Separator Insulating Performance Evaluation Method
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for evaluating the insulating performance of separators in electrochemical devices, such as lithium secondary batteries, fail to accurately measure the dielectric breakdown voltage after lamination with electrodes, as the separator is deformed and impurities can affect the results, making it difficult to distinguish the separator's performance from the electrode assembly's.
Innovation Solution
A method involving a measurement subject with a metal contact layer interposed between two sheets of separator to simulate the lamination environment, where a voltage varying with time is applied between jigs, allowing for the determination of dielectric breakdown voltage by measuring current flow, thereby evaluating the insulating performance reliably.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the separator is laminated with electrodes using a roller, then the electrode assembly is formed, but the separator is deformed and fine unevenness is formed on the surface, leading to variation in thickness and changed dielectric breakdown voltage
Solution Approach 1:
The patent applies preliminary compression between two rollers before the final lamination process. This preliminary action pre-compresses the separator and electrode materials, reducing the formation of fine unevenness and thickness variation during subsequent lamination, thereby maintaining better separator thickness uniformity while still forming the electrode assembly
Solution Approach 2:
The patent changes the compression parameters by applying controlled compression force through two rollers with specific pressure distribution. By adjusting the compression force, roller speed, and temperature parameters during the preliminary compression stage, the separator thickness uniformity is improved while still enabling effective electrode assembly formation
2Ease of manufacture
If electrode active material particles or foreign impurities are interposed between the separator and electrodes during lamination, then the dielectric breakdown voltage changes, but the insulating performance worsens due to decreased separator thickness at contact regions
Solution Approach 1:
The patent introduces a release film or protective layer as an intermediary between the separator and electrode materials during the lamination process. This intermediary prevents direct contact and potential damage from sharp particle edges, reducing the formation of thin regions and maintaining the separator's insulating performance while still allowing effective lamination
Solution Approach 2:
The patent applies a protective coating or cushioning layer to the separator surface before lamination. This beforehand cushioning protects the separator from direct contact with sharp electrode particles and foreign impurities, preventing local thickness reduction and maintaining insulating performance during the lamination process
3Measurement precision
If the dielectric breakdown voltage of the separator itself is measured, then the insulating performance of the separator can be evaluated, but the dielectric breakdown voltage of the electrode assembly where the separator is laminated with electrodes cannot be measured
Solution Approach 1:
The patent creates a test specimen that copies the structure of the actual electrode assembly by laminating a separator with electrode materials using the same lamination process. This copied structure allows measurement of the dielectric breakdown voltage in a configuration that accurately represents the real electrode assembly, enabling evaluation of the separator's insulating performance in situ
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 reliable evaluation of the insulating performance of separators laminated with electrodes, simulating the actual use environment and accounting for changes due to electrode material particles and impurities, without requiring high-pressure apparatuses.
Implementation Method 1
applying a voltage the magnitude of which varies with time between the upper jig and the lower jig... determining a dielectric breakdown voltage by determining the voltage value when the magnitude of the current value is equal to or greater than a preset critical value
Data Source
AI summary
A method for evaluating the insulating performance of a separator using an insulating performance evaluation system according to an exemplary embodiment of the present disclosure includes: preparing a measurement subject wherein a metal contact layer is interposed between two sheets of separator so as to form a plurality of local contacts with the surface of the separator; sandwiching the measurement subject between an upper jig and a lower jig; applying a voltage the magnitude of which varies with time between the upper jig and the lower jig using a voltage application unit; receiving a current measurement value flowing between the upper jig and the lower jig as an input from a current measurement unit; and determining the voltage value at which the current measurement value is equal to or greater than a preset critical value as a dielectric breakdown voltage, by a control unit.