System for online testing of sagging degree of thin film and battery diaphragm

Abstract

The invention discloses a system for performing online measurement on the sagging degree of a thin film and immediately performing improvement on the sagging of the thin film according to a measurement result. With the system, on-line measurement and improvement can be performed on all width ranges of the thin film; and a time interval is provided for collection of the on-line measurement data. Through the measurement and improvement system, the sagging degree is reduced by 15%-50% compared with the condition that the sagging degree is not subjected to the system. Meanwhile, the invention further discloses a battery diaphragm. The sagging degree is smaller than or equal to 100 mm when the measurement system is adopted for measurement, and a difference value of the sagging degree between two points in any length direction on a fixed width position is smaller than or equal to 50 / 1000 mm.

Description

technical field [0001] The invention belongs to the field of detection and processing of plastic films, and in particular relates to a detection method for the collapse (or sagging, wavy edge, etc.) of a lithium-ion battery separator, and a processing method for improving the degree of collapse through online response. Background technique [0002] With the popularization of mobile terminals such as mobile phones and notebook computers, and the increasing promotion of electric vehicles, lithium-ion batteries, as their energy sources, are used more and more widely, and their requirements are getting higher and higher. The most obvious of these is the need for lithium-ion batteries to be both high-performance and safe. This places stringent requirements on the materials used in lithium-ion batteries. [0003] As an important part of the lithium-ion battery, the separator plays the role of providing lithium-ion movement channels while isolating the contact between the positive...

AI Technical Summary

Problems solved by technology

For example, the invention patent CN105222728A discloses a test method for the flatness of the isolation film, but it can only test the few meters of the end of the roll, and cannot obtain the data of the entire roll of film, and it belongs to offline detection, which reduces the production efficiency

The utility model patent CN205748152U discloses a method for testing the collapse of copper-aluminum foil for lithium-ion batteries. This method can also be used for testing the separator, but this method can only test the edge of the copper-aluminum foil or the separator, and cannot measure the overall width. take measurements

The utility model patent CN205594143U discloses a detection device for the wavy edge of a lithium-ion battery. The device uses laser distance measurement, and the measured data is more accurate, but it uses a point laser, and can only measure the distance of a certain point at the same time. The overall width cannot be measured at the same time. In addition, the device needs to manually adjust the test position on the edge of the isolation film, resulting in a large error in the test position and affecting the accuracy of the test results.

Utility model patent CN205808353U discloses a device that can test the wavy edge of the isolation film while heating. This device can be used to explore the heating temperature required for improving the wavy edge, but it is limited to the exploration of temperature and cannot be directly applied and isolated Film processing, and there is also the problem that only the edge is tested and the full width cannot be measured

For example, the invention patent CN105328261A discloses a method for improving the flatness of the separator during slitting, which reduces the collapse and sagging of the separator by adjusting the tension between the rollers during slitting, but the tension adjustment process of this method is an artificial process based on experience. Adjustment, unable to achieve precise adjustment after digital measurement of the actual situation of the isolation diaphragm

The utility model patent CN205810928U discloses an on-line improvement device for the wavy edge of the isolation film, which uses a laser detector to measure the wavy edge value of the isolation film and then feeds it back to the oven, changes the set temperature of the oven, and performs heat treatment on the isolation film at different temperatures , so as to slow down the wavy edge of the isolation film, but this method is still limited to the sag value measurement and online improvement of the isolation film edge, and has the same disadvantages as the aforementioned utility model patent CN205594143U that it is difficult to accurately locate the edge and the test results are inaccurate. In practical applications, Since it is impossible to move the laser detector in real time to capture the edge position of the isolation film, it is often impossible to measure the data on the edge, which makes the subsequent online improvement process invalid, and even heats up by mistake, resulting in thermal shrinkage of the isolation film

Images