminants continuously, simplifying the overall manufacturing process while avoiding the need for complex external purification systems.
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 system achieves stable storage capacity with minimal hydrogen evolution, utilizing abundant iron and chromium, and effectively manages metal impurities, ensuring long-term energy storage efficiency and reducing material costs.
Implementation Method 1
reducing chromium ore using a carbon source to convert the chromium ore to an iron/chromium alloy with carbon particles
Implementation Method 2
dissolving the iron/chromium alloy with carbon particles in sulfuric acid to form a first solution
Implementation Method 3
The cleaning solution includes ferric ions
Implementation Method 4
the cleaning solution includes hydrogen peroxide or ferric chloride
Implementation Method 5
iron-chromium (Fe—Cr) redox flow battery systems
Data Source
AI summary
A method for preparation of electrolyte for a redox flow battery includes reducing chromium ore using a carbon source to convert the chromium ore to an iron/chromium alloy with carbon particles; dissolving the iron/chromium alloy with carbon particles in sulfuric acid to form a first solution; adding calcium chloride or barium chloride to the first solution to produce a second solution including FeCl3 and CrCl3; and adding an acid to the second solution to form the electrolyte. Other methods can be used for preparing an electrolyte from chromium waste material.