Redox Flow Battery Membrane Structure for Dry Storage and Leak Resistance
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Solution Overview
Problem
Conventional separation membranes for redox flow batteries are prone to electrolyte-solution leakage and require constant wet storage, which complicates handling and durability, and they have limitations in proton permeability and chemical resistance.
Innovation Solution
A separation membrane with a protective film on both surfaces of a sheet substrate, featuring pores communicating between surfaces, and an ion-exchange membrane with a matrix of sulfonated rosin-based ion-exchange resin dispersed with an inorganic porous powdery body, such as diatomaceous earth, enhancing proton permeability and preventing electrolyte leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ion-exchange membranes are used, then proton permeability is achieved, but electrolyte-solution leakage occurs and durability deteriorates
Solution Approach 1:
The patent applies composite materials by combining a porous film substrate with an ion-exchange resin layer containing inorganic porous powdery bodies (such as diatomaceous earth). This composite structure prevents electrolyte-solution leakage through the inorganic powder filling while maintaining proton permeability through the ion-exchange resin, thereby resolving the contradiction between durability and harmful leakage.
Solution Approach 2:
The patent utilizes porous materials at multiple levels: the porous film substrate provides structural support and fluid flow paths, while the inorganic porous powdery bodies within the ion-exchange resin layer prevent leakage by filling larger pores. This hierarchical porous structure maintains proton permeability while preventing electrolyte-solution leakage, addressing the durability contradiction.
2Reliability
If membranes are stored in wet conditions, then membrane performance is maintained, but handling complexity increases and storage requirements become stringent
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition and structural parameters of the membrane to enable dry storage capability. The specific combination of porous film substrate, ion-exchange resin, and inorganic porous powdery bodies creates a structure that maintains performance stability even in dry conditions, fundamentally changing the storage parameter from wet-required to dry-compatible, thereby improving ease of operation.
3Ease of manufacture
If porous film substrates with large pore diameter distribution are used, then manufacturing is simplified, but electrolyte-solution leakage increases
Solution Approach 1:
The patent resolves this contradiction by creating a composite structure where the porous film substrate (easy to manufacture with large pores) is combined with an ion-exchange resin layer containing inorganic porous powdery bodies. The inorganic powder fills and blocks the large pores that would cause leakage, while the overall composite structure maintains manufacturing simplicity through conventional coating and drying processes.
Solution Approach 2:
The patent applies local quality by having different regions of the membrane structure serve different functions: the porous film substrate provides structural support and general fluid flow with large pores for ease of manufacture, while the ion-exchange resin layer with inorganic porous powdery bodies provides localized leakage prevention at the pore level. This spatial differentiation of qualities resolves the contradiction between manufacturing simplicity and leakage prevention.
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 membrane is dry-storable, easy to handle, and exhibits improved proton permeability, reduced electrolyte-solution leakage, and increased durability, allowing for mass production and automated assembly without a wet environment, while maintaining excellent chemical resistance.
Implementation Method 1
a stable separation membrane which is resistant to detachment of the ion-exchange resin even when a battery is repeatedly charged and discharged and is capable of preventing electrolyte leakage and enhancing proton permeation, could be obtained as a result of attaching a phenolic ion-exchange resin to an inorganic porous powdery body of diatomaceous earth whose pore diameters are distributed, within a range of, e.g., 2 to 50 nm
Implementation Method 2
an ion-exchange membrane having a matrix formed of an ion-exchange resin dispersed therein with an inorganic porous powdery body attached with the ion-exchange resin obtained as a result of sulfonating rosin
Data Source
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AI summary
The invention is: a separation membrane for a redox flow battery, obtained by forming a protective film on a sheet substrate that has a large number of voids communicating between front and rear, and bonding to the protective film an ion-exchange membrane obtained by causing an inorganic porous powdery/granular body, to which an ion-exchange resin obtained by sulfonating rosin has been attached, to be dispersed in a matrix constituted of ion-exchange resin; as well as a method of producing a separation membrane for a redox flow battery, the method comprising a step for forming a protective film on a sheet substrate, a step for attaching to the protective film a coating solution in which an inorganic porous powdery/granular body and a sulfonating agent are contained in a rosin solution obtained by mixing rosin and solvent, and a step for introducing a sulfonic acid group to the rosin to make an ion-exchange resin. The use of such an ion-exchange membrane for which rosin is the raw material makes it possible to achieve a separation membrane for a redox flow battery that can be stored dry, can be handled with ease, is particularly superior in preventing electrolyte leakage and in proton permeability, and also has a high tensile strength and high water pressure resistance.