What comprehensive tests can the lithium battery testing system achieve for batteries?
With the continuous progress of technology, the workmanship of battery packs has also become increasingly advanced. At present, the volume energy density and capacity of lithium battery packs are becoming increasingly high, so the safety of lithium battery packs has also received widespread attention from the public. Before the lithium battery pack leaves the factory, manufacturers will conduct specialized battery pack tests on it. And the detection technology of lithium batteries also directly affects the quality of lithium batteries.
In general, the performance test of lithium battery pack mainly includes voltage, internal resistance, capacity, internal pressure, self-discharge rate, cycle life, sealing performance, safety performance, storage performance, appearance, etc. Other test items include overcharge, overdischarge, solderability, corrosion resistance, etc. There are several slightly important testing projects among them
1、 Lithium battery pack aging test: The activation stage of the lithium battery pack includes stages such as pre charging, formation, aging, and constant capacity. The effect of aging is to stabilize the properties and composition of the SEI film formed after initial charging. The aging test of lithium batteries is to improve the infiltration of electrolyte, which is conducive to the stability of battery performance.
2、 Lithium battery pack cycle life test: Lithium battery cycle life test has national standards, GB/T31484, mainly for charging and discharging experiments. However, if the capacity of the battery is lower than 80% of the rated capacity, it is considered that the battery has failed. The cycle life test mainly tests the charging and discharging times of lithium battery packs when the available capacity drops to the allowable value.
3、 Measurement of Internal Resistance of Lithium Batteries: The internal resistance of lithium batteries refers to the resistance experienced by the current flowing through the battery during operation. It is generally divided into AC internal resistance and DC internal resistance. Due to the small internal resistance of rechargeable batteries, when measuring DC internal resistance, the actual value cannot be measured because the electrodes are prone to polarization, resulting in polarization internal resistance; Measuring its AC internal resistance can eliminate the influence of polarization internal resistance and obtain the true internal value.