Self-discharge screening method for improving matching consistency of lithium ion batteries

Abstract

The invention discloses a self-discharge screening method for improving the matching consistency of lithium ion batteries. The self-discharge screening method for improving the matching consistency ofthe lithium ion batteries comprises the following steps that after the same batch of batteries are subjected to conventional capacity grading, 5-20% SOC state-of-charge electric quantity is charged in a 4-6A current constant current charging mode. After the batteries are put on hold at normal temperature for 24-48h, the battery voltage is measured as OCV1, then the temperature is turned to 45 DEGC, and the batteries are put on hold for 120-168h, then the battery voltage is measured as OCV 2, then the batteries are put on hold at normal temperature, the battery voltage is measured as OCV3 again, values of OCV1, OCV2 and OCV3 are measured, and the voltage difference is calculated, that is , delta V1= OCV1-OCV2 and delta V2= OCV2-OCV3; and an out-of-tolerance value code of the delta V1 is VO1, an out-of-tolerance value code of the delta V2 is VO2, a batch of out-of-tolerance batteries can be roughly eliminated with a VO1 set value, and then a batch of the batteries can be finely eliminated with a VO2 set value. The self-discharge screening method for improving the matching consistency of the lithium ion batteries has simple and convenient implementation, high matching precision, good consistency and high matching efficiency, and is especially suitable for batch production application.

Description

technical field [0001] The invention belongs to the technical field of electrochemistry. Specifically, the invention relates to a lithium ion battery, especially a self-discharge screening method for improving the consistency of lithium ion battery matching. Background technique [0002] Lithium-ion battery is an energy storage product with high specific energy, low self-discharge and good high and low voltage performance. It is widely used in modern office equipment, communication equipment and electric tools. In reality, lithium-ion batteries are usually composed of several single batteries connected in series or in parallel, which is commonly known as grouping in this industry. However, the batteries connected in groups have a "bucket effect", that is, the performance of the battery pack is determined by the worst single cell. Therefore, screening single cells with basically consistent performance is a key link in battery assembly and an important task for lithium-ion ba...

AI Technical Summary

Problems solved by technology

However, this method has low screening accuracy and low efficiency. On the one hand, it cannot meet the supporting requirements of modern equipment, and on the other hand, it is not suitable for mass production applications.

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