Battery cell performance prediction method

Abstract

The invention provides a battery cell performance prediction method which is characterized in that performance characteristics and OCV information of a small-capacity battery cell under a specified working condition are obtained by testing the performance of the small-capacity battery cell manufactured based on the same specification, and the performance characteristics and the OCV information serve as test data of the small-capacity battery cell. Calculating the speculated internal resistance and thermal parameters of the to-be-verified high-capacity battery cell according to the test data of the low-capacity battery cell, and manufacturing a three-dimensional thermal model of the high-capacity battery cell according to the structural characteristics such as the size and the tab position of the to-be-verified high-capacity battery cell, the thermal parameters and the speculated internal resistance; and obtaining a performance prediction result of the to-be-verified high-capacity battery cell through simulation. According to the invention, the prediction results of various performances of the high-capacity battery cell are obtained by testing the low-capacity battery cell, and the accuracy of the prediction results can be ensured.

Description

Technical Field

[0001] The present invention relates to the field of secondary battery prediction, in particular to a method and device for predicting the electrical performance and temperature rise of large-capacity battery cells. Background Art

[0002] With the development of the energy storage field, under the technical architecture of CTP, large-capacity battery cells have become the mainstream in the current market. However, for large-capacity battery cells, it is relatively difficult to achieve high-current testing and safety testing, and it is difficult for experimental equipment to meet the conditions. In addition, even if it can be achieved, a large number of battery cells and testing costs are required. In contrast, the simulation method can predict the electrical performance behavior and temperature rise trend under high-current testing conditions by means of a small amount of experimental test data and calibration of corresponding physical equations and model parameters, which can solve the problem of difficult testing of large-capacity battery cells, thus saving R & D costs.

[0003] However, in the case of simulating and modeling the electrical performance behavior and temperature rise trend of battery cells, there are many problems such as numerous model parameters, difficult parameter calibration, and poor calibration accuracy. Moreover, the model parameters must be calibrated according to the actual working condition data of the battery cells, so it is necessary to trial-produce battery cells of various specifications, and the costs and testing expenses are still high. Summary of the Invention

[0004] In view of the above problems of the prior art, the present invention provides a method for predicting the electrical performance and temperature rise information of large-capacity battery cells through the measured data of small-capacity battery cells.

[0005] The battery cell performance prediction method of the present invention is characterized in that by testing the performance of small-capacity battery cells made of the same specification, the performance characteristics and OCV information of the small-capacity battery cells under specified working conditions are obtained as the test data of the small-capacity battery cells. According to the test data of the small-capacity battery cells, the inferred internal resistance and thermal parameters of the large-capacity battery cell to be verified are calculated. According to the structural characteristics, thermal parameters and inferred internal resistance of the large-capacity battery cell to be verified, a three-dimensional thermal model of the large-capacity battery cell is made, and the performance prediction result of the large-capacity battery cell to be verified is obtained through simulation.

[0006] Among them, the performance of the large-capacity battery cell includes electrical performance and temperature rise characteristics.

[0007] Preferably, the battery cell performance prediction method of the present invention is characterized in that the same specification includes that the positive and negative electrode plates, the separator and the electrolyte used in the small-capacity battery cell are the same as those of the large-capacity battery cell to be verified.

[0008] In addition, preferably, the battery cell performance prediction method of the present invention is characterized in that the capacity of the small-capacity battery cell is less than or equal to 2 Ah, and the capacity of the large-capacity battery cell to be verified is greater than or equal to 10 Ah.

[0009] Furthermore, the preferred method for predicting the performance of the battery cells of the present invention is characterized by including the following steps:

[0010] Battery cell manufacturing: Design and manufacture small-capacity battery cells according to the large-capacity battery cells to be verified.

[0011] Small-capacity battery cell testing: Test the electrical performance, temperature rise curve, and OCV of the small-capacity battery cells according to the operating conditions to be verified.

[0012] Internal resistance calculation: Calculate the internal resistance of the small-capacity battery cells according to Ohm's law, and infer the OCV and internal resistance information of the large-capacity battery cells based on the correlation between the internal resistances of the small-capacity battery cells and the large-capacity battery cells to be verified.

[0013] Ambient heat transfer coefficient calculation: Obtain the specific heat capacity and thermal conductivity of the battery cells through the thermal parameter test of the small-capacity battery cells, and calculate the ambient heat transfer coefficient through the temperature rise data during the charging or discharging rest period.

[0014] Model construction: Construct a three-dimensional thermal model according to the structural characteristics of the large-capacity battery cells to be verified.

[0015] Simulation: Perform simulation according to the three-dimensional thermal model to obtain the performance prediction results of the large-capacity battery cells to be verified.

[0016] Among them, in the internal resistance calculation step, based on the data of the small-capacity battery cells, calculate the internal resistance of the small-capacity battery cells according to Ohm's law, and infer the OCV and internal resistance information of the large-capacity battery cells based on the correlation between the internal resistances of the small-capacity battery cells and the large-capacity battery cells to be verified. The internal resistance of the large-capacity battery cells to be calculated is:

[0017]

[0018] Among them, R Al and R Cu are the current collector resistances, R Al,Tab is the tab contact resistance, R Ni,Tab is the contact resistance at the connection of the current collectors inside the battery cell, R ion is the total resistance of the positive electrode coating, separator, and negative electrode coating units.

[0019] Among them, N is determined according to the battery cell composition form.

[0020] Preferably, the following tests are included in the ambient heat transfer coefficient calculation step: Perform a thermal conductivity test on the small-capacity battery cells to obtain the thermal conductivity parameters of the battery cells, perform a temperature rise test on the battery cells to obtain the specific heat capacity of the battery cells, and calculate the ambient heat transfer coefficient through the temperature rise data at the end of the battery cell discharge or charge.

[0021] More preferably, the ambient heat transfer coefficient is obtained by the following method:

[0022] mC p dΔT = -hSΔTdt (5)

[0023]

[0024] Wherein, m is the mass of the battery cell, Cp is the specific heat capacity of the battery cell, ΔT is the temperature rise, h is the environmental heat transfer coefficient of the battery cell, S is the surface area of the battery cell, t is the time, and C1 is a coefficient.

[0025] Further preferably, in the model construction step, the temperature distribution of the battery obeys:

[0026]

[0027] Wherein, p represents the battery cell density, C p represents the specific heat capacity of the battery cell, k in represents the in-plane thermal conductivity of the battery cell, k th represents the normal thermal conductivity of the battery cell, Q is the heat generation power of the battery, which at least includes the battery cell body and the tab part, T represents the temperature of the battery cell, t represents the time, and X, Y, and Z respectively represent the three directions of the Cartesian coordinate system.

[0028] Furthermore preferably, the heat generation power of the battery cell body includes Joule heat power and reversible heat power, wherein the Joule heat power P ire is:

[0029] P ire = I(U - OCV) (7)

[0030] The reversible heat power P re is:

[0031]

[0032] Wherein represents the entropy heat coefficient of the battery, and T is the temperature of the battery cell.

[0033] It is also preferably that the heat generation power of the tab part includes the heat generation power of the tab itself and the heat generation power of the contact resistance. Among them, the heat generation power of the tab itself is obtained by Equation 9

[0034] P1 = I 2 R1 (9);

[0035] The heat generation power of the contact resistance is obtained by Equation 10

[0036] P2 = I 2 R2 (10)

[0037] Wherein R1 is the resistance of the tab, and R2 is the contact resistance of the tab.

[0038] Preferably, the boundary conditions on the large-capacity battery cell to be verified and the tab are as follows:

[0039] q = h(T - T amb ) (11)

[0040] where q is the heat flux density, h is the environmental heat transfer coefficient, T amb is the environmental temperature, and T is the temperature of the battery cell.

[0041] According to the battery cell performance prediction method of the present invention, it is not necessary to prepare a large-capacity battery cell to obtain various parameters required for three-dimensional modeling. Instead, only small-capacity battery cells of the same specification, following the same system and the same design principle, can be used. By testing the small-capacity battery cells, a three-dimensional thermal model for predicting various performances of battery cells of various capacities based on this principle, including electrical performance and temperature rise characteristics, can be obtained. Thus, the large-capacity battery cells of the same specification can be accurately simulated, and prediction results of various performances including electrical performance and temperature rise characteristics can be obtained. And it can ensure the accuracy of the prediction results. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a flowchart of a preferred embodiment of the present invention.

[0043] Figure 2 is a schematic diagram of the principle of a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0044] Next, with reference to the drawings, the preferred embodiments of the present invention will be described in detail.

[0045] As a preferred embodiment of the present invention, a method for predicting the electrical performance and temperature rise of a large-capacity battery cell includes the following steps.

[0046] First, in step S1, according to the design scheme of the large-capacity battery cell (the large-capacity battery cell to be verified), a small-capacity battery cell based on the same specification is designed and manufactured. The so-called same specification based on which the small-capacity battery cell is manufactured means following the same system and the same design principle when designing and manufacturing the small-capacity battery cell.

[0047] More specifically, for the positive and negative electrode sheet materials, separator materials, and electrolytes of the small-capacity battery cell, and the cell configuration forms including, for example, wound cells and laminated cells, they are the same as those of the large-capacity battery cell to be verified. Therefore, for the small-capacity battery cell, although it is not the optimal design, it ensures that its positive and negative electrode sheet specifications including material composition, mass ratio, thickness, and surface density, separator specifications including thickness, porosity, and material type, and electrolyte specifications including material type and ion conductivity dosage ratio are the same as those of the large-capacity battery cell to be verified.

[0048] Preferably, the capacity of the small-capacity battery cell produced is less than or equal to 2 Ah, and more preferably 0.1 Ah - 2 Ah.

[0049] As will be described later, according to the prediction method of the present embodiment, the electrical performance and temperature rise characteristics of a large-capacity battery cell with a capacity greater than or equal to 10 Ah can be predicted using the small-capacity battery cell, and for large-capacity battery cells with a capacity of 10 Ah - 350 Ah, the requirements for prediction deviation are met.

[0050] Then, in step S2, the electrical performance, temperature rise curve, and OCV (Open Circuit Voltage) of the small-capacity battery cell are tested according to the working conditions to be verified.

[0051] Specifically, in this step, the design working conditions of the large-capacity battery cell are used to test the electrical performance and collect temperature rise information of the small-capacity battery cell, so as to ensure the accuracy of estimating the electrical performance and temperature rise conditions of the large-capacity battery cell using the small-capacity battery cell.

[0052] Next, in step S3, the internal resistance of the small-capacity battery cell is calculated according to Ohm's law, and the OCV and internal resistance information of the large-capacity battery cell are speculated based on the correlation between the internal resistances of the small-capacity and large-capacity battery cells.

[0053] Specifically, based on the measured data of the small-capacity battery cell obtained in step S2, the internal resistance of the small-capacity battery cell is calculated according to Ohm's law, and the OCV and internal resistance information of the large-capacity battery cell are speculated based on the correlation between the internal resistances of the small-capacity and large-capacity battery cells.

[0054] Among them, the internal resistance of the small-capacity battery cell can be obtained through Ohm's law:

[0055]

[0056] where U and I are the dynamic voltage and dynamic current measured for the small-capacity battery cell, and OCV SOC is the open circuit voltage of the battery, and SOC represents the state of charge of the battery.

[0057] Furthermore, the internal resistance of the small-capacity battery cell includes tab resistance, current collector resistance, and coating / separator / coating resistance. Among them

[0058] The tab resistance further includes the tab itself resistance and the contact resistance.

[0059] The tab resistance is:

[0060]

[0061] where l represents the length of the current collector, w represents the width of the current collector, d represents the thickness of the current collector, and σ is the conductivity of the current collector.

[0062] For the resistance R of the coating / diaphragm / coating ion , it is as follows:

[0063]

[0064] As shown above, the effective resistance of the overall large-capacity battery cell to be verified is:

[0065]

[0066] Among them, R Al and R Cu are the resistances of the current collectors, which can be obtained through the corresponding size specifications and conductivity of the current collectors; R Al,Tab is the tab contact resistance, and R Ni,Tab is the contact resistance at the connection of the current collectors inside the battery cell, which can be measured by connecting the positive and negative electrodes to the tabs and the inside of the current collectors with a resistance meter; R ion is the total resistance of the positive electrode coating, diaphragm, and negative electrode coating unit of the battery cell, which can be obtained by calculation with the same specific resistance. Thus, the internal resistance of the large-capacity battery cell to be verified can be obtained.

[0067] In addition, N is determined according to the form of the battery cell structure. That is, when the battery cell is a stacked battery cell, N is the number of positive electrode sheets inside the battery cell; when the battery cell is a wound battery cell, N is the number of winding turns of the positive electrode sheets inside the battery cell. Of course, if the battery cell has other forms of structure, it can also be determined without doubt according to the regular configuration method of the battery cell.

[0068] Since in step S1, even though the physical parameters of the small-capacity battery cell and the large-capacity battery cell to be verified are different, due to following the principle of the same system and the same design scheme, therefore, the coating / diaphragm / coating of the small-capacity battery cell is actually the same as that of the large-capacity battery cell to be verified. Therefore, for the measured small-capacity battery cell and the large-capacity battery cell to be verified, R ion S is a fixed value, that is, the cross-sectional area through which the current passes is a fixed value.

[0069] In addition, since the systems of the small-capacity battery cell and the large-capacity battery cell to be verified are exactly the same, their OCV (open circuit voltage) is consistent.

[0070] Then, in step S4, the specific heat capacity, thermal conductivity and other thermal parameters of the battery cell are obtained through the thermal parameter test of the small-capacity battery cell, and the environmental heat transfer coefficient is calculated through the temperature rise data in the discharge and rest period.

[0071] In this step, the following tests are included:

[0072] 1) Conduct a thermal conductivity test on the small-capacity battery cell to obtain the thermal conductivity parameter of the battery cell,

[0073] 2) Conduct a temperature rise test on the battery cell to obtain the specific heat capacity of the battery cell,

[0074] 3) The exchange coefficient of the environment. Calculate the environmental heat transfer coefficient through the temperature rise data at the end of the battery cell discharge or charge.

[0075] For the heat transfer coefficient with the environment, according to the law of conservation of energy:

[0076] mC p dΔT = -hSΔTdt (5)

[0077]

[0078] Where m is the mass of the battery cell, Cp is the specific heat capacity of the battery cell, ΔT is the temperature rise, h is the environmental heat transfer coefficient of the battery cell, S is the surface area of the battery cell, and t is the time. C1 is a coefficient.

[0079] Next, in step S5, construct a three-dimensional thermal model based on the size and tab position of the large-capacity battery cell to be verified. Substantially, this model is applicable to all-capacity battery cells that follow the same system and the same design principle.

[0080] In this step, construct a three-dimensional thermal model according to the energy conservation equation, where

[0081] The temperature distribution of the battery obeys:

[0082]

[0083] In the formula, p represents the battery cell density, C p represents the specific heat capacity of the battery cell, k in represents the in-plane thermal conductivity of the battery cell, that is, the thermal conductivity in the X and Y directions on the plane perpendicular to the battery cell thickness direction, k th represents the normal thermal conductivity of the battery cell, that is, the thermal conductivity along the battery cell thickness direction. Q is the heat generation power of the battery, mainly including the battery cell body and the tab part. T represents the temperature of the battery cell; t represents the time, and X, Y, and Z respectively represent the three directions of the Cartesian coordinate system.

[0084] Among them, the heat generation power of the battery cell body mainly includes Joule heat power and reversible heat power.

[0085] The Joule heat power P ire is:

[0086] P ire = I(U - OCV) (7)

[0087] And the reversible heat power P re is:

[0088]

[0089] In the formula represents the entropy heat coefficient of the battery, and T is the temperature of the battery cell

[0090] For the tab part, the heat generation is mainly due to the joule heat of the tab itself and the heat generation caused by the contact resistance of the tab

[0091] Among them, the heat generation power of the tab itself is obtained through Equation 9

[0092] P1 = I 2 R1 (9);

[0093] The heat generation power of the contact resistance is obtained through Equation 10

[0094] P2 = I 2 R2 (10)

[0095] Where R1 is the resistance of the tab, and R2 is the contact resistance of the tab

[0096] The boundary conditions on the large-capacity battery cell and the tab surface are as follows

[0097] q = h(T - T amb ) (11)

[0098] In the formula, q is the heat flux density, h is the environmental heat transfer coefficient, T amb is the environmental temperature, and T is the temperature of the battery cell

[0099] Finally, in step S6, according to the parameters obtained in step S3 and step S4 and the model established in step S5, the voltage and temperature rise curves of the large-capacity battery cell to be verified are simulated

[0100] In this step, the model can be solved using various finite element software including LUSAS n, MSC.Nastran, Ansys, Abaqus, LMS-Samtech, Algor, Femap / NX Nastran, Hypermesh, Solidworks, Siemens STAR-CCM+ etc. including comsol mulphysics

[0101] When using a small-capacity battery cell to predict the electrical performance curve and temperature rise performance of a large-capacity battery cell, due to the relationship between the electrical performance curve and temperature rise behavior, voltage relationship and heat conduction law being a complex and non-linear relationship, it cannot be calculated through a simple conversion relationship

[0102] However, in the present embodiment, in step S1, based on the principle of the same system and the same design concept, a small-capacity battery cell is fabricated according to the design concept of a large-capacity battery cell for testing. Then, in combination with the three-dimensional thermal model, a correlation is established between the electrical performance curve and the temperature rise performance of the small-capacity battery cell and those of the large-capacity battery cell. Thus, by measuring the electrical performance curve and the temperature rise performance of the small-capacity battery cell, the electrical performance curve and the temperature rise performance of the large-capacity battery cell can be inferred.

[0103] Specifically, in the present embodiment, by adopting the principle of the same system and the same design concept, the following correlations are established between the small-capacity battery cell and the large-capacity battery cell. Correlation 1: As described above, in terms of the internal resistance of the coating / diaphragm / coating unit, a correlation is established between the large-capacity battery cell to be verified and the measured small-capacity battery cell. Correlation 2: Except for the internal resistance of the coating / diaphragm / coating unit, the correlations of other parts are defined by conductivity. Therefore, in the present embodiment, by establishing a specific correlation method for specific parameters and establishing a correlation between the small-capacity battery cell and the large-capacity battery cell, a three-dimensional thermal model is fabricated. Thus, by testing the electrical performance curve and the temperature rise performance of the actually fabricated small-capacity battery cell, the electrical performance curve and the temperature rise performance of the large-capacity battery cell can be predicted more accurately according to the test results.

[0104] Therefore, it is not necessary to actually fabricate a large-capacity battery cell. Only by fabricating a small-capacity battery cell that meets the principle of the same system and the same design concept, testing it, and establishing a three-dimensional thermal model based on the test results of the small-capacity battery cell, can the electrical performance curve and the temperature rise performance of the large-capacity battery cell be predicted quickly and accurately. This greatly shortens the time period for testing the designed battery in the development and design of the large-capacity battery cell, and avoids the cost of experimentally fabricating a large-capacity battery. At the same time, it overcomes the problem of simulation deviation caused by various factors when simulating and emulating a large-capacity battery.

[0105]

Principle Explanation

[0106] Figure 2 is the principle explanatory diagram of the preferred embodiment of the present invention.

[0107] As Figure 2 shown, by testing the small-capacity battery cell, the voltage and temperature rise curves (step 101) under specified working conditions, as well as the OCV information (step 102) of the small-capacity battery cell, are obtained as the test data of the small-capacity battery cell (step 103).

[0108] Based on the test data of the small-capacity battery cell, on the one hand, the internal resistance of the large-capacity battery cell to be verified can be calculated (step 104), and on the other hand, the thermal parameters of the large-capacity battery cell to be verified can be obtained (step 105).

[0109] Therefore, according to the structural features such as the size and tab position of the large-capacity battery cell to be verified (step 106), thermal parameters (step 105), and internal resistance (step 104), a three-dimensional thermal model of the large-capacity battery cell is made (step 107). As can be seen from the above, this three-dimensional thermal model is applicable to battery cells based on the same system and the same design principle.

[0110] Finally, the voltage curve and temperature rise curve of the large-capacity battery cell to be verified are obtained through simulation (step 108) (steps 109, 110), thereby completing the prediction of the electrical performance and temperature rise characteristics of the large-capacity battery cell to be verified.

[0111] The preferred embodiments of the present invention have been described in detail above. Those skilled in the art can make various modifications, changes, and combinations on the basis of the idea of the present invention, but these modifications, changes, combinations, etc. are all within the scope of the gist of the present invention.

Claims

1. A method for predicting the performance of an electric cell, characterized in that: By testing the performance of small-capacity electric cells made based on the same specifications, obtaining the performance characteristics and OCV information of the small-capacity electric cells under specified working conditions as the test data of the small-capacity electric cells. Deducing the speculated internal resistance and thermal parameters of the large-capacity electric cell to be verified according to the test data of the small-capacity electric cell. Making a three-dimensional thermal model of the large-capacity electric cell according to the structural characteristics, thermal parameters and speculated internal resistance of the large-capacity electric cell to be verified. Obtaining the performance prediction result of the large-capacity electric cell to be verified through simulation.

2. The method for predicting the performance of an electric cell according to claim 1, characterized in that: The performance of the large-capacity electric cell includes electrical performance and temperature rise characteristics.

3. The method for predicting the performance of an electric cell according to claim 1, characterized in that: The same specifications include that the positive and negative electrode plates, the separator and the electrolyte used in the small-capacity electric cell are the same as those of the large-capacity electric cell to be verified.

4. The method for predicting the performance of an electric cell according to claim 1, characterized in that: The capacity of the small-capacity electric cell is less than or equal to 2 Ah. The capacity of the large-capacity electric cell to be verified is greater than or equal to 10 Ah.

5. The method for predicting the performance of an electric core according to claim 1, characterized in that, It includes the following steps: Electric cell manufacturing: Designing and manufacturing a small-capacity electric cell according to the large-capacity electric cell to be verified. Small-capacity electric cell testing: Testing the electrical performance, temperature rise curve and OCV of the small-capacity electric cell according to the working conditions to be verified. Internal resistance calculation: Calculating the internal resistance of the small-capacity electric cell according to Ohm's law, and speculating the OCV and internal resistance information of the large-capacity electric cell based on the correlation between the internal resistance of the small-capacity electric cell and the large-capacity electric cell to be verified. Environmental heat transfer coefficient calculation: Obtaining the specific heat capacity and thermal conductivity of the electric cell through testing the thermal parameters of the small-capacity electric cell, and calculating the environmental heat transfer coefficient through the temperature rise data in the charging or discharging static period. Model construction: Constructing a three-dimensional thermal model according to the structural characteristics of the large-capacity electric cell to be verified. Simulation: Performing simulation according to the three-dimensional thermal model to obtain the performance prediction result of the large-capacity electric cell to be verified.

6. The method for predicting the performance of an electric cell according to claim 5, characterized in that: In the internal resistance calculation step: Based on the data of the small-capacity electric cell, calculating the internal resistance of the small-capacity electric cell according to Ohm's law, and speculating the OCV and internal resistance information of the large-capacity electric cell based on the correlation between the internal resistance of the small-capacity electric cell and the large-capacity electric cell to be verified. The internal resistance of the large-capacity electric cell to be calculated is: Among them, R Al , R Cu is the current collector resistance, R Al,Tab is the tab contact resistance, R Ni,Tab is the contact resistance at the connection of the current collector inside the battery cell, R ion is the total resistance of the positive electrode coating, separator, and negative electrode coating unit, Wherein, N is determined according to the cell composition form.

7. The method for predicting the performance of an electric cell according to claim 5, characterized in that: The following tests are included in the environmental heat transfer coefficient calculation step: Performing a thermal conductivity test on the small-capacity electric cell to obtain the thermal conductivity parameter of the electric cell. Performing a temperature rise test on the electric cell to obtain the specific heat capacity of the electric cell. The exchange coefficient of the environment, calculating the environmental heat transfer coefficient through the temperature rise data at the end of the discharge or charge of the electric cell.

8. The method for predicting the performance of an electric cell according to claim 7, characterized in that: The environmental heat transfer coefficient is obtained through the following method: mC p dΔT = -hSΔTdt (5) In the formula, m is the mass of the electric cell, Cp is the specific heat capacity of the electric cell, ΔT is the temperature rise, h is the environmental heat transfer coefficient of the electric cell, S is the surface area of the electric cell, t is the time, and C1 is a coefficient.

9. The method for predicting the performance of an electric cell according to claim 5, wherein in the model construction step, the temperature distribution of the battery obeys: where p represents the cell density, C p represents the specific heat capacity of the cell, k in represents the in-plane thermal conductivity of the cell, k th represents the normal thermal conductivity of the cell, Q is the heat generation power of the battery, including the cell body and the tab part, T represents the temperature of the cell, t represents time, and X, Y, and Z respectively represent the three directions of the Cartesian coordinate system.

10. The method for predicting the performance of an electric cell according to claim 9, wherein the heat generation power of the electric cell body includes Joule heat power and reversible heat power, where Joule heat power P ire is as follows: P ire = I (U - OCV) (7) Reversible thermal power P re is as follows: In the formula represents the entropy heat coefficient of the battery, and T is the temperature of the battery cell.

11. The method for predicting the performance of an electric cell according to claim 9, wherein the heat generation power of the tab part includes the heat generation power of the tab itself and the heat generation power of the contact resistance, wherein, the heat generation power of the tab itself is obtained by Equation 9 P1 = I 2 R1 (9); the heat generation power of the contact resistance is obtained by Equation 10 P2 = I 2 R2 (10) where R1 is the resistance of the tab and R2 is the contact resistance of the tab.

12. The method for predicting the performance of an electric cell according to claim 9, wherein the boundary conditions on the large-capacity electric cell to be verified and the tab surface are: q = h(T - T amb ) (11) where q is the heat flux density, h is the environmental heat transfer coefficient, T amb is the environmental temperature, and T is the temperature of the battery cell.

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