Method for evaluating insulating performance of separator for electrochemical device

A method for evaluating the insulating performance of a separator for use in blocking contact between positive and negative electrodes in an electrochemical device, comprising:

• preparing a measurement subject having the separator to be evaluated therein, wherein the measurement subject includes a metal contact layer is interposed between two sheets of the separator so as to form a plurality of local contacts with surfaces of each of the two sheets of the separator, and wherein the surface area of the metal contact layer is less than the total surface area of the separator such that the metal contact layer is spaced apart from the edges of each of the two sheets 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.