Analysis method, storage medium, electronic device and system for internal temperature of battery cell

Abstract

This application provides a method, storage medium, electronic device, and system for analyzing the internal temperature of a battery cell. The method comprises: obtaining the ambient temperature and surface temperature corresponding to the battery at different times; determining the instantaneous spatial distribution of the internal temperature of the battery cell at the current time based on the ambient temperature and surface temperature; and determining the internal temperature of the battery cell corresponding to different times using the distribution parameters contained in the instantaneous spatial distribution. By constructing and solving a physical mathematical model, this application can obtain the internal temperature distribution of the battery cell without destroying the battery cell, simply by measuring the surface temperature.

Description

Technical Field

[0001] The present application belongs to the technical field of battery monitoring and relates to a temperature analysis method, and in particular to a method for analyzing the internal temperature of a battery cell, a storage medium, an electronic device, and a system. Background Art

[0002] Thermal management of lithium-ion batteries has always been a concern in the industry. Effective thermal management can improve battery efficiency, maximize battery energy efficiency, and avoid thermal runaway.

[0003] During the charge and discharge process, lithium-ion batteries undergo electrochemical reactions within the positive and negative electrodes of each cell, accompanied by polarization. This, combined with the influence of the battery's internal resistance, causes continuous heat generation and temperature fluctuations. If the heat generation rate is excessive, the ability to dissipate heat from the battery surface to the outside world is limited, and the thermal conductivity of the electrode material is insufficient to quickly transfer the heat to the battery surface, heat accumulation can cause the internal temperature to rise rapidly beyond the safety threshold, leading to thermal runaway. Furthermore, a fire in a single cell can spread rapidly, threatening the safety of the entire module and even the entire system.

[0004] Currently, common battery temperature monitoring methods typically place temperature sensors on the battery surface. However, this approach introduces certain inaccuracies. Due to the thermal conductivity of electrode materials, heat transfer from internal heat sources to the battery surface takes time, resulting in temperature discrepancies between the battery surface and the interior of the cell. This discrepancy becomes more pronounced with increasing charge and discharge rates, and the temperature difference between inside and outside increases. This temperature discrepancy significantly impacts temperature monitoring accuracy. Placing the temperature sensor inside the cell, however, compromises its integrity. Summary of the Invention

[0005] The purpose of this application is to provide a method, storage medium, electronic device and system for analyzing the internal temperature of a battery cell, so as to solve the problem of how to accurately analyze the internal temperature of a battery cell without destroying the integrity of the battery cell.

[0006] A first aspect of an embodiment of the present application provides a method for analyzing the internal temperature of a battery cell, the method comprising: obtaining the ambient temperature and surface temperature corresponding to the battery at different times; determining the instantaneous spatial distribution of the internal temperature of the battery cell at the current moment based on the ambient temperature and the surface temperature; and determining the internal temperature of the battery cell corresponding to different moments using the distribution parameters contained in the instantaneous spatial distribution.

[0007] In an implementation of the first aspect, the step of obtaining the ambient temperature corresponding to the battery at different times includes: allowing the battery to stand still sufficiently so that the battery temperature is the same as room temperature, and using the surface temperature of the battery at this time as the ambient temperature.

[0008] In an implementation of the first aspect, the interior of the battery cell is spatially divided into three parts: a positive electrode, a negative electrode, and a diaphragm; the step of obtaining the surface temperature of the battery corresponding to different moments includes: in response to the battery changing from a static state to a working state, recording the moment of state change as the initial moment and setting a time step; starting from the initial moment, recording the surface temperature of each time node according to the time step until charging and discharging are completed; the recorded surface temperature includes positive electrode surface temperature data and negative electrode surface temperature data.

[0009] In an implementation of the first aspect, the step of obtaining the surface temperature corresponding to the battery at different times further includes: adding and averaging the positive electrode surface temperature data and the negative electrode surface temperature data at each time node, and determining the average positive electrode surface temperature and the average negative electrode surface temperature corresponding to each time node.

[0010] In an implementation of the first aspect, the step of determining the instantaneous spatial distribution of the internal temperature of the battery cell at the current moment based on the ambient temperature and the surface temperature includes: substituting the ambient temperature and the surface temperature into the battery cell temperature function model respectively to determine the distribution parameters contained in the negative electrode temperature function, the diaphragm temperature function and the positive electrode temperature function; reversely substituting the distribution parameters contained in the negative electrode temperature function into the negative electrode temperature function to determine the instantaneous spatial distribution of the negative electrode surface temperature inside the battery cell at the current moment; reversely substituting the distribution parameters contained in the diaphragm temperature function into the diaphragm temperature function to determine the instantaneous spatial distribution of the diaphragm surface temperature inside the battery cell at the current moment; reversely substituting the distribution parameters contained in the positive electrode temperature function into the positive electrode temperature function to determine the instantaneous spatial distribution of the positive electrode surface temperature inside the battery cell at the current moment.

[0011] In an implementation of the first aspect, the method further includes: performing definite integrals on the negative electrode temperature function, the diaphragm temperature function, and the positive electrode temperature function, respectively, to correspondingly solve the negative electrode surface average temperature, the diaphragm surface average temperature, and the positive electrode surface average temperature; and determining the overall average temperature inside the battery cell based on the negative electrode surface average temperature, the diaphragm surface average temperature, and the positive electrode surface average temperature.

[0012] In an implementation of the first aspect, the step of using the distribution parameters contained in the instantaneous spatial distribution to determine the internal temperature of the battery cell corresponding to different moments includes: calculating the first-order derivative of the negative electrode temperature function, the diaphragm temperature function and the positive electrode temperature function with respect to time; combining the first-order derivative with the partial differential function of the battery cell temperature and the boundary conditions to obtain the time-based expression function of the average temperature of the negative electrode, diaphragm and positive electrode; wherein the boundary conditions include: the boundary temperature on both sides of the positive and negative electrodes is equal to the surface temperature, and the temperature at each location at the initial moment is the ambient temperature; the temperature at the interface between the electrode and the diaphragm remains continuous, the spatial rate of change of temperature also remains continuous, and the spatial rate of change of temperature at the boundaries on both sides is equivalent to the heat dissipation rate between the surface and the surrounding environment; the distribution parameters contained in the instantaneous spatial distribution are substituted into the time-based expression function of the average temperature of the negative electrode, diaphragm and positive electrode to determine the internal temperature of the battery cell corresponding to different moments.

[0013] A second aspect of an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, which implements the method described when the computer program is executed by a processor.

[0014] The third aspect of the embodiment of the present application provides an electronic device, comprising: a processor and a memory; the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the electronic device executes the method described in

[0015] A fourth aspect of an embodiment of the present application provides a system for analyzing the internal temperature of a battery cell, the system comprising: the electronic device and a temperature measuring device; the temperature measuring device is communicatively connected to the electronic device; the temperature measuring device is disposed on the surface of the battery and is configured to measure the ambient temperature and surface temperature corresponding to the battery at different times, and transmit the ambient temperature and the surface temperature to the electronic device.

[0016] As described above, the method, storage medium, electronic device, and system for analyzing the internal temperature of a battery cell described in this application have the following beneficial effects:

[0017] This application simplifies the physical and mathematical model. Without destroying the battery cell, it is only necessary to measure the surface temperature to calculate the temperature distribution inside the battery cell. Under the premise of ensuring that the actual physical scene can be restored, the calculation speed is fast and the computing power requirement is low. The physical and mathematical model is combined with actual data such as the battery surface temperature at different times, and the calculation accuracy of the internal temperature distribution of the battery is high. This application uses the surface temperature of the battery cell to further realize the internal temperature of the battery cell as a battery monitoring indicator, which can more sensitively capture anomalies and greatly reduce the risk of thermal runaway. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1Shown is a schematic diagram of an application scenario of the method for analyzing the internal temperature of a battery cell described in an embodiment of the present application.

[0019] Figure 2 Shown is a principle flow chart of the method for analyzing the internal temperature of a battery cell according to an embodiment of the present application.

[0020] Figure 3 Shown is a flow chart of the method for analyzing the internal temperature of a battery cell according to an embodiment of the present application.

[0021] Figure 4 A simplified schematic diagram of a battery cell is shown, illustrating the method for analyzing the internal temperature of a battery cell according to an embodiment of the present application.

[0022] Figure 5 A comparison chart showing the measured temperature and calculated temperature of the battery cell internal temperature analysis method described in an embodiment of the present application is shown.

[0023] Figure 6 Shown is a temperature spatial distribution diagram at different discharge stages of the method for analyzing the internal temperature of a battery cell described in an embodiment of the present application.

[0024] Figure 7 Shown is a schematic diagram of the structural connection of the electronic device described in an embodiment of the present application.

[0025] Figure 8 Shown is a structural principle diagram of the battery cell internal temperature analysis system described in an embodiment of the present application.

[0026] Component number description

[0027] 1 Electronic devices

[0028] 11 Processor

[0029] 12 Memory

[0030] 13 Communication Interface

[0031] 14 System Bus

[0032] 2 Temperature measurement device

[0033] Steps S21 to S23 DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present application through specific examples. Those skilled in the art can easily understand the other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other unless they conflict.

[0035] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. Therefore, the illustrations only show components related to the present application and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0036] The following embodiments of the present application provide a method for analyzing the internal temperature of a battery cell, a storage medium, an electronic device, and a system, including but not limited to applications in an electronic device. The following description will be given using this hardware application scenario as an example.

[0037] See also Figure 1 , which is a schematic diagram showing an application scenario of the method for analyzing the internal temperature of a battery cell according to an embodiment of the present application. Figure 1 As shown, this embodiment provides a hardware application scenario for a method for analyzing the internal temperature of a battery cell, specifically comprising: an electronic device and a temperature measurement device. The temperature measurement device is located on the surface of the battery cell and transmits the measured ambient temperature and surface temperature to a computer device via wired or wireless means, so that the electronic device executes the method for analyzing the internal temperature of the battery cell and outputs the analysis results of the internal temperature of the battery cell.

[0038] The electronic device may be, for example, a computer including all or part of the components such as a memory, a storage controller, one or more processing units (CPUs), a peripheral interface, an RF circuit, an audio circuit, a speaker, a microphone, an input / output (I / O) subsystem, a display screen, other output or control devices, and an external port; the computer includes but is not limited to personal computers such as desktop computers, laptop computers, tablet computers, smart phones, and personal digital assistants (PDAs). In other embodiments, the electronic device may also be a server, which may be arranged on one or more physical servers based on various factors such as function and load, or may be a cloud server composed of a distributed or centralized server cluster, which is not limited in this embodiment.

[0039] The technical solutions in the embodiments of the present application will be described in detail below with reference to the accompanying drawings in the embodiments of the present application.

[0040] See also Figure 2 , which is a flow chart showing the principle of the method for analyzing the internal temperature of the battery cell according to the embodiment of the present application. Figure 2 As shown, this embodiment provides a method for analyzing the internal temperature of a battery cell, which can be applied to calculate the internal temperature distribution of a lithium-ion battery cell, and specifically includes the following steps:

[0041] S21, obtaining the ambient temperature and surface temperature of the battery at different times.

[0042] See also Figure 3 , which is a flow chart showing the method for analyzing the internal temperature of the battery cell according to the embodiment of the present application. Figure 3 As shown, the analysis method of the internal temperature of the battery cell described in this application is based on Figure 3 The third part is as follows: A. Simplify the physical field to construct a mathematical model, so that the present application can construct an approximate model of the internal temperature of the battery cell by simplifying the physical field and mathematical modeling; B. Measure the surface temperature of the battery cell, so that the present application can use the actual measured surface temperature data to solve the temperature model and obtain the temperature distribution inside the battery cell without disassembling the battery; C. Calculate the mathematical model to obtain the internal temperature distribution, so that the present application can use the calculation results of the temperature model to determine the safety status inside the battery cell. The basis for the implementation of the analysis method of the internal temperature of the battery cell described in the present application is to complete the simplified physical field to construct the mathematical model and pre-set the temperature measurement device on the battery surface to measure the surface temperature of the battery cell.

[0043] In Part A, the process of constructing the physical mathematical model of the battery is as follows:

[0044] See also Figure 4 , which is a simplified schematic diagram of a battery cell according to the method for analyzing the internal temperature of a battery cell according to an embodiment of the present application. Figure 4 As shown, a simplified physical model of a single battery cell is shown. The interior of the battery cell can be briefly divided into three parts: positive electrode, negative electrode and separator, where Lp, Ln and Ls are the thickness of the positive electrode, negative electrode and separator respectively. The positive and negative electrodes contain solid-phase active material reaction particles and liquid-phase electrolyte, and the separator contains only liquid-phase electrolyte. The outer surfaces of the positive and negative electrodes are in contact with the surrounding environment, and there is convection heat transfer. When the battery is in working state, there is a non-zero current, and all three parts will generate heat. Electrochemical reactions occur at the solid-liquid interface in the positive and negative electrodes, generating heat including reaction heat, polarization heat and ohmic heat, while the separator only contains electrolyte, which is only responsible for the transmission of lithium ions and only generates ohmic heat. Therefore, the heat generated by the electrodes on both sides is greater than that of the separator.

[0045] This simplified physical model can be abstracted into a one-dimensional heat conduction model, where the dimension is the X-axis where the three domains are located. Combined with this simplified physical model and based on Fourier's law, the partial differential equation expression for the cell temperature can be obtained as follows:

[0046]

[0047] Where T is temperature, t is time, x is the x-axis coordinate, k is a thermal conductivity parameter related to the material properties, and Q is a heat generation related parameter.

[0048] According to physical facts, the above partial differential equation has boundary conditions as follows:

[0049] (1) The boundary temperature on both sides of the positive and negative electrodes is equal to the surface temperature. At the initial moment, the temperature everywhere is the ambient temperature, that is,

[0050] T(0, t) = T surface_neg , T(L, t) = T surface_pos , T(x, 0) = T amb Formula (2)

[0051] (2) The temperature at the interface between the electrode and the diaphragm remains continuous, and the spatial temperature change rate also remains continuous, that is,

[0052]

[0053]

[0054] (3) The spatial temperature change rate at the boundaries on both sides is equivalent to the heat dissipation rate between the surface and the surrounding environment, that is,

[0055]

[0056] In the above boundary condition expressions, namely formula (2) to formula (5), T surface_neg is the surface temperature of the negative electrode, T surface_pos is the positive electrode surface temperature, T amb is the ambient temperature, L - 、L + The superscript (positive and negative signs) indicates the left and right sides of the same interface, k n 、k s 、k p The thermal conductivity parameters of the three parts are: air_1 ,q air_2 are the heat dissipation parameters of the positive and negative electrode outer surfaces and the environment respectively.

[0057] Referring to the positive electrode, negative electrode and diaphragm in the cell space, the temperature function is also divided into three sub-functions f n 、f s and f p The specific expression is as follows:

[0058]

[0059] In the above expression, a1-a11 are 11 unknowns set according to the calculation needs. Among them, because the heat generation of the electrodes on both sides is greater than that of the diaphragm, and the geometric size is also larger than that of the diaphragm, the thermal field is more complex, and the highest order term of the electrode temperature expression is correspondingly higher than that of the diaphragm. The negative electrode temperature function f n and the positive electrode temperature function f pThe number of distribution parameters included is greater than that of the diaphragm temperature function f s The number of distributed parameters involved is greater, meaning that the 11 unknowns a1-a11 are distributed more across the electrode functions than the diaphragm functions. In practical applications, in addition to setting these 11 unknowns a1-a11, more or fewer unknowns can be set based on computational needs.

[0060] At the same time, the definite integral of the temperature field in each region is used to calculate the average temperature, and the expression is as follows:

[0061]

[0062] Among them, T avg,n 、T avg,s 、T avg,p are the average temperatures of the negative electrode, separator, and positive electrode, respectively.

[0063] Combining all the above expressions, namely formula (1) to formula (7), we can get a system of equations containing 11 equations, as follows

[0064]

[0065] Among them, L n 、L s 、L p are the thicknesses of the negative electrode, separator, and positive electrode of the battery cell, respectively, which can be obtained by actual measurement. The remaining mathematical symbols have the same meanings as those in formulas (1) to (7). By solving the above equations, the values of the distribution parameters a1-a11 can be obtained. Substituting these values into f in formula (6) n 、f s and f p , you can get the instantaneous temperature spatial distribution, you can also get the average temperature of each part according to formula (7), and you can also get the overall average temperature of the battery cell according to the following formula (9). The calculation formula for the overall average temperature is as follows:

[0066]

[0067] Among them, T avg,total is the overall average temperature.

[0068] f n 、f s and f p By taking the first-order derivative with respect to time t and combining the partial differential equation of the cell temperature (1) and the boundary condition formulas (2) to (5), we can get the expression of the average temperature of each part in time, as follows:

[0069]

[0070]

[0071]

[0072] The superscripts t and t+1 of temperature T represent time t and the next time (time t+1), respectively, Δt is the time step between the two times, and Q n , Q s , Q p are the heat generation efficiencies of the negative electrode, separator, and positive electrode, respectively. The remaining mathematical symbols have the same meanings as those in the above formula.

[0073] In summary, in Part A, physical simplification is first performed, and then mathematical modeling is used to construct a mathematical model that can calculate the temperature distribution of the battery cell. This model can calculate the spatial distribution of the temperature inside the battery cell and also obtain the temporal change of the average temperature of the battery cell.

[0074] In Part B, the process of measuring the cell surface temperature is as follows:

[0075] Selecting multiple temperature sensors of uniform specifications can avoid errors caused by different sensor models. Divide these sensors into two groups according to the number of sensors and evenly place the two groups of sensors at different positions on the outer surface of the positive and negative electrodes of the battery cell. Let the battery rest for a long time to ensure that its temperature is the same as the room temperature. Record the temperature at this time, which is the ambient temperature T amb It's worth noting that at this point, because the battery is in steady state and there's no heat source, the internal temperature field is stable, and the temperature everywhere in the space is equal to the ambient temperature. Naturally, the average temperature is also equal to the ambient temperature. When the battery begins operating from rest, the moment of state transition is the initial time t = 0. Set the time step to Δt. Starting from this initial time, all sensor parameters are recorded at each time step of Δt until the charge and discharge cycle is complete. The recorded data is grouped as described above, into positive and negative electrode temperature data. The data from each group can also be summed and averaged at each time point to reduce spatial error.

[0076] For example, a lithium-ion battery cell is discharged from a fully charged state at a constant current of 1C for one hour, with a time step Δt of 1 second. Four temperature sensors are placed on each of the positive and negative electrodes. Following the above implementation details and recording the data, 3600 seconds × 2 electrodes × 4 sensor data points are obtained. Within each second, the four data points for a single electrode are summed and averaged to obtain the instantaneous electrode surface temperature. The same operation is performed on the other electrode, yielding 3600 seconds × 2 electrodes of surface temperature data. This surface temperature data can then be used for the model calculation in Part A.

[0077] In one embodiment, the step of obtaining the ambient temperature corresponding to the battery at different times includes: allowing the battery to stand still until the battery temperature is equal to the room temperature, and using the surface temperature of the battery at this time as the ambient temperature T amb .

[0078] In one embodiment, the interior of the battery cell is spatially divided into three parts: a positive electrode, a negative electrode, and a separator; and the step of obtaining the surface temperature of the battery at different times includes:

[0079] In response to the battery changing from a rest state to a working state, the moment of state change is recorded as the initial moment and a time step is set; starting from the initial moment, the surface temperature of each time node is recorded according to the time step until the charge and discharge are completed; the recorded surface temperature includes the positive electrode surface temperature data T surface_neg And the negative electrode surface temperature data T surface_pos .

[0080] In one embodiment, the step of obtaining the surface temperature of the battery at different times further includes:

[0081] At each time node, the positive electrode surface temperature data and the negative electrode surface temperature data are summed and averaged to determine the positive electrode surface temperature average value and the negative electrode surface temperature average value corresponding to each time node.

[0082] S22: Determine the instantaneous spatial distribution of the internal temperature of the battery cell at the current moment according to the ambient temperature and the surface temperature.

[0083] In one embodiment, step S22 specifically includes:

[0084] Substitute the ambient temperature and the surface temperature into the battery core temperature function model, that is, combine the formula (1) to the formula (7) to derive the formula (8) to determine the negative electrode temperature function f n , diaphragm temperature function f s And the positive electrode temperature function f p The distribution parameters a1-a contained in each 11 ;

[0085] Combined with formula (6), the negative electrode temperature function f n The included distribution parameters a1-a4 are reversely substituted into the negative electrode temperature function f n In the process, the instantaneous spatial distribution of the surface temperature of the negative electrode inside the battery cell at the current moment is determined; the diaphragm temperature function f s The included distribution parameters a5-a7 are reversed into the diaphragm temperature function f s In the process, the instantaneous spatial distribution of the surface temperature of the diaphragm inside the cell at the current moment is determined; the positive electrode temperature function f pContains the distribution parameters a8-a 11 Substitute the positive electrode temperature function f in reverse p In the process, the instantaneous spatial distribution of the positive electrode surface temperature inside the battery cell at the current moment is determined.

[0086] In one embodiment, the method further includes:

[0087] Combined with formula (7), the negative electrode temperature function f n , the diaphragm temperature function f s And the positive electrode temperature function f p Definite integrals are performed separately to solve the average surface temperature of the negative electrode, the average surface temperature of the diaphragm, and the average surface temperature of the positive electrode. Combined with formula (9), the overall average temperature inside the battery cell is determined based on the average surface temperature of the negative electrode, the average surface temperature of the diaphragm, and the average surface temperature of the positive electrode.

[0088] See also Figure 5 , which shows a comparison diagram of the measured temperature and the calculated temperature of the battery cell internal temperature analysis method described in the embodiment of the present application. Figure 5 As shown in Figure 1, taking a lithium iron phosphate battery cell with a 1C discharge as an example, the overall average temperature of the battery cell is calculated by measuring the surface temperatures of the positive and negative electrodes and combining them with formula (9). It can be seen that except for the initial moment when all temperatures are ambient temperature, at any other time, the average temperature of the battery cell is significantly higher than the surface temperature of any electrode, indicating that heat accumulation does occur inside the battery cell, and the internal temperature distribution is uneven and higher than the surface temperature.

[0089] S23 , using the distribution parameters included in the instantaneous spatial distribution, determining the internal temperature of the battery cell corresponding to different moments.

[0090] In one embodiment, step S23 specifically includes:

[0091] (1) For the negative electrode temperature function f n , the diaphragm temperature function f s And the positive electrode temperature function f p Take the first derivative with respect to time.

[0092] (2) The first-order derivative is combined with the partial differential function formula (1) of the battery cell temperature and the boundary conditions to obtain the time-based expression function formulas (10) to (12) of the average temperature of the negative electrode, diaphragm and positive electrode; wherein the boundary conditions include: the boundary temperature on both sides of the positive and negative electrodes is equal to the surface temperature, and the temperature at each location at the initial moment is the ambient temperature, that is, formula (2); the temperature at the interface between the electrode and the diaphragm remains continuous, and the spatial temperature change rate also remains continuous, that is, formula (3) to formula (4) and the spatial temperature change rate at the boundaries on both sides is equivalent to the heat dissipation rate between the surface and the surrounding environment, that is, formula (5).

[0093] (3) The distribution parameter a1-a contained in the instantaneous spatial distribution 11 Substitute the time-based expression function formulas (10) to (12) for the average temperature of the negative electrode, diaphragm, and positive electrode respectively to determine the internal temperature of the battery cell corresponding to different times.

[0094] See also Figure 6 , which shows the temperature spatial distribution diagram of different discharge stages of the method for analyzing the internal temperature of the battery cell according to the embodiment of the present application. Figure 6 As shown in the figure, the spatial distribution of the internal temperature at different discharge stages is shown, namely the initial stage (a), the middle stage (b) and the final stage of discharge (c). Figure 6 It can be seen that at the initial time t = 0-3 seconds, the thermal field inside the battery cell suddenly changes from a steady state to a transient state, and the temperature change trend has obvious fluctuations. In the middle and late stages of discharge t = 1800-1803 seconds and t = 3400-3403 seconds, the thermal field trend does not change much, only the temperature value range changes (about 31-42 ° C in the middle stage and about 40-47 ° C in the final stage). Figure 5 、 Figure 6 The presented results are consistent with the actual physical scenario, indicating that the internal calculation method of the battery cell in this application has certain feasibility.

[0095] Therefore, this application only needs to measure the surface temperature of the battery cell to know the temperature distribution inside the battery cell, and based on the internal temperature, the thermal state of the battery can be determined. It is generally believed that the temperature of a healthy lithium-ion battery cannot exceed 50°C; based on this judgment standard, given the known surface temperature of the battery cell, the internal temperature distribution of the battery cell can be calculated, and the maximum internal temperature can be determined. If the calculated result shows that the maximum temperature exceeds 50°C, even if the surface measurement data is still below 50°C, the corresponding battery cell can still be judged to have a thermal runaway risk, and relevant measures should be taken immediately to stop the battery from working and cool it down to avoid more serious fires and explosions.

[0096] The protection scope of the method for analyzing the internal temperature of the battery cell described in the embodiment of the present application is not limited to the execution order of the steps listed in this embodiment. All solutions implemented by adding, reducing, or replacing steps in the prior art based on the principles of the present application are included in the protection scope of the present application.

[0097] The embodiment of the present application also provides a computer-readable storage medium. Those skilled in the art will understand that all or part of the steps in the method for implementing the above embodiment can be completed by instructing the processor through a program, and the program can be stored in a computer-readable storage medium, and the storage medium is a non-transitory medium, such as a random access memory, a read-only memory, a flash memory, a hard disk, a solid-state drive, a magnetic tape, a floppy disk, an optical disc, and any combination thereof. The above storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server or a data center that includes one or more available media. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a tape), an optical medium (for example, a digital video disc (DVD)), or a semiconductor medium (for example, a solid-state drive (SSD)), etc.

[0098] See also Figure 7 , which shows a schematic diagram of the structural connection of the electronic device described in the embodiment of the present application. Figure 7 As shown, the electronic device 1 of the present application includes: a processor 11, a memory 12, a communication interface 13 and / or a system bus 14. The memory 12 and the communication interface 13 are connected to the processor 11 via the system bus 14 and communicate with each other. The memory 12 is used to store computer programs, the communication interface 13 is used to communicate with other devices, and the processor 11 is used to run the computer program to enable the electronic device 1 to perform each step of the method for analyzing the internal temperature of the battery cell.

[0099] The above-mentioned processor 11 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0100] The memory 12 may include a random access memory (RAM), and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0101] The system bus 14 mentioned above can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. The system bus 14 can be divided into an address bus, a data bus, a control bus, etc. The communication interface is used to implement communication between the database access device and other devices (such as clients, read-write libraries, and read-only libraries).

[0102] An embodiment of the present application also provides a system for analyzing the internal temperature of a battery cell. The system for analyzing the internal temperature of a battery cell can implement the method for analyzing the internal temperature of a battery cell described in the present application. However, the device for implementing the method for analyzing the internal temperature of a battery cell described in the present application includes but is not limited to the structure of the system for analyzing the internal temperature of a battery cell listed in the present embodiment. All structural deformations and replacements of the prior art made according to the principles of the present application are included in the scope of protection of the present application.

[0103] See also Figure 8 , which shows the structural principle diagram of the analysis system of the internal temperature of the battery cell according to the embodiment of the present application. Figure 8 As shown, this embodiment provides a system for analyzing the internal temperature of a battery cell, comprising: the electronic device 1 and a temperature measuring device 2 ; the temperature measuring device 2 is communicatively connected to the electronic device 1 .

[0104] The temperature measuring device 2 is disposed on the battery surface and is configured to measure the battery's ambient temperature and surface temperature at different times and transmit the ambient and surface temperatures to the electronic device 1. In practical applications, the temperature measuring device 2 can be any temperature sensor that meets the requirements for battery cell surface temperature testing.

[0105] The electronic device 1 executes the method for analyzing the internal temperature of the battery cell, which includes: obtaining the ambient temperature and surface temperature corresponding to the battery at different times; determining the instantaneous spatial distribution of the internal temperature of the battery cell at the current moment based on the ambient temperature and the surface temperature; and determining the internal temperature of the battery cell corresponding to different moments using the distribution parameters contained in the instantaneous spatial distribution.

[0106] In the several embodiments provided in this application, it should be understood that the disclosed system or method can be implemented in other ways. For example, the system embodiments described above are only schematic. For example, the division of modules / units is only a logical function division. There may be other division methods in actual implementation. For example, multiple modules or units can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or modules or units, which can be electrical, mechanical or other forms.

[0107] The modules / units described as separate components may or may not be physically separate, and the components displayed as modules / units may or may not be physical modules, that is, they may be located in one place or distributed across multiple network elements. Some or all of the modules / units may be selected according to actual needs to achieve the purpose of the embodiments of the present application. For example, the functional modules / units in the various embodiments of the present application may be integrated into a processing module, or each module / unit may exist physically separately, or two or more modules / units may be integrated into a single module / unit.

[0108] Those skilled in the art should further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the composition and steps of each example according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0109] The descriptions of the processes or structures corresponding to the above figures have different emphases. For parts that are not described in detail in a certain process or structure, please refer to the relevant descriptions of other processes or structures.

[0110] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical concepts disclosed in this application shall be covered by the claims of this application.

Claims

1. A method for analyzing the internal temperature of a battery cell, characterized in that: The method comprises: Get the ambient temperature and surface temperature of the battery at different times; Determining the instantaneous spatial distribution of the internal temperature of the battery cell at the current moment according to the ambient temperature and the surface temperature, including: substituting the ambient temperature and the surface temperature into the battery cell temperature function model respectively to determine the distribution parameters contained in the negative electrode temperature function, the diaphragm temperature function and the positive electrode temperature function; reversely substituting the distribution parameters contained in the negative electrode temperature function into the negative electrode temperature function to determine the instantaneous spatial distribution of the negative electrode surface temperature inside the battery cell at the current moment; reversely substituting the distribution parameters contained in the diaphragm temperature function into the diaphragm temperature function to determine the instantaneous spatial distribution of the diaphragm surface temperature inside the battery cell at the current moment; reversely substituting the distribution parameters contained in the positive electrode temperature function into the positive electrode temperature function to determine the instantaneous spatial distribution of the positive electrode surface temperature inside the battery cell at the current moment; The distribution parameters contained in the instantaneous spatial distribution are used to determine the internal temperature of the battery cell corresponding to different moments, including: calculating the first-order derivatives of the negative electrode temperature function, the diaphragm temperature function and the positive electrode temperature function with respect to time; combining the first-order derivatives with the partial differential function of the battery cell temperature and the boundary conditions to obtain the time-based expression function of the average temperature of the negative electrode, diaphragm and positive electrode; wherein the boundary conditions include: the boundary temperature on both sides of the positive and negative electrodes is equal to the surface temperature, and the temperature at each location is the ambient temperature at the initial moment; the temperature at the interface between the electrode and the diaphragm remains continuous, the spatial rate of change of temperature also remains continuous, and the spatial rate of change of temperature at the boundaries on both sides is equivalent to the heat dissipation rate between the surface and the surrounding environment; the distribution parameters contained in the instantaneous spatial distribution are respectively substituted into the time-based expression function of the average temperature of the negative electrode, diaphragm and positive electrode to determine the internal temperature of the battery cell corresponding to different moments.

2. The method according to claim 1, characterized in that The step of obtaining the ambient temperature corresponding to the battery at different times includes: The battery is allowed to stand still until the battery temperature is equal to the room temperature, and the surface temperature of the battery at this time is taken as the ambient temperature.

3. The method according to claim 1, characterized in that The interior of the battery cell is spatially divided into three parts: a positive electrode, a negative electrode, and a separator; and the step of obtaining the surface temperature of the battery at different times includes: In response to the battery changing from a rest state to a working state, recording the moment of state transition as an initial moment and setting a time step; Starting from the initial moment, the surface temperature of each time node is recorded according to the time step until the charging and discharging is completed; the recorded surface temperatures include the positive electrode surface temperature data and the negative electrode surface temperature data.

4. The method according to claim 3, characterized in that The step of obtaining the surface temperature of the battery at different times also includes: At each time node, the positive electrode surface temperature data and the negative electrode surface temperature data are summed and averaged to determine the positive electrode surface temperature average value and the negative electrode surface temperature average value corresponding to each time node.

5. The method according to claim 1, wherein The method further comprises: Performing definite integrals on the negative electrode temperature function, the diaphragm temperature function, and the positive electrode temperature function, respectively, to obtain the negative electrode surface average temperature, the diaphragm surface average temperature, and the positive electrode surface average temperature; The overall average temperature inside the battery cell is determined according to the average surface temperature of the negative electrode, the average surface temperature of the separator, and the average surface temperature of the positive electrode.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

7. An electronic device, characterized in that: include: processor and memory; The memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the electronic device performs the method according to any one of claims 1 to 5.

8. A system for analyzing the internal temperature of a battery cell, characterized in that: The system comprises: the electronic device according to claim 7 and a temperature measuring device; the temperature measuring device is communicatively connected to the electronic device; The temperature measuring device is disposed on the surface of the battery and is configured to measure the ambient temperature and surface temperature of the battery at different times, and transmit the ambient temperature and the surface temperature to the electronic device.

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