Simulation method, program, storage medium, simulation device, and data structure

Abstract

A simulation device 100 executes a simulation related to an internal short circuit occurring in an electricity storage device. An input unit 130 inputs a physical property value of a material constituting the power storage device. Here, the physical property value includes at least one of density having temperature dependency, specific heat having temperature dependency, thermal conductivity having temperature dependency, and resistivity having temperature dependency. A processing unit 132 uses the physical property value to execute coupled calculations of heat and electricity by means of a finite element method, to thereby acquire a change in voltage and / or current and a temperature distribution when an internal short circuit occurs. An output unit 136 outputs the change in voltage and / or current and the temperature distribution.

Description

Simulation Method, Program, Storage Medium, Simulation Device, Data Structure

[0001] The present disclosure relates to simulation technology, and particularly to a simulation method, program, storage medium, simulation device, and data structure for simulating an internal short circuit in a power storage device.

[0002] The temperature distribution within the power storage device due to an internal short circuit occurring within the power storage device has been evaluated by simulation. In this simulation, the amount of heat generated measured during the temperature rise of the battery is input, and the amount of heat generated is calculated from the short-circuit voltage / current behavior of the nail penetration test of the battery, thereby obtaining the temperature distribution of the battery during an internal short circuit (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2006-10648

[0004] In the safety test of a power storage device, the human and time costs are high, and high skills are required for the operator. Therefore, by replacing the safety test with a simulation, it is expected to improve the efficiency of development and eliminate dependence on human evaluation. In the simulation such as Patent Document 1, since measured values are used, the simulation cannot be executed without conducting an actual test. It is desirable to execute a highly accurate simulation without conducting an actual test.

[0005] The present disclosure has been made in view of such circumstances, and its object is to provide a technique for executing a simulation regarding an internal short circuit occurring within a power storage device with high accuracy without an actual test.

[0006] To solve the above problems, a simulation method according to one aspect of the present disclosure is a simulation method for an internal short circuit occurring in an energy storage device, comprising the steps of: inputting physical properties of the materials constituting the energy storage device; obtaining changes in voltage and / or current and temperature distribution when an internal short circuit occurs by performing coupled thermal and electrical calculations using the finite element method with respect to the physical properties; and outputting changes in voltage and / or current and temperature distribution. The physical properties include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity.

[0007] Another aspect of the present disclosure is a storage medium. This storage medium stores a program that causes a computer to perform a simulation of an internal short circuit occurring in an energy storage device, comprising the steps of: inputting physical properties of materials constituting the energy storage device; using the physical properties to perform coupled thermal and electrical calculations by the finite element method to obtain changes in voltage and / or current and temperature distribution in the event of an internal short circuit; and outputting changes in voltage and / or current and temperature distribution. The storage medium stores a program that causes a computer to perform a simulation of the physical properties including at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity.

[0008] A further aspect of this disclosure is a simulation apparatus. This apparatus is a simulation apparatus for an internal short circuit occurring in an energy storage device, comprising: an input unit for inputting material properties of the materials constituting the energy storage device; a processing unit that uses the material properties to perform coupled thermal and electrical calculations by the finite element method to obtain the voltage and / or current changes and temperature distribution when an internal short circuit occurs; and an output unit for outputting the voltage and / or current changes and temperature distribution. The material properties include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity.

[0009] A further aspect of this disclosure is a data structure. This data structure comprises changes in voltage and / or current and temperature distribution when an internal short circuit occurs in an energy storage device, obtained by a computer performing coupled thermal and electrical calculations by the finite element method using physical properties of a material constituting an energy storage device, which include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity, and a message indicating that the physical properties include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity. (1) The physical properties include a first value for a first material and a second value for a second material, wherein the disappearance of the first material due to temperature rise is indicated by the computer converting the physical properties from the first value to the second value, or (2) The physical properties include a first value for temperatures below a threshold during heating, a second value for temperatures above a threshold during heating, and a second value during cooling.

[0010] Furthermore, any combination of the above components, as well as any conversion of the expressions of this disclosure between methods, apparatus, systems, recording media, or computer programs, are also valid forms of this disclosure.

[0011] According to this disclosure, simulations of internal short circuits occurring within energy storage devices can be performed with high accuracy without the need for actual testing.

[0012] Figures 1(a) and 1(b) illustrate the situation in which a short circuit occurs inside the energy storage device according to this embodiment. Figures 1(a) and 1(b) show the change in voltage over time in the situation shown. Figures 1(a) and 1(b) show the configuration of the simulation device according to this embodiment. Figures 1(a) and 1(b) show the configuration of the simulation system according to this embodiment. Figures 1(a) and 1(b) show the simulation model in this embodiment. Figure 3 shows the input screen displayed on the display device of Figure 3. Figure 3 shows the screen displaying the physical property values ​​on the display device of Figure 3. Figure 3 shows the temperature change of the resistivity of the current collector foil stored in the memory unit of Figure 3. Figure 3 shows an overview of the processing in the processing unit of Figure 3. Figures 10(a) and 10(d) show the temperature distribution output from the output unit of Figure 3. Figure 3 shows the change in voltage over time from the output unit of Figure 3. Figure 3 is a flowchart showing the simulation procedure by the simulation device of Figure 3.

[0013] Before specifically describing the embodiments of this disclosure, an overview of the embodiments will be provided. This embodiment relates to a simulation device for performing simulations concerning internal short circuits occurring within an energy storage device. As mentioned above, it is desirable to perform highly accurate simulations without conducting actual tests. Internal short circuits in energy storage devices, which are one of the unsafe events, are phenomena accompanied by temperature changes. Therefore, in order to accurately simulate the current (voltage) behavior or temperature behavior of the battery during an internal short circuit, it is essential to consider the temperature dependence of the material properties of the materials constituting the energy storage device. In this embodiment, temperature-dependent material properties are input and used in the simulation. As a result of the simulation, the short-circuit current (voltage) behavior and heat generation distribution (velocity) due to Joule heating of the short-circuit resistance are obtained.

[0014] The embodiments described below all represent preferred specific examples of the present disclosure. Therefore, the numerical values, shapes, materials, components, arrangement and connection configurations of components, as well as the steps (processes) and their order shown in the following embodiments are examples and are not intended to limit the present disclosure. Accordingly, components in the following embodiments that are not described in the independent claims representing the highest-level concepts of the present disclosure will be described as optional components. In addition, substantially identical components are denoted by the same reference numerals in each figure, and redundant explanations are omitted or simplified.

[0015] Figures 1(a) and 1(b) illustrate the situation in which a short circuit occurs inside an energy storage device. These are cross-sectional views of a part of the battery contained in the energy storage device. In the battery, a sheet-like positive electrode 10, a separator 30, and a negative electrode 20 are stacked in order. The positive electrode 10 has a structure in which a composite material 14, a current collector foil 12, and another composite material 14 are stacked in order. The current collector foil 12 is, for example, aluminum foil, and the composite material 14 is, for example, lithium cobalt oxide or lithium iron phosphate. The negative electrode 20 has a structure in which a composite material 24, a current collector foil 22, and another composite material 24 are stacked in order. The current collector foil 22 is, for example, copper foil, and the composite material 24 is, for example, graphite. The composite materials 14 and 24 are obtained by kneading materials such as electrode active material, binder, and conductive material into a dispersion medium and dispersing them uniformly. The separator 30 is, as an example, composed of a microporous film made of polypropylene resin or the like. The separator 30 electrically insulates the positive electrode 10 and the negative electrode 20.

[0016] In Figure 1(a), a short-circuiting object 40 is inserted into the laminate of the positive electrode 10, separator 30, and negative electrode 20. The short-circuiting object 40 is conductive and is, for example, a metal object such as a nail. The short-circuiting object 40 comes into contact with both the current collector foil 12 and the current collector foil 22. As a result, a conductive path 50 is formed between the current collector foil 12 and the current collector foil 22 via the short-circuiting object 40, and the current collector foil 12 and the current collector foil 22 are short-circuited. To explain the change in voltage in this state, Figure 2 is also used here. Figure 2 shows the change in voltage over time in the situation of Figures 1(a)-(b). The horizontal axis represents time and the vertical axis represents voltage. From time "T0" to "T1", the short-circuiting object 40 has not been inserted, so the voltage is constant. At time "T1", the short-circuiting object 40 is inserted. Due to the insertion of the short-circuiting object 40, the current collector foil 12 and the current collector foil 22 are short-circuited, causing the voltage to drop.

[0017] Figure 1(b) shows the state following Figure 1(a). When Joule heating occurs due to a short circuit, the temperatures of the positive electrode 10, the negative electrode 20, and the separator 30 rise. When the temperature reaches 660°C, the melting point of aluminum, the current collector foil 12 melts, and the two composite materials 14 sandwiching the current collector foil 12 come into contact. As a result, the conductive path 50 is interrupted, and the Joule heating ends. At time "T2" in Figure 2, the current collector foil 12 melts. After time "T2", the conductive path 50 is interrupted, so the voltage increases over time.

[0018] Figure 3 shows the configuration of the simulation device 100. The simulation device 100 performs simulations related to internal short circuits occurring in an energy storage device, as shown in Figures 1(a)-(b) and 2. The simulation device 100 is connected to an operating device 110 and a display device 120, and includes an input unit 130, a processing unit 132, a storage unit 134, and an output unit 136. The operating device 110 and the display device 120 may be included in the simulation device 100.

[0019] The operating device 110 is a user interface operated by the user. The operating device 110 is, for example, a keyboard or mouse. The operating device 110 outputs the operations received from the user to the simulation device 100. The display device 120 is a display that shows a screen for inputting information to set up the simulation (hereinafter referred to as the "input screen"), a screen for showing the results of the simulation (hereinafter referred to as the "results screen"), etc. The display device 120 receives information from the simulation device 100 and displays the received information. The operating device 110 and the display device 120 may be integrated into a touch-enabled display.

[0020] The input unit 130 receives information for setting up the simulation from the operating device 110. The input unit 130 may also receive information for setting up the simulation from the storage unit 134.

[0021] The processing unit 132 is, for example, a CPU (Central Processing Unit), which reads programs stored in the memory unit 134 and executes them. One of the programs executed by the processing unit 132 is a program for simulation. Here, the processing unit 132 displays the input screen on the display device 120, then receives information for setting up the simulation from the input unit 130, and uses the received information when executing the program. The processing unit 132 also stores the simulation results in the memory unit 134 and outputs the simulation results to the output unit 136.

[0022] The storage unit 134 is a medium capable of storing electronic information, such as an HDD (Hard Disk Drive) or SSD (Solid State Drive). As mentioned above, the storage unit 134 stores programs, especially programs and information for simulations. The storage unit 134 also stores the results of the simulations.

[0023] The output unit 136 receives the simulation results from the processing unit 132. The output unit 136 displays the simulation results as a results screen on the display device 120.

[0024] The simulation device 100 may be configured as a system. Figure 4 shows the configuration of the simulation system 150. The simulation system 150 includes a terminal device 160, a network 170, and a server 180. The terminal device 160 is an electronic device operated by a user. The terminal device 160 is, for example, a personal computer, a smartphone, or a tablet terminal. The terminal device 160 has a communication function for communicating with the network 170. The terminal device 160 corresponds to the aforementioned operating device 110 and display device 120.

[0025] Network 170 is composed of wireless communication, wired communication, and a combination of wireless and wired communication. Terminal devices 160 and server 180 are connected to network 170, and terminal devices 160 and server 180 communicate with each other via network 170. Server 180 corresponds to the simulation device 100 mentioned above and performs simulations. The following description of this embodiment will be based on the configuration of Figure 3, but this embodiment may also be performed with the configuration of Figure 4.

[0026] Figure 5 shows the simulation model. The simulation is performed on a short circuit of the energy storage device. The short circuit of the energy storage device includes a short circuit model 250, an electromotive force of the energy storage device 260, and an internal resistance of the energy storage device 262. The short circuit model 250 models the short circuit shape and corresponds to a portion of the battery of the energy storage device where the short circuit occurs. The short circuit model 250 includes a positive electrode 210, a negative electrode 220, a separator 230, and a short-circuit component 240. The positive electrode 210 includes a current collector foil 212 and a composite material 214, and the negative electrode 220 includes a current collector foil 222 and a composite material 224.

[0027] The positive electrode 210, current collector foil 212, composite agent 214, negative electrode 220, current collector foil 222, composite agent 224, separator 230, and short-circuiting element 240 correspond to the positive electrode 10, current collector foil 12, composite agent 14, negative electrode 20, current collector foil 22, composite agent 24, separator 30, and short-circuiting element 40 mentioned above, respectively. In the short-circuiting section model 250, the positive electrode 210, separator 230, and negative electrode 220 are stacked in order. The positive electrode 210 has a structure in which composite agent 214, current collector foil 212, and composite agent 214 are stacked in order, and the negative electrode 220 has a structure in which composite agent 224, current collector foil 222, and composite agent 224 are stacked in order. The simulation device 100 performs coupled thermal and electrical calculations on such a simulation model using the finite element method. Return to Figure 3.

[0028] The processing unit 132 displays the input screen on the display device 120. The user inputs parameters for the simulation model by operating the control device 110 while viewing the input screen displayed on the display device 120. Figure 6 shows the input screen displayed on the display device 120. The value of the electromotive force 260 of the energy storage device is input in "Energy storage device voltage," and the value of the internal resistance 262 of the energy storage device is input in "Energy storage device internal resistance." The internal resistance 262 of the energy storage device is a value derived from electrochemical theoretical equations or an equivalent circuit that represents the internal resistance of a battery (for example, a value with current dependence based on a polarization curve), or a fixed value.

[0029] In "Positive Electrode Design," parameters for the positive electrode 210 (current collector foil 212, mixture 214) are input, and in "Negative Electrode Design," parameters for the negative electrode 220 (current collector foil 222, mixture 224) are input. In "Separator," parameters for the separator 230 are input, and in "Foreign Matter," parameters for the short-circuiting object 240 are input. These parameters will be described later.

[0030] Furthermore, the lower part of the input screen displays multiple combinations of the positional relationship between the short-circuit object 240, the positive electrode 210, the negative electrode 220, and the separator 230, and the shape of the short-circuit object 240, as patterns A to C, representing the short-circuit shape within the short-circuit model 250. Patterns A to C are pre-prepared in the storage unit 134, but the number of pre-prepared combinations is not limited to "3". In addition, the user may create a new combination by operating the operating device 110. The user selects one of the combinations by operating the operating device 110, and the input unit 130 accepts the user's selection.

[0031] Figure 7 shows the screen displaying the physical properties on the display device 120. This is the screen displayed when "Positive electrode design" is selected in Figure 6. The same screen is displayed when "Negative electrode design," "Separator," or "Foreign matter" is selected in Figure 6. It includes tabs for "Current collector foil" and "Compound agent." Parameters for the current collector foil 212 are entered in the "Current collector foil" tab, and parameters for the compound agent 214 are entered in the "Compound agent" tab. As parameters for the current collector foil 212, physical properties such as density, specific heat, thermal conductivity, and resistivity can be entered. Since these are temperature-dependent physical properties, temperature-dependent values ​​are entered. Changes to material properties are not limited to the separator 230 and current collector foil (current collector foil 212, current collector foil 222).

[0032] To explain the temperature-dependent physical properties, we will also use Figure 8. Figure 8 shows the temperature dependence of the resistivity of the current collector foil 212 stored in the memory unit 134. The horizontal axis represents temperature, and the vertical axis represents the resistivity of the current collector foil 212. When the temperature increases from a low temperature to a high temperature, within the range of 660°C or less, the resistivity increases as a function of f(x). Here, x represents temperature, so the resistivity is shown as a function of temperature. Above 660°C, the resistivity is shown as a constant value with respect to temperature. On the other hand, when the temperature decreases from a high temperature to a low temperature, the resistivity is shown as a constant value with respect to temperature. In particular, the resistivity during cooling is equal to the resistivity when the temperature is higher than 660°C during heating. Thus, the resistivity has different temperature dependences and irreversible changes during heating and cooling. Return to Figure 7.

[0033] As mentioned above, resistivity values ​​are entered for both heating and cooling. In particular, resistivity includes a first value (function) for temperatures below the threshold (660°C) during heating, a second value (constant value) for temperatures above the threshold during heating, and a second value (constant value) during cooling. Thermal conductivity values ​​are entered for both heating and cooling. In particular, thermal conductivity includes a first value (constant value) for temperatures below the threshold (660°C) during heating, a second value (constant value) for temperatures above the threshold during heating, and a second value (constant value) during cooling.

[0034] Furthermore, the thickness value of the current collector foil 212 is input. As described above, the parameters (physical properties) input to the operating device 110 are output from the operating device 110 to the simulation device 100. The input unit 130 receives the physical properties of the materials constituting the energy storage device from the operating device 110. The input unit 130 may also receive the physical properties of the materials constituting the energy storage device from the storage unit 134.

[0035] The processing unit 132 receives physical property values ​​from the input unit 130. The processing unit 132 uses the physical property values ​​to perform coupled thermal and electrical calculations using the finite element method. Based on the value of the electromotive force 260 of the energy storage device and the value of the internal resistance 262 of the energy storage device, the processing unit 132 calculates the current value applied to the short-circuit model 250 as follows. Here, E is the set voltage (value of the electromotive force 260 of the energy storage device), Rint is the electrical resistance (value of the internal resistance 262 of the energy storage device), and EV is the potential difference between the positive and negative terminals (calculated value). This can also be considered the boundary condition of the positive terminal, which is set in the same way as the circuit settings of the cutting test machine.

[0036] The processing unit 132 performs coupled thermal and electrical calculations, including the Poisson equation and the heat conduction equation, based on the applied current value and the material properties. The processing unit 132 obtains the electric potential field from the following Poisson equation. Here, Φ is the electric potential (calculated value), J is the current density vector (calculated value), and σ is the electrical conductivity (input value for each material). The relationship between electrical conductivity σ and resistivity r is r = 1 / σ.

[0037] The processing unit 132 obtains the temperature field, including Joule heating due to the above current, from the following heat conduction equation. Here, T is the temperature (calculated value), ρ is the density (input value for each material), Cp is the specific heat (input value for each material), q is the heat flux vector (calculated value), Q is the heat generation density (calculated value), and k is the thermal conductivity (input value for each material). The processing unit 132 repeatedly performs coupled calculations using the finite element method as time progresses. As a result, the processing unit 132 obtains the time change of voltage or current when an internal short circuit occurs, as well as the time change of the temperature distribution. At least one of the time change of voltage or current when an internal short circuit occurs and the time change of the temperature distribution are also called "simulation results".

[0038] Here, we will explain the process in the processing unit 132 when the temperature reaches 150°C, which is the melting point of the separator 230, using Figure 9 as well. Figure 9 shows an overview of the process in the processing unit 132. The short-circuit model 250 includes the positive electrode 210, the negative electrode 220, the separator 230, and the short-circuited object 240, as before. The short-circuit model 250 is divided into multiple meshes using the finite element method. Here, multiple meshes 270 that divide the separator 230 are shown.

[0039] When the temperature reaches 150°C, melting of a portion of the separator 230 begins. To reflect this in the simulation, the processing unit 132 converts the physical properties of the separator 230 to those of the negative electrode 220 in some of the meshes 270. The processing unit 132 may also convert the physical properties of the separator 230 to those of the positive electrode 210 in some of the meshes 270. Furthermore, in the simulation, the processing unit 132 retains the physical properties of the negative electrode 220 or positive electrode 210 for any mesh 270 that has reached 150°C and melted, even if the temperature subsequently drops below 150°C. This represents an irreversible change.

[0040] That is, the physical property values include a first value with respect to the separator 230 and a second value with respect to the negative electrode 220 (positive electrode 210), and the disappearance of the separator 230 due to temperature rise is indicated by converting the physical property values from the first value to the second value. Return to FIG. 3. The processing unit 132 stores the simulation result in the storage unit 134 and outputs it to the output unit 136.

[0041] As described above, the output unit 136 causes the display device 120 to display the simulation result as a result screen. That is, the change in voltage and / or current and the temperature distribution are displayed on the display device 120. FIGS. 10(a)-(d) show the temperature distribution output from the output unit 136. The change in the temperature distribution when time elapses in the order of FIGS. 10(a), 10(b), 10(c), and 10(d) is shown. These show a short-circuit part model 250 including the positive electrode 210, the negative electrode 220, the separator 230, and the short-circuit object 240. Also, it is shown that the joule heat generation in the vicinity of the short-circuit object 240 spreads to the surroundings as time elapses. On the result screen, "a message indicating that at least one of the density having temperature dependence, the specific heat having temperature dependence, the thermal conductivity having temperature dependence, and the resistivity having temperature dependence is included in the physical property values" may be shown together with the change in voltage and / or current and the temperature distribution shown in FIGS. 10(a)-(d). Here, the change in voltage and / or current and the temperature distribution are shown as a moving image that changes in the order from FIG. 10(a) to FIG. 10(d).

[0042] FIG. 11 shows the time change of the voltage output from the output unit 136. The horizontal axis indicates time, and the vertical axis indicates voltage. As shown in the figure, similar to FIG. 2, the voltage changes with time.

[0043] The subject of the device, system, or method in the present disclosure includes a computer. By executing a program on this computer, the functions of the subject of the device, system, or method in the present disclosure are realized. The computer mainly includes a processor that operates according to the program as a hardware configuration. The type of the processor is not limited as long as it can realize functions by executing the program. The processor is composed of one or more electronic circuits including a semiconductor integrated circuit (IC) or LSI (Large Scale Integration). The plurality of electronic circuits may be integrated on one chip or provided on a plurality of chips. The plurality of chips may be aggregated into one device or provided in a plurality of devices. The program is recorded on a non-temporary recording medium such as a computer-readable ROM, optical disk, or hard disk drive. The program may be pre-stored in the recording medium or supplied to the recording medium via a wide-area communication network including the Internet or the like.

[0044] The operation of the simulation device 100 with the above configuration will be described. FIG. 12 is a flowchart showing the simulation procedure by the simulation device 100. The input unit 130 inputs information (S10). The processing unit 132 performs a coupled calculation of heat and electricity by the finite element method (S12). The storage unit 134 stores the simulation result (S14). The output unit 136 outputs the simulation result (S16).

[0045] According to the present embodiment, when performing a coupled calculation of heat and electricity by the finite element method using the input physical property values, since at least one of the density having temperature dependence, the specific heat having temperature dependence, the thermal conductivity having temperature dependence, and the resistivity having temperature dependence is included, simulation regarding an internal short circuit generated in the power storage device can be executed with high accuracy without actual tests. Further, since the physical property values have different temperature dependences during temperature rise and temperature fall, the accuracy of the simulation can be improved. Further, since the physical property values are shown as functions with respect to temperature, the temperature dependence of the physical property values can be accurately reflected.

[0046] Furthermore, a first value for the separator 230 and a second value for the negative electrode 220 are input as physical properties, and the disappearance of the separator 230 due to temperature rise is shown by converting the physical properties from the first value to the second value, thus accurately simulating the disappearance of the separator 230. In addition, since the physical properties include a first value for temperatures below the threshold during heating, a second value for temperatures above the threshold during heating, and a second value during cooling, irreversible changes can be accurately simulated.

[0047] Furthermore, since the coupled calculation includes the Poisson equation and the heat conduction equation, it can simulate the spread of heat and electricity. In addition, the short circuit of the energy storage device when performing the coupled calculation includes the short circuit model 250, the electromotive force 260 of the energy storage device, and the internal resistance 262 of the energy storage device, so it can model the internal short circuit of the energy storage device. Moreover, multiple types of short circuit models 250 are provided in advance, and the user can select from an input screen that displays multiple combinations of these models, so the appropriate short circuit model 250 can be used.

[0048] An outline of one aspect of the present disclosure is as follows: (Item 1) A simulation method for an internal short circuit occurring in an energy storage device, comprising the steps of: inputting physical properties of the material constituting the energy storage device; obtaining changes in voltage and / or current and temperature distribution when an internal short circuit occurs by performing coupled thermal and electrical calculations using the finite element method with respect to the physical properties; and outputting the changes in voltage and / or current and temperature distribution, wherein the physical properties include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity.

[0049] (Item 2) The simulation method described in Item 1, wherein the physical properties have different temperature dependencies during heating and cooling.

[0050] (Item 3) The simulation method described in Item 1 or 2, wherein the physical properties are expressed as a function of temperature.

[0051] (Item 4) The simulation method according to any one of Items 1 to 3, wherein the physical property values ​​include a first value for the first material and a second value for the second material, and the disappearance of the first material due to temperature rise is shown by converting the physical property values ​​from the first value to the second value.

[0052] (Item 5) The simulation method described in any one of Items 1 to 4, wherein the physical property value includes a first value for temperatures below a threshold during heating, a second value for temperatures above a threshold during heating, and a second value during cooling.

[0053] (Item 6) The coupled calculation is a simulation method described in any one of Items 1 to 5, which includes the Poisson equation and the heat conduction equation.

[0054] (Item 7) The simulation method according to any one of Items 1 to 6, wherein the short circuit of the energy storage device when performing the coupled calculation includes a short-circuit model that models the short-circuit shape, the electromotive force and internal resistance of the energy storage device, and the internal resistance value of the energy storage device is a value that has current dependence based on a polarization curve or a fixed value.

[0055] (Item 8) The simulation method according to Item 7, further comprising a step of accepting a user's selection from an input screen displaying multiple types of combinations, where multiple types of combinations are provided in advance as short-circuit shapes in the short-circuit model, and the positional relationship between the short-circuit object, the positive electrode, the negative electrode, and the separator, and the shape of the short-circuit object.

[0056] (Item 9) A program for causing a computer to perform a simulation of an internal short circuit occurring in an energy storage device, comprising the steps of: inputting physical properties of the materials constituting the energy storage device; using the physical properties to perform a coupled thermal and electrical calculation by the finite element method to obtain the changes in voltage and / or current and the temperature distribution when an internal short circuit occurs; and outputting the changes in voltage and / or current and the temperature distribution, wherein the physical properties include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity.

[0057] (Item 10) A storage medium for storing a program that causes a computer to perform a simulation of an internal short circuit occurring in an energy storage device, comprising the steps of: inputting physical properties of the materials constituting the energy storage device; obtaining changes in voltage and / or current and temperature distribution when an internal short circuit occurs by performing a coupled thermal and electrical calculation using the finite element method with respect to the physical properties; and outputting the changes in voltage and / or current and temperature distribution, wherein the physical properties include temperature-dependent resistivity or temperature-dependent thermal conductivity.

[0058] (Item 11) A simulation device relating to an internal short circuit occurring in an energy storage device, comprising: an input unit for inputting material properties of the materials constituting the energy storage device; a processing unit that uses the material properties to perform coupled thermal and electrical calculations by the finite element method to obtain changes in voltage and / or current and temperature distribution when an internal short circuit occurs; and an output unit for outputting the changes in voltage and / or current and temperature distribution, wherein the material properties include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity.

[0059] (Item 12) A data structure comprising: (1) The physical properties of a material constituting an energy storage device, which include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity, obtained by a computer performing coupled thermal and electrical calculations using the finite element method, the changes in voltage and / or current and temperature distribution when an internal short circuit occurs in the energy storage device; and a message indicating that the physical properties include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity, wherein (1) the physical properties include a first value for a first material and a second value for a second material, and the disappearance of the first material due to temperature rise is indicated by the computer converting the physical properties from the first value to the second value, or (2) the physical properties include a first value for temperatures below a threshold during heating, a second value for temperatures above a threshold during heating, and a second value during cooling.

[0060] The present disclosure has been described above based on examples. These examples are illustrative, and it will be understood by those skilled in the art that various modifications are possible for each component or combination of processing steps, and that such modifications are also within the scope of the present disclosure.

[0061] According to this disclosure, simulations of internal short circuits occurring within energy storage devices can be performed with high accuracy without the need for actual testing.

[0062] 10 Positive electrode, 12 Current collector foil, 14 Compound, 20 Negative electrode, 22 Current collector foil, 24 Compound, 30 Separator, 40 Short circuit component, 50 Conductive path, 100 Simulation device, 110 Operating device, 120 Display device, 130 Input unit, 132 Processing unit, 134 Storage unit, 136 Output unit, 150 Simulation system, 160 Terminal device, 170 Network, 180 Server, 210 Positive electrode, 212 Current collector foil, 214 Compound, 220 Negative electrode, 222 Current collector foil, 224 Compound, 230 Separator, 240 Short circuit component, 250 Short circuit model, 260 Electromotive force of energy storage device, 262 Internal resistance of energy storage device 270 mesh.

Claims

1. A simulation method for an internal short circuit occurring in an energy storage device, comprising the steps of: inputting physical properties of the materials constituting the energy storage device; obtaining changes in voltage and / or current and temperature distribution when an internal short circuit occurs by performing coupled thermal and electrical calculations using the finite element method with respect to the physical properties; and outputting the changes in voltage and / or current and temperature distribution, wherein the physical properties include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity.

2. The simulation method according to claim 1, wherein the physical properties have different temperature dependencies during heating and cooling.

3. The simulation method according to claim 1, wherein the physical properties are expressed as a function of temperature.

4. The simulation method according to claim 1, wherein the physical property values ​​include a first value for the first material and a second value for the second material, and the disappearance of the first material due to temperature rise is shown by converting the physical property values ​​from the first value to the second value.

5. The simulation method according to claim 1, wherein the physical property value includes a first value for temperatures below a threshold during heating, a second value for temperatures above a threshold during heating, and a second value during cooling.

6. The simulation method according to any one of claims 1 to 5, wherein the coupled calculation includes the Poisson equation and the heat conduction equation.

7. The simulation method according to any one of claims 1 to 5, wherein the short circuit of the energy storage device when performing the coupled calculation includes a short-circuit model that models the short-circuit shape, the electromotive force and internal resistance of the energy storage device, and the internal resistance value of the energy storage device is a value that has current dependence based on a polarization curve or a fixed value.

8. The simulation method according to claim 7, further comprising the step of accepting a user's selection from an input screen displaying multiple types of combinations, where a plurality of combinations are pre-prepared as the short-circuit shape in the short-circuit model, and the positional relationship between the short-circuit object, the positive electrode, the negative electrode, and the separator, and the shape of the short-circuit object.

9. A program for causing a computer to perform a simulation of an internal short circuit occurring in an energy storage device, comprising the steps of: inputting physical properties of the materials constituting the energy storage device; obtaining changes in voltage and / or current and temperature distribution when an internal short circuit occurs by performing a coupled thermal and electrical calculation using the finite element method with respect to the physical properties; and outputting the changes in voltage and / or current and temperature distribution, wherein the program causes the computer to perform the simulation of the physical properties including at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity.

10. A storage medium for storing a program that causes a computer to perform a simulation of an internal short circuit occurring in an energy storage device, comprising the steps of: inputting physical properties of materials constituting the energy storage device; obtaining changes in voltage and / or current and temperature distribution in the event of an internal short circuit by performing a coupled thermal and electrical calculation using the finite element method with respect to the physical properties; and outputting the changes in voltage and / or current and temperature distribution, wherein the physical properties include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity.

11. A simulation device relating to an internal short circuit occurring in an energy storage device, comprising: an input unit for inputting material properties of the materials constituting the energy storage device; a processing unit that uses the material properties to perform coupled thermal and electrical calculations by the finite element method to obtain changes in voltage and / or current and temperature distribution when an internal short circuit occurs; and an output unit for outputting the changes in voltage and / or current and temperature distribution, wherein the material properties include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity.

12. A data structure comprising: changes in voltage and / or current and temperature distribution when an internal short circuit occurs in the energy storage device, obtained by a computer performing coupled thermal and electrical calculations by the finite element method using physical properties of a material constituting the energy storage device, which include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity; and a message indicating that the physical properties include at least one of temperature-dependent density, temperature-dependent specific heat, temperature-dependent thermal conductivity, and temperature-dependent resistivity, wherein (1) the physical properties include a first value for a first material and a second value for a second material, and the disappearance of the first material due to temperature rise is indicated by the computer converting the physical properties from the first value to the second value; or (2) the physical properties include a first value for temperatures below a threshold during heating, a second value for temperatures above a threshold during heating, and a second value during cooling.

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