WO2022228284A1

WO2022228284A1 - Method and apparatus for obtaining contact resistance of cell structural member, device, and storage medium

Info

Publication number: WO2022228284A1
Application number: PCT/CN2022/088333
Authority: WO
Inventors: 李峰宇; 何见超; 王连旭; 陈思
Original assignee: 蜂巢能源科技股份有限公司
Priority date: 2021-04-30
Filing date: 2022-04-22
Publication date: 2022-11-03
Also published as: CN113051852A; CN113051852B

Abstract

Disclosed in embodiments of the present application are a method and apparatus for obtaining the contact resistance of a cell structural member, a device, and a storage medium. The method for obtaining the contact resistance of a cell structural member comprises: using an electrochemical thermal model to correct charge/discharge voltage simulation curves and temperature simulation curves at different rates; simulating electrochemical heat generation under set working conditions by means of the corrected electrochemical thermal model; establishing an electrothermal coupling model and importing same into the electrochemical heat generation; loading the set working conditions on the electrothermal coupling model; adjusting the contact resistances at different welding positions to match the simulated temperature data of each test area with the measured temperature data; and in response to the simulated temperature data of the test area being matched with the measured temperature data, obtaining the contact resistance of the structural member.

Description

Method, device, device and storage medium for obtaining contact resistance of cell structure

This application claims the priority of the Chinese patent application with application number 202110477611.5 filed with the China Patent Office on April 30, 2021, the entire contents of the above application are incorporated into this application by reference.

technical field

The present application relates to the field of battery technology, for example, to a method, device, device, and storage medium for obtaining the contact resistance of a battery cell structure.

Background technique

With the continuous development of new energy hybrid vehicles, the demand for power-type batteries is also increasing. Power-type batteries have higher requirements for rate performance. Under the condition of high-rate charge and discharge, the temperature rise of the battery cells is higher, and large-scale power batteries Performance is greatly affected by temperature rise and temperature distribution.

As one of the core components of the cell, the evaluation of the overcurrent capability of the structure is extremely important at the beginning of the cell design. Under certain fast charging conditions, if the temperature rise of the cell structure is high, different components Due to the heat conduction between the cells, the temperature of the core (jellyroll) of the cell also increases, which will inevitably affect the performance of the cell and increase the safety hazard of the cell. The evaluation of the overcurrent capability of structural parts under complex fast charging conditions will undoubtedly increase the difficulty of engineers.

The heat generation of structural parts mainly comes from the Joule heat generated by the flow of electric current. The pure resistance of structural parts is generally in the order of 10 ^-6 Ω, but the contact resistance is bound to be introduced in the laser welding and ultrasonic welding of structural parts. The resistance of the structural parts after welding is measured by a resistance meter. The order of magnitude is generally 10 ^-4 Ω. This value is not accurate as a calculation of heat generation. Contact resistance is related to factors such as contact pressure, contact state, and surface roughness. However, there is no better way to measure this contact resistance.

SUMMARY OF THE INVENTION

Embodiments of the present application provide a method, device, device, and storage medium for obtaining the contact resistance of a cell structure.

In a first aspect, an embodiment of the present application provides a method for obtaining the contact resistance of a cell structure, including:

The electrochemical thermal model is used to correct the charge-discharge voltage simulation curves and temperature simulation curves of different rates;

The electrochemical heat generation under the set operating conditions is simulated by the modified electrochemical thermal model;

establishing an electrothermal coupling model and importing the electrochemical heat generation; loading the set operating conditions on the electrothermal coupling model;

The contact resistances of different welding positions are adjusted to match the simulated temperature data of each test area with the measured temperature data; in response to the simulated temperature data of the test area matching the measured temperature data, the contact resistance value of the structural member is obtained.

In a second aspect, an embodiment of the present application further provides a device for obtaining the contact resistance of a cell structure, including:

The module calibration unit is set to use the electrochemical thermal model to correct the charge-discharge voltage simulation curves and temperature simulation curves of different magnifications;

An electrochemical simulation unit, configured to simulate the electrochemical heat generation under the set working conditions by using the revised electrochemical thermal model;

an electro-thermal coupling simulation unit, configured to establish an electro-thermal coupling model and import the electrochemical heat generation; load the set working condition on the electro-thermal coupling model;

A contact resistance modulation unit, configured to adjust the contact resistance of different welding positions, so that the simulated temperature data of each test area matches the measured temperature data; in response to the simulated temperature data of the test area matching the measured temperature data, the structure is obtained contact resistance value of the parts.

In a third aspect, the embodiments of the present application also provide a device for obtaining the contact resistance of a cell structure, including:

one or more processors;

storage means arranged to store one or more programs,

When the one or more programs are executed by the one or more processors, the one or more processors implement the method for obtaining the contact resistance of a cell structure provided by any embodiment of the present application.

In a fourth aspect, the embodiments of the present application further provide a storage medium containing computer-executable instructions, when executed by a computer processor, the computer-executable instructions are used to perform the contacting of the cell structure components provided by any embodiment of the present application How to get resistance.

Description of drawings

1 is a schematic flowchart of a method for obtaining the contact resistance of a cell structure provided by an embodiment of the present application;

FIG. 2 is a schematic diagram of the geometric structure of a cell provided by an embodiment of the present application;

FIG. 3 is a schematic top-view structural diagram of a battery cell provided by an embodiment of the present application;

4 is a schematic flowchart of another method for obtaining the contact resistance of a cell structure provided by an embodiment of the present application;

5 is a schematic diagram of a P2D model provided by an embodiment of the present application;

6 is a schematic diagram of a coupling relationship provided by an embodiment of the present application;

7 is a comparison diagram of simulated voltage curves of different magnifications and measured voltages provided by an embodiment of the present application;

8 is a comparison diagram of the simulated temperature curve of the center of the large surface of the shell with different magnifications and the measured temperature change provided by the embodiment of the present application;

9 is a schematic structural diagram of a device for obtaining the contact resistance of a cell structure provided by an embodiment of the present application;

FIG. 10 is a schematic structural diagram of a device for obtaining the contact resistance of a cell structure according to an embodiment of the present application.

Detailed ways

The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but not to limit the present application. In addition, it should be noted that, for the convenience of description, the drawings only show some but not all the structures related to the present application.

In the related art, the overall resistance of the cell structure is often measured under static conditions. For example, a resistance meter is used to measure the resistance of the whole structure and different parts of the structure, and the above-mentioned measured resistance is used as the resistance measurement value of the cell structure. First, the overall resistance of the cell structure measured in static state cannot reflect the real resistance of the cell structure under the working state of the cell; secondly, the overall value measured by the resistance meter may have exceeded the DCR (internal resistance, Direct Current Resistance), and cannot effectively quantify the proportion of structural resistance in the overall DCR of the cell; in addition, for companies with many product projects, if each project needs to be measured, it will undoubtedly increase the research and development cost, and the test resources are limited. In this case, it will also delay the progress of product development. In order to solve the above problems, the applicant built an electrochemical thermal model and an electrothermal coupled model, obtained the contact resistance at the welding position of the structural parts during the actual charging and discharging process by combining simulation and actual measurement, and obtained the charging and discharging process of the battery cell by means of simulation. The contact resistance value in .

An embodiment of the present application provides a method for obtaining the contact resistance of a cell structure. FIG. 1 is a schematic flowchart of a method for obtaining the contact resistance of a cell structure provided by the embodiment of the present application. As shown in FIG. 1 , this embodiment The method for obtaining the contact resistance of the cell structure in the example includes the following steps:

S110, using an electrochemical thermal model to correct the charge-discharge voltage simulation curves and temperature simulation curves of different rates.

The rate is used to indicate the rate of battery charge and discharge capacity. 1C represents the amperage when the battery is fully discharged in one hour. For example, a 18650 battery with a nominal name of 2200mA·h is discharged for 1 hour at 1C intensity, and the discharge current is 2200mA at this time. Charge-discharge rate=charge-discharge current/rated capacity; for example, when a battery with a rated capacity of 100A·h is discharged with 20A, its discharge rate is 0.2C. 1C, 2C, 0.2C is the battery discharge rate: a measure of how fast the discharge is. In one embodiment, the value range of the magnification in this embodiment may be 0.1C to 5C, so as to calibrate the electrochemical thermal model from different working conditions. In this embodiment, several magnifications can be selected, for example, 0.33C, 0.5C, 1C, 2C, etc., to correct the charge-discharge simulation curve and temperature simulation curve, and use other magnifications to modify the charge-discharge simulation curve and temperature simulation curve. curve to verify.

The electrothermal model is the main model for obtaining the contact resistance. It is necessary to consider the electrochemical heat generation (heat generation power W/m^3) of the electrode group under the condition of charge and discharge. Therefore, the purpose of constructing the electrochemical heat model in this example is to obtain the battery cell. At a specific rate or under specific working conditions, the electrochemical heat generation power of the battery is difficult to directly calculate the electrochemical heat generation of the battery due to the fact that the battery has convective heat transfer during the actual charging and discharging process of the battery. , modify the simulation curve of charge and discharge voltage at different magnifications to make it infinitely close to the measured data or equal to the measured data, and according to the measured temperature data of different magnifications, correct the temperature simulation curves of different magnifications to make it infinitely close to The measured data may be equal to or equal to the measured data.

That is, in this embodiment, the electrochemical thermal model is calibrated according to the measured data of charge and discharge voltages at different rates and the measured data of temperature changes at different positions, so that the actual measurement and simulation can be in good agreement, and then the electrochemical thermal model is used to obtain the electrochemical production at a specific rate. thermal power.

S120 , simulating the electrochemical heat generation under the set working condition through the revised electrochemical thermal model.

The electrochemical thermal model after the above correction can simulate the set working conditions, so as to obtain the electrochemical heat production close to the actual measurement under the set working conditions. The above set working conditions can be charge and discharge voltages such as 0.25C or 0.35C The unsimulated magnification value during the correction process of the simulation curve and the temperature simulation curve, or, the above-mentioned set working condition can also be a working condition of step charging or a complex working condition where the current changes all the time.

For example, there may be unsimulated override values left for verification after curve correction.

S130 , establishing an electrothermal coupling model and importing electrochemical heat generation; loading and setting working conditions for the electrothermal coupling model.

S140. Adjust the contact resistances of different welding positions to match the simulated temperature data of each test area with the measured temperature data; in response to matching the simulated temperature data of the test area with the measured temperature data, obtain the contact resistance value of the structural member at this time .

The above-mentioned relatively accurate electrochemical heat generation is used as the input of the electrothermal coupling model, that is, the heat source of the electrothermal coupling model comes from the heat generation power calculated by the electrochemical thermal model. And control the electrothermal coupling model to simulate the set working conditions of the electrochemical thermal model that produces the above electrochemical heat generation. When the electrothermal coupling model is loaded with the set working conditions, the adjustment (the adjustment here is not limited to manual adjustment and optimization through the interface or program). Optimization of parameters) contact resistance at the welding position, so that the simulated temperature data in different test areas have a good match with the measured temperature data, and the contact resistance value of the welding position during the actual charging and discharging process can be obtained, which can be used as the electrochemical value under other working conditions. Input to the thermal model. By obtaining the contact resistance value, it is possible to further simulate and predict the temperature distribution of the structural parts under different fast charging conditions, and evaluate the overcurrent capability of the structural parts.

In the embodiment of the present application, the contact resistance of the cell structure is obtained by combining the electrochemical thermal model with the electrothermal coupling model, wherein the electrochemical thermal model can correct the charge-discharge voltage simulation curves and temperature simulation curves of different magnifications. Make the charge-discharge voltage simulation curve closer to the actual measurement value, and make the temperature simulation curve closer to the actual measurement value, so that at least one parameter of the electrochemical thermal model can be corrected, and the electricity can be obtained through the corrected electrochemical thermal model. The electrochemical heat generation of the core under the set working conditions, the electro-thermal coupling model can be imported into the above electrochemical heat generation as a heat source, and the electro-thermal coupling model is loaded with a set working condition. In this set working condition, different welding positions can be adjusted. Therefore, the contact resistance of the welding position during the actual charging and discharging process can be obtained, which can be used as the input of the electrochemical thermal model under other working conditions, and then can simulate different The temperature rise of different positions of the battery cell under fast charging conditions speeds up the performance evaluation of structural parts, shortens the mold opening of the battery core structural parts and the development cycle of the battery cell products.

The above is the core idea of the present application, and the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative work fall within the protection scope of the present application.

As shown in FIG. 2 and FIG. 3 , FIG. 2 is a schematic diagram of the geometric structure of a cell provided by an embodiment of the present application, and FIG. 3 is a schematic diagram of a top-view structure of a cell provided by an embodiment of the present application, as shown in FIGS. 2 and 3 As shown, the battery cell includes a casing 14, a pole group (not shown in FIG. 2) and structural parts, the structural parts include a positive pole pole 11, a negative pole pole 12, a positive pole connector 15, a positive pole lug 18, and a negative pole connecting piece 16 and negative tab 17. The pole group is formed by stacking N pole piece units, and one pole piece unit is composed of a positive electrode current collector, a positive electrode, a separator, a negative electrode and a negative electrode current collector. It should be noted that the connector needs to be welded with the cover plate and the tab respectively. In one embodiment, the welding position may include a laser welding position and an ultrasonic welding position; the laser welding position is the welding between the connecting piece and the cover plate; ultrasonic welding The welding position is the welding between the tab and the connecting piece. In this embodiment, since the tabs are thin, ultrasonic welding can be used to weld the tabs and the connecting piece to avoid damage to the tabs, while the cover plate is thicker, and the connecting piece and the cover plate can be directly welded by laser welding.

The correction of the electrochemical thermal model requires the measured data of voltage changes and temperature changes at different positions under different charging and discharging rates. In one embodiment, the test area for temperature testing in this embodiment may include: positive pole 11 , negative pole 12 , the center 141 of the large surface of the casing and the center 13 of the bipolar group, in this embodiment, the above-mentioned several representative positions of the cell structure are selected as the test areas. In one embodiment, the measured temperature data of the test area may be acquired by temperature sensors distributed on the cell structure. The temperature sensor can be arranged inside and outside the cell to obtain temperature changes at different positions of the cell.

In one embodiment, before using the electrochemical thermal model to correct the charge-discharge voltage simulation curves and temperature simulation curves of different magnifications, the method may further include: acquiring model parameters; the model parameters include design parameters, cell geometric parameters and thermal parameters ; The geometrical parameters of the cell include the geometrical parameters of the shell, the geometrical parameters of the pole group and the geometrical parameters of the structural parts; the thermal parameters include thermal conductivity, specific heat capacity and density.

In one embodiment, the pole group may include a plurality of pole piece units; each pole piece unit may include a multi-layer material; the multi-layer material includes a positive electrode current collector, a positive electrode, a separator, a negative electrode and a negative electrode current collector arranged in sequence; the specific heat capacity C _P is obtained according to ρC _P =Σ _i ρ _i CP _i d _i /Σ _i d _i ; where ρ _i is the density of each layer of material; C _Pi is the specific heat capacity of each layer of material; d _i is the thickness of each layer of material; ρ is Equivalent density; the thermal conductivity includes normal thermal conductivity k _z and extensional thermal conductivity k _r ;

k _r Σ _i d _i =Σ _i k _i d _i ; where _ki is the thermal conductivity of each layer of material.

The parameters include design parameters, cell geometric parameters (which may include the geometric parameters of the casing, the geometric parameters of the pole group, and the geometric parameters of the structural components), and thermal parameters (which may include thermal conductivity, specific heat capacity, and density). The pole group is formed by superimposing N pole piece units. One pole piece unit is composed of positive electrode current collector, positive electrode, diaphragm, negative electrode and negative electrode current collector. The positive electrode current collector can be composed of aluminum foil, and the negative electrode current collector can be composed of copper foil. constitute. Then the pole group belongs to the composite material including the above five materials, and the specific heat capacity is calculated by using the formula ρC _P =Σ _i ρ _i C _P i d _i /Σ _i d _i . where ρ _i , C _Pi , and d _i are the density, specific heat capacity, and thickness of each layer of material, respectively, that is, i represents different materials. If the above at least one layer of materials includes 5 layers of materials, the value range of i can be 1~ 5. The thermal conductivity adopts the calculation method of equivalent thermal resistance in series and parallel:

k _r Σ _i d _i =Σ _i k _i d _i . where k _z and k _r are the normal thermal conductivity and the extensional thermal conductivity, respectively.

For example, design parameters may include the areal density of the pole pieces.

On the basis of the above embodiments, the electrochemical thermal model may include the mutually coupled lithium battery field and the first heat transfer field, and the electrothermal coupled model may include the mutually coupled electric field and the second heat transfer field. The embodiments of the present application also provide A method for obtaining the contact resistance of a cell structure. FIG. 4 is a schematic flowchart of another method for obtaining the contact resistance of a cell structure provided by an embodiment of the present application. As shown in FIG. 4 , the cell structure of this embodiment is shown in FIG. The method for obtaining the contact resistance of the component includes the following steps:

S210, acquiring design parameters.

S220 , converting the design parameters into model parameters, and establishing a one-dimensional lithium battery field and a three-dimensional first heat transfer field.

Exemplarily, the built-in lithium battery interface of the COMSOL Multiphisics simulation software can be used. In this embodiment, the electrochemical thermal model can include a lithium battery field and a first heat transfer field, and the design parameters are converted into parameters required by the model. The lithium battery field A traditional P2D (pseudo two dimensional, pseudo two-dimensional) model is established, that is, a one-dimensional model, and the first heat transfer field adopts three dimensions.

The P2D model, also known as the pseudo-two-dimensional model, is a model jointly designed by Newman and Doyle for lithium battery simulation. The creation of a P2D model can include the basic composition of a lithium-ion battery. As shown in FIG. 5, FIG. 5 is a schematic diagram of a P2D model provided by the embodiment of the present application, including electrodes (positive and negative electrodes), diaphragms, electrolytes and current collectors, which is actually a one-dimensional model model, because two Dimension: The thickness direction dimension of the pole piece and the dimension of the spherical particle, so it is called a pseudo-two-dimensional model.

In Figure 5, δn is the length of the negative electrode on the _z -axis, _δse is the length of the separator on the z-axis, _δp is the length of the positive electrode on the z-axis, and L is the distance between the negative electrode current collector and the positive electrode current collector . r is the radius, cs,n is the solid-phase lithium ion concentration of the negative electrode, and cs, _p is the solid-phase lithium ion concentration of the positive electrode.

Since the P2D model has long been widely used in lithium battery simulation, the introduction of the principle is basically the same, and the P2D principle will not be repeated in this embodiment, and the electrochemical thermal model is mainly used to obtain the electrochemical heat generation power.

S230. Set the first boundary condition of the lithium battery field; the first boundary condition includes initial capacity, initial voltage, initial current density, charge-discharge rate, and cut-off voltage; set the second boundary condition of the first heat transfer field; the second boundary condition Convective heat transfer coefficient, heat source and thermal conductivity are included.

The electrochemical thermal model is divided into two parts: the physical field of the lithium battery adopts one dimension, and the model considers the thickness direction of the electrode of a single pole piece unit, so different line segments are used to represent different components. The first boundary conditions that need to be set for the lithium battery field include initial current density A/m^2, initial voltage E _cell unit V, initial capacity Q ₀ unit C, charge-discharge rate and cut-off voltage.

The first heat transfer field is a heat transfer physical field. It adopts three dimensions and needs to set the second boundary condition: the thermal conductivity (anisotropy) of the pole group, the convection heat transfer coefficient h, q ₀ =h·( _Text -T), q ₀ is the heat exchange amount, T _ext is the external temperature, and T is the battery temperature. The heat generating source Qh is an electrochemical heat generating source, which is derived from the one-dimensional lithium battery physical field. Their coupling relationship is shown in FIG. 6 , which is a schematic diagram of a coupling relationship provided by an embodiment of the present application. Electrochemical heat generation acts on the battery cell to make the battery cell have a temperature distribution, and the temperature change of the battery will affect the battery temperature. performance, the lithium battery field and the first heat transfer field are bidirectionally coupled.

In one embodiment, the convective heat transfer coefficient h _c is based on

Obtain;

T is the temperature that changes in real time, T _max is the maximum temperature, and T _∞ is the static end temperature; A is the heat exchange area; m is the quality of the cell; t is the time; C _p is the specific heat capacity.

The temperature rise of the battery cell under the condition of rate charging is related to the heat generation and heat exchange of the battery cell. In order to ensure the accuracy of the subsequent model building, it is necessary to determine the convective heat transfer coefficient between the battery cell and the air under the test conditions in advance. After the battery is charged and tested, it can be allowed to stand for a certain period of time, and the temperature changes at different positions can be monitored during the standstill process. At this time, the cell has no heat generation and only heat exchange, and satisfies the heat balance formula:

Transform the formula

Integrate both sides at the same time

The final formula becomes

The convective heat transfer coefficient h _c can be obtained by curve fitting through the temperature change of the measured data, and the convection numbers at different positions of the shell can be fitted separately. T is the temperature that changes in real time, T _max is the maximum temperature, and T _∞ is the static end temperature.

S240, calibrate the electrochemical thermal model according to the measured charge and discharge voltage, so that the measured curve of the charge and discharge voltage matches the simulation curve of the charge and discharge voltage; calibrate the electrochemical thermal model according to the measured temperature, so that the measured temperature curve matches the temperature simulation curve.

The above steps S220 to S240 are specific processes of correcting the charge-discharge voltage simulation curves and temperature simulation curves of different magnifications by using an electrochemical thermal model.

The electrochemical thermal model calibration is carried out according to the measured data, which includes the calibration of the voltage curve and the calibration of the temperature change. Part of the measured and simulated data is compared with Figure 7 and Figure 8. Figure 7 is the simulation voltage curve of different magnifications provided by the embodiment of the application and Figure 8 is a comparison diagram of the simulated temperature curve of the center of a large surface of a shell with different magnifications provided by the embodiment of the present application and the comparison diagram of the measured temperature change. In Figures 7 and 8, the simulation data is represented by the curve, and the measured data is represented by the circle, and the simulation and correction of the working conditions are carried out under the working conditions of 0.33C, 0.5C, 1C, and 2C, respectively. When the simulated voltage curve is infinitely close to the measured voltage, and the simulated temperature curve is infinitely close to the actual temperature, it means that the accuracy of the electrochemical thermal model has reached the expectation. Input as a heat source for the electrothermal coupled model.

S250 , simulating the electrochemical heat generation under the set working condition through the revised electrochemical thermal model.

S260, establishing an electric field and a second heat transfer field according to design parameters.

S270 , adding soldering information of the soldering position.

The solder printing information includes solder printing shape, effective area, solder printing position, solder printing number and solder printing penetration.

The electro-thermal coupling model can include an electric field and a second heat transfer field. The electro-thermal coupling model adopts the electric field and heat transfer module in COMSOL Multiphisics. The electro-thermal coupling model adopts the full coupling method of the real structure of the cell, and is realized by the software multi-physics coupling interface.

Add laser welding (connecting piece and cover plate welding) and ultrasonic welding (electrode and connecting piece welding) welding marks, wherein the welding mark information includes but not limited to the shape and effective area of the welding mark, the position of the welding mark, the number of welding marks, the welding mark Imprint penetration, etc.

S280, set a heat source; the heat source includes electrochemical heat generation and structural member heat source; the electrochemical heat generation is imported through an interpolation function; the structural member heat source Qe=J*E; J is the electric field, and E is the current density; wherein, when the current flows through the structure The current density is different at different positions of the parts, so that the heat source of the structural parts is a distributed heat source that simulates the actual working conditions.

Heat source settings: 1) The heat generation of the jellyroll comes from the revised electrochemical heat model, and the electrochemical heat generation is imported into the electrothermal coupled model through an interpolation function; 2) The heat generation of the structural parts is calculated by the electrothermal coupled model, and the heat source of the structural parts is obtained. Qe=J*E; J is the electric field, E is the current density, the electric field flows through each part after applying current, and the electrothermal coupling model is obtained based on the coupling of current and heat. It should be noted that the heat source of the structural member is a distributed heat source that is infinitely close to the actual working condition, and the current density is different when the current flows through different positions of the structural member.

S290. Set a third boundary condition of the electric field, and add contact impedance to each welding position; the third boundary condition includes initial current and electrical grounding; set a fourth boundary condition of the second heat transfer field; the fourth boundary condition includes convection heat transfer coefficient, heat source and thermal conductivity.

First, set the third boundary conditions for the electric field: the initial current setting, and the electrical grounding setting. The electric field action area is the area where the current of the structural member flows, and the current here sets the current at a specific rate; then, COMSOL is used in the electric field. The Multiphisics software preset interface adds contact resistance to each weld area. At this time, the contact impedance is the initial value set manually.

The fourth boundary condition is set for the second heat transfer field. The fourth boundary condition that needs to be set for the second heat transfer field is consistent with the electrochemical thermal model. The heat source here comes from the heat production power calculated by the electrochemical thermal model. The active area of the heat transfer module is all areas, and the electrochemical heat generating heat source is manually imported by means of an interpolation function, and can be called by the rules of the COMSOL Multiphisics software. In one embodiment, the second heat transfer field may include: heat conduction between the pole group and the structural member; convection heat exchange between the cover plate, the casing and the air; heat conduction between the pole group and the casing; hot.

The above steps S260 to S290 are the specific process of establishing the electrothermal coupling model and importing the electrochemical heat generation; loading the electrothermal coupling model to set the working conditions.

S300 , adjusting the contact resistances of different welding positions to match the simulated temperature data of each test area with the measured temperature data; in response to matching the simulated temperature data of the test area with the measured temperature data, obtain the contact resistance value of the structural member at this time .

Adjust the contact resistance value of different welding places to make the simulation match well with the actual measurement at different positions. At this time, the contact resistance value is considered to be the real contact resistance value.

The embodiment of the present application provides a method for obtaining the contact resistance of a cell structure, so as to obtain an accurate contact resistance value, so as to facilitate the evaluation of the overcurrent capability of the cell structure under different working conditions.

FIG. 9 is a schematic structural diagram of a device for acquiring the contact resistance of a cell structure provided by an embodiment of the present application. The device for obtaining the contact resistance of the cell structure provided in this embodiment can obtain the contact resistance, for example, the contact resistance of the cell structure can be obtained.

As shown in Figure 9, the device for obtaining the contact resistance of the cell structure includes:

The module calibration unit 310 is configured to use an electrochemical thermal model to correct the charge-discharge voltage simulation curves and temperature simulation curves of different magnifications;

The electrochemical simulation unit 320 is configured to simulate the electrochemical heat generation under the set operating conditions through the revised electrochemical thermal model;

The electrothermal coupling simulation unit 330 is configured to establish an electrothermal coupling model and import the electrochemical heat generation; load the electrothermal coupling model to set working conditions;

The contact resistance modulation unit 340 is configured to adjust the contact resistance of different welding positions, so as to match the simulated temperature data of each test area with the measured temperature data; in response to the simulated temperature data of the test area matching the measured temperature data, obtain the structural component contact resistance value.

The device for obtaining contact resistance provided by the embodiment of the present disclosure can execute the method for obtaining the contact resistance of a cell structure provided by any embodiment of the present disclosure, and has functional modules and beneficial effects corresponding to the execution method.

It is worth noting that the units and modules included in the above device are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be realized; in addition, the specific names of the functional units are only For the convenience of distinguishing from each other, it is not used to limit the protection scope of the embodiments of the present disclosure.

FIG. 10 is a schematic structural diagram of a device for obtaining contact resistance of a cell structure provided by an embodiment of the present application, and FIG. 10 shows a structural diagram of the internal components of a terminal device or a server. In this embodiment, the terminal device is suitable for realizing this The device 600 for obtaining the contact resistance of the cell structure of the disclosed embodiment is disclosed. Terminal devices in the embodiments of the present disclosure may include, but are not limited to, such as mobile phones, notebook computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (tablets), PMPs (Portable Media Players, portable multimedia players) Players), in-vehicle terminals (eg, in-vehicle navigation terminals), etc., and stationary terminals such as digital TVs (Television), desktop computers, and the like. The device shown in FIG. 10 is only an example, and should not impose any limitation on the function and scope of use of the embodiments of the present disclosure.

As shown in FIG. 10 , the device 600 for obtaining the contact resistance of the cell structure may include a processing device 601 (such as a central processing unit, a graphics processing unit, etc.), which may be stored in a read-only memory (Read-Only Memory, ROM) 602 according to the Various appropriate actions and processes are performed by the program in the storage device 608 or the program loaded into the random access memory (RAM) 603 from the storage device 608 . In the RAM 603, various programs and data required for the operation of the acquisition device 600 of the contact resistance of the cell structure are also stored. The processing device 601, the ROM 602, and the RAM 603 are connected to each other through a bus 604. An Input/Output (I/O) interface 605 is also connected to the bus 604 .

Typically, the following devices can be connected to the I/O interface 605: input devices 606 including, for example, a touch screen, touchpad, keyboard, mouse, camera, microphone, accelerometer, gyroscope, etc.; including, for example, a Liquid Crystal Display (LCD) Output device 607 , speaker, vibrator, etc.; storage device 608 , including, for example, magnetic tape, hard disk, etc.; and communication device 609 . The communication means 609 may allow the acquisition device 600 of the contact resistance of the cell structure to perform wireless or wired communication with other devices to exchange data. While FIG. 10 shows a cell structure contact resistance acquisition apparatus 600 having various means, it should be understood that not all of the illustrated means are required to be implemented or provided. More or fewer devices may alternatively be implemented or provided.

In particular, the processes described above with reference to the flowcharts may be implemented as computer software programs according to embodiments of the present disclosure. For example, embodiments of the present disclosure include a computer program product comprising a computer program carried on a non-transitory computer readable medium, the computer program containing program code for performing the method illustrated in the flowchart. In such an embodiment, the computer program may be downloaded and installed from the network via the communication device 609, or from the storage device 608, or from the ROM 602. When the computer program is executed by the processing device 601, the above-mentioned functions defined in the method for obtaining the contact resistance of the cell structure in the embodiment of the present disclosure are executed.

The device provided by the embodiment of the present disclosure and the method for obtaining the contact resistance of the cell structure provided by the above-mentioned embodiment belong to the same disclosed concept. For the technical details not described in detail in this embodiment, please refer to the above-mentioned embodiment, and this embodiment is similar to the above-mentioned embodiment. The embodiments have the same beneficial effect.

Embodiments of the present disclosure provide a computer storage medium, where a computer program is stored on the computer storage medium, and when the program is executed by a processor, the method for obtaining the contact resistance of a cell structure provided by the foregoing embodiments is implemented.

It should be noted that the computer-readable medium mentioned above in the present disclosure may be a computer-readable signal medium or a computer-readable storage medium, or any combination of the above two. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, or a combination of any of the above. More specific examples of computer readable storage media may include, but are not limited to, electrical connections with one or more wires, portable computer disks, hard disks, random access memory (RAM), read only memory (ROM), erasable Erasable Programmable Read-Only Memory (EPROM) or Flash Memory (FLASH), Optical Fiber, Portable Compact Disc Read-Only Memory (CD-ROM), Optical Storage Devices, Magnetic Storage Devices, or Any suitable combination of the above. In this disclosure, a computer-readable storage medium may be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In the present disclosure, however, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave with computer-readable program code embodied thereon. Such propagated data signals may take a variety of forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the foregoing. A computer-readable signal medium can also be any computer-readable medium other than a computer-readable storage medium that can transmit, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device . The program code contained on the computer-readable medium can be transmitted by any suitable medium, including but not limited to: electric wire, optical cable, RF (Radio Frequency, radio frequency), etc., or any suitable combination of the above.

In some embodiments, the client and server can use any currently known or future developed network protocol such as HTTP (Hyper Text Transfer Protocol) to communicate, and can communicate with digital data in any form or medium. Data communications (eg, communication networks) are interconnected. Examples of communication networks include Local Area Networks (LANs), Wide Area Networks (WANs), the Internet (eg, the Internet), and peer-to-peer networks (eg, ad hoc peer-to-peer networks), as well as any currently Known or future developed networks.

The above-mentioned computer-readable medium may be included in the above-mentioned apparatus; or may exist alone without being incorporated into the apparatus.

The above-mentioned computer-readable medium carries one or more programs, and when the above-mentioned one or more programs are executed by the device, causes the device to:

establishing an electro-thermal coupling model and importing the electrochemical heat generation; loading the set operating conditions on the electro-thermal coupling model;

Adjust the contact resistance of different welding positions to match the simulated temperature data of each test area with the measured temperature data; in response to the simulated temperature data of the test area matching the measured temperature data, obtain the contact resistance value of the structural member at this time .

Computer program code for performing operations of the present disclosure may be written in one or more programming languages, including but not limited to object-oriented programming languages—such as Java, Smalltalk, C++, and This includes conventional procedural programming languages - such as the "C" language or similar programming languages. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer, or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any kind of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (eg, using an Internet service provider through Internet connection).

The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code that contains one or more logical functions for implementing the specified functions executable instructions. It should also be noted that, in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It is also noted that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented in dedicated hardware-based systems that perform the specified functions or operations , or can be implemented in a combination of dedicated hardware and computer instructions.

The units involved in the embodiments of the present disclosure may be implemented in a software manner, and may also be implemented in a hardware manner. Wherein, the names of units and modules do not constitute limitations on the units and modules themselves in certain circumstances. For example, the data generation module may also be described as a "video data generation module".

The functions described herein above may be performed, at least in part, by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that may be used include: Field Programmable Gate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs), Application Specific Standard Products (Application Specific Standard Products) Standard Parts, ASSP), system on chip (System on Chip, SOC), complex programmable logic device (Complex Programmable Logic Device, CPLD) and so on.

In the context of the present disclosure, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in connection with the instruction execution system, apparatus or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. Machine-readable media may include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media would include one or more wire-based electrical connections, portable computer disks, hard disks, random access memory (RAM), read only memory (ROM), erasable programmable read only memory (EPROM or flash memory), fiber optics, compact disk read only memory (CD-ROM), optical storage, magnetic storage, or any suitable combination of the foregoing.

The storage medium may be a non-transitory storage medium.

The above are only some embodiments of the present application and applied technical principles. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present application. Therefore, although the present application has been described in detail through the above embodiments, the present application is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention. The scope is determined by the scope of the appended claims.

Claims

A method for obtaining the contact resistance of a cell structure, comprising:

The electrochemical thermal model is used to correct the charge-discharge voltage simulation curves and temperature simulation curves of different rates;

The electrochemical heat generation under the set operating conditions is simulated by the modified electrochemical thermal model;

establishing an electro-thermal coupling model and importing the electrochemical heat generation; loading the set operating conditions on the electro-thermal coupling model;

The contact resistances of different welding positions are adjusted to match the simulated temperature data of each test area with the measured temperature data; in response to the simulated temperature data of the test area matching the measured temperature data, the contact resistance value of the structural member is obtained.
The method for obtaining the contact resistance of a cell structure according to claim 1, wherein the test area includes: a positive pole, a negative pole, the center of the large surface of the case, and the center of the bipolar group.
The method for obtaining the contact resistance of a cell structure according to claim 1, before using the electrochemical thermal model to correct the charge-discharge voltage simulation curves and temperature simulation curves of different magnifications, further comprising:

obtaining model parameters; the model parameters include design parameters, cell geometric parameters and thermal parameters;

The geometrical parameters of the cell include the geometrical parameters of the casing, the geometrical parameters of the pole group and the geometrical parameters of the structural member; the thermal parameters include thermal conductivity, specific heat capacity and density.
The method for obtaining the contact resistance of a cell structure according to claim 3, wherein the pole group comprises a plurality of pole piece units; each pole piece unit comprises a multi-layer material; the multi-layer material comprises positive electrodes arranged in sequence Current collectors, positive electrodes, separators, negative electrodes and negative current collectors;

The specific heat capacity C P is obtained according to ρC P =∑ i ρ i C Pi d i /∑ i d i ; where ρ i is the density of each layer of material; C Pi is the specific heat capacity of each layer of material; d i is the thickness of each layer of material;

The thermal conductivity includes normal thermal conductivity k z and extensional thermal conductivity k r ;

k r ∑ i d i =∑ i k i d i ; wherein, k i is the thermal conductivity of each layer of material.
The method for obtaining the contact resistance of a cell structure according to claim 3, wherein the electrochemical thermal model comprises a lithium battery field and a first heat transfer field coupled with each other;

The electrochemical thermal model is used to correct the charge-discharge voltage simulation curve and temperature simulation curve at different rates, including:

establishing a one-dimensional lithium battery field and a three-dimensional first heat transfer field according to the design parameters;

Setting the first boundary condition of the lithium battery field; the first boundary condition includes initial capacity, initial voltage, initial current density, charge-discharge rate and cut-off voltage; setting the second boundary condition of the first heat transfer field; The second boundary condition includes convective heat transfer coefficient, heat source and thermal conductivity;

The electrochemical thermal model is calibrated according to the measured charge and discharge voltage, so that the measured curve of the charge and discharge voltage matches the simulation curve of the charge and discharge voltage; the electrochemical thermal model is calibrated according to the measured temperature, so that the measured temperature curve and the temperature simulation curve are match.
The method for obtaining the contact resistance of a cell structure according to claim 3 or 5, wherein the electrothermal coupling model comprises a mutually coupled electric field and a second heat transfer field;

establishing an electrothermal coupling model and importing the electrochemical heat generation; loading the set operating conditions on the electrothermal coupling model, including:

establishing the electric field and the second heat transfer field according to the design parameters;

Add the welding stamp information of the welding position; the welding stamp information includes the welding stamp shape, the effective area, the welding stamp position, the welding stamp number and the welding stamp penetration depth;

A heat source is set; the heat source includes the electrochemical heat generation and the structural member heat source; the electrochemical heat generation is imported through an interpolation function; the structural member heat source Qe=J*E; J is the electric field, and E is the current density; wherein , the current density is different when the current flows through different positions of the structural member, so that the heat source of the structural member is a distributed heat source that simulates actual working conditions;

Set the third boundary condition of the electric field, adding contact resistance to each welding position; the third boundary condition includes initial current and electrical grounding; set the fourth boundary condition of the second heat transfer field; the fourth boundary condition Boundary conditions include convective heat transfer coefficient, heat source and thermal conductivity;

The welding positions include laser welding positions and ultrasonic welding positions;

The laser welding position is the welding between the connecting piece and the cover plate; the ultrasonic welding position is the welding between the tab and the connecting piece.
The method for obtaining the contact resistance of a cell structure part according to claim 6, wherein the second heat transfer field comprises: heat conduction between the electrode group and the structure part; convection heat exchange between the cover plate, the casing and the air; The heat conduction between the pole group and the shell; the electrochemical heat generation of the set working condition.
A method for obtaining the contact resistance of a cell structure, comprising:

Adopt an electrochemical thermal model, and modify the charge-discharge voltage simulation curves and temperature simulation curves of different rates corresponding to the electrochemical thermal model;

The electrochemical heat generation under the set operating conditions is simulated by the modified electrochemical thermal model;

establishing an electro-thermal coupling model and importing the electrochemical heat generation; loading the set operating conditions on the electro-thermal coupling model;

The contact resistances of different welding positions are adjusted to match the simulated temperature data of each test area with the measured temperature data; in response to the simulated temperature data of the test area matching the measured temperature data, the contact resistance value of the structural member is obtained.
A device for acquiring contact resistance of a cell structure, comprising:

The module calibration unit is set to use the electrochemical thermal model to correct the charge-discharge voltage simulation curves and temperature simulation curves of different magnifications;

an electrochemical simulation unit, configured to simulate the electrochemical heat generation under the set operating conditions by using the revised electrochemical thermal model;

an electro-thermal coupling simulation unit, configured to establish an electro-thermal coupling model and import the electrochemical heat generation; load the set working condition on the electro-thermal coupling model;

A contact resistance modulation unit, configured to adjust the contact resistance of different welding positions, so that the simulated temperature data of each test area matches the measured temperature data; in response to the simulated temperature data of the test area matching the measured temperature data, the structure is obtained contact resistance value of the parts.
A device for obtaining the contact resistance of a cell structure, comprising:

one or more processors;

storage means arranged to store one or more programs,

When the one or more programs are executed by the one or more processors, the one or more processors implement the contact resistance of the cell structure according to any one of claims 1-7 or 8. get method.
A storage medium containing computer-executable instructions, when executed by a computer processor, the computer-executable instructions are used to execute the method for obtaining the contact resistance of a cell structure member according to any one of claims 1-7 or 8 .