NaSICON Ceramic Membrane for Aqueous Redox Flow Battery
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Solution Overview
Problem
Conventional redox flow batteries suffer from crossover mixing of anolyte and catholyte active species and solvents, leading to performance degradation and safety concerns, as existing ion-conducting materials like LiSICON and β″-alumina have low conductivity and are not suitable for aqueous environments.
Innovation Solution
A redox flow battery employing a sodium super-ionic-conductor (NaSICON) barrier that is highly permeselective, preventing the crossover of solvents and active redox species while allowing sodium ions to balance electron flow, thereby maintaining separation between the anode and cathode portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ion permeable membranes are used to separate anolyte and catholyte, then ionic conductivity is maintained, but active redox species and solvents crossover leading to performance degradation
Solution Approach 1:
The patent changes the fundamental parameters of the membrane material from conventional organic polymers to inorganic ceramic materials (NaSICON, LiSICON, beta-alumina). This material parameter change enables simultaneous achievement of high separation effectiveness and high ionic conductivity, resolving the contradiction between preventing species crossover and maintaining ionic transport.
Solution Approach 2:
The patent employs composite membrane structures combining inorganic ceramic materials with appropriate binders or matrices. This composite approach maintains the high separation effectiveness of the ceramic materials while providing mechanical stability and optimized ion transport pathways, addressing both reliability and energy loss concerns.
2Reliability
If LiSICON is used as the solid state ionic conducting material, then species crossover is reduced, but ionic conductivity at room temperature is low
Solution Approach 1:
The patent changes the ionic conductor material from LiSICON to NaSICON (sodium super-ionic-conductor). This material substitution fundamentally changes the ionic conductivity parameter at room temperature from 10^-6 S/cm to significantly higher values, while maintaining the separation effectiveness. The NaSICON material inherently provides both high power and high reliability.
3Reliability
If beta''-alumina is used as the solid state ionic conducting material, then species crossover is reduced, but the material degrades quickly in the presence of water
Solution Approach 1:
The patent changes the material composition from beta''-alumina to NaSICON ceramic material. This chemical parameter change provides superior stability in aqueous environments, preventing the degradation issues experienced with beta''-alumina. The NaSICON material maintains both high separation effectiveness and long-term durability in water-based electrolytes.
4Duration of action of stationary object
If organic solvents are used to avoid water degradation, then membrane stability is improved, but conductivity decreases and safety concerns arise
Solution Approach 1:
The patent changes the electrolyte solvent from organic to aqueous (water-based). Combined with the NaSICON membrane material, this parameter change enables high ionic conductivity in water while maintaining membrane stability. The inorganic ceramic membrane is inherently stable in water, eliminating the need for organic solvents and their associated safety and conductivity problems.
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 NaSICON barrier effectively maintains separation between anolyte and catholyte solutions, enhancing the energy capacity and safety of the battery by preventing solvent and species crossover, while ensuring high ionic conductivity and stability in aqueous conditions.
Implementation Method 1
The NaSICON barrier is highly permeselective, such that the Na+ ions readily migrate across the NaSICON barrier to balance the flow of electrons
Implementation Method 2
The NaSICON barrier is highly permeselective, such that the Na+ ions readily migrate across the NaSICON barrier to balance the flow of electrons while there is substantially no crossover of solvent or active redox species
Implementation Method 3
the redox active species of the anode portion is oxidized. Free electrons flow from the anode portion of the RFB to the cathode portion of the RFB, resulting in a current that flows through the load. The free electrons reduce the redox active species of the cathode portion.
Data Source
AI summary
A redox flow battery is described herein that has a sodium-super-ionic-conductor NaSICON barrier disposed between an anolyte chamber of the battery and the catholyte chamber of the battery. The NaSICON barrier prevents crossover of solvents or active redox species between the anolyte chamber and the catholyte chamber, while permitting transport of sodium ions between the chambers. In exemplary embodiments, the anolyte chamber includes an anolyte solution that comprises a first active redox species dissolved in a first solvent, while the catholyte chamber includes a catholyte solution that comprises a second active redox species dissolved in a second solvent.