CN108287192A - Breakdown voltage method for detecting aluminum plastic film qualification - Google Patents

Abstract

The invention discloses a breakdown voltage method for testing the qualification of aluminum-plastic films, which comprises the following steps: taking two pieces of aluminum-plastic films to be tested, and coating electrolyte solution on one of the aluminum-plastic films to be heat-sealed area, and then heat seal the two pieces of aluminum-plastic film in the area to be heat-sealed; tear off the plastic layer on the inner side and opposite side of the same end of the two pieces of aluminum-plastic film bonded together to expose the aluminum layer, forming a clamping end ;The clamping ends clamped on two pieces of aluminum-plastic films by crocodile clips are respectively connected to the positive and negative poles of the short-circuit tester or potentiometer; use the short-circuit tester or potentiometer to gradually apply voltage to the set voltage, Within this voltage range, if the short-circuit tester shows normal, it means that the aluminum-plastic film is qualified; if the short-circuit tester shows NG, it means that the aluminum-plastic film is unqualified. The invention can quickly detect the qualification of the aluminum-plastic film, and can also detect the breakdown voltage and the breakdown current of the aluminum-plastic film at the same time, the detection process is fast and efficient, and the result is accurate.

Description

A Breakdown Voltage Method for Detecting the Qualification of Aluminum Plastic Film

technical field

The invention relates to the technical field of battery detection, in particular to a breakdown voltage method for detecting the qualification of an aluminum-plastic film.

Background technique

With the development of social economy and the needs of environmental protection, lithium-ion batteries are widely used. More and more automotive power batteries and consumer products have higher and higher performance requirements for lithium-ion batteries, especially safety and reliability. aspect. Aluminum-plastic film is used as the outer packaging of lithium-ion batteries to package the cells. Qualified aluminum-plastic film products are a necessary condition to ensure battery safety. Among them, the detection of defects such as damage to the aluminum-plastic film is a mandatory inspection item for batteries when they leave the factory, and it is also a must for IQC. project. Aluminum-plastic film is usually composed of three layers: the outermost nylon layer, the middle layer of aluminum foil and the innermost PP layer. Among them, the nylon layer on the outermost layer of the aluminum-plastic film has good anti-wear and damage functions, the aluminum layer in the middle functions to block air and moisture, and the innermost PP layer functions to isolate electrolyte corrosion and fuse and seal. The inside of the polymer lithium-ion battery is in a vacuum state, completely isolated from the air and water in the external environment. Due to mechanical action or over-melting during heat sealing, the inner layer of the aluminum-plastic film is damaged, and the aluminum layer is directly in contact with the electrolyte. At this time, the trace amount of hydrofluoric acid in the electrolyte will contact the aluminum layer and cause pitting corrosion. Corrosion at the heat seal position of the negative tab will accelerate electrochemical corrosion, change the composition of the electrolyte, and in severe cases, corrode the aluminum layer and cause battery leakage, which will bring serious safety hazards and cause the battery to be scrapped.

The damage of the inner layer of the aluminum-plastic film is an important reason for battery leakage, IV and other defects. During the process of side sealing and top sealing of the battery cell, the innermost layer of the aluminum-plastic film may be severely thermally deformed or damaged. But this phenomenon, especially the slight damage, is difficult to distinguish completely with the eyes. Therefore, how to accurately detect these defects of aluminum-plastic films has become one of the problems that need to be solved urgently.

Application publication number CN103048376A, the Chinese patent application publication date of 2015.02.04 discloses a method for quickly determining the poor insulation of the aluminum-plastic film of a soft-packed lithium-ion battery. The steps are to pierce the probe into the position of the sealed aluminum-plastic film, apply a voltage ≥ 400 V to the battery, and observe whether there is leakage, breakdown or smoke. Its shortcoming is that the battery needs to be put on hold at 30-50°C for 1-5h, and the cycle is long. Each test needs to consume a certain amount of electrolyte and battery cells, and it is impossible to judge the quality of the same batch of aluminum-plastic film. Happening. In addition, although this method can determine the location of the poor insulation of the aluminum-plastic film, it cannot accurately give the voltage and current values when the poor insulation of the aluminum-plastic film occurs, which is not conducive to technicians setting inspection standards for incoming materials.

Contents of the invention

In view of this, the purpose of the present invention is to provide a convenient, fast, accurate and efficient breakdown voltage method for testing the qualification of aluminum-plastic films.

A kind of breakdown voltage method for testing the qualification of aluminum-plastic film, it comprises the following steps:

(1) Take two pieces of aluminum-plastic film to be tested, apply the electrolyte on the area to be heat-sealed of one of the aluminum-plastic films, and then heat-seal the two pieces of aluminum-plastic film in the area to be heat-sealed, and then seal the aluminum-plastic film Wipe off the electrolyte on the membrane except the heat-sealed area;

(2) Tear off the plastic layer on the inner side and opposite side of the same end of the two pieces of aluminum-plastic film bonded together to expose the aluminum layer and form a clamping end;

(3) The clamping ends clamped on two pieces of aluminum-plastic film by crocodile clips are respectively connected to the positive and negative poles of the short-circuit tester or potentiometer;

(4) Use a short-circuit tester or potentiometer to gradually apply voltage to the set voltage. If the short-circuit tester shows normal within this voltage range, it means that the aluminum-plastic film is qualified; if the short-circuit tester shows NG, it means that the aluminum-plastic film is qualified. If the aluminum-plastic film is unqualified, the voltage at this time is the breakdown voltage, and the current is the breakdown current.

In a further solution, the two pieces of aluminum-plastic films are heat-sealed by using a direct sealing machine, and the outer or inner plastic layers of the two pieces of aluminum-plastic films are hot-melt-bonded into one.

In a further solution, the aluminum-plastic film to be tested is an aluminum-plastic film of a polymer lithium battery, which is composed of an inner layer, an aluminum layer and an outer layer, wherein both the inner layer and the outer layer are plastic layers.

In a further solution, the voltage set in step (4) is not greater than 1000 volts.

In the present invention, the electrolytic solution is first applied to the area to be heat-sealed, and then the two pieces of aluminum-plastic film are heat-sealed in the area to be heat-sealed to form a whole, and then a short-circuit tester or a potentiometer is used to test the aluminum-plastic film at one end where the aluminum layer is exposed. Gradually apply high voltage. If NG is not displayed on the interface within the voltage range, the aluminum-plastic film meets the requirements. If NG occurs before reaching the set high voltage, the aluminum-plastic film does not meet the requirements and the aluminum-plastic film is broken down. At the same time, the breakdown voltage and breakdown current of the aluminum-plastic film can also be detected. The detection process is fast and efficient, and the result is accurate.

The electrolyte in the present invention is the electrolyte of polymer lithium battery. Wipe off the electrolyte in the area outside the heat seal to prevent breakdown in the non-heat seal area.

The invention can be used to assist in finding the root cause of poor insulation voltage, and at the same time can provide inspection methods for incoming material inspection departments. According to the detection method of the present invention, it can be determined whether the aluminum-plastic film of the same batch has a breakdown risk.

Detailed ways

A kind of breakdown voltage method for testing the qualification of aluminum-plastic film, it comprises the following steps:

(1) Take two pieces of aluminum-plastic film to be tested, apply the electrolyte on the area to be heat-sealed of one of the aluminum-plastic films, and then heat-seal the two pieces of aluminum-plastic film in the area to be heat-sealed, and then seal the aluminum-plastic film Wipe off the electrolyte on the membrane except the heat-sealed area;

(2) Tear off the plastic layer on the inner side and opposite side of the same end of the two pieces of aluminum-plastic film bonded together to expose the aluminum layer and form a clamping end;

(3) The clamping ends clamped on two pieces of aluminum-plastic film by crocodile clips are respectively connected to the positive and negative poles of the short-circuit tester or potentiometer;

(4) Use a short-circuit tester or potentiometer to gradually apply voltage to the set voltage of 1000 volts. If the short-circuit tester displays "OK" within this voltage range, it indicates that the aluminum-plastic film is qualified; if the short-circuit tester displays NG, it indicates that the aluminum-plastic film is unqualified. At this time, the voltage is the breakdown voltage, and the current is the breakdown current.

In a further solution, the two pieces of aluminum-plastic films are heat-sealed by using a direct sealing machine, and the outer or inner plastic layers of the two pieces of aluminum-plastic films are hot-melt-bonded into one.

In a further solution, the aluminum-plastic film to be tested is an aluminum-plastic film of a polymer lithium battery, which is composed of an inner layer, an aluminum layer and an outer layer, wherein both the inner layer and the outer layer are plastic layers.

The present invention is not limited to the specific implementations disclosed and described in the above examples, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention.

Claims (4)

1. A breakdown voltage method for detecting the qualification of aluminum-plastic film, is characterized in that: comprise the following steps: (1) Take two pieces of aluminum-plastic film to be tested, apply the electrolyte on the area to be heat-sealed of one of the aluminum-plastic films, and then heat-seal the two pieces of aluminum-plastic film in the area to be heat-sealed, and then seal the aluminum-plastic film Wipe off the electrolyte on the membrane except the heat-sealed area; (2) Tear off the plastic layer on the inner side and opposite side of the same end of the two pieces of aluminum-plastic film bonded together to expose the aluminum layer and form a clamping end; (3) The clamping ends clamped on two pieces of aluminum-plastic film by crocodile clips are respectively connected to the positive and negative poles of the short-circuit tester or potentiometer; (4) Use a short-circuit tester or potentiometer to gradually apply voltage to the set voltage. If the short-circuit tester shows normal within this voltage range, it means that the aluminum-plastic film is qualified; if the short-circuit tester shows NG, it means that the aluminum-plastic film is qualified. If the aluminum-plastic film is unqualified, the voltage at this time is the breakdown voltage, and the current is the breakdown current. 2. The method according to claim 1, characterized in that: said two pieces of aluminum-plastic films are heat-sealed by using a direct sealing machine to heat-melt the outer or inner plastic layers of the two pieces of aluminum-plastic films bonded together. 3. The method according to claim 1, characterized in that: the aluminum-plastic film to be tested is an aluminum-plastic film of a polymer lithium battery, which is composed of an inner layer, an aluminum layer and an outer layer, wherein the inner layer Both the layer and the outer layer are plastic layers. 4. The method according to claim 1, characterized in that: the set voltage in step (4) is not greater than 1000 volts.