Soft package polymer lithium ion battery corner sealing process

Abstract

The invention discloses a soft package polymer lithium ion battery corner sealing process which comprises the following steps: corner sealing is carried out by using a runway-shaped corner sealing head, the orientation of a runway is parallel to the height direction of a battery cell, the height from the lower edge of a corner sealing seal to a side edge corner line of an air bag at the bottom of the battery cell is 2-18mm, a reserved position in the corner sealing is 0.2-1.0 mm, the aluminum-plastic film is a nylon aluminum-plastic film of a three-layer structure or a PET aluminum-plastic film of a three-layer structure, and the deformation rate of the PP layer at the sealing position of the corner seal is 10%-55%. According to the invention, gas in the cell pit body can be extracted from a reserved position in the top sealing edge and can also be extracted from the bottom of the cell during air extraction, and a gas flow channel is added during air extraction, so that the probability of softening and cracking of the cell is reduced, the hardness of the cell is increased, and the service life of the cell is prolonged. The reject ratio of the air exhaust procedure and the possibility of corner breakage of the side corners of the air bag at the bottom of the battery cell are reduced; and meanwhile, the runway-shaped sealing head avoids serious damage to the aluminum plastic film due to overlarge local pressure of the corners of the sealing head.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery manufacturing, in particular to a corner sealing process for a soft-packed polymer lithium-ion battery. Background technique [0002] With the continuous improvement of the energy density requirements of lithium-ion batteries, many soft-package polymer lithium-ion battery manufacturers have designed the cell structure to be very compact and extreme. At the same time, the width of the top sealing edge of the battery cell packaged by the hard sealing process is getting smaller and smaller, so that the width of the reserved position inside the top sealing edge of the gas flow channel is also getting smaller and smaller when the pumping packaging process is used as the pumping process. , and in order to prevent a relatively large displacement of the internal cell body during the process of formation and pumping, in the existing manufacturing process of flexible packaging polymer lithium-io...

AI Technical Summary

Problems solved by technology

[0002] With the continuous improvement of the energy density requirements of lithium-ion batteries, many soft-package polymer lithium-ion battery manufacturers have designed the cell structure to be very compact and extreme. At the same time, the width of the top sealing edge of the battery cell packaged by the hard sealing process is getting smaller and smaller, so that the width of the reserved position inside the top sealing edge of the gas flow channel is also getting smaller and smaller when the pumping packaging process is used as the pumping process. , and in order to prevent a relatively large displacement of the internal cell body during the process of formation and pumping, in the existing manufacturing process of flexible packaging polymer lithium-ion batteries, the cell will be sealed after the top seal and side seal are completed. Corner sealing process, and the position of the corner seal is exactly at the corner of the airbag side at the bottom of the cell, so that the potential air extraction channel at the bottom of the cell is completely blocked, and the reserved space inside the top sealing edge where the space is gradually compressed becomes the most Important air extraction channel, if the control is not good during the manufacturing process, the width of the reserved space inside the top sealing edge may be almost zero, and the cells with too small or almost zero reserved space inside the top sealing edge will be very difficult to pump air. It may be difficult to extract the gas inside the battery core, and the battery core may become soft or even burst, which reduces the pass rate of the pumping process.

At the same time, when the corner seal is at the corner of the airbag side at the bottom of the battery cell, the corner is prone to breakage and the battery will be scrapped

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