Ternary lithium battery stability analysis method, device, equipment, medium and product

Abstract

The invention discloses a ternary lithium battery stability analysis method, device and equipment, a medium and a product, and relates to the field of lithium battery stability analysis, and the method comprises the following steps: storing a ternary lithium battery in-situ electrochemical cell within a preset time period and at a preset temperature; in the storage process, circuit parameters and the concentration of each gas are obtained in real time, and the interface resistance value is obtained at an interval preset sampling frequency; obtaining the content of each component in the positive pole piece and the negative pole piece after storage; performing principal component analysis on the acquired circuit parameters, the concentration of each gas, the interface resistance value and the content of each component in the pole piece to obtain parameters remarkably related to the stability degradation of the ternary lithium battery; according to the obtained values of the parameters significantly related to the stability degradation of the ternary lithium battery, the stability degradation time period is determined, and the stability analysis efficiency can be improved.

Description

Technical Field

[0001] This application relates to the field of lithium battery stability analysis, and in particular to a method, apparatus, equipment, medium, and product for stability analysis of ternary lithium batteries. Background Technology

[0002] Ternary lithium batteries are widely used in new energy vehicles, low-altitude aircraft, and other fields due to their high energy density and high power density. However, when ternary lithium batteries are used or stored in high-temperature environments, they are prone to problems such as interface degradation, electrolyte decomposition and gas generation, and electrode component loss, which seriously affect the battery's storage life and safety. Therefore, accurately capturing the changes in interface dynamics (interfacial resistance), gas generation evolution, and electrode component degradation characteristics of ternary lithium batteries during high-temperature service and storage is of great significance for optimizing battery material systems, improving battery structural design, and enhancing battery high-temperature storage performance.

[0003] In related technologies, stability analysis of ternary lithium batteries during high-temperature storage often employs a single testing method, such as studying interfacial resistance changes solely through electrochemical impedance spectroscopy (EIS) or studying gas generation behavior solely through differential electrochemical mass spectrometry (DEMS), resulting in low efficiency of stability analysis. Summary of the Invention

[0004] The purpose of this application is to provide a method, apparatus, equipment, medium, and product for stability analysis of ternary lithium batteries, which can improve the efficiency of stability analysis.

[0005] To achieve the above objectives, this application provides the following solution: In a first aspect, this application provides a method for analyzing the stability of ternary lithium batteries, including: storing the ternary lithium battery in-situ electrochemical cell within a preset time period and at a preset temperature.

[0006] During storage, the circuit parameters of the in-situ electrochemical cell of the ternary lithium battery and the concentrations of various gases generated by the in-situ electrochemical cell are acquired in real time, and the interface resistance of the in-situ electrochemical cell is acquired at preset sampling frequencies. The circuit parameters are open-circuit voltage or discharge capacity.

[0007] The content of each component in the positive and negative electrode plates of the ternary lithium battery in situ electrochemical cell was obtained after storage.

[0008] Principal component analysis was performed on the obtained circuit parameters of the ternary lithium battery in-situ electrochemical cell, the concentration of each gas generated by the ternary lithium battery in-situ electrochemical cell, the interfacial resistance of the ternary lithium battery in-situ electrochemical cell, and the content of each component in the positive and negative electrode plates of the ternary lithium battery in-situ electrochemical cell to obtain parameters that are significantly related to the stability degradation of the ternary lithium battery.

[0009] Based on the values ​​of parameters that are significantly related to the stability degradation of ternary lithium batteries, the time period of stability degradation of the in-situ electrochemical cell of ternary lithium batteries is determined.

[0010] Secondly, this application provides a ternary lithium battery stability analysis device, including: a storage module for storing the in-situ electrochemical cell of the ternary lithium battery within a preset time period and at a preset temperature.

[0011] The first acquisition module is used to acquire, in real time during the storage process, the circuit parameters of the ternary lithium battery in-situ electrochemical cell and the concentrations of various gases generated by the ternary lithium battery in-situ electrochemical cell, and to acquire the interface resistance of the ternary lithium battery in-situ electrochemical cell at preset sampling frequencies. The circuit parameters are open-circuit voltage or discharge capacity.

[0012] The second acquisition module is used to acquire the content of each component in the positive electrode and negative electrode in the in-situ electrochemical cell of the ternary lithium battery after storage.

[0013] The principal component analysis module is used to perform principal component analysis on the obtained circuit parameters of the ternary lithium battery in-situ electrochemical cell, the concentration of each gas generated by the ternary lithium battery in-situ electrochemical cell, the interfacial resistance of the ternary lithium battery in-situ electrochemical cell, and the content of each component in the positive and negative electrode plates of the ternary lithium battery in-situ electrochemical cell, to obtain parameters that are significantly related to the stability degradation of the ternary lithium battery.

[0014] The stability analysis module is used to determine the time period of stability degradation of the in-situ electrochemical cell of ternary lithium battery based on the values ​​of parameters that are significantly related to the stability degradation of ternary lithium battery.

[0015] Thirdly, this application provides a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-described ternary lithium battery stability analysis method.

[0016] Fourthly, this application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the aforementioned ternary lithium battery stability analysis method.

[0017] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the aforementioned ternary lithium battery stability analysis method.

[0018] According to the specific embodiments provided in this application, this application has the following technical effects: This application provides a method, apparatus, equipment, medium, and product for stability analysis of ternary lithium batteries. In related technical solutions, it is difficult to achieve correlation analysis between interface dynamics, gas generation process, and component degradation in the stability analysis of ternary lithium batteries during high-temperature storage, resulting in low efficiency of stability analysis. This application performs principal component analysis on circuit parameters, the concentration of various gases generated in the in-situ electrochemical cell of the ternary lithium battery, the interfacial resistance, and the content of various components in the electrode to obtain parameters that are significantly related to the stability degradation of the ternary lithium battery. Based on the values ​​of the parameters that are significantly related to the stability degradation of the ternary lithium battery, the time period of stability degradation of the in-situ electrochemical cell of the ternary lithium battery is determined, thereby achieving correlation analysis between interface dynamics, gas generation process, and component degradation, and improving the efficiency of stability analysis. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart illustrating a method for analyzing the stability of a ternary lithium battery, as provided in an embodiment of this application.

[0021] Figure 2 This is a schematic diagram of in-situ electrochemical cell and differential chemical mass spectrometry testing.

[0022] Figure 3 This is a schematic diagram of the functional modules of a ternary lithium battery stability analysis device provided in an embodiment of this application.

[0023] Figure 4 This is a schematic diagram of the structure of a computer device provided in an embodiment of this application.

[0024] Figure 5 For R during the loop s R SEI R w Correlation loadings of CO2, CH4 and H2.

[0025] Figure 6 For R during the loop s R SEI Rw Principal component plot of CO2, CH4 and H2 versus discharge capacity.

[0026] Figure 7 For NMC811 system batteries during cycling, R s R SEI R w Scoring graph of CO2, CH4 and H2 with discharge capacity.

[0027] Figure 8 For NMC811 system batteries during cycling, R s R SEI R w Projection diagrams of CO2, CH4 and H2 with discharge capacity, where (a) is the projection diagram in the PC1-PC2 plane, (b) is the projection diagram in the PC1-PC3 plane, and (c) is the projection diagram in the PC2-PC3 plane.

[0028] Figure 9 For R in the 10th, 15th, 30th and 45th laps of the cycle. s R SEI R w Correlation loadings of CO2, CH4 and H2.

[0029] Figure 10 This is a graph showing the open-circuit voltage of the battery during storage at 60℃.

[0030] Figure 11 This is a graph showing the CO2 concentration during storage at 60℃.

[0031] Figure 12 This is a graph showing the CH4 concentration during storage at 60℃.

[0032] Figure 13 The graph shows the ToF-SIMS concentration curves during storage at 60℃; where (a) shows the initial sample of the battery cathode and the sample after storage at 60℃. Content change curves, (b) show the initial sample of the battery cathode and the sample after storage at 60℃. Content change curves, (c) show the initial sample of the battery cathode and the sample after storage at 60℃. Content change curves, (d) show the initial sample and the content change curve after storage at 60℃ for the battery cathode. Content change curves, (e) show the initial sample of the battery cathode and the sample after storage at 60℃. Content change curves, (f) show the initial sample of the battery cathode and the sample after storage at 60℃. Content change curves, (g) represent the initial sample of the battery negative electrode and the sample after storage at 60℃. Content change curves, (h) represent the initial sample of the battery negative electrode and the sample after storage at 60℃. Content change curves, (i) showing the initial sample and the sample after storage at 60℃ for the battery negative electrode. Content change curves, (j) show the initial sample and the sample after storage at 60℃ for the battery negative electrode. Content change curves, (k) represent the initial sample and the content change curves after storage at 60℃ for the battery negative electrode. Content change curves, (l) are the organic oxygen content change curves of the initial sample of the battery negative electrode and after storage at 60℃.

[0033] Figure 14 The graphs show the correlation between substances and gases and open-circuit voltage. (a) shows the correlation between open-circuit voltage, CO2 concentration, CH4 concentration, and component content. (b) shows the representative correlation values ​​of open-circuit voltage, CO2 concentration, CH4 concentration, and component content marked in (a).

[0034] Reference numerals: 1-Top cover; 2-Cavity; 3-Base; 4-Positive electrode; 5-Negative electrode; 6-Carrier gas inlet end of top cover; 7-Carrier gas outlet end of base; 8-Connection interface with temperature control device. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] In one exemplary embodiment, such as Figure 1 As shown, a method for stability analysis of ternary lithium batteries is provided, including: Step 201: storing the ternary lithium battery in-situ electrochemical cell within a preset time period and at a preset temperature.

[0038] Step 202: During the storage process, the circuit parameters of the ternary lithium battery in-situ electrochemical cell and the concentrations of various gases generated by the ternary lithium battery in-situ electrochemical cell are acquired in real time, and the interface resistance of the ternary lithium battery in-situ electrochemical cell is acquired at preset sampling frequencies. The circuit parameters are open-circuit voltage (OCV) or discharge capacity.

[0039] Step 203: Obtain the content of each component in the positive and negative electrode plates of the ternary lithium battery in situ electrochemical cell after storage.

[0040] Step 204: Perform principal component analysis on the obtained circuit parameters of the ternary lithium battery in-situ electrochemical cell, the concentration of each gas generated by the ternary lithium battery in-situ electrochemical cell, the interfacial resistance of the ternary lithium battery in-situ electrochemical cell, and the content of each component in the positive and negative electrode plates of the ternary lithium battery in-situ electrochemical cell to obtain parameters that are significantly related to the stability degradation of the ternary lithium battery.

[0041] Step 205: Based on the values ​​of the parameters that are significantly related to the stability degradation of ternary lithium batteries, determine the time period of stability degradation of the in-situ electrochemical cell of ternary lithium batteries.

[0042] In practical applications, the process before step 201 includes: preparing an in-situ electrochemical cell for a ternary lithium battery. The positive electrode, negative electrode, separator, and electrolyte of the ternary lithium battery are assembled in an in-situ electrochemical cell mold, ensuring that the positive and negative electrodes are aligned and do not have direct contact. The electrochemical cell has good sealing and conductivity, and can adapt to high-temperature storage environments and the gas extraction requirements of differential electrochemical mass spectrometry testing.

[0043] In another exemplary embodiment of this application, the in-situ electrochemical cell of a ternary lithium battery is stored within a preset time period and at a preset temperature, specifically including: storing the in-situ electrochemical cell of a ternary lithium battery using a temperature control device within a preset time period and at a preset temperature.

[0044] In another exemplary embodiment of this application, the circuit parameters of the in-situ electrochemical cell of the ternary lithium battery and the concentration of each gas generated by the in-situ electrochemical cell of the ternary lithium battery are acquired in real time, specifically including: acquiring the circuit parameters of the in-situ electrochemical cell of the ternary lithium battery in real time using an electrochemical workstation.

[0045] The partial pressures of various gases generated in the in-situ electrochemical cell of a ternary lithium battery were obtained in real time using differential electrochemical mass spectrometry.

[0046] The concentration of each gas is determined based on its partial pressure.

[0047] In another exemplary embodiment of this application, the interface resistance of the in-situ electrochemical cell of the ternary lithium battery is obtained at preset sampling frequencies, specifically including: at each preset sampling frequency, an electrochemical impedance spectroscopy test is performed on the in-situ electrochemical cell of the ternary lithium battery using an electrochemical workstation.

[0048] Based on the data obtained from each electrochemical impedance spectroscopy (EIS) test, an equivalent circuit model corresponding to each EIS test is constructed.

[0049] The interfacial resistance of the ternary lithium battery in-situ electrochemical cell corresponding to each electrochemical impedance spectroscopy test is determined based on the equivalent circuit model corresponding to each electrochemical impedance spectroscopy test.

[0050] In practical applications, for any given electrochemical impedance spectroscopy (EIS) test, an equivalent circuit model corresponding to this EIS test is constructed based on the data obtained from the test (the real and imaginary impedances of the in-situ electrochemical cell of a ternary lithium battery at different frequencies). Then, the interface resistance is extracted using ZView software. Specifically, in the circuit model module of ZView software, the constructed equivalent circuit model is selected, and the fitting button is clicked to obtain the fitted data. The fitted data is the interface resistance, which includes: ohmic resistance (R...). s ), charge transfer resistance (R) ct ), interfacial film resistance (R) SEI Solid-phase diffusion resistance (R) w ).

[0051] In practical applications, the base of the prepared ternary lithium battery in-situ electrochemical cell is connected to the fuse of a temperature control device, and a preset temperature is set. Simultaneously, the ternary lithium battery in-situ electrochemical cell is connected to both an electrochemical workstation and a differential electrochemical mass spectrometer (DEMS). A collaborative monitoring program is initiated, allowing the electrochemical workstation to collect real-time circuit parameters of the ternary lithium battery in-situ electrochemical cell, and the DEMS to monitor the types and partial pressures of gases generated within the cell during storage. The DEMS primarily records gases including Ar, H2, CO, CO2, CH4, C2H4, C3H6, and POF3, directly displaying the partial pressures in mbar. The reference electrode and counter electrode of the electrochemical workstation are connected to the negative electrode line of the ternary lithium battery in-situ electrochemical cell, while the working electrode of the electrochemical workstation is connected to the positive electrode line of the ternary lithium battery in-situ electrochemical cell. During this process, the wiring used to record the electrochemical circuit parameters remains unchanged, without affecting the mechanism voltage data of the new equipment; every 3 days, an electrochemical impedance spectroscopy test is performed on the in-situ electrochemical cell of the ternary lithium battery using an electrochemical workstation to obtain the interfacial resistance value of the battery.

[0052] In practical applications, the preset temperature is between 40℃ and 80℃, and the preset time period is 28 to 30 days. The frequency range of the electrochemical impedance spectroscopy test is 10. -2 Hz-10 5 Hz, the test voltage amplitude is 5mV-10mV.

[0053] In another exemplary embodiment of this application, obtaining the content of each component in the positive and negative electrode sheets of the ternary lithium battery in-situ electrochemical cell after storage specifically includes: transferring the ternary lithium battery in-situ electrochemical cell after storage to a glove box filled with inert gas for disassembly to obtain the positive and negative electrode sheets. Specifically, after a preset time period (end of storage), monitoring and heating are stopped, and the ternary lithium battery in-situ electrochemical cell is removed, transferred to a glove box filled with inert gas for disassembly, and the positive and negative electrode sheets are taken out.

[0054] Dimethyl carbonate is used to clean the electrolyte on the surfaces of the positive and negative electrode sheets. Specifically, the removed electrode sheets are cleaned 2-3 times with dimethyl carbonate to remove residual electrolyte from the electrode surface. The cleaning process is as follows: dimethyl carbonate solution is drawn up with a pipette and dripped onto the electrode surface, and the cleaning is repeated 2-3 times.

[0055] The cleaned positive and negative electrode sheets were transferred to a drying oven via a sealed centrifuge tube for drying. Specifically, the cleaned electrode sheets were placed in a sealed centrifuge tube, then removed and placed in a drying oven for drying. The vacuum drying conditions were: drying temperature 80℃, drying time 1 hour.

[0056] The dried positive and negative electrode sheets were sealed and transferred to a time-of-flight secondary ion mass spectrometry (TOF-MS) instrument via a vacuum transfer chamber. Compositional analysis was performed on the dried positive and negative electrode sheets using TOF-MS to determine the content of each component. Specifically, the dried electrode sheets were placed back in a glove box, cut to a specific size, and then placed in a vacuum transfer chamber (approximately 1mm × 1mm). After fixing the sample to the operating stage with plastic tweezers, the sample was gently cleaned of any residue around and on the sample surface using a syringe, and then the sample stage was placed in the vacuum transfer chamber. The chamber was then sealed and transferred to the TOF-MS instrument for compositional analysis to determine the content of each component. The vacuum level of the vacuum transfer chamber was ≤1 Pa to ensure that the electrode sheets did not come into contact with air during the transfer process.

[0057] In another exemplary embodiment of this application, the time period of stability degradation of the in-situ electrochemical cell of the ternary lithium battery is determined based on the values ​​of the parameters that are significantly related to the stability degradation of the ternary lithium battery. Specifically, this includes plotting curves corresponding to the parameters that are significantly related to the stability degradation of the ternary lithium battery at each time point, with time as the abscissa and the values ​​of the parameters that are significantly related to the stability degradation of the ternary lithium battery at each time point as the ordinate.

[0058] The time period of in-situ electrochemical cell stability degradation in ternary lithium batteries is determined by analyzing the curves corresponding to parameters significantly associated with the degradation of ternary lithium battery stability. Specifically, the time period with the most significant change rate of each curve is identified to enable early identification of battery stability decline.

[0059] In practical applications, step 204 specifically involves: First, integrating the acquired circuit parameters, gas concentrations, interfacial resistances, and component contents across multiple dimensions. Then, principal component analysis based on the Pearson correlation coefficient is used for dimensionality reduction. The extraction criteria are set as principal component eigenvalues ​​greater than 1 and cumulative variance contribution exceeding 20%, and the number of principal components is determined using a scree plot. The angles between parameter vectors are observed through the load plot to determine the correlation between parameters: angles less than 90° indicate positive correlation, greater than 90° indicate negative correlation, and equal to 90° indicate no significant correlation. Further analysis of the evolution of data points in the principal component space is performed using the score plot: when only two principal components are retained, the dynamic evolution path of the parameters is analyzed in the two-dimensional plane based on the quadrant distribution of data points over time, combined with the meaning of the coordinate axes; when three or more principal components are retained, the three-dimensional image is projected onto the XY, XZ, and YZ planes respectively, and the two-dimensional analysis logic is used to analyze each projection plane. Finally, ion fragments related to electrolyte decomposition and organic matter decomposition caused by transition metal dissolution were extracted from time-of-flight secondary ion mass spectrometry analysis. These were substituted into the aforementioned system, and Pearson correlation analysis was used again to accurately establish the correlation between gas concentration, component content, interfacial resistance and macroscopic degradation indicators (circuit parameters) of battery performance, thereby determining the parameters that are significantly related to the stability degradation of ternary lithium batteries.

[0060] More specifically, after inputting the gas concentration, interfacial impedance, and discharge capacity data into the principal component analysis module of the Origin data processing software, the results are as follows: Figures 5 to 9 As shown. Figure 5 The first quadrant contains the concentration of CO2 gas, R SEI R ct and R w The results showed that changes in CO2 concentration were significantly positively correlated with the other three variables; that is, the smaller the angle between two vectors in the same quadrant, the stronger the correlation. The CO2 component in principal component 1 (PC1) was close to zero, indicating its weak contribution to PC1. This variable mainly explains the positive variation in principal component 2 (PC2). R SEI R ct and R wThe projection of CH4 in the PC1 direction is far from the origin, indicating that all three factors contribute significantly to both PC1 and PC2. The second quadrant contains only CH4, and the angle between this variable and other variables is close to 90°-180°, indicating a weak correlation between CH4 and CO2, interfacial resistance, and discharge capacity. The projections of CH4 in the PC1 and PC2 directions fall in the negative direction of PC1 and the positive direction of PC2, respectively. The third quadrant contains only discharge capacity, and this variable is related to CO2 and R in the first quadrant. SEI R ct and R w The included angle is approximately 180°, indicating a strong negative correlation between discharge capacity and these variables. H2 and R exist in the fourth quadrant. s Two variables, H2 and R s There is a strong positive correlation between H2 concentration and R, while there is a negative correlation with discharge capacity, indicating that as H2 concentration increases, R... s Increasing the resistance will cause a decrease in discharge capacity, but H2 and R s Its impact on capacity is less than that on CO2 and R SEI R ct and R w The above analysis shows that PC1 is mainly related to battery performance, while PC2 is related to gas type and concentration.

[0061] This method was used to study the levels of CO2, CH4, H2, and R at laps 10, 15, 30, and 45. SEI R ct and R w The change is correlated; one revolution represents one charge and one discharge cycle of the battery. For example... Figure 6 As shown, PC1 (61.8%) was selected to explain the core patterns, PC2 (18.3%) to explain the subdivision differences of variables, and PC3 (11.1%) to reveal the secondary associations. Figure 9 The load diagram results show that R SEI R ct R SEI and R wThe positive correlation in three-dimensional space indicates that the impedance changes in the electrolyte system are synergistic. CO2 shows a strong positive correlation with various impedances, and the variables are all in the same quadrant in the PC1-PC2 and PC1-PC3 planes, indicating that CO2 and impedance increases occur synchronously. CH4 is related to impedance variables in a secondary dimension, mainly originating from the decomposition of DEC or DMC, and has no significant relationship with battery performance. Furthermore, discharge capacity shows a strong negative correlation with impedance changes and CO2 and H2 concentrations, indicating that the core driving factors for discharge capacity decay during high-rate discharge and rapid aging cycles are the overall increase in impedance and the accumulation of CO2 and H2. Based on the above discussion, it is clear that: PC1 is the performance decay axis, with its positive direction representing high impedance, high H2 concentration, and low discharge capacity, and its negative direction representing low impedance, low H2 concentration, and high discharge capacity; secondly, PC2 is the gas generation differentiation axis, with its positive direction representing high CO2 concentration and high CH4 concentration, and its negative direction representing low CO2 concentration, low CH4 concentration, and high discharge capacity. PC3 is the resistance subdivision axis, with its positive direction representing high R... SEI R ct R SEI and R w Direction, negative direction represents low R s R SEI R ct and R w High discharge capacity and high CH4 concentration are the directions.

[0062] The evolution behavior of each battery parameter is as follows Figure 7 and Figure 8 As shown, during cycling, the battery parameter values ​​shift along the positive direction of PC1 and are mainly distributed in the negative direction of PC2 on the PC2 axis, indicating that the battery produces low CO2 and H2 concentrations while maintaining a high discharge capacity. Figure 8 (as shown in part (a)). Figure 8 The evolution of parameters in the PC1-PC3 plane shown in section (b) indicates that the battery's discharge capacity decreases with cycling (shifting in the positive direction of PC1). In the PC3 direction, the battery resistance first decreases and then increases. Initially, the battery exhibits the highest resistance value. In the PC2-PC3 plane, the battery produces less CO2 and H2 during cycling, accompanied by a lower resistance value, thus exhibiting excellent discharge capacity. Figure 8 (as shown in section (c)). Figure 8The first quadrant represents a region with high impedance and high gas concentration, while the third quadrant represents a region with high capacity, low gas concentration, and low impedance. Batteries tend to reside near the third quadrant as cycling progresses, while the other two systems tend to appear more in the first quadrant later in the cycle. When the electrolyte is unstable, it easily decomposes to produce CO2. The SEI film ruptures and thickens during high-rate discharge, leading to increased interfacial impedance. Simultaneously, charge transfer is hindered and ion diffusion is restricted, reducing the electrolyte's ionic conductivity. Additives enable the formation of a dense SEI film on the negative electrode surface, inhibiting electrolyte decomposition, reducing CO2 and H2 concentrations, maintaining low impedance values, and stabilizing capacity.

[0063] This application also provides a more specific embodiment, detailing the above-mentioned method for analyzing the stability of ternary lithium batteries. The specific steps include: S1. Preparing a ternary lithium battery in-situ electrochemical cell: Selecting NCM811 ternary positive electrode sheet, graphite negative electrode sheet, polyethylene separator, and LiPF6 / EC+ dimethyl carbonate electrolyte, assembling them into a button-type in-situ electrochemical cell in the order of "positive electrode sheet - separator - negative electrode sheet," as shown in the diagram. Figure 2 As shown, the system includes a top cover 1, a cavity 2, a base 3, a positive electrode post 4, a negative electrode post 5, a carrier gas inlet end 6 on the top cover, a carrier gas outlet end 7 on the base, and a connection interface 8 for a temperature control device. The cavity 2 is the gas generation area. After installation, it is necessary to ensure that the electrochemical cell is well-sealed, and that the reserved gas inlet channel (top cover carrier gas inlet end 6) and outlet channel (base carrier gas outlet end 7) are connected to the DEMS.

[0064] S2. High-Temperature Storage and Collaborative Monitoring: The in-situ electrochemical cell and temperature control device are connected via interface 8. The temperature control device is set to maintain a storage temperature of 60°C for 5 days. Simultaneously, the positive electrode 4 and negative electrode 5 of the in-situ electrochemical cell are connected to an electrochemical workstation to achieve collaborative monitoring of open-circuit voltage and partial pressure of each gas during storage. The open-circuit voltage is collected in real time by the electrochemical workstation at a sampling frequency of 1 time / 30 seconds. The partial pressures of gases such as CO2, H2, and CH4 are monitored in real time by DEMS at a sampling interval of 1 minute. The gas partial pressure is approximated to gas concentration using the formula PV=CRT, where P represents gas pressure (i.e., partial pressure of the gas), V represents gas volume, C represents gas concentration, R represents molar gas constant, and T represents gas temperature.

[0065] S3. Sample processing after storage: After 5 days of high-temperature storage, remove the in-situ electrochemical cell and quickly transfer it to a glove box filled with argon (the water and oxygen content in the glove box is ≤0.1ppm). Disassemble the in-situ electrochemical cell and remove the positive and negative electrode plates. Drip dimethyl carbonate solution onto the surface of the electrode plates using a pipette and repeat the cleaning process 2-3 times. Place the cleaned electrode plates in a centrifuge tube, seal it, and then place it in a drying oven at 80℃ for 1 hour.

[0066] S4. ToF-SIMS Test: The dried electrode sheets are placed in a vacuum transfer chamber (vacuum degree 0.5 Pa), sealed, and then transferred to the ToF-SIMS device using Bi3O4. + Primary Ion Beam performed scanning tests on the electrode surface to analyze Li. + Ni 2+ Co 2+ Mn 2+ And the content of components decomposed by electrolyte.

[0067] S5. Data Correlation Analysis: Integrating open-circuit voltage, gas concentration, and component content data obtained from ToF-SIMS testing during 60℃ storage, Pearson correlation coefficient analysis revealed that the voltage drop in the later stages of storage occurred simultaneously with a significant increase in CH4 and CO2 concentrations, and that the Li on the electrode surface... + The loss was positively correlated with the content of electrolyte decomposition products, indicating that CH4 concentration and CO2 concentration were significantly correlated with battery performance degradation.

[0068] S6. Early identification of battery stability degradation: Plot a curve with time as the x-axis and the values ​​of one or more parameters that are significantly related at each time (e.g., CO2 concentration and CH4 concentration at each time) as the y-axis, and determine the time period of stability degradation based on the curve.

[0069] The following is specific test data: S5: Data Correlation Analysis: Open Circuit Voltage During Storage at 60℃, such as... Figure 10 As shown, the open-circuit voltage decreased significantly on days 1, 2.6, and 4.7, while the CO2 concentration increased significantly during these periods (e.g., Figure 11 As shown), the CH4 concentration showed a partial increase (e.g. Figure 12 As shown in the figure, the above results indicate that the voltage decrease during storage occurred almost simultaneously with the changes in CH4 and CO2 concentrations. Component content data during storage at 60℃ are as follows: Figure 13 As shown, by integrating open-circuit voltage, gas concentration, and component content data obtained from ToF-SIMS testing, Figure 13 The content of Li in the components x PO y F z and Organic oxygen is represented by the element F, and organic oxygen is represented by the element O. Represented by element C, the relationship between open-circuit voltage, CH4 concentration, CO2 concentration, and component content obtained using the Pearson correlation coefficient analysis method is as follows: Figure 14As shown, the Li content on the electrode surface is negatively correlated with the O and C elements. According to battery literature, O and C elements can represent electrolyte decomposition products, indicating that the active Li... + The lithium ions are lost and combine with the electrolyte to form inactive decomposition products containing lithium ions, thus the Li on the electrode surface... + The amount of electrolyte loss is positively correlated with the content of electrolyte decomposition products. Figure 14 It can be seen that CH4 concentration and CO2 concentration are correlated with battery performance degradation.

[0070] This application constructs a collaborative testing system with an in-situ electrochemical cell as the core to achieve dynamic monitoring of interfacial resistance, open-circuit voltage, and gas concentration during high-temperature storage. Combined with standardized sample processing and transfer procedures after storage, ToF-SIMS testing, and Pearson correlation analysis, it reveals the thermal-gas-chemical degradation mechanism of ternary lithium batteries during high-temperature storage and provides reliable technical support for battery material design and performance optimization using multidimensional online signals.

[0071] Current research lacks a systematic research approach that uses an in-situ electrochemical cell as the core research carrier to achieve real-time synchronous monitoring of open-circuit voltage and gas concentration during storage, combined with regular EIS testing. This approach fails to comprehensively and dynamically reveal the high-temperature storage degradation mechanism of ternary lithium batteries. This application uses an in-situ electrochemical cell as the carrier to monitor open-circuit voltage and gas concentration in real time during high-temperature storage, performing EIS testing every 3 days. After storage, the batteries are disassembled in a glove box, cleaned with dimethyl carbonate, and vacuum dried. Electrodes are then transferred through a vacuum transfer chamber for ToF-SIMS testing. Finally, the data are integrated for stability analysis, which can accurately reveal the high-temperature storage degradation mechanism of ternary lithium batteries. This provides precise experimental data support for battery material screening, electrolyte formulation optimization, and battery structure design, and has significant academic and industrial value.

[0072] This application uses an in-situ electrochemical cell as the core research carrier to achieve real-time synchronous monitoring of circuit parameters and gas concentration during the high-temperature storage of ternary lithium batteries. Combined with regular EIS testing, it can dynamically capture the changing patterns of battery interface resistance at different storage stages. By combining the Pearson correlation coefficient analysis method, a dynamic correlation between interface dynamics and gas generation process is established, filling the gap in the current known technology where a single testing method cannot achieve multi-parameter coordinated monitoring.

[0073] Traditional methods for analyzing the electrode components of stored batteries suffer from problems such as susceptibility to air contamination during sample transfer and incomplete cleaning of electrolyte residues, leading to poor test results. This application designs a standardized sample handling and transfer process after storage. Through a series of operations including disassembly in a glove box, cleaning with dimethyl carbonate, drying, and transfer in a vacuum transfer chamber, the process effectively avoids oxidation or contamination of the electrode sheets by air during handling and transfer, ensuring the accuracy and reliability of ToF-SIMS test results and providing a guarantee for the precise analysis of electrode component degradation characteristics.

[0074] Based on the same inventive concept, this application also provides a ternary lithium battery stability analysis device for implementing the aforementioned ternary lithium battery stability analysis method. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more embodiments of the ternary lithium battery stability analysis device provided below can be found in the limitations of the ternary lithium battery stability analysis method described above, and will not be repeated here.

[0075] In one exemplary embodiment, such as Figure 3 As shown, a ternary lithium battery stability analysis device is provided, including: a storage module for storing the in-situ electrochemical cell of the ternary lithium battery within a preset time period and at a preset temperature.

[0076] The first acquisition module is used to acquire, in real time during the storage process, the circuit parameters of the ternary lithium battery in-situ electrochemical cell and the concentrations of various gases generated by the ternary lithium battery in-situ electrochemical cell, and to acquire the interface resistance of the ternary lithium battery in-situ electrochemical cell at preset sampling frequencies. The circuit parameters are open-circuit voltage or discharge capacity.

[0077] The second acquisition module is used to acquire the content of each component in the positive electrode and negative electrode in the in-situ electrochemical cell of the ternary lithium battery after storage.

[0078] The principal component analysis module is used to perform principal component analysis on the obtained circuit parameters of the ternary lithium battery in-situ electrochemical cell, the concentration of each gas generated by the ternary lithium battery in-situ electrochemical cell, the interfacial resistance of the ternary lithium battery in-situ electrochemical cell, and the content of each component in the positive and negative electrode plates of the ternary lithium battery in-situ electrochemical cell, to obtain parameters that are significantly related to the stability degradation of the ternary lithium battery.

[0079] The stability analysis module is used to determine the time period of stability degradation of the in-situ electrochemical cell of ternary lithium battery based on the values ​​of parameters that are significantly related to the stability degradation of ternary lithium battery.

[0080] In one exemplary embodiment, a computer device is provided, which may be a server or a terminal, and its internal structure diagram may be as follows. Figure 4 As shown, this computer device includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operating system and computer programs stored in the non-volatile storage media. The database stores stability analysis data for ternary lithium batteries. The I / O interfaces are used for exchanging information between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a method for stability analysis of ternary lithium batteries.

[0081] Those skilled in the art will understand that Figure 4 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0082] In one exemplary embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the above-described method embodiments.

[0083] In one exemplary embodiment, a computer-readable storage medium is provided storing a computer program that, when executed by a processor, implements the above-described method embodiments.

[0084] In one exemplary embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the above-described method embodiments.

[0085] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of the relevant data must comply with relevant regulations.

[0086] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0087] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, etc., and are not limited to these.

[0088] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0089] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for stability analysis of ternary lithium batteries, characterized in that, The stability analysis method for ternary lithium batteries includes: The ternary lithium battery in-situ electrochemical cell is stored within a preset time period and at a preset temperature. During the storage process, the circuit parameters of the ternary lithium battery in-situ electrochemical cell and the concentration of each gas generated by the ternary lithium battery in-situ electrochemical cell are acquired in real time, and the interface resistance of the ternary lithium battery in-situ electrochemical cell is acquired at preset sampling frequencies; the circuit parameters are open circuit voltage or discharge capacity. The content of each component in the positive and negative electrode plates of the ternary lithium battery in situ electrochemical cell after storage was obtained; Principal component analysis was performed on the obtained circuit parameters of the ternary lithium battery in-situ electrochemical cell, the concentration of each gas generated by the ternary lithium battery in-situ electrochemical cell, the interfacial resistance of the ternary lithium battery in-situ electrochemical cell, and the content of each component in the positive and negative electrode plates of the ternary lithium battery in-situ electrochemical cell to obtain parameters that are significantly related to the stability degradation of the ternary lithium battery. Based on the values ​​of parameters that are significantly related to the stability degradation of ternary lithium batteries, the time period of stability degradation of the in-situ electrochemical cell of ternary lithium batteries is determined.

2. The method for stability analysis of ternary lithium batteries according to claim 1, characterized in that, The in-situ electrochemical cell of a ternary lithium battery is stored within a preset time period and at a preset temperature, specifically including: The in-situ electrochemical cell of ternary lithium battery is stored using temperature control equipment within a preset time period and at a preset temperature.

3. The method for stability analysis of ternary lithium batteries according to claim 1, characterized in that, Real-time acquisition of circuit parameters of the in-situ electrochemical cell for ternary lithium batteries and the concentrations of various gases generated by the in-situ electrochemical cell for ternary lithium batteries, specifically including: The circuit parameters of the in-situ electrochemical cell of the ternary lithium battery were acquired in real time using an electrochemical workstation. The partial pressures of various gases generated in the in-situ electrochemical cell of a ternary lithium battery were obtained in real time using differential electrochemical mass spectrometry. The concentration of each gas is determined based on its partial pressure.

4. The method for stability analysis of ternary lithium batteries according to claim 1, characterized in that, The interfacial resistance of the in-situ electrochemical cell of the ternary lithium battery is obtained at preset sampling frequencies, specifically including: At each preset sampling frequency, an electrochemical impedance spectroscopy test is performed on the in-situ electrochemical cell of the ternary lithium battery using an electrochemical workstation. Construct an equivalent circuit model corresponding to each electrochemical impedance spectroscopy test based on the data obtained from each test. The interfacial resistance of the ternary lithium battery in-situ electrochemical cell corresponding to each electrochemical impedance spectroscopy test is determined based on the equivalent circuit model corresponding to each electrochemical impedance spectroscopy test.

5. The method for stability analysis of ternary lithium batteries according to claim 1, characterized in that, After storage, the content of each component in the positive and negative electrode plates of the ternary lithium battery in situ electrochemical cell was obtained, specifically including: After storage, the in-situ electrochemical cell of the ternary lithium battery was transferred to a glove box filled with inert gas for disassembly, yielding positive and negative electrode plates. Dimethyl carbonate was used to clean the electrolyte on the surfaces of the positive and negative electrode sheets. The cleaned positive and negative electrode sheets were transferred to a drying oven through a centrifuge tube for drying. The dried positive and negative electrode sheets were sealed and transferred to a time-of-flight secondary ion mass spectrometry (TIMS) instrument through a vacuum transfer chamber. The components of the dried positive and negative electrode sheets were analyzed in the TIMS instrument to obtain the content of each component in the dried positive and negative electrode sheets.

6. The method for stability analysis of ternary lithium batteries according to claim 1, characterized in that, Based on the values ​​of parameters significantly correlated with the stability degradation of ternary lithium batteries, the time period of stability degradation in the in-situ electrochemical cell of ternary lithium batteries is determined, specifically including: Plot the curves corresponding to the parameters that are significantly related to the stability degradation of ternary lithium batteries at each time point with time as the x-axis and the values ​​of the parameters at each time point as the y-axis. The time period of stability degradation of the in-situ electrochemical cell of ternary lithium battery was determined based on the curves corresponding to the parameters that are significantly related to the stability degradation of ternary lithium batteries.

7. A ternary lithium battery stability analysis device, characterized in that, The ternary lithium battery stability analysis device includes: The storage module is used to store the in-situ electrochemical cell of the ternary lithium battery within a preset time period and at a preset temperature. The first acquisition module is used to acquire the circuit parameters of the ternary lithium battery in-situ electrochemical cell and the concentration of each gas generated by the ternary lithium battery in-situ electrochemical cell in real time during the storage process, and to acquire the interface resistance of the ternary lithium battery in-situ electrochemical cell at preset sampling frequencies; the circuit parameters are open circuit voltage or discharge capacity. The second acquisition module is used to acquire the content of each component in the positive electrode and negative electrode in the in-situ electrochemical cell of the ternary lithium battery after storage. The principal component analysis module is used to perform principal component analysis on the obtained circuit parameters of the ternary lithium battery in-situ electrochemical cell, the concentration of each gas generated by the ternary lithium battery in-situ electrochemical cell, the interfacial resistance of the ternary lithium battery in-situ electrochemical cell, and the content of each component in the positive electrode and negative electrode in the ternary lithium battery in-situ electrochemical cell, to obtain parameters that are significantly related to the stability degradation of the ternary lithium battery. The stability analysis module is used to determine the time period of stability degradation of the in-situ electrochemical cell of ternary lithium battery based on the values ​​of parameters that are significantly related to the stability degradation of ternary lithium battery.

8. A computer device, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the ternary lithium battery stability analysis method according to any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the ternary lithium battery stability analysis method according to any one of claims 1-6.

10. A computer program product, comprising a computer program, characterized in that, When executed by a processor, the computer program implements the ternary lithium battery stability analysis method according to any one of claims 1-6.

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