The external short circuit test of lithium-ion batteries is an important means to test the safety of lithium-ion batteries in the case of abuse and optimize the battery structure design.
The external short-circuit test connects the lithium-ion battery to a fixed-value resistor. The external resistance is close to or even smaller than the internal resistance during the test. At this time, most of the voltage will be added to the internal resistance, and the output voltage of the external circuit will decrease. Suppose the voltage on the internal resistance of the battery is too large. In that case, the heating power will be very high, and a large amount of heat is generated inside the lithium-ion battery in a short time, which will burn the battery. Due to the limitation of the structure of the lithium-ion battery, the heat cannot be quickly diffused to the outside of the battery, resulting in an excessively high temperature of the lithium-ion battery, which may cause the decomposition and combustion of the active material and the electrolyte, resulting in thermal runaway.
If the lithium-ion battery can pass the external short-circuit test, it proves that the lithium-ion battery is very safe under this kind of abuse.