Ionic Liquid Electrolyte for Gas Sensor Leakage
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Solution Overview
Problem
Existing electrochemical gas sensors face challenges with hygroscopic electrolytes, which absorb excessive water in high-humidity environments leading to leakage, and ionic liquids often exhibit high viscosities and gel formation when additives are incorporated, affecting sensitivity, response time, and robustness.
Innovation Solution
The use of an ionic liquid electrolyte with specific cations such as monoalkylammonium, dialkylammonium, or trialkylammonium cations, combined with anions like nitrate, tetrafluoroborate, and additives like metal phthalocyanines or alkali halides, absorbed in solid materials like silicates or glass fibers, to create a quasi-solid electrolyte system that maintains fluidity and enhances sensitivity and selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hygroscopic electrolytes are used to delay drying of the cell in dry environments, then the electrolyte can absorb water from the surround environment, but in high-humidity environments the electrolyte absorbs so much water that electrolyte leaks from the cell
Solution Approach 1:
The patent changes the chemical composition parameters of the electrolyte by using ionic liquids with specific cation-anion combinations (e.g., imidazolium with BF4- or PF6- anions) that have inherently low hygroscopicity, thereby preventing water absorption and electrolyte leakage in high-humidity environments while maintaining functional reliability
Solution Approach 2:
The patent employs composite ionic liquid systems combining specific cations (imidazolium, pyridinium, tetraalkylammonium) with particular anions (BF4-, PF6-, CF3SO3-) to create an electrolyte composition that achieves both low hygroscopicity and high ionic conductivity, resolving the contradiction between stability and leakage prevention
2Object-affected harmful factors
If organic liquids with conducting salts are used as electrolytes to limit water absorption in high-humidity environments, then water absorption is limited, but at low humidity and/or high ambient temperatures vaporized solvent cannot be reabsorbed and is thus irrecoverably lost from the sensor cell
Solution Approach 1:
The patent transitions from organic liquid electrolytes to ionic liquid electrolytes, changing the physical state and chemical composition parameters. Ionic liquids have negligible vapor pressure due to their salt-like structure, eliminating solvent evaporation and irrecoverable loss while maintaining low water absorption characteristics
Solution Approach 2:
The patent replaces volatile organic solvents with non-volatile ionic liquids, effectively creating an indisposable electrolyte system that does not require replenishment due to evaporation losses, thereby eliminating the substance loss problem
3Object-affected harmful factors
If ionic liquids are used as electrolytes to achieve low hygroscopicity and high ionic conductivity, then water absorption is reduced, but certain ionic liquids exhibit high viscosities and gel formation when additives are incorporated, affecting sensitivity and response time
Solution Approach 1:
The patent optimizes the molecular structure parameters of ionic liquids by selecting specific cation sizes and anion types (e.g., smaller imidazolium cations with BF4- or PF6- anions) that inherently exhibit lower viscosity and prevent gel formation, even when additives like metal phthalocyanines or alkali halides are incorporated, thereby maintaining both low water absorption and good fluidity
Solution Approach 2:
The patent creates optimized composite ionic liquid systems where specific cation-anion combinations are selected to work synergistically with additives, achieving a balance between low hygroscopicity, high ionic conductivity, and maintained fluidity without gel formation
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 configuration reduces water absorption, maintains electrolyte fluidity, and improves sensitivity and selectivity in gas detection, minimizing cross-sensitivity and allowing for compact sensor design.
Implementation Method 1
Ionic liquids are defined as liquid salts with a melting point below 100° C. The salt-like structure of certain ionic liquids results in the absence of a measurable vapor pressure. The properties of ionic liquids vary substantially and are dependent, for example, upon the type and the number of organic side chains present in the ionic liquid, as well as the anions and cations thereof.
Implementation Method 2
The electrolytes described therein are hygroscopic (that is, they can absorb water from the surround environment). A hydroscopic electrolyte can be desirable for use in dry or low-humidity environments to delay drying of the cell. In high-humidity environments, however, a hydroscopic electrolyte can absorb so much water that electrolyte leaks from the cell.
Implementation Method 3
On the side of the cell which is open to the atmosphere, gas can flow to one of the electrodes (the working or sensing electrode), at which it is electrochemically converted. The current generated by the conversion is proportional to the quantity of gas present.
Data Source
AI summary
An electrochemical gas sensor includes an ionic liquid as electrolyte. The ionic liquid includes at least one cation selected from the group of a monoalkylammonium cation, a dialkylammonium cation, and a trialkylammonium cation. The individual alkyl groups of the cation can be branched or unbranched and have 1 to 4 carbon atoms. The individual alkyl groups of the cation can be the same or different in case of the dialkylammonium cation and the trialkylammonium cation. In a number of embodiments, the individual alkyl groups have 2 to 4 carbon atoms.