Separator Coating Measurement with Boehmite Detection
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Solution Overview
Problem
Existing methods for measuring the thickness of ceramic coatings on separator membranes in lithium-ion batteries are inaccurate due to the presence of contaminants like boehmite, which affect the coating's density and composition, leading to potential battery failures.
Innovation Solution
A combined x-ray and infrared (IR) sensor system is used to detect the presence and concentration of boehmite in alumina coatings on separator membranes, enabling accurate determination of coating thickness and density by employing multivariate regression algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If absorption measurement techniques (X-ray, beta particle, or infrared) are used to measure coating thickness, then thickness measurement is enabled, but measurement accuracy deteriorates because these techniques are essentially weight measurement techniques that cannot accurately distinguish between different coating materials with different densities
Solution Approach 1:
The measurement system is segmented into multiple independent measurement channels: X-ray absorption measurement for total coating weight, infrared spectroscopy for material composition identification, and beta particle measurement for additional density information. Each channel provides specific information that, when combined, resolves the ambiguity of coating thickness measurement in mixed-material coatings.
Solution Approach 2:
The invention uses a composite measurement approach combining three different physical measurement techniques (X-ray absorption, infrared spectroscopy, beta particle measurement) to create a comprehensive analysis system. This composite approach allows simultaneous determination of both coating thickness and material composition, overcoming the limitations of individual measurement techniques.
2Reliability
If alumina coating is applied to separator membrane to improve temperature stability, then thermal stability is improved, but coating composition purity deteriorates due to presence of boehmite contaminant or additive
Solution Approach 1:
The measurement system performs preliminary detection of boehmite content in the coating before battery assembly. By identifying the presence and concentration of boehmite contaminant in advance, the system enables quality control decisions to be made before the coating causes potential battery failures, preventing defective products from reaching customers.
Solution Approach 2:
The system provides feedback on coating composition quality by measuring and reporting boehmite content levels. This feedback mechanism enables manufacturers to adjust coating processes to maintain alumina purity within specified limits, ensuring consistent thermal stability performance across production batches.
3Quantity of substance
If boehmite is present in alumina coating, then coating density decreases, but measurement accuracy deteriorates because absorption techniques cannot distinguish between different materials
Solution Approach 1:
Infrared spectroscopy acts as an intermediary measurement technique that provides material-specific information to complement X-ray absorption measurements. The IR spectral fingerprint identifies whether the coating material is alumina, boehmite, or a mixture, enabling the system to correct density assumptions and calculate accurate thickness values from the X-ray absorption data.
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 system provides precise measurement of coating thickness and contaminant concentration, ensuring consistent battery performance by identifying and quantifying boehmite in alumina coatings, thereby improving manufacturing quality control.
Implementation Method 1
an x-ray source having a high voltage power supply coupled thereto for emitting x-rays and an x-ray detector for providing a x-ray signal responsive to the x-rays received after being transmitted through the coated separator membrane
Implementation Method 2
The IR sensor provides IR signals from the coated separator membrane including at least two spectral components, a first peak for the separator membrane and at least a second peak for the boehmite
Data Source
AI summary
A method includes receiving an x-ray signal transmitted from an x-ray transmitter through a coated separator membrane. The method also includes obtaining infrared (IR) signals from the coated separator membrane. The IR signals include two or more spectral components including peaks that include a first peak from the separator membrane. The method also includes the processor determining whether a second peak is present, and determining if at least one contaminant/additive exists in the coating present within the coated separator membrane. The method also includes calculating, by the processor, a concentration/area weight of the at least one contaminant/additive and a weight, density, or thickness of the coating.