Soft package lithium ion battery and online detection method for cathode short circuit of soft package lithium ion battery

Abstract

The invention discloses a soft package lithium ion battery. The lithium ion battery comprises a battery cell, an electrolyte, an aluminum-plastic film, a positive electrode metal strip and a negative electrode metal strip; the aluminum-plastic film comprises a protective layer, a middle layer and a heat sealing layer, wherein the middle layer of the aluminum-plastic film is an aluminum layer; the positive electrode metal strip is communicated with the aluminum layer of the aluminum-plastic film through a conductive piece; and when the whole lithium ion battery is electrified, the aluminum layer of the aluminum-plastic film is positively charged. According to the lithium ion battery, the positive electrode metal strip is communicated with the aluminum layer of the outer packaging material aluminum-plastic film through the conductive piece; and when the lithium ion battery is detected, if a negative electrode is short-circuited, the whole battery shows a self-discharge phenomenon, so that the voltage attenuation of the battery is obvious; and a batter with abnormal voltage attenuation is determined as an unqualified battery. The detection method can quickly identify the lithium ion batteries with short-circuited cathodes, and improves the precision measurement efficiency and precision.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a soft-pack lithium-ion battery and an online detection method for short-circuiting of negative poles thereof. Background technique [0002] As a secondary rechargeable battery, lithium-ion batteries can be divided into cylindrical, square, and soft-pack batteries according to the packaging shape and structure; among them, soft-pack lithium-ion batteries are favored by virtue of their advantages such as large capacity, light weight, small internal resistance, flexible design, and high safety performance. Widely used in digital, mobile phones, mobile energy, and wearable electric vehicles; currently, soft-pack batteries account for 30% of the market in the power field, and 90% in the consumer battery field; soft-pack lithium-ion batteries usually use aluminum-plastic film As packaging and encapsulation methods. [0003] During the entire battery manufact...

AI Technical Summary

Problems solved by technology

[0004] In order to prevent the outflow of defective batteries, that is, unqualified batteries, there are three impedance tests from the beginning to the end during the battery manufacturing process, including: short-circuit voltage test of pole piece, edge resistance test of aluminum-plastic film and internal resistance test of battery cell; There is a possibility of corrosion on defective film side resistors, and it usually takes a period of time to finally show up at the customer. Its failure is manifested in the appearance that the aluminum is corroded, damaged, blackened, and the battery cell is swollen and cannot be used. It can be said to be the most serious. The performance of bad products is a very scary thing

Aiming at the increase of bad side resistance products caused by short circuit of the negative electrode, the existing detection method mainly checks the side resistance and side voltage of the finished battery by detecting the side resistance after liquid injection and before formation; The time is short, and its electronic channels and ion channels cannot be effectively detected; the latter method is currently mainly completed by manual detection, and the main defect is that there is a poor contact between the contact probe and the aluminum layer of the aluminum-plastic film, which leads to misjudgment, because the aluminum layer The thickness is thin, only 35-40μm, and it is easy to be interfered by the outer layer and inner layer materials. In the actual detection process, it is easy to have poor contact between the detection terminal and the aluminum layer on the end face.

In addition, manual full inspection increases inspection costs and output efficiency, and requires high staff responsibility and operating techniques

Through the above two methods of detection, there are still bad batteries flowing into the client and causing customer complaints, which indirectly shows that the sensitivity of the above methods still has limitations.

[0005] In view of the technical problem that the negative short circuit of the existing lithium ion battery is difficult to identify, a new detection method is urgently needed to detect and identify the lithium ion battery with the negative short circuit problem