Cyclic Carbonate Electrolyte Solvents for Low-Volatile Electro-Optic Devices
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Solution Overview
Problem
Current electrolyte solvents used in electrochromic and electro-optic devices, such as propylene carbonate, are flammable and volatile, leading to issues like uncontrolled solvent loss, crystallite formation, and incompatibility with certain substrates, especially at elevated temperatures, which can result in device defects and reduced functionality.
Innovation Solution
A low-volatile organic electrolyte solvent based on cyclic carbonate esters with a vapor pressure of 0.0023 kPa or less at 20°C and a boiling point of at least 350°C is used, which is non-flammable and compatible with various device components, minimizing solvent loss and enhancing device stability across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If propylene carbonate (PC) is used as electrolyte solvent, then the device can operate properly with good ionic conductivity, but the solvent becomes flammable and continues to burn after flame source removal
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte solvent by replacing PC with cyclic carbonate esters having different molecular structures and physical properties, specifically those with lower vapor pressure and higher flash points, thereby reducing flammability while maintaining ionic conductivity
Solution Approach 2:
The patent uses composite electrolyte systems combining cyclic carbonate esters with other solvents or polymer gels to achieve both low flammability and good ionic conductivity, creating a multi-component system that balances safety and performance
2Reliability
If propylene carbonate (PC) is used as electrolyte solvent, then the device can function properly, but the solvent evaporates causing uncontrolled concentration variations and crystallite formation
Solution Approach 1:
The patent changes the vapor pressure parameter of the electrolyte solvent by selecting cyclic carbonate esters with significantly lower vapor pressure than PC, thereby reducing evaporation rate and preventing solvent loss, concentration variations, and crystallite formation during device operation
3Reliability
If propylene carbonate (PC) is used as electrolyte solvent, then the device can operate, but the solvent is incompatible with certain substrates at elevated temperatures causing device defects
Solution Approach 1:
The patent changes the chemical compatibility parameters by replacing PC with cyclic carbonate esters that have different chemical properties and lower reactivity toward substrate materials at elevated temperatures, thereby preventing degradation and device defects while maintaining operational 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 low-volatile organic carbonate solvents reduce flammability, solvent evaporation, and substrate incompatibility issues, resulting in higher quality electrochromic and electro-optic devices with improved stability and performance, including reduced film thickness variations and prolonged darkening/clearing times.
Implementation Method 1
The vapor pressure of the low volatile organic electrolyte solvent may be about 0.0023 kPa or less measured at 20 deg. C.
Implementation Method 2
The electrolyte solvent allows for the free diffusion of electrochromic compounds, electroactive compounds, and/or supporting electrolyte materials through EC films and between anodic and cathodic electrodes.
Implementation Method 3
The low volatile organic electrolyte solvent may have a boiling point of at least 350° C. at 1.0 atmosphere pressure.
Data Source
AI summary
An electrochromic medium for use in an electro-optic device comprises a solvent comprising at least one low-volatile organic electrolyte solvent based on a cyclic carbonate ester; an anodic electroactive material; and a cathodic electroactive material; and at least one of the anodic and cathodic electroactive materials is electrochromic.