Standing method for self-discharge detection of lithium ion battery

Abstract

The invention discloses a standing method for self-discharge detection of a lithium ion battery. The method comprises the following process. The process comprises the following steps of charging a battery with a certain electric quantity, completing primary voltage screening on charging and discharging equipment, applying a certain pressure to the battery, standing in a high-temperature environment, standing in a normal-temperature environment, measuring a first open-circuit voltage of the battery and recording time, standing in the normal-temperature environment, measuring a second open-circuit voltage of the battery and recording time, and screening a battery cell with abnormal voltage and self-discharge. Certain pressure is applied to the battery in the standing process of self-discharge detection, and the direction of the force is perpendicular to the layered structure of the positive plate-diaphragm-negative plate, so that the problem that the abnormal battery cell cannot be identified due to an overlarge gap between the plate pieces of the self-discharge abnormal battery cell is avoided. The method is short in screening time and high in efficiency, the screening rate is closeto 100%, and the screening accuracy is greatly improved.

Description

technical field [0001] The invention belongs to the field of self-discharge detection of lithium-ion batteries, in particular to a static method for self-discharge detection of lithium-ion batteries. Background technique [0002] The self-discharge phenomenon of lithium-ion batteries refers to the spontaneous loss of capacity when the battery is placed in an open circuit. For the same batch of batteries, the materials used and the process control are basically the same. When the white discharge of individual batteries is obviously too large, the reason is likely to be a serious micro-short circuit caused by impurities, foreign matter, burrs piercing the diaphragm, or the diaphragm is folded. At present, the self-discharge measurement method in the industry generally adopts the open circuit voltage decay rate measurement method. The open circuit voltage is directly related to the SOC of the battery state of charge. It only needs to measure the change rate of the battery's OCV...

AI Technical Summary

Problems solved by technology

[0004] The current static method for self-discharge detection and measurement generally takes 5-30 days. If the static period of self-discharge detection is shortened, there is a risk of unrecognized abnormal batteries; increasing the static period of self-discharge detection can reduce the leakage of abnormal batteries. Probability, but increase the manufacturing cycle, energy consumption, resulting in high static cost

Abnormal self-discharge batteries are high-risk items. In normal static mode, abnormal batteries are prone to missed inspections.

During the production process of lithium-ion batteries, the battery is measured under certain pressure (such as hi-pot short circuit test, fixture formation process, fixture capacity separation process, after module assembly), and the actual conditions of direct users and end users. The battery is also under certain pressure during use. There are differences between standing without pressure and some production process conditions and the actual use of customers. During use, problems such as abnormal self-discharge may be triggered due to pressure on the battery.

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