Research on Puncture Testing of Lithium Battery Separators

Lithium-ion secondary batteries, also known as rechargeable batteries (hereinafter referred to as lithium batteries), are widely used as power sources in information terminals and consumer electronics due to their high energy density and high battery voltage. In recent years, their application range has gradually expanded to daily life fields (including hybrid electric vehicles), and future demand will further increase.

Among the components of lithium batteries, the lithium battery separator prevents contact between the positive and negative electrodes while serving as a barrier that allows lithium ions to pass through. The puncture resistance of the separator has a significant impact on the safe use of lithium batteries.

The growth of lithium dendrites is one of the fundamental issues affecting the safety and stability of lithium-ion batteries. The formation of lithium dendrites can pierce the separator, causing internal short circuits in the lithium-ion battery, leading to thermal runaway and resulting in fire and explosion. Therefore, the puncture resistance of the separator has a major impact on battery life and safety.

The puncture strength test of the separator follows the standard "GB / T 36363-2018 Polyolefin Separator for Lithium-ion Batteries," using a speed of 1 00 mm /min and a puncture needle with a diameter of 1mm and a spherical tip radius R 0.5 to pierce 10 a separator fixed by a ring with a diameter of mm, evaluating the puncture resistance of the separator.

2. Experimental Introduction

2.1  Test Method

This test uses a 500 N pneumatic puncture fixture. The fixture opens and closes via a hand toggle switch on the right side of the fixture. The clamping force of the sample is provided by a cylinder, and the inner diameter of the upper and lower rings fixing the sample is Ø 10mm Figure 1 shows the actual state of the puncture test.

Sample size length 245mm width 150mm thickness 12u m, provided by a specialized separator manufacturer (see Figure 1).

The puncture needle used in the puncture test has a diameter of 1mm and a spherical tip radius R 0.5。

Figure 1. Separator sample and puncture test diagram

2.2  Test Results

Figure 2. Puncture test curve (displacement - load) -load)

Table 1  Test data

Figure 2 and Table 1 are the puncture test curves and test result data respectively.

From the data, it can be seen that the data obtained from the same puncture needle are highly consistent with small errors, indicating high stability of the entire test system.

During the test, it was found that B OYI 2025 has good stability, high accuracy, and reliability at low force values. The pneumatic puncture fixture is easy to operate, has high testing efficiency, and the sample fixation consistency is good, ensuring good repeatability of the test results.

3. Conclusion

In summary, the use of BOYI 2025 Electronic Universal Testing Machine, N sensor, and 500N pneumatic puncture fixture in this test meets the requirements of the standard "GB T 36363-2018 Polyolefin Separator for Lithium-ion Batteries," enabling the acquisition of puncture strength and other data of lithium battery separators with good stability and high consistency. 50N传感器、500N气动穿刺夹具，可以满足标准《GB T 36363-2018 锂离子电池用聚烯烃隔膜》要求，获取锂电池隔离膜穿刺强度等数据，稳定性好，一致性高。