SPEEK/IL Sandwich Reference Electrode for Stable Offshore Measurements
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Solution Overview
Problem
Commercial Ag/AgCl reference electrodes are prone to potential drift in complex offshore environments due to Cl− concentration changes, affecting detection accuracy, and SPEEK films suffer from phase separation and reduced proton conductivity in polar conditions.
Innovation Solution
A reference electrode with a SPEEK/IL sandwich structure, comprising two layers of SPEEK/IL composite film and a SPEEK film as the outermost layer, with IL layers in between, using [HOEtMIM][Cl] to enhance conductivity and stability, and optionally incorporating SiOx for improved mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SPEEK film is used to improve chemical stability and high-temperature resistance, then proton exchange capacity and ion conductivity are improved, but in polar environments phase separation occurs allowing smaller-radius particles to pass through
Solution Approach 1:
The patent combines SPEEK with ionic liquid (IL) to form a composite membrane structure. The IL fills the phase-separated clusters in SPEEK, creating a composite material that maintains the chemical stability and high-temperature resistance of SPEEK while blocking the passage of small ions like sulfide ions that would otherwise pass through the phase-separated regions.
Solution Approach 2:
The patent introduces ionic liquid specifically into the phase-separated cluster regions of SPEEK to create local structural modifications. This local quality enhancement blocks ion transport pathways in the problematic regions while preserving the overall chemical stability and proton conductivity of the SPEEK matrix.
2Reliability
If sulfonic acid groups are increased to improve proton exchange capacity, then ion conductivity is improved, but electromagnetic attraction causes clustering and phase separation
Solution Approach 1:
The ionic liquid acts as an intermediary substance that infiltrates the phase-separated clusters formed by sulfonic acid groups. It mediates between the clustered sulfonic acid groups and the fluorocarbon backbone, preventing complete phase separation while maintaining high proton exchange capacity and ion conductivity.
3Reliability
If Ag/AgCl reference electrode with saturated KCl is used to provide stable reference potential, then in deep sea environments the glass shell is easily damaged
Solution Approach 1:
The patent replaces the traditional glass shell with a flexible polymer membrane structure (SPEEK/IL composite). This thin film structure provides the necessary mechanical flexibility to withstand deep sea pressure while maintaining the reference electrode's functional integrity, eliminating the fragility of glass shells.
4Temperature
If Ag/AgCl semi-reference electrode is used to work under high temperature and pressure, then in complex chemical environments potential drift occurs due to Cl− concentration changes
Solution Approach 1:
The patent changes the electrolyte composition from aqueous KCl to ionic liquid, fundamentally altering the chemical environment. This parameter change allows the reference electrode to maintain stable potential in complex chemical environments while retaining high-temperature resistance, as the ionic liquid provides a non-aqueous, chemically stable medium that prevents potential drift.
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 SPEEK/IL sandwich structure maintains consistent Cl− concentration, reduces phase separation, and increases proton conductivity, providing stable and accurate electrochemical measurements in challenging environments.
Implementation Method 1
SPEEK films have desirable chemical stability, excellent high-temperature resistance, and high electrical conductivity. With the introduction of sulfonic acid groups, the sulfonation degree of the SPEEK is correspondingly increased, thus greatly improving the proton exchange capacity and ion conductivity of the film.
Implementation Method 2
In a polar environment, sulfonic acid groups of SPEEK's fluorocarbon backbone side chains tend to gather in clusters due to electromagnetic attraction. As a result, microscopic phase separation occurs between the sulfonic acid groups and the fluorocarbon backbone, allowing the passage of smaller-radius particles such as sulfide ions.
Data Source
AI summary
A reference electrode with a sulfonated polyether ether ketone/ionic liquid (SPEEK/IL) sandwich structure, and a preparation method and use thereof are provided. In the reference electrode, an end of a reference electrode main body is provided with the SPEEK/IL sandwich structure; the SPEEK/IL sandwich structure includes two layers of SPEEK/IL composite film and one layer of SPEEK film, and the SPEEK film is arranged at an outermost layer of the SPEEK/IL sandwich structure.