Polycarbonate Polyurethane Separator for Non-Aqueous Flow Cells
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Solution Overview
Problem
Current separators for non-aqueous flow cells, particularly those using polyether polymers, exhibit poor conductivity and excessive swelling in organic solvents, limiting their effectiveness and mechanical stability, while NAFION-based separators are more suited for aqueous systems.
Innovation Solution
A polycarbonate-based polyurethane separator is developed, which maintains dimensional stability and enhances ion transport when swelled by organic solvents, incorporating metal salts to improve conductivity without excessive swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polyether polymer separators are used in non-aqueous flow cells, then the separators can be used with organic solvents, but they exhibit excessive swelling and poor conductivity
Solution Approach 1:
The patent changes the chemical composition parameters of the separator by using polycarbonate-based polyurethane instead of polyether polymers. This material substitution fundamentally alters the separator's interaction with organic solvents, reducing excessive swelling while maintaining ion conductivity through appropriate polymer structure design and metal salt incorporation.
Solution Approach 2:
The patent creates a composite separator system by combining polycarbonate-based polyurethane with metal salts (such as lithium perchlorate, lithium tetrafluoroborate, or lithium hexafluorophosphate). This composite approach enhances ion conductivity while the polycarbonate matrix provides dimensional stability, resolving the contradiction between solvent compatibility and structural integrity.
2Reliability
If NAFION-based separators are used, then ion selectivity is improved, but they are more suited for aqueous systems rather than non-aqueous flow cells
Solution Approach 1:
The patent changes the chemical parameters of the separator material from NAFION (a perfluorosulfonic acid polymer designed for aqueous environments) to polycarbonate-based polyurethane with metal salt additives. This parameter change enables the separator to function effectively in non-aqueous organic solvents while maintaining adequate ion selectivity through the polymer's inherent properties and controlled pore structure.
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 polycarbonate-based polyurethane separator provides improved ion selectivity, conductivity, and mechanical stability, making it suitable for non-aqueous flow cells with minimal water content, enhancing energy storage device performance.
Implementation Method 1
maintains dimensional stability and enhances ion transport when swelled by organic solvents
Implementation Method 2
incorporating metal salts to improve conductivity
Data Source
AI summary
A non-aqueous flow cell energy storage device comprises a ionically conductive separator, which separator comprises a polyurethane prepared by curing an isocyanate capped prepolymer, which prepolymer was prepared from a polyol having polycarbonate backbone, wherein the separator may be impregnated with electrolyte salts and/or swelled by an organic solvent.