Method for evaluating insulating performance of separator for electrochemical device

Patent metadata

Field	Value
Publication number	US-2019265305-A1
Application number	US-201916285926-A
Country	US
Kind code	A1
Filing date	Feb 26, 2019
Priority date	Feb 26, 2018
Publication date	Aug 29, 2019
Grant date	—

Abstract

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.

First claim

1 . A method for evaluating the insulating performance of a separator for an electrochemical device, comprising:
(a) 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; (b) sandwiching the measurement subject between an upper jig and a lower jig; (c) applying a voltage the magnitude of which varies with time between the upper jig and the lower jig using a voltage application unit; (d) receiving a current measurement value flowing between the upper jig and the lower jig as an input from a current measurement unit; and (e) 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.

2 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 1 , wherein the metal contact layer is formed of a metal mesh, and (a) comprises: inserting the metal mesh between two sheets of separator; and forming a plurality of local contacts between the separator and the metal mesh by thermally compressing the two sheets of separator having the metal mesh inserted.

3 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 1 , wherein the metal contact layer is formed of a metal particle layer comprising a plurality of metal particles, and (a) comprises: scattering the plurality of metal particles onto one of the two sheets of separator; and forming a plurality of local contacts between the separator and the plurality of metal particles by positioning the other separator on the separator onto which the plurality of metal particles have been scattered.

4 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 1 , wherein the metal contact layer is formed of a metal particle layer comprising a plurality of metal particles and an organic binder binding them, and (a) comprises: preparing a slurry comprising the plurality of metal particles, the organic binder and a volatile solvent; forming a metal contact layer by coating the slurry onto one of the two sheets of separator and drying the same; and forming a plurality of local contacts between the separator and the plurality of metal particles by positioning the other separator on the separator onto which the metal contact layer has been formed and then thermally compressing the two sheets of separator.

5 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 1 , wherein the area of the metal contact layer is 60-70% of the total area of the separator, and the metal contact layer is formed with a predetermined spacing from the edge of the separator.

6 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 2 , wherein the metal mesh has a diameter of a weft and a warp of 15-2000 μm and a gap between the weft and the warp of 15-10000 μm.

7 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 3 , wherein the metal particle comprised in the metal particle layer has a size of 15-1000 μm.

8 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 1 , wherein, in (e), when the current measurement value is equal to or greater than the critical value for a preset reference time, the control unit determines the voltage value measured immediately after the reference time has passed as a dielectric breakdown voltage.

9 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 1 , which further comprises, between (a) and (b), interposing metal foils between the measurement subject and the upper jig and between the measurement subject and the lower jig.

10 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 1 , wherein, in (c), the measurement subject is compressed by applying pressure to the upper jig and the lower jig.

11 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 1 , wherein, in (c), at least one of the upper jig and the lower jig is heated.

12 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 10 , wherein the pressure applied the upper jig and the lower jig is 5 kPa to 30 MPa.

13 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 1 , which further comprises recording the determined dielectric breakdown voltage in a storage unit.

14 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 1 , which further comprises displaying the determined dielectric breakdown voltage by a display unit.

15 . The method for evaluating the insulating performance of a separator for an electrochemical device according to claim 1 , wherein the voltage is a DC voltage or a pulse voltage the magnitude of which increases with time.

Assignees

• Lg Chemical Ltd

Inventors

• Shin Hyun-Kyung
• Sung Dong-Wook
• Lee Sang-Joon

Classifications

• G01R19/16571

  comparing AC or DC current with one threshold, e.g. load current, over-current, surge current or fault current (G01R19/16514, G01R19/16519, G01R19/16528, G01R19/16533, G01R19/1659 take precedence; measuring currents by using elements sensitive to the magnetic field generated G01R15/14; measuring earth resistance G01R27/18; testing for leakage or short circuits in electrical apparatus G01R31/52) · CPC title

• G01R31/16

  Construction of testing vessels; Electrodes therefor · CPC title

• G01R31/20

  Preparation of articles or specimens to facilitate testing · CPC title

• G01R31/3865

  related to manufacture, e.g. testing after manufacture · CPC title

• H01M10/4285

  Testing apparatus · CPC title