A screening method for the consistency of soft-pack lithium-ion batteries

Abstract

The invention discloses a method for screening the consistency of soft-packed lithium-ion batteries. After screening the abnormal batteries according to the nominal capacity of the batteries after formation, the charging and discharging efficiency of the battery formation and the change of internal resistance before and after formation and the change of internal resistance are calculated. Average value, make a curve of internal resistance change deviating from the average value, and screen the battery; measure and record the voltage and internal resistance of the battery at the end of formation, then put the battery at 40°C for 24 hours, measure the internal resistance and voltage again, and pass the internal resistance before and after high temperature The battery is classified according to the change average value and the internal resistance change deviates from the average value curve; after the battery is divided into capacity, it is grouped according to the voltage difference and tolerance of the battery in a certain charged state. After the batteries are sorted for the first time according to this method, the group consistency is significantly improved.

Description

technical field [0001] The invention belongs to the technical field of screening methods for soft-pack lithium-ion batteries, and in particular relates to a screening method for the consistency of soft-pack lithium-ion batteries. Background technique [0002] Because lithium-ion batteries are affected by various factors such as raw materials, equipment, environment, and human factors during the manufacturing process, there will inevitably be performance differences. Most lithium-ion battery companies will use the capacity, This method can screen batteries to a certain extent, but the parameters used are all static parameters, which cannot guarantee the consistency of batteries in the actual charging and discharging process. There is also screening through the charge-discharge curve of the battery, such as the invention and creation of CN201710363716.1 "a lithium battery consistency sorting method and lithium battery", firstly screen the battery cells according to the voltage...

AI Technical Summary

Problems solved by technology

[0002] Because lithium-ion batteries are affected by various factors such as raw materials, equipment, environment, and human factors during the manufacturing process, there will inevitably be performance differences. Most lithium-ion battery companies will use the capacity, The voltage and internal resistance are used to match the battery and screen the battery. This method can screen the battery to a certain extent, but the parameters used are all static parameters, which cannot guarantee the consistency of the battery in the actual charging and discharging process.

There is also screening through the charge-discharge curve of the battery, such as the invention and creation of CN201710363716.1 "a lithium battery consistency sorting method and lithium battery", firstly screen the battery cells according to the voltage drop, and then according to the The charge-discharge curve of the battery cell is screened and classified. This method has certain advantages over the simple screening of static parameters such as voltage and capacity, but the charge-discharge curve has no obvious boundaries to classify the battery.

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