Separator Surface Inspection for Thin Polymer Layer Coverage
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Solution Overview
Problem
Existing methods for measuring the area coverage of adhesive layers on separators for lithium ion secondary batteries are inefficient and imprecise, particularly due to the difficulty in discerning the borders between organic component substrate surfaces and adhesive layers, which are typically thin and have minimal height differences.
Innovation Solution
An inspection device is employed that uses a light source to irradiate light at an angle of 60° to 90° and a camera to precisely measure the area coverage of a thermoplastic polymer layer on a separator surface, allowing for accurate detection of the adhesive layer without destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive layers are made thin (0.1 μm to several μm) to reduce battery resistance, then battery output and life are improved, but it becomes extremely difficult to detect the adhesive layer portion alone
Solution Approach 1:
The patent introduces an inorganic filler layer as an intermediary between the organic separator substrate and the adhesive layer. This inorganic layer provides a height difference and visual contrast that enables detection of the adhesive layer's area coverage using optical inspection devices, while the adhesive layer itself remains thin to maintain low battery resistance
Solution Approach 2:
The patent creates a three-dimensional structure by adding an inorganic filler layer between the substrate and adhesive layer. This dimensional change introduces height variation that makes the thin adhesive layer detectable through optical means, allowing area coverage measurement without increasing the adhesive layer thickness
2Measurement precision
If conventional inspection methods are used to measure area coverage, then measurement can be performed, but it requires extraction for each sample and evaluation using scanning electron microscope which takes large number of steps and long time
Solution Approach 1:
The patent replaces the mechanical extraction and SEM evaluation process with an optical inspection device that uses light reflection. This substitution enables non-destructive, online inspection during manufacturing, dramatically improving productivity while maintaining measurement precision through the height difference created by the inorganic filler layer
Solution Approach 2:
The inorganic filler layer serves a dual function: it provides structural support and enables self-detection of the adhesive layer's area coverage through optical inspection. The structure inspects itself during the manufacturing process without requiring separate extraction and laboratory analysis steps
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 enables precise and efficient measurement of the area coverage of the thermoplastic polymer layer, facilitating more manageable production steps and ensuring high-quality separators for electrical storage devices.
Implementation Method 1
an inspection device for a separator having a thermoplastic polymer layer, wherein the separator comprises a substrate and a thermoplastic polymer layer disposed on a part of one or both sides of the substrate, and the inspection device has a light source that irradiates light onto an inspection portion of the separator at an incident angle θ of 60° to 90°
Data Source
AI summary
Provided is an inspection device or a manufacturing method for a separator having a thermoplastic polymer layer. A separator S includes a substrate, and a thermoplastic polymer layer disposed on a portion of one side or both sides of the substrate. The present invention is characterized by including a step for inspecting the surface of the separator S, wherein the separator is inspected by using an inspection device having a camera 2 and a light source 1 that irradiates an inspection portion of the separator with light at an incident angle of 60° to 90°.