Method for enhancing screening consistency of lithium-ion power battery

Abstract

The invention relates to a method for enhancing the screening consistency of lithium-ion power batteries. The method comprises the steps of (1) screening single batteries produced under the same condition; (2) carrying out full-charging full-discharging test for N times on the single batteries, and screening the single batteries with constant current ratio more than 90%, platform time being 45 minutes and capacity difference values less than 50mAh; (3) standing at high temperature of 45 DEG C for 10 days under an uncharged condition; (4) standing at normal temperature for 4-6 hours, and screening the single batteries with inner resistance difference of 2-3m omega and uncharged open-circuit voltage difference less than 100 mV; (5) respectively discharging for 10 seconds through 3-5C current in a 10%-20% SOC state and charging for 10 seconds through 2-3C under a 80%-90% SOC condition, acquiring transient dynamic voltage of charging and discharging at the 10th second, and screening the single batteries with dynamic voltage difference values of charging and discharging within 10mV. Compared with the prior art, the method disclosed by the invention has the advantages that the polarization difference of the single batteries can be increased, so that the state difference inside the batteries can be represented, and the batteries subjected to a pulse test have very high consistency.

Description

【Technical field】 [0001] The invention relates to the technical field of battery detection, in particular to a method for improving the consistency of screening lithium-ion power batteries. 【Background technique】 [0002] At present, lithium-ion batteries, a green power source with high energy density, long service life and good safety performance, are widely used. Lithium-ion batteries are widely used in energy storage, power vehicles and other fields. Tests have found that when batteries made in the same way are combined into a battery pack, its service life is lower than that of a single battery. This shows that the consistency of the single battery significantly affects the service life of the battery pack. In the series-parallel application of batteries, the consistency of single cells affects the efficiency and life of the battery pack, and safety issues also have an impact. Therefore, the requirements for the consistency of single cells assembled into a battery pack...

AI Technical Summary

Problems solved by technology

[0003] To ensure the consistency of the single battery, first of all, it is necessary to ensure that the initial performance of the single battery is consistent, the self-discharge of the single battery must be consistent, and the decline rate during use must be consistent. The current screening of battery consistency There are mainly platform voltage sorting methods, static capacity sorting methods, and internal resistance sorting methods. In practical applications, we found that batteries sorted by these static methods cannot characterize the polarization differences in single cells. After being assembled into a battery pack, under the same working conditions, the performance of the battery itself will change greatly, and the capacity, internal resistance and charge-discharge curve of the battery will change, resulting in a serious decline in the overall performance of the battery pack

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