Moisture Measurement in Battery Separators Using Gas Chromatography
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Solution Overview
Problem
Conventional methods, such as Karl-Fisher titration, fail to accurately measure moisture content in secondary battery separators, particularly when inorganic substances are present in the form of hydrates, affecting battery performance and lifespan.
Innovation Solution
A method utilizing a gas chromatograph equipped with a headspace sampler, where an internal standard solution is prepared with tetrahydrofuran and dimethylformamide, and the samples are analyzed at temperatures between 140°C and 160°C using a thermal conductivity detector, allowing for accurate measurement of moisture content in both free and hydrate forms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Karl-Fisher titration method is used to measure moisture content in separator, then the measurement process is simple and commonly available, but the measured value is not accurate especially when inorganic substances are present
Solution Approach 1:
The patent replaces the chemical titration system (Karl-Fisher method) with a physical analysis system (gas chromatography). The GC system uses thermal conductivity detection to measure moisture content, avoiding the chemical reactions and assumptions that limit the accuracy of Karl-Fisher titration, especially in the presence of inorganic substances.
Solution Approach 2:
The patent changes the measurement parameter from chemical equivalence (Karl-Fisher reagent consumption) to physical property detection (thermal conductivity of gas phase moisture). This parameter change enables accurate measurement of moisture in complex matrices containing inorganic substances without the interference that plagues chemical titration methods.
2Measurement precision
If headspace sampling method is used with gas chromatograph, then moisture content measurement accuracy is improved, but the measurement process becomes more complex
Solution Approach 1:
The patent introduces a headspace sampler as an intermediary device between the sample and the gas chromatograph. This automated intermediary handles the complex tasks of sample preparation, heating, and gas phase extraction, transforming a complex manual process into an automated sequence that improves accuracy while reducing operational complexity.
Solution Approach 2:
The headspace sampling method performs preliminary actions of sample heating and moisture extraction into the gas phase before the actual GC analysis. This preliminary preparation separates the complex sample matrix from the moisture analyte, simplifying the subsequent measurement process and improving accuracy by eliminating interference from inorganic substances.
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 method provides more accurate moisture content measurements in secondary battery separators, improving battery performance and lifespan by identifying internal states and moisture sources effectively.
Implementation Method 1
measuring a moisture content in the standard sample and a moisture content in the test sample with a gas chromatograph equipped with a headspace sampler
Implementation Method 2
temperature of the vessel is from 140 to 160° C.
Implementation Method 3
mixing the solvent with water and then introducing the internal standard solution hereto to prepare a standard sample
Data Source
AI summary
The present invention provides a method for measuring moisture content in a separator of secondary battery by using a gas chromatograph equipped with a headspace sampler. The separator of secondary battery may be a safety reinforced separator (SRS) in which inorganic substance particles and a binder polymer are coated on a polyolefin substrate.