CN-122017624-A - Lithium ion battery lithium separation judging method based on characteristic frequency disturbance and impedance response

CN122017624ACN 122017624 ACN122017624 ACN 122017624ACN-122017624-A

Abstract

The invention relates to the technical field of safety detection and state monitoring of lithium ion batteries, in particular to a lithium ion battery lithium analysis judging method based on characteristic frequency disturbance and impedance response. The method comprises the steps of placing a lithium ion battery to be tested in an incubator for standing, starting a conventional charge-discharge process, synchronously applying characteristic single-frequency sinusoidal alternating current signals in the conventional charge-discharge process to develop a single-frequency impedance test, collecting impedance real part parameters in the single-frequency impedance test according to set intervals, drawing an SOC (state of charge) relation diagram of an impedance real part value and a charge state of charge according to the impedance real part parameters, and identifying abrupt inflection points of the impedance real part in the SOC relation diagram to finish lithium analysis judgment of the battery. Therefore, the lithium ion battery cell provided by the invention is simple in equipment, the battery is not required to be disassembled, the lithium analysis boundary of the battery cell under different working conditions is drawn in a mode of accurately identifying the lithium analysis starting point through the dynamic response of the characteristic frequency, and the lithium ion battery cell can be suitable for the lithium ion battery cell under different working conditions.

Inventors

YAN JIAQI
ZHENG HAIYU
Lei boyi
YU HUACHAO
PAN QINGRUI
YANG CHANGJUN

Assignees

深圳市华美兴泰科技股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260203

Claims (10)

1. The lithium ion battery lithium analysis judging method based on characteristic frequency disturbance and impedance response is characterized by comprising the following steps of: Step S1, placing a lithium ion battery to be tested in an incubator for standing, and starting a conventional charging and discharging process; step S2, synchronously applying characteristic single-frequency sinusoidal alternating current signals in a conventional charge-discharge process, and carrying out single-frequency impedance test; S3, acquiring impedance real part parameters in single-frequency impedance test according to set intervals; s4, drawing an SOC relation diagram of the real impedance value and the charge and discharge states according to the real impedance parameter; S5, identifying abrupt inflection points of the real part of the impedance in the SOC relation diagram, and finishing the lithium precipitation judgment of the battery; and S6, adjusting the temperature of the incubator and the charging rate of the battery, sequentially executing the steps S1 to S5, and drawing a lithium-precipitation boundary Mapping graph of the battery based on the lithium-precipitation judgment results under all working conditions.
2. The lithium ion battery lithium analysis judging method based on characteristic frequency disturbance and impedance response according to claim 1 is characterized in that the lithium ion battery to be detected in the step S1 is specifically a lithium ion battery composed of lithium iron phosphate, ternary material, lithium-rich manganese-based positive electrode material, graphite and silicon-based negative electrode material.
3. The lithium ion battery lithium-ion battery analysis judging method based on characteristic frequency disturbance and impedance response according to claim 1, wherein in the step S1, the time for placing the lithium ion battery to be tested in an incubator is not less than 4 hours, the whole temperature of a battery core is kept consistent with the set temperature of the incubator in the standing process, and the conventional charge-discharge voltage range of a lithium iron phosphate soft-package battery core of the lithium ion battery to be tested is set to 2.5-3.65V.
4. The lithium ion battery lithium-ion battery analysis determination method based on characteristic frequency disturbance and impedance response according to claim 1, wherein the step S2 of synchronously applying the characteristic single-frequency sinusoidal alternating current signal in the conventional charge and discharge process comprises: Carrying out wide-band impedance spectrum test on lithium ion battery cells of different anode and cathode material systems, screening out turning point frequencies of transfer impedance and diffusion impedance as characteristic single frequency, and limiting the value range of the characteristic single frequency to 0.1-3Hz; 1Hz is selected as a fixed characteristic single frequency, and a sinusoidal alternating current signal with the fixed characteristic single frequency is continuously and synchronously applied in the conventional charge and discharge process of the lithium ion battery.
5. The lithium ion battery analysis determination method based on characteristic frequency disturbance and impedance response according to claim 1, wherein the developing of the single frequency impedance test in step S2 includes: before a characteristic single-frequency sinusoidal alternating current signal is applied, measuring the internal resistance of a battery core of the lithium ion battery to be measured; determining the amplitude of a sinusoidal alternating current signal according to the internal resistance of the battery cell, and converting the amplitude into a voltage excitation signal to be no more than 10mV; And (3) fixedly setting the disturbance current of the sinusoidal alternating current signal to be 100mA, synchronously acquiring impedance data of the battery according to the sinusoidal alternating current signal, and performing the acquisition process and the charging and discharging process in parallel to form a continuous single-frequency impedance test data stream.
6. The lithium ion battery lithium analysis judging method based on characteristic frequency disturbance and impedance response according to claim 1 is characterized in that in the step S3, the real part impedance parameters in the single-frequency impedance test are collected according to a set interval, wherein the set collection interval is adjusted according to the performance of test equipment and actual test requirements, and the collection interval range is 1-5S.
7. The lithium ion battery lithium analysis judging method based on characteristic frequency disturbance and impedance response according to claim 1 is characterized in that in the step S4, an SOC relation diagram of an impedance real part value and a charge-discharge charge state is drawn according to an impedance real part parameter, namely corresponding data of charge-discharge time and the impedance real part value are synchronously recorded in the drawing process, and a multidimensional data correlation diagram is formed.
8. The lithium ion battery lithium analysis judging method based on characteristic frequency disturbance and impedance response according to claim 1, wherein the identifying of the abrupt inflection point of the real part of the impedance in the SOC relation diagram in step S5 is specifically: the real part of the impedance consists of an ohmic impedance R0, a membrane impedance Rsei and a charge transfer impedance Rct; When lithium precipitation occurs at the negative electrode of the battery, the charge transfer impedance Rct is reduced, and the real part of the impedance presents a sudden change inflection point which corresponds to the starting point of the lithium precipitation reaction.
9. The lithium ion battery lithium-ion battery analysis determination method based on characteristic frequency disturbance and impedance response according to claim 1, wherein the adjusting of the temperature of the incubator and the battery charging rate in step S6 is specifically: the temperature of the temperature-adjusting box is at least 10 ℃ below zero, 0 ℃ below zero, 10 ℃ below zero and 15 ℃ below zero; the adjusted charging rate at least covers 0.3C, 0.5C, 0.7C, 1C and 1.5C; All combined working conditions of the temperature of the incubator and the charging rate execute the operations from the step S1 to the step S5.
10. The lithium ion battery lithium analysis judging method based on characteristic frequency disturbance and impedance response is characterized in that the equipment used in the testing process of the steps S1 to S5 comprises an electrochemical workstation, a charging and discharging equipment and an incubator, wherein the electrochemical workstation is used for applying sinusoidal alternating current signals and collecting impedance data, the charging and discharging equipment is used for executing a conventional charging and discharging process, the incubator is used for regulating and controlling the testing environment temperature, under a single temperature condition, when testing is carried out by adopting four multiplying factors of 0.3C, 0.5C, 1C and 1.5C, the single-channel testing duration is not more than 7h, and when the double-channel parallel testing is adopted, the testing duration is controlled within 3.5 h.

Description

Lithium ion battery lithium separation judging method based on characteristic frequency disturbance and impedance response Technical Field The invention relates to the technical field of safety detection and state monitoring of lithium ion batteries, in particular to a lithium ion battery lithium analysis judging method based on characteristic frequency disturbance and impedance response. Background The lithium ion battery can seriously influence the safety, the cycle life and the electrochemical performance of the battery due to the lithium precipitation phenomenon in the charge and discharge process, so that the lithium precipitation starting point is accurately identified, and the lithium precipitation boundary diagrams under different working conditions are drawn, which is a key requirement in the fields of safety detection and state monitoring of the lithium ion battery. In the prior art, CN120522584a proposes a method for in-situ detection of sweep frequency impedance under dynamic conditions, and a lithium-ion separation signal is obtained by applying a sinusoidal ac signal with a certain frequency range to a cell in the charge-discharge process and by means of an impedance test. However, the method adopts a sweep frequency mode, and the full-band scanning needs to be completed for a long time in a dynamic charge-discharge scene, so that the method is difficult to adapt to the rapid detection requirement in the actual working condition, and the starting point of the lithium precipitation reaction cannot be captured in time due to the long test period, so that the hysteresis of the lithium precipitation identification exists. In another prior art CN114578243a, the limiting current of the battery Map is measured by a pulse mode, but the performance boundary evaluation under a part of working conditions can be realized, but the method is not focused on the accurate identification of the lithium precipitation starting point, and cannot systematically cover the full working interval formed by temperature, multiplying power and state of charge (SOC), so that a complete lithium precipitation boundary Map is difficult to form. In conclusion, the prior art has the technical defects of insufficient lithium-precipitation starting point identification precision, low test efficiency, incapability of fully covering multiple working conditions to draw a complete lithium-precipitation boundary diagram and the like under dynamic working conditions, the core requirements of rapid, accurate and comprehensive monitoring on the lithium ion battery lithium-separating state in engineering application are not solved. Disclosure of Invention Based on this, it is necessary to provide a lithium ion battery lithium analysis determination method based on characteristic frequency disturbance and impedance response, so as to solve at least one of the above technical problems. In order to achieve the above object, a lithium ion battery lithium analysis judging method based on characteristic frequency disturbance and impedance response comprises the following steps: Step S1, placing a lithium ion battery to be tested in an incubator for standing, and starting a conventional charging and discharging process; step S2, synchronously applying characteristic single-frequency sinusoidal alternating current signals in a conventional charge-discharge process, and carrying out single-frequency impedance test; S3, acquiring impedance real part parameters in single-frequency impedance test according to set intervals; s4, drawing an SOC relation diagram of the real impedance value and the charge and discharge states according to the real impedance parameter; S5, identifying abrupt inflection points of the real part of the impedance in the SOC relation diagram, and finishing the lithium precipitation judgment of the battery; and S6, adjusting the temperature of the incubator and the charging rate of the battery, sequentially executing the steps S1 to S5, and drawing a lithium-precipitation boundary Mapping graph of the battery based on the lithium-precipitation judgment results under all working conditions. The invention has the beneficial effects that the electrochemical device can be realized by simple equipment configuration only by an electrochemical workstation, a charging and discharging device and an incubator, and a complex device is not needed. The battery is not required to be disassembled in the testing process, so that a large amount of battery core loss and resource waste are avoided, and the testing cost is reduced. And the fixed characteristic frequency of 1Hz is selected within the range of 0.1-3Hz, and the lithium precipitation starting point can be accurately identified by combining with accurate parameter control, so that the judgment accuracy is high. The battery core can be suitable for various anode and cathode material system battery cores such as lithium iron phosphate, ternary materials and the like, and can cover the wo