Negative Electrolyte Rebalancing With Fe0 and Segmented H2 Storage
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Solution Overview
Problem
Redox flow batteries face limitations in cycling capabilities due to side reactions at the plating electrode, leading to iron plating loss, unwanted precipitation of iron hydroxides, and inefficiencies in electrolyte rebalancing, which can clog passages and reduce capacity, and existing rebalancing methods rely on costly catalysts and require frequent maintenance.
Innovation Solution
A redox rebalancing cell using Fe0 as a reducing agent to decrease Fe3+ concentrations in the negative electrolyte without a catalyst, combined with a gas storage system that uses a weighted main tank to accurately measure pressure and decouple from the rebalancing reactor when empty, and a hydrogen catalytic rebalancing cell to address gas storage challenges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If catalytic electrolyte rebalancing is used to address hydrogen gas generation and electrolyte charge imbalances, then rebalancing performance is improved, but system cost increases due to expensive catalysts and maintenance requirements
Solution Approach 1:
The patent extracts and removes the catalyst component from the electrolyte rebalancing system. Instead of using catalytic rebalancing, the system employs direct hydrogen gas injection into the electrolyte tank, allowing the rebalancing reaction to occur without a catalyst. This eliminates the need for expensive catalyst materials and reduces maintenance requirements while maintaining effective electrolyte rebalancing.
2Quantity of substance
If a single large gas storage tank is used to store hydrogen gas, then gas storage capacity is improved, but pressure measurement accuracy deteriorates due to minimal pressure changes
Solution Approach 1:
The patent divides the gas storage system into two segments: a small auxiliary tank and a large main tank. The auxiliary tank is used for storage when the main tank is being filled or emptied, and the main tank provides the primary storage capacity. This segmentation allows the small auxiliary tank to provide sufficient pressure changes for accurate measurement while the large main tank provides the required gas storage capacity.
3Volume of stationary object
If the gas storage tank volume increases, then gas storage capacity is improved, but pressure change detection becomes difficult due to minimal pressure variations
Solution Approach 1:
The gas storage system is segmented into a small auxiliary tank and a large main tank. The small auxiliary tank volume ensures that when gas is added or removed, there are sufficient pressure changes to be accurately detected by pressure sensors. The large main tank provides the necessary total storage capacity. The tanks work in coordination to resolve the contradiction between large volume and detectable pressure changes.
4Quantity of substance
If iron plating is performed on the plating electrode, then battery capacity is improved, but iron plating loss occurs due to side reactions reducing cycling capabilities
Solution Approach 1:
The patent converts the harmful effect of hydrogen gas (a byproduct of side reactions that causes safety issues and rebalancing problems) into a beneficial resource. The hydrogen gas generated during battery operation is captured and stored, then used as a reducing agent in the electrolyte rebalancing process. This eliminates the need for external catalysts or chemicals while addressing the root cause of iron plating loss and improving overall system reliability.
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 solution reduces maintenance costs, eliminates the need for expensive catalysts, and enhances cycling performance by maintaining Fe0 availability, while accurately monitoring gas volume and preventing overpressure events, thus improving the overall efficiency and longevity of the redox flow battery system.
Implementation Method 1
A redox rebalancing cell using Fe0 as a reducing agent to decrease Fe3+ concentrations in the negative electrolyte
Implementation Method 2
A gas storage system including a first tank fluidly coupled to a second tank. The first tank may be a smaller auxiliary tank and the second tank may be a larger main tank. A weight may be unevenly distributed across the main tank. A change in pressure in the weighted main tank may be readily detected
Implementation Method 3
A change in pressure in the weighted main tank may be readily detected and provide a linear signal at a pressure transducer which may be readily interpreted by a controller
Implementation Method 4
In other examples, a trickle bed or jelly roll reactor setup may similarly include catalyst surfaces whereon the H2 gas and the electrolyte may react. The H2 gas may be evolved from side reactions described by equations (1) and (2) as above and collected from electrolyte storage tanks to be stored in an expandable gas storage tank fluidly coupled to the electrolyte storage tanks and to the rebalancing reactors
Data Source
AI summary
Systems and methods are provided for managing health of electrolytes of redox flow battery system. Components of the system may include a redox rebalancing cells and a gas storage system. The redox rebalancing cell may be operated by plating iron on a plating electrode, treating a negative electrolyte of the redox flow battery system with the plated iron and returning the negative electrolyte to an electrolyte tank. The gas storage system may include a set of expandable gas storage tanks coupled to at least one electrolyte storage tank and an electrolyte rebalancing system of the redox flow battery system.