Method for judging whether moisture of baked lithium ion batteries is qualified or not

Abstract

The invention relates to a method for judging whether the moisture of baked lithium ion batteries is qualified or not. The method specifically comprises the following steps: selecting a plurality of lithium ion batteries with qualified moisture as standard batteries, and establishing a standardized dQ / dV-V curve of the plurality of lithium ion batteries; obtaining a plurality of dQ / dV peak values in a 0.8-1.5 V interval from the curve, and selecting the maximum peak value as a standard peak value; taking the baked lithium ion battery as ato-be-detected battery, and establishing an actual formation dQ / dV-V curve of the lithium ion battery; judging whether the moisture of the to-be-detected battery is qualified or not according to the standard peak value and the dQ / dV peak value in the 0.8-1.5 V interval of the to-be-detected battery: if the dQ / dV peak value of the to-be-detected battery is not greater than the standard peak value, judging that the moisture of the to-be-detected battery is qualified, otherwise, judging that the moisture of the to-be-detected battery is unqualified. According to the method for judging whether the moisture of the baked lithium ion battery is qualified, the battery is fully inspected, whether the moisture of the baked lithium ion battery is qualified or not can be quickly judged, the battery with unqualified moisture is removed, and the quality of the delivered battery is ensured.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion battery water content testing technology, and in particular relates to a method for judging the qualified water content of a baked lithium-ion battery. Background technique [0002] Due to the advantages of high energy density, light weight, no memory effect, green environmental protection and long service life, lithium-ion batteries are widely used in power, energy storage, digital and other fields, and have broad application prospects. In the production process of lithium-ion batteries, moisture is the key process control index. Once the moisture content exceeds the standard, the performance of lithium-ion batteries will be seriously affected, and even the safety performance of batteries will be affected. Moisture control and testing is particularly critical. [0003] Among them, cell baking is an important process for lithium-ion batteries to remove moisture. The value of moisture after ce...

AI Technical Summary

Problems solved by technology

Among them, whether the sampling environment and the moisture test environment are qualified can be realized by monitoring the environmental dew point, but whether the pole piece moisture is representative or not, there is a great risk. In short, the pole piece moisture content is strictly speaking, it cannot represent the oven All the batteries in the battery are all qualified, that is, the single test result cannot represent the overall moisture content of the electrode after the battery is baked, so it can only be judged by the battery cycle performance test in the later stage. It is impossible to wait for the cycle test to be completed before shipping, and batteries with unqualified moisture cannot be completely eliminated

[0004] Chinese patent CN201911119763.7 discloses a method for detecting moisture in lithium-ion battery pole pieces before liquid injection, including preparation operation steps, measurement operation steps, and post-processing operation steps. In the measurement operation step, a baked battery is taken out Disassemble in the glove box, and measure the moisture content of the positive and negative electrodes and diaphragm. If one fails, it will be re-dried, and then tested until the moisture is qualified. Therefore, it may be necessary to repeat the test many times and collect a large amount of moisture test data. The test process cycle Too long, low efficiency, and a single test result may not represent the overall moisture content of the battery after baking and the moisture content of other batteries in the same oven, and the accuracy is low

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