CN-121978542-A - Semi-solid lithium battery safety test method

CN121978542ACN 121978542 ACN121978542 ACN 121978542ACN-121978542-A

Abstract

The invention particularly relates to a semi-solid lithium battery safety test method, which relates to the technical field of lithium battery safety test and comprises the steps of collecting sufficient baseline capacitance data in a standard environment and a battery state matched with the test, calculating a capacitance average value and a standard deviation, and storing qualified baseline parameters after the validity verification is completed. According to the invention, a main loop, a signal injection branch and a signal acquisition branch integrated high-frequency test circuit are adopted, orthogonal demodulation and real-time equivalent capacitance calculation are matched, the measurement precision and in-situ characterization capability of the lithium battery safety test are obviously improved, the interference problem of charge and discharge direct current and environmental noise on high-frequency signals in the traditional test is solved by isolating direct current components through AC coupling and shielding wiring, the microstructure changes of electrode distance, electrolyte dielectric state, interface contact and the like in the battery core can be captured in real time by means of optimal frequency band injection and high-speed acquisition demodulation, and the defect that the traditional test can only monitor macroscopic parameters such as voltage, temperature, external force and the like is overcome.

Inventors

ZHOU ZHONGSHENG
ZHOU YONG
TANG WENMING

Assignees

云南领沃电子科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260324

Claims (10)

1. The semi-solid lithium battery safety test method is characterized by comprising the following steps of: Setting up an integrated high-frequency injection test circuit comprising a main loop, a signal injection branch and a signal acquisition branch, and performing debugging and calibration after device selection, connection and parameter setting are completed; Preprocessing the collected high-frequency alternating-current voltage response signals, decomposing in-phase and quadrature components, and calculating a real-time equivalent capacitance value; Collecting sufficient baseline capacitance data under a standard environment and a battery state matched with a test, calculating a capacitance average value and a standard deviation, and storing qualified baseline parameters after the validity verification is completed; Preparing equipment and parameters of an extrusion/needling mechanical abuse test according to a standard, fixing a battery, synchronously executing the test and dynamically monitoring an equivalent capacitor, and completing early warning, alarming and failure three-stage state judgment according to a related parameter threshold value of the capacitor; and (3) performing time stamp synchronous alignment, screening complementation and classified storage on various data acquired by the test, performing correlation analysis of capacitance and mechanical parameters, extracting critical deformation points and repeatedly verifying, and outputting a test result.
2. The method for testing the safety of the semi-solid lithium battery according to claim 1, wherein an integrated high-frequency injection testing circuit comprising a main loop, a signal injection branch and a signal acquisition branch is built, and debugging and calibration are carried out after device selection, connection and parameter setting are completed, and the method specifically comprises the following steps: The test circuit integrally comprises three parts, namely a main loop, a signal injection branch and a signal acquisition branch, wherein the branches are mutually independent and noninterfere, and are connected with a tested semi-solid battery through a shared interface; The main loop provides a conventional charge and discharge environment for the tested semi-solid battery or maintains the open state of the battery, and simulates the actual working scene of the battery; The signal injection branch injects a stable single-frequency high-frequency sine wave current signal to the anode and the cathode of the tested semi-solid battery to be used as an excitation signal for capacitance monitoring, and the frequency and the amplitude of the high-frequency sine wave current signal are set according to preset requirements.
3. The method for testing the safety of the semi-solid lithium battery according to claim 2, further comprising: The signal acquisition branch circuit acquires high-frequency alternating-current voltage response signals at two ends of the tested semi-solid battery With injected high-frequency current signals Corresponding to the above; After the circuit is constructed, debugging and calibration are carried out, including no-load debugging, load calibration and linkage debugging.
4. The method for testing the safety of the semi-solid lithium battery according to claim 1, wherein the method for testing the safety of the semi-solid lithium battery is characterized by preprocessing the collected high-frequency alternating voltage response signals, decomposing in-phase and quadrature components, and calculating real-time equivalent capacitance values, and specifically comprises the following steps: Filtering the acquired voltage signal by adopting a high-pass filtering algorithm to remove direct current components in the signal, and only retaining high-frequency alternating current components; smoothing the voltage signal after removing the direct current component by adopting a moving average filtering algorithm; The voltage signal after pretreatment With injected high-frequency current signals Performing time axis synchronous alignment; generating two reference signals, respectively in-phase reference signals And orthogonal reference signals Wherein , For injecting the frequency of the high frequency signal; frequency, amplitude and injection current signal of reference signal Consistent, only phase is different; The voltage signal after pretreatment Wherein For the amplitude of the voltage signal, Is the phase difference between the voltage signal and the injection current signal and is respectively equal to the in-phase reference signal Orthogonal reference signals Mixing to obtain two mixed signals, namely in-phase mixed signals Quadrature mixing signal ; And respectively carrying out low-pass filtering treatment on the two mixing signals, removing high-frequency harmonic components, and extracting low-frequency direct current components, namely the amplitudes of the in-phase components and the quadrature components.
5. The method for testing the safety of the semi-solid lithium battery according to claim 4, further comprising the steps of calculating the equivalent capacitance in real time: reactance of capacitance according to ohm's law Equal to the voltage of the quadrature component And injecting alternating current Is a ratio of (2); Capacitive reactance And equivalent capacitance The relation of (2) is that (Negative sign indicates that the capacitive reactance is opposite to the phase of the inductance), the formula is deformed, and the calculation formula for obtaining the real-time equivalent capacitance is as follows: ; Wherein, the For injecting the frequency of the high frequency signal.
6. The method for testing the safety of the semi-solid lithium battery according to claim 1, wherein sufficient baseline capacitance data are collected in a standard environment and a battery state matched with the test, a capacitance average value and a standard deviation are calculated, and baseline parameters which are qualified in storage after the validity verification are completed, specifically comprising the following steps: The baseline acquisition environmental condition control comprises the steps of testing the environmental temperature, humidity, no electromagnetic interference and no vibration; the battery state maintains the working state of the main loop, and ensures that the electrochemical state of the battery is consistent with the test state; The baseline acquisition time length meets the preset time length requirement, ensures that enough capacitance data are acquired, and can accurately reflect the fluctuation range of background noise.
7. The method for testing the safety of a semi-solid lithium battery according to claim 6, further comprising: after the baseline data is acquired, the real-time equivalent capacitance value during the baseline period Statistical analysis is carried out to calculate the average value of capacitance And standard deviation ; After the calculation of the baseline parameters is completed, verifying the effectiveness of the baseline, ensuring that the baseline can accurately reflect the initial stable state of the battery, and avoiding the follow-up monitoring misjudgment caused by invalid baselines, wherein the specific verification method comprises fluctuation amplitude verification, trend verification and repeatability verification; The validated baseline parameters are stored in a computer as threshold settings.
8. The method for testing the safety of the semi-solid lithium battery according to claim 1, wherein the method is characterized in that equipment and parameters of an extrusion/needling mechanical abuse test are prepared according to the standard, the battery is fixed, the test and equivalent capacitance dynamic monitoring are synchronously executed, and early warning, alarming and failure three-stage state judgment are completed according to a capacitance related parameter threshold value, and the method specifically comprises the following steps: The mechanical abuse test is an extrusion test or a needling test, wherein the termination conditions of the extrusion test are two, and the test can be terminated after any condition is met, and the mechanical abuse test comprises short circuit of a tested battery; In the extrusion process, extrusion force and extrusion displacement data are acquired in real time; Early warning stage decision logic, simultaneously satisfying: condition one is the real-time capacitance change rate , Setting a baseline parameter for the deformation threshold; condition two, terminal voltage across battery Remain unchanged; Deformation threshold Is set by the following steps: wherein As a standard deviation of the baseline, the standard deviation, A period is calculated for the capacitance.
9. The method for testing the safety of the semi-solid lithium battery according to claim 1, further comprising: alarm stage decision logic: any one of the following conditions is satisfied: Condition one, real-time capacitive second derivative , Setting a baseline parameter for an interface destruction threshold; second condition is equivalent capacitance value And the rate of change of capacitance Continuously greater than ; Threshold of interface destruction Is set by the following steps: ; Failure phase decision logic: any one of the following conditions is satisfied: Condition one is real-time equivalent capacitance value ; Second condition, battery terminal voltage The descending amplitude is larger than a preset allowable threshold value within a preset duration, and continuously descends until the difference value between the descending amplitude and 0V is smaller than the preset threshold value, and the short circuit failure is judged by combining the fact that the capacitance value change difference value within the preset duration is larger than the preset threshold value.
10. The method for testing the safety of the semi-solid lithium battery according to claim 1, wherein the method is characterized in that various data acquired by testing are subjected to time stamping synchronous alignment, screening completion and classified storage, correlation analysis of capacitance and mechanical parameters, critical deformation point extraction and repeatability verification are carried out, and a test result containing complete information is finally output, and the method specifically comprises the following steps: the data are synchronously aligned, and then the aligned and screened data sets are classified and stored according to baseline data, early warning stage data, alarm stage data and failure stage data, and meanwhile a data index table is generated and the time range and key data nodes of each stage are marked; Based on the data set after synchronous alignment, the association relation between the equivalent capacitance change and the mechanical acting force and displacement is analyzed, and the validity is verified, and the method specifically comprises association analysis of capacitance and mechanical parameters, critical deformation point extraction and repeatability verification analysis; after the data association analysis is completed, outputting a formal test report, wherein the report comprises test basic information, baseline parameters, a data abstract of the whole test process and association analysis results; and evaluating the mechanical safety grade of the tested semi-solid battery based on the test result.

Description

Semi-solid lithium battery safety test method Technical Field The invention relates to the technical field of safety test of lithium batteries, in particular to a semi-solid state lithium battery safety test method. Background The semi-solid lithium battery has the advantages of friendly interface contact of the liquid lithium battery and high safety of the solid lithium battery, and is an important development direction of new energy power batteries. However, the internal part of the interface between the liquid electrolyte and the solid-liquid composite is still at risk of internal short circuit and thermal runaway under mechanical abuse such as extrusion, needling and the like, and an accurate safety test method capable of early warning is needed. The existing semi-solid lithium battery safety test is mainly based on the traditional liquid battery standard, depends on parameter monitoring such as terminal voltage, temperature, extrusion force/displacement and the like, can only trigger an alarm after short circuit and thermal runaway occur, cannot realize the grading early judgment of physical deformation, interface damage and short circuit failure, and meanwhile, the semi-solid electrolyte has rheological property, and the traditional direct current parameter is difficult to reflect the internal dielectric state and microstructure change of the semi-solid electrolyte. The high-frequency signal injection method can reflect the tiny changes of the internal polar distance, the dielectric constant of electrolyte and the interface contact state through the equivalent capacitance of the battery, and is suitable for the structural characteristics of the semi-solid battery. However, the prior art has the following defects: The main loop, the signal injection and the signal acquisition integrated anti-interference circuit are not constructed, and the high-frequency signal is easily influenced by the charge-discharge direct current component and the electromagnetic interference; lack of dynamic baseline calibration and validity verification for adapting to rheological characteristics of semi-solid batteries, and background noise is easy to cause erroneous judgment; The grading threshold judgment logic of the capacitance change rate/second derivative is not established, and the accurate distinction of early warning, alarming and failure three stages cannot be realized; the signal processing real-time performance is poor, the mechanical parameters and the dynamic changes of the capacitor cannot be synchronously related, and the test data integrity and traceability are insufficient. Therefore, a method for testing the safety of a semi-solid lithium battery is proposed to address the above-mentioned problems. Disclosure of Invention The invention aims to solve the problems and provides a semi-solid lithium battery safety test method. In order to achieve the above purpose, the present invention adopts the following technical scheme: a semi-solid lithium battery safety test method comprises the following steps: Setting up an integrated high-frequency injection test circuit comprising a main loop, a signal injection branch and a signal acquisition branch, and performing debugging and calibration after device selection, connection and parameter setting are completed; Preprocessing the collected high-frequency alternating-current voltage response signals, decomposing in-phase and quadrature components, and calculating a real-time equivalent capacitance value; Collecting sufficient baseline capacitance data under a standard environment and a battery state matched with a test, calculating a capacitance average value and a standard deviation, and storing qualified baseline parameters after the validity verification is completed; Preparing equipment and parameters of an extrusion/needling mechanical abuse test according to a standard, fixing a battery, synchronously executing the test and dynamically monitoring an equivalent capacitor, and completing early warning, alarming and failure three-stage state judgment according to a related parameter threshold value of the capacitor; and (3) performing time stamp synchronous alignment, screening complementation and classified storage on various data acquired by the test, performing correlation analysis of capacitance and mechanical parameters, extracting critical deformation points and repeatedly verifying, and outputting a test result. Preferably, the building of the integrated high-frequency injection test circuit including a main loop, a signal injection branch and a signal acquisition branch, after device selection, connection and parameter setting are completed, debugging and calibration are performed, and the method specifically comprises the following steps: The test circuit integrally comprises three parts, namely a main loop, a signal injection branch and a signal acquisition branch, wherein the branches are mutually independent and noninterfere, and are connected with a t