Skip to content

Tensile, Puncture, and Peel Testing of Lithium-Ion Batteries

Tensile, Puncture, and Peel Testing of Lithium-Ion Batteries
With the rapid development of science and technology, smartphones, robots, drones, and similar gadgets have become a natural part of our daily lives. As an important carrier of energy and power for these and similar devices, lithium-ion batteries are used more often than ever. To ensure the safety, longevity, and general quality of manufactured lithium-ion batteries, high-quality materials testing of the batteries before they leave the manufacturing facility is crucial. To make the testing easy, accurate and consistent, some of the manufacturers of materials testing machines offer test solutions specifically developed for the lithium battery industry. In this article, we will take a look at the solutions ideal for tension, puncture, and peel testing of those batteries.

Solutions for Lithium-Ion Battery Testing
A test solution for the lithium-ion battery industry would typically consist of material testing machine, fitted with a high accuracy load cell, analytical software and grips suitable for securing the battery during the test. As there are many different grips solutions on the market when purchasing a materials testing system, the question is “which grip should you choose for testing lithium-ion batteries?”. The answer depends on what type of test you want to carry out. Key to any type of grip is that it keeps the battery properly aligned, does not influence specimen performance and that it under no circumstances allows the battery to slip during the test. Regardless of the materials tester used, selecting the wrong set of grips will result in inaccurate test results. 

In this article, we will go through the grip recommendations to the most common tests types within lithium-ion battery testing. These are tension, puncture, and peel. For these tests, pneumatic tensile grips, pneumatic puncture grips, and special peeling grips are ideal, as these greatly improve the testing efficiency and performance of the physical strength of battery separators.

With these grips, the operator will be able to perform the following tests:

1) Tensile test on the battery separator
2) Puncture test on the battery separator
3) Coating peel test

Tensile Test on Lithium-Ion Battery Separator 
When combining the materials tester with a pneumatic grip for tensile testing, the test process will be greatly improved as the operator’s manual fastening of the battery separator is made more efficient. Another advantage gained by using the pneumatic grips for the tensile testing of the battery separator is that slippage caused by a low force manual fastening grip is avoided, as constant pressure is applied to the specimen. This in turn ensures that data stability, repeatability and accuracy is improved. Using a footswitch for actuation of the pneumatic grips frees the hands of the operator so securing of the battery separator is fast and efficient.

Puncture Test on Lithium-Ion Battery Separator 
To ensure stability and efficiency in the puncture test of the battery separator, the materials tester combined with a pneumatic puncture test fixture is the ideal solution. The pneumatic puncture test fixture offers the flexibility to feed the specimen from different directions. After fastening the battery separator, the test can easily be started either manually, or by using a footswitch.

Coating Separator Peel Test on Lithium-Ion Battery
The coating quality of a lithium-ion battery separator is directly related to the performance of the battery's electrical properties. The peel strength test can not only effectively identify the coating quality and show the coating strength and uniformity, it can also guide the production line in regards to the adjustment of the coating. Performing a peel test on the coating of the lithium-ion battery will ensure that the finished product is uniform and reliable. Using the materials tester with a customized grip will ensure stability throughout the entire peel test.

Materials Testing Software for Analysis
During the tests, a materials testing software monitors the specimen under test, controls the test process, and accurately records test data. This data can automatically be exported to Excel for further analysis and analytical reports and can be printed or created as a PDF file. Some of the manufacturers of materials testing machines offer analysis software with built-in libraries of pre-set test methods that adhere to international standards along with the opportunity of creating custom multi-stage tests for more complex or unique test demands. 

Testing Batteries Under Varying Temperatures
To simulate the performance of membranes under varying temperature conditions, a temperature chamber can be coupled to the test machine and optionally, automatically controlled by the software. This can be to either simulate normal operating conditions or be used to push the specimen to extreme limits whilst under test.