Porous Polymer Substrate Defect Screening by SEM Pore Index
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for quality control of porous polymer substrates used in separators for lithium secondary batteries are inadequate, as they rely on post-manufacturing air permeability tests, which are time-consuming and costly, and cannot accurately detect non-uniform pore sizes or morphologies before the formation of an organic-inorganic composite porous layer.
Innovation Solution
A method involving scanning electron microscopy (SEM) to observe and quantify the pore distribution index (PDI) of porous polymer substrates, with correction factors applied to classify them as good or defective products based on predetermined reference values, allowing for pre-detection before forming the composite layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air permeability tests are performed after manufacturing the separator, then the quality control of the final separator can be ensured, but the detection time is extended and the cost increases
Solution Approach 1:
The patent applies preliminary action by performing SEM observation and PDI calculation on the porous polymer substrate before forming the organic-inorganic composite porous layer. This allows defective substrates to be identified and removed early in the manufacturing process, preventing the need for time-consuming air permeability tests on finished separators while maintaining quality control.
2Reliability
If air permeability tests are performed after manufacturing the separator, then the quality control of the final separator can be ensured, but the manufacturing cost increases
Solution Approach 1:
The patent performs the detection action preliminarily by using SEM observation and automated PDI calculation on substrates before composite layer formation. This shifts the detection cost from final product testing to raw material inspection, reducing overall manufacturing costs by avoiding the need for expensive air permeability testing equipment and procedures on finished separators.
Solution Approach 2:
The patent replaces the mechanical air permeability testing system with an optical imaging system (SEM) combined with automated image processing. This substitution eliminates the need for physical air flow measurements, reducing equipment costs and simplifying the quality control process while maintaining detection accuracy.
3Measurement precision
If capillary flow porometer is used to determine pore size, then the pore size can be measured, but the measurement varies from site to site making it unfavorable for quality control
Solution Approach 1:
The patent applies universality by using SEM imaging combined with automated PDI calculation that can evaluate the entire porous structure comprehensively. Unlike capillary flow porometry that measures only local pore sizes, the PDI method provides a unified quantitative metric that reflects the overall pore distribution and morphology consistency across the entire substrate, enabling reliable quality control.
Solution Approach 2:
The patent implements feedback by calculating the PDI from SEM images and using this quantitative value to determine whether the substrate meets quality standards. This closed-loop feedback mechanism provides objective, consistent criteria for quality control decisions, eliminating the subjectivity and site-to-site variation inherent in manual capillary flow porometer measurements.
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 approach enables early detection of defective substrates, reducing time and cost by evaluating the substrate before forming the composite layer, ensuring improved air permeability and thermal stability of the final separator.
Implementation Method 1
observing the selected porous polymer substrate with a scanning electron microscope (SEM) to obtain an image of the porous polymer substrate
Data Source
AI summary
Disclosed is a method for pre-detecting a defective porous polymer substrate for a separator, including selecting a porous polymer substrate having a plurality of pores; observing the selected porous polymer substrate with a scanning electron microscope (SEM) to obtain an image of the porous polymer substrate; quantifying the average value of pore distribution index (PDI); correcting the quantified average value of pore distribution index to obtain the corrected average value of pore distribution index; determining whether or not the corrected average value of pore distribution index is 60 a.u. (arbitrary unit) or less; and classifying the porous polymer substrate as a good product, when the corrected average value of pore distribution index is determined to be 60 a.u. or less, and classifying the porous polymer substrate as a defective product, when the corrected average value of pore distribution index is determined to be larger than 60 a.u.