How to test the safety of 18650 lithium battery?

In order to know how safe the 18650 lithium battery is, it must be tested. The important test methods are divided into the following 4 categories: 1. Electrical test overcharge, overdischarge, external torque circuit, forced discharge, etc. 2. Mechanical testing of falling body, impact, needle stabbing, vibration, squeezing, acceleration. 3. Heat test fire, sand bath, hot plate, thermal shock, oil bath. 4. Environmental testing for pressure reduction, height, immersion, bacteria resistance, etc. Extrusion test There are two types of extrusion experiments: one is a plate type, and the other is a strip type. During the extrusion test, the diaphragm is damaged in some places, causing an internal short circuit and a large current; ②The diaphragm is broken, causing the positive electrode It mixes with the active material of the negative electrode, and an exothermic reaction occurs; ③The diaphragm ruptures when it is squeezed, and an electric spark appears, causing the electrolyte to catch fire. The acupuncture test is important to simulate the internal short circuit of the battery. Insert a needle with a diameter of 3mm into the battery. Same as the extrusion test, if the safety factor is not high, it will catch fire within 3s. But at present, there is no conclusion as to why the diameter is 3mm instead of other sizes. Of course, the smaller the diameter of the needle, the easier it is to pass the safety test. Of course, this does not mean that the safety factor of the battery has changed. The battery for fire test is thrown into charcoal fire, boiling water or heated oil bath. Of course, the battery will burn, but it should not explode. It can also be tested by heating to 180 degrees Celsius on a hot plate. The high temperature and low temperature cycle tests are repeated at high temperature and low temperature. The high temperature condition is 65 degrees Celsius, the relative humidity is 90%, and the time is 8H; the low temperature condition is -30 degrees Celsius, the time is 8H, and the number of cycles is 5 times. The safety of the battery should also include post-processing issues, that is, it will not cause serious environmental pollution after the battery is used up. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous post: What are the fundamental differences between lithium batteries and polymer lithium batteries?