What is the lithium-ion battery needle puncture extrusion test?

In the field of new energy, the safety of lithium-ion batteries has always been an important consideration in the research and development and application process. In order to ensure the performance of batteries under various extreme conditions, the power battery industry has conducted a series of safety tests. Among them, the needle puncture extrusion test is known as the most stringent test, and its purpose is to deeply simulate the safety performance of the battery during internal short circuit.

As the core power source of modern electronic products and electric vehicles, the performance and safety of lithium-ion batteries are directly related to the stable operation of the equipment and the life safety of users.

However, during the production and use of batteries, internal short circuits may occur due to a variety of reasons. For example, metal particles mixed in the production process, lithium dendrites generated during low-temperature charging, or copper dendrites formed during overdischarge may become hidden dangers that cause positive and negative short circuits.

When a lithium-ion battery has an internal short circuit, the energy inside the battery will be quickly released through a narrow short circuit point. According to research, after a short circuit occurs, up to 70% of the energy inside the battery may be released in just 60 seconds.

This rapid release of energy in a short period of time will cause the internal temperature of the battery to rise sharply, which will in turn cause the decomposition of the positive and negative active materials and the combustion of the electrolyte. In severe cases, this internal short circuit may even cause the battery to catch fire and explode, posing a great threat to users and the surrounding environment.

In order to effectively evaluate the safety performance of lithium-ion batteries under internal short circuit conditions, the needle puncture squeeze test came into being. The original intention of this test method is to verify whether the safety design of the battery is reliable enough by simulating the internal short circuit of the battery.

In the needle puncture test, a sharp object (such as a steel needle) will penetrate the battery's diaphragm and directly cause a short circuit between the positive and negative electrodes. In this way, testers can observe the reaction of the battery under extreme conditions, including temperature changes, electrolyte leakage, and whether there are phenomena such as fire or explosion.

In addition to the needle puncture test, the squeeze test is also one of the common methods to simulate the internal short circuit of lithium-ion batteries. In the squeeze test, the battery will be compressed by external force, causing the diaphragm to fail, thereby causing direct contact and short circuit between the positive and negative electrodes. This method can also effectively evaluate the safety performance of the battery when it is compressed by external force.

Although the needle puncture and squeeze tests are relatively simple to operate, they also have certain limitations. For example, the results of the puncture test may be affected by many factors such as the puncture speed, puncture depth and puncture position. The extrusion test may vary due to different extrusion speeds, extrusion forces and extrusion methods. Therefore, when conducting these tests, the test conditions need to be strictly controlled to ensure the accuracy and reliability of the test results.

Horizontal battery extrusion puncture test machine

In addition to puncture and extrusion tests, there are several other methods to simulate internal short circuits in lithium-ion batteries, such as internal short circuiters and external heating. Internal short circuiters are created by creating defects inside the battery, adding insulating materials (such as paraffin), and then melting the insulating materials through external heating, thereby causing a short circuit between the positive and negative electrodes.

This method can more accurately control the time and location of the short circuit, but requires more complex operations and equipment support. The external heating method directly heats the battery through an external heat source to observe its safety performance under high temperature conditions.

In summary, the puncture extrusion test of lithium-ion batteries is one of the important means to evaluate the safety performance of batteries. Through these rigorous testing methods, we can have a deeper understanding of the performance of batteries under extreme conditions such as internal short circuits, thereby providing a more reliable basis for battery design and production.

At the same time, these tests also help us to promptly identify and resolve potential safety hazards and ensure the safety and stability of lithium-ion batteries in various application scenarios.