Method for measuring alternating current impedance of failed battery

Abstract

The invention provides a method for testing the alternating current impedance of a failed battery, which comprises the following steps of: S1, disassembling the failed battery to be analyzed, separating a positive plate, a negative plate and a diaphragm, and preventing the treated positive plate and negative plate from being contacted for later use; S2, assembling a lithium sheet and the positive plate and the negative plate which are treated in the step S1 into three electrodes; and S3, respectively testing AC impedance spectrums of the positive electrode pair lithium sheet, the negative electrode pair lithium sheet and the positive electrode pair negative electrode. The method for testing the alternating current impedance of the failed battery can accurately and effectively test the alternating current impedance spectrums of the positive electrode to the lithium, the negative electrode to the lithium and the positive electrode to the negative electrode of the failed battery, is used for analyzing the impedance of the positive electrode and the negative electrode of the failed battery and helps to determine the failure position. According to the invention, different positions of the pole sheets and alternating-current impedance spectroscopy of the battery cell in different states can be selected to be tested, so powerful and accurate data support is provided for the internal resistance analysis of the failed battery.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, in particular to a method for measuring the AC impedance of a failed battery. Background technique [0002] The existing technical solutions are generally divided into three types. The first one is to obtain the corresponding electrical signal feedback in the frequency domain by applying sine wave AC signals with a certain amplitude and different frequencies to the failed battery, and obtain the corresponding electrical signal feedback from the test results. The kinetic parameters of lithium ions during the deintercalation process of positive and negative electrode materials, such as ohmic resistance, charge transfer resistance, electronic resistance, diffusion resistance and SEI film resistance, etc. The second is to disassemble the failed batteries, clean, wipe and cut the positive and negative electrodes respectively, and then assemble button batteries (such as LIR2032), by apply...

AI Technical Summary

Problems solved by technology

[0003] When performing failure analysis on a failed battery, it is necessary to determine the increase in the impedance of the positive and negative electrodes to determine the cause of the failure of the positive and negative electrodes. By performing an AC impedance test on the failed battery, only the AC impedance spectrum of the failed battery can be obtained, and the dynamic parameters of the positive and negative electrodes cannot be determined. Analysis cannot help to determine the specific failure location of the failed battery, and thus cannot determine the cause of failure

For the method of assembling positive and negative pole pieces after dismantling the failed batteries, the operation steps are cumbersome and troublesome. The surface condition of the pole pieces of the failed batteries is generally poor. Relatively fine steps, a slight operation error, battery assembly failure, in short, the assembly test of the buckle battery is greatly disturbed by external factors, and the success rate of production is low

When reassembling a three-electrode battery for a failed battery, the appearance and internal structure of the failed battery are often not good, such as flatulence, lithium precipitation, and dry electrolyte, etc. In this state, the battery is then disassembled and assembled with lithium sheets with higher activity The three-electrode operation is difficult, and the whole process is relatively dangerous; in addition, due to the relatively low potential of the negative electrode and assembly problems, it is difficult to obtain valid data for the negative AC impedance of the battery three-electrode test

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