Redox Flow Battery Solvent Condensation for Electrolyte Rebalancing
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Solution Overview
Problem
Redox flow batteries face efficiency limitations due to solvent migration across the barrier layer, leading to concentration imbalances in electrolyte solutions, especially in systems with incompatible electrolytes where mixing is not an option.
Innovation Solution
A rebalancing system using a separator that condenses vaporized base solvent from the first electrolyte solution and returns it to the second electrolyte solution, reversing concentration imbalances, which includes a heat exchanger condenser and evaporator to enhance solvent recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a barrier layer is used to separate electrolytes in a redox flow battery, then the electrolytes are prevented from mixing, but solvent migration across the barrier layer causes concentration imbalance
Solution Approach 1:
The patent extracts the migrated solvent from the first electrolyte solution by evaporating it into a vapor phase, then condensing and collecting it separately. This removes the harmful migrated solvent from the system and allows it to be returned to the second electrolyte solution, resolving the concentration imbalance caused by barrier layer permeation.
Solution Approach 2:
The patent changes the physical state of the migrated solvent from liquid to vapor through evaporation, then back to liquid through condensation. This phase change enables separation and recovery of the solvent, allowing it to be redirected to the appropriate electrolyte solution to maintain concentration balance.
2Reliability
If incompatible electrolytes are used in a redox flow battery, then electrochemical stability is improved, but concentration rebalancing becomes difficult without mixing
Solution Approach 1:
The patent introduces an intermediary system consisting of an evaporator and condenser that mediates the rebalancing process. The evaporator converts migrated solvent to vapor, the condenser condenses it back to liquid, and the system redirects it to the appropriate electrolyte. This intermediary apparatus enables rebalancing of incompatible electrolytes without direct mixing.
3Power
If solvent migration is allowed across the barrier layer, then ion transport is maintained, but electrolyte concentration imbalance increases
Solution Approach 1:
The patent implements a feedback mechanism where the evaporator continuously monitors and removes migrated solvent from the first electrolyte solution, and the condenser returns the recovered solvent to the second electrolyte solution. This closed-loop feedback system maintains concentration balance while allowing the barrier layer to remain permeable for necessary ion transport.
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 approach maintains electrolyte concentration and volume balances, enhancing the electrical storage capacity and efficiency of redox flow batteries, particularly in systems with incompatible electrolytes, without the need for mixing the electrolytes.
Implementation Method 1
The separator is operable to condense the base solvent from the vapor phase to produce recovered base solvent
Implementation Method 2
an evaporator that is operable to evaporate the base solvent from the first electrolyte solution to produce the vapor phase
Implementation Method 3
The separator prevents the electrolytes from freely and rapidly mixing but selectively permits ions to pass through to complete the redox reactions
Data Source
AI summary
In a redox flow battery (RFB), the base solvent of the electrolytes tends to migrate across the barrier layer from one electrode toward the other. This can result in a volume and concentration imbalance between the electrolytes that is detrimental to battery efficiency and capacity. Compatible electrolytes can be mixed to rebalance the system, but for incompatible electrolytes mixing is not a viable option. To this end, the RFB herein includes a separator that recovers base solvent from the vapor phase of one of the electrolytes and returns the recovered base solvent to the other electrolyte to thereby reverse the imbalance.