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

Abstract

An input unit 130 accepts, as inputs thereto, information relating to the shape of a battery, information relating to the physical properties of an electrode body of the battery, and information relating to conditions for heating the battery. A processing unit 132 calculates, through simulation on the basis of the information relating to the shape of the battery, the information relating to the physical properties of the electrode body, and the information relating to the heating conditions, heat conduction and gas advection caused by heating in the battery, thereby acquiring a temporal change in the heat distribution of the battery. An output unit 136 outputs the temporal change in the heat distribution of the battery 202.

Description

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

[0001] The present disclosure relates to simulation technology, and more particularly to a simulation method, program, storage medium, simulation device, and data structure for calculating the overheating phenomenon of a battery.

[0002] The temperature distribution within a power storage device due to an internal short circuit occurring therein is 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 internal short circuit / thermal decomposition (see, for example, Patent Document 1).

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

[0004] From the viewpoint of safety, there is a demand for the design of a battery module in which the surrounding batteries do not overheat due to gas released from a battery overheated for some reason. The overheating test of a battery module is costly in terms of manpower, equipment, and time. In recent years, in order to reduce costs, prediction of overheating by numerical simulation has been utilized. In a combustion reaction occurring inside an electrode body, high-temperature gas generated from a starting point moves and transfers heat, causing the combustion to occur chain-reactionally. However, in conventional simulations, the influence of gas movement inside the electrode body is ignored, so the chain reaction rate of the combustion reaction is predicted to be too small.

[0005] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a technique for accurately predicting the overheating phenomenon of a battery.

[0006] In order to solve the above problems, a simulation method according to an aspect of the present disclosure includes: a step of inputting information regarding the shape of a battery, information regarding the physical properties of the electrode body of the battery, and information regarding the conditions for heating the battery; and a step of obtaining a time change in the heat distribution of the battery by calculating, by simulation, heat conduction and gas advection due to heating in the battery based on the information regarding the shape of the battery, the information regarding the physical properties of the electrode body, and the information regarding the heating conditions; and a step of outputting the time change in the heat distribution of the battery.

[0007] Another aspect of this disclosure is a storage medium. This storage medium stores a program that causes a computer to perform the following steps: inputting information about the shape of a battery, information about the physical properties of the battery's electrodes, and information about the conditions for heating the battery; obtaining the time change of the battery's heat distribution by simulating and calculating the heat conduction and gas advection due to heating in the battery based on the information about the shape of the battery, the physical properties of the electrodes, and the heating conditions; and outputting the time change of the battery's heat distribution.

[0008] A further aspect of this disclosure is a simulation device. This device includes an input unit that inputs information about the shape of a battery, information about the physical properties of the battery's electrodes, and information about the conditions for heating the battery; a processing unit that obtains the time change of the battery's heat distribution by calculating the heat conduction and gas advection due to heating in the battery through simulation based on the information about the shape of the battery, the physical properties of the electrodes, and the heating conditions; and an output unit that outputs the time change of the battery's heat distribution.

[0009] Another aspect of this disclosure is a data structure. This data structure comprises a time change in the heat distribution of a battery obtained by a computer simulating and calculating the heat conduction and gas advection due to heating in the battery based on information about the shape of the battery, information about the physical properties of the battery electrodes, and information about the conditions for heating the battery, and a message indicating that heat conduction and gas advection have been calculated by simulation.

[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, it is possible to predict battery overheating with high accuracy.

[0012] Figures 1(a)-(b) show the structure of a battery according to Example 1. Figures 2(a)-(b) show a simulation model of an electrode body according to Example 1. Figure 1 shows the configuration of a simulation device according to Example 1. Figure 2 shows the configuration of a simulation system according to Example 1. Figures 5(a)-(c) show the input screen displayed on the display device in Figure 3. Figure 3 shows the data structure of physical property information input to the input section of Figure 3. Figures 7(a)-(b) show a simulation model reflecting the settings in Figure 5(a). Figures 8(a)-(d) show the result screen displayed on the display device in Figure 3. Figures 9(a)-(b) show the results of a simulation by the processing unit in Figure 3. Figures 10(a)-(b) show the results of another simulation by the processing unit in Figure 3. Figure 3 shows yet another result screen displayed on the display device in Figure 3. Figure 4 is a flowchart showing the simulation procedure by the simulation device in Figure 3. Figures 13(a)-(b) show an overview of the simulation by the processing unit according to Example 2. Figure 5 shows an overview of the simulation by the processing unit according to Example 2.

[0013] (Example 1) Before specifically describing the embodiments of this disclosure, an overview of the embodiments will be given. This embodiment relates to a simulation device for simulating the time change of heat distribution when a battery in an energy storage device overheats. As a result of the inventors' diligent research into the combustion reaction occurring inside the electrode body, they found that inside the electrode body of an overheating battery, high-temperature gas is generated and moves from a starting point, transferring heat and causing a chain reaction of combustion. Previous simulations have calculated the temperature distribution inside the electrode body using only solid heat conduction without considering gas, ignoring the important heat transfer factor of gas movement. Therefore, the chain reaction rate of the combustion reaction is underestimated. This embodiment accurately predicts the temperature and flow velocity of the gas released from the battery through simulation.

[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) show the structure of battery 2. Figure 1(a) is an exploded perspective view of battery 2. Battery 2 is a rechargeable secondary battery such as a lithium-ion battery, nickel-metal hydride battery, or nickel-cadmium battery. Battery 2 includes an electrode body 40, a positive electrode terminal 50, a negative electrode terminal 52, a sealing body 54, a gasket 56, and a gas discharge valve 58. The negative electrode terminal 52 corresponds to the outer casing. In one example, battery 2 has a structure in which the electrode body 40 is housed in an outer casing together with an electrolyte (not shown). The electrode body 40 is, for example, cylindrical and has a wound structure in which a strip-shaped positive electrode 10 and a strip-shaped negative electrode 20 are stacked with a strip-shaped separator 30 in between and wound in a spiral shape.

[0016] The positive electrode 10 and the negative electrode 20 have a structure in which an electrode active material layer is laminated on a current collector. In the case of a typical lithium-ion secondary battery, the current collector is made of aluminum foil or the like for the positive electrode 10, and copper foil or the like for the negative electrode 20. The electrode active material layer can be formed by coating the surface of the current collector with an electrode composite material using a known coating device, drying, and rolling. The electrode composite material is obtained by kneading materials such as electrode active material, binder, and conductive material in a dispersion medium and dispersing them uniformly. In the case of a typical lithium-ion secondary battery, the electrode active material is lithium cobalt oxide or lithium iron phosphate for the positive electrode 10, and graphite for the negative electrode 20. The separator 30 is made of a microporous film made of polypropylene resin or the like, as an example.

[0017] The outer casing (negative electrode terminal 52) is made of, for example, copper, nickel, iron, or an alloy thereof. The negative electrode 20 is joined to the inner bottom surface of the outer casing by welding or the like. The positive electrode 10 is joined to a sealing body 54 made of the same metal as the outer casing by welding or the like. The sealing body 54 is fitted into the opening of the outer casing via a gasket 56. This seals the electrode body 40 and electrolyte inside the outer casing. The sealing body 54 is also provided with a positive electrode terminal 50 that protrudes outward, and the positive electrode terminal 50 is electrically connected to the positive electrode 10. Furthermore, the sealing body 54 is provided with a gas discharge valve 58 for discharging gas generated inside the battery 2. Here, the space inside the gas discharge valve 58 is defined as the inside of the battery 2.

[0018] Figure 1(b) is a cross-sectional view showing the internal structure of the battery 2. When a short circuit occurs inside the battery 2, gas is generated by heating the electrode body 40. The generated gas moves through the inside of the battery 2 toward the gas discharge valve 58 and is discharged to the outside of the battery 2 from the gas discharge valve 58. The movement of the gas is shown as gas advection 72.

[0019] Figures 2(a) and 2(b) show a simulation model of the electrode body 240. Figures 2(a) and 2(b) are cross-sectional views showing a part of the electrode body 240. The electrode body 240 is a simulation model for the electrode body 40 described above. In the electrode body 240, the positive electrode 210 and the negative electrode 220 are stacked alternately, with a separator 230 sandwiched between the positive electrode 210 and the negative electrode 220. The positive electrode 210, the negative electrode 220, and the separator 230 correspond to the positive electrode 10, the negative electrode 20, and the separator 30 described above, respectively. In this embodiment, the separator 230 is defined as the gas-permeable portion, and the positive electrode 210 and the negative electrode 220, i.e., the portion other than the gas-permeable portion, are defined as the gas-impermeable portion. The definitions of the gas-permeable portion and the gas-impermeable portion are not limited to this.

[0020] Figure 2(a) shows an overview of the simulations performed so far. When heat is generated inside the positive electrode 210 and the negative electrode 220, the heat generated is transferred as thermal conduction 270. On the other hand, an important heat transfer factor, gas transfer, is ignored. As mentioned above, by considering only thermal conduction 270, the chain rate of the combustion reaction is underestimated.

[0021] Figure 2(b) shows an overview of the simulation according to this embodiment. When heat is generated inside the positive electrode 210 and the negative electrode 220, the heat generated by the heat is transferred as thermal conduction 270, as before. Furthermore, the gas generated by the heat generated inside the positive electrode 210 and the negative electrode 220 moves to the separator 230, and moves through the separator 230 as gas advection 272. In other words, the gas moves through the gas-passable portion.

[0022] Figure 3 shows the configuration of the simulation device 100. The simulation device 100 predicts the behavior of heat generation and gas generation due to overheating of the cell material. 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.

[0023] 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.

[0024] The input unit 130 receives information to be used in the simulation from the operating device 110. The input unit 130 may also receive information to be used in the simulation from the storage unit 134.

[0025] 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 to be used for 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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 in the configuration of Figure 3.

[0030] The processing unit 132 displays the input screen on the display device 120. The user inputs the information to be used for the simulation by operating the control device 110 while looking at the input screen displayed on the display device 120. Figures 5(a)-(c) show the input screens displayed on the display device 120. In these, "3D shape of the battery" contains information about the 3D shape of the battery 202 (hereinafter referred to as "shape information"). Battery 202 is a simulation model for battery 2. "Physical properties of the electrode body" contains information about the physical properties of the electrode body 240 (hereinafter referred to as "physical property information"). "Heating conditions" contains information about the conditions for heating battery 202 (hereinafter referred to as "heating conditions"). Details of the shape information, physical property information and heating conditions will be described later. Also, in Figures 5(a)-(c), the heating conditions are different from each other. Return to Figure 3.

[0031] As described above, the shape information, physical property information, and heating conditions input to the operating device 110 are output from the operating device 110 to the simulation device 100. The input unit 130 receives the shape information, physical property information, and heating information from the operating device 110. The input unit 130 may also receive the shape information, physical property information, and heating information from the storage unit 134.

[0032] Shape information is represented as the three-dimensional shape of the battery 2 shown in Figure 1(a). Shape information is represented in a format such as CAD (Computer-Aided Design) data. In addition, gas-permeable and gas-non-permeable portions are specified in the shape information. Gas-permeable portions include the separator 230 and the space within the battery 202, while gas-non-permeable portions include parts other than the gas-permeable portions, such as the positive electrode 210 and the negative electrode 220.

[0033] The physical property information includes the heat generation rate of the electrode body 240 and the gas generation rate of the electrode body 240. Figure 6 shows the data structure of the physical property information input to the input unit 130. Here, the heat generation rate and gas generation rate are temperature dependent. The heat generation rate is derived using the Arrhenius equation as the rate equation for the exothermic reaction. Here, an upper limit on the heat generation rate may be set. Similarly, the gas generation rate is derived using the Arrhenius equation as the rate equation for the gas generation reaction. Here, an upper limit on the gas generation rate may be set. Measured data may be used for the heat generation rate and gas generation rate of the electrode body 240. In this case, the temperature-dependent heat generation rate and temperature-dependent gas generation rate are selected from the table data. Return to Figure 3.

[0034] The heating conditions include one of the following types of heating: nail-driven short circuit, internal short circuit, or external heating. When nail-driven short circuit is included, the input screen is shown as in Figure 5(a), and "nail position" is entered as the position where the nail is driven. When internal short circuit is included, the input screen is shown as in Figure 5(b), and "short circuit position" is entered as the position where the short circuit occurs. When external heating is included, the input screen is shown as in Figure 5(c), and "heating position" is entered as the position where heating occurs. Here, the nail position, short circuit position, and heating position are all positions that serve as the starting point for heat generation. The heating conditions also include the amount of heat generated.

[0035] Figures 7(a) and 7(b) show simulation models that reflect the settings in Figure 5(a). In particular, these show simulation models when the type of heating under the heating conditions is a nail-piercing short circuit. Figure 7(a) shows the case where the nail 260 is inserted into the central part 262 of the battery 202. Figure 7(b) shows the case where the nail 260 is inserted into the bottom part 264 of the battery 202 can. Return to Figure 3.

[0036] The processing unit 132 receives shape information, material property information, and heating conditions from the input unit 130. The processing unit 132 incorporates the temperature-dependent heat generation rate and temperature-dependent gas generation rate into the governing equations. Using the shape information and heating conditions, the processing unit 132 calculates the heat conduction and gas advection due to heating in the battery 202 by simulation by calculating the governing equations using the finite element method. This is equivalent to meshing the three-dimensional shape data, including the shape information of the gas-impermeable and gas-permeable parts inside the battery 202, and calculating the heat generation rate and gas generation rate for each mesh. Known techniques can be used for the governing equations and finite element method, so their explanation is omitted here.

[0037] As a result, the processing unit 132 acquires the time change in the thermal distribution of the battery 202. In this time change in the thermal distribution of the battery 202, as shown in Figure 2(b), the heat generated by heat generation moves as thermal conduction 270, and the gas generated by heat generation inside the positive electrode 210 and negative electrode 220 moves to the separator 230, where it moves as gas advection 272. The processing unit 132 stores the time change in the thermal distribution of the battery 202 as a simulation result in the storage unit 134 and outputs it to the output unit 136.

[0038] As described above, the output unit 136 displays the simulation results as a result screen on the display device 120. In other words, the output unit 136 outputs the time change in the heat distribution of the battery 202. Figures 8(a) to 8(d) show the result screens displayed on the display device 120. The result screen changes over time in the order of Figure 8(a), Figure 8(b), Figure 8(c), and Figure 8(d). Each result screen includes the time change in the heat distribution 280 and a message 282. The time change in the heat distribution 280 includes the battery 202, the electrode body 240, and the short-circuit portion 284. The short-circuit portion 284 is located outside the electrode body 240. In the time change in the heat distribution 280, the high-temperature portion expands in the order of Figure 8(a), Figure 8(b), Figure 8(c), and Figure 8(d). The message 282 indicates that "heat conduction and gas advection have been calculated by simulation," which means that heat conduction and gas advection have been calculated by simulation.

[0039] Figures 9(a) and 9(b) show the simulation results performed by the processing unit 132. Figure 9(a) shows the simulation results for which heat conduction and gas advection were calculated for the battery 202. Figure 9(b) shows the simulation results for which only heat conduction was calculated for the battery 202, and gas advection was not calculated. The time elapsed since the start of superheating is the same in Figure 9(a) and Figure 9(b). Comparing these, Figure 9(a), which also considers gas advection, shows a faster combustion rate than Figure 9(b), which does not consider gas advection.

[0040] Figures 10(a) and 10(b) show the results of another simulation performed by the processing unit 132. In Figures 10(a) and 10(b), the battery 202 is shown in three dimensions. Figure 10(a) shows the simulation results in which heat conduction and gas advection were calculated for the battery 202. Figure 10(b) shows the simulation results in which only heat conduction was calculated for the battery 202, and gas advection was not calculated. The time elapsed since the start of superheating is the same in Figure 10(a) and Figure 10(b). Comparing these, the combustion rate in Figure 10(a), which also considers gas advection, is faster than in Figure 10(b), which does not consider gas advection. Return to Figure 3.

[0041] The processing unit 132 may calculate the time change of the average temperature of the entire battery 202 based on the time change of the heat distribution. The processing unit 132 outputs the time change of the average temperature to the output unit 136, and the output unit 136 displays the time change of the average temperature on the display device 120. Figure 11 shows yet another results screen displayed on the display device 120. The results screen shows the time change graph 288 of the average temperature and a message 282.

[0042] The subject of the apparatus, system, or method in this disclosure comprises a computer. The functions of the subject of the apparatus, system, or method in this disclosure are realized by the computer executing a program. The computer comprises a processor as its main hardware component, which operates according to the program. The processor is of any type as long as it can realize its functions by executing the program. The processor consists of one or more electronic circuits, including semiconductor integrated circuits (ICs) or LSIs (Large Scale Integrations). Multiple electronic circuits may be integrated on one chip or provided on multiple chips. Multiple chips may be aggregated in one device or provided on multiple devices. The program is recorded on a non-temporary recording medium such as ROM, optical discs, or hard disk drives that can be read by the computer. The program may be pre-stored on the recording medium or supplied to the recording medium via a wide-area communication network, including the Internet.

[0043] The operation of the simulation device 100 with the above configuration will now be explained. Figure 12 is a flowchart showing the simulation procedure by the simulation device 100. The input unit 130 receives information regarding the shape of the battery 202, information regarding the physical properties of the electrode body 240, and information regarding the heating conditions (S10). The processing unit 132 calculates heat conduction and gas advection through simulation (S12). The storage unit 134 stores the simulation results (S14). The output unit 136 outputs the simulation results (S16).

[0044] According to this embodiment, based on the shape information, physical property information, and heating conditions, by calculating the heat conduction and gas advection due to heating in the battery 202 through simulation, the time change of the heat distribution in the battery 202 is obtained, so that overheating in the battery 202 can be predicted with high accuracy. Further, since gas generation, gas movement, and heat transfer inside the battery 202 are considered, overheating in the battery 202 can be predicted with high accuracy. Further, in the simulation, after reflecting the heat generation rate and gas generation rate in the governing equation, the governing equation is calculated by the finite element method using the shape information and heating conditions, so that heat conduction 270 and gas advection 272 can be calculated. Further, an input screen for inputting the shape information, physical property information, and heating conditions is displayed, and a result screen showing the time change of the heat distribution in the battery 202 is displayed, so that the operability of the user can be improved.

[0045] (Embodiment 2) Next, Embodiment 2 will be described. Embodiment 2 relates to a simulation device that simulates the time change of the heat distribution when the battery of the power storage device overheats, similar to Embodiment 1. In Embodiment 1, the time change of the heat distribution inside the battery is predicted. On the other hand, in Embodiment 2, the time change of the heat distribution spreading from inside the battery to the outside of the battery is predicted. The gas generated in the electrode body inside the battery flows out into the gap space with the can at the upper part of the electrode body, and then is discharged to the outside of the battery through the opening at the upper part of the battery. The outside of the battery is a general term for the outside of the battery, such as a battery module, a drive unit of an electric vehicle, or a rack of a power storage system. The flow near the opening is fast and typically becomes a turbulent flow. Therefore, near the opening, the flow contracts and passes through the opening, and the flow expands outside the battery. Such a flow becomes a highly turbulent flow and is accompanied by a sudden change in pressure, which is a problem that is difficult to solve even for experts in thermal fluid simulation.

[0046] Further, typically, the size of the inside of the battery is several millimeters to several tens of millimeters, while the size of the outside of the battery is several millimeters to several tens of meters. In such a simulation, in accordance with the small size of the inside of the battery, the size of the mesh of the finite element method also becomes small, so that the total number of calculation elements increases. It is difficult to robustly execute such a simulation within a realistic time.

[0047] In Example 2, based on the finding that in the simulation for evaluating thermal safety, it is not necessary to accurately solve the pressure after valve opening, the pressure is simplified and calculated while correctly solving the flow velocity and temperature that are important in terms of safety. The simulation device 100 and the simulation system 150 according to Example 2 are of the same type as those in FIGS. 3 and 4. Here, the description will focus on the differences from the previous ones.

[0048] FIGS. 13(a)-(b) are diagrams showing the outline of the simulation by the processing unit 132. FIG. 13(a) is a simulation model for the inside of the battery 202. This is the same as in Example 1, and inside the battery 202, the gas advection 272 is directed toward the gas discharge valve 258. FIG. 13(b) is a simulation model for the outside of the battery 202, and it is a model for simulating the phenomenon that the high-temperature gas (gas advection 272) released from the battery 202 heats up other batteries 202 (not shown).

[0049] The processing unit 132 performs simulations for the inside and the outside of the battery 202 respectively. That is, the processing unit 132 divides the inside and the outside of the battery 202 into regions and performs simulations separately. At that time, the processing unit 132 makes the size of the mesh of the finite element method in the simulation of the inside of the battery 202 smaller than the size of the mesh of the finite element method in the simulation of the outside of the battery 202.

[0050] FIG. 14 is a diagram showing the outline of the simulation by the processing unit 132. The processing unit 132 defines a simulation model that does not include the upper opening of the battery 202 inside the battery 202 as the "first model", and defines a simulation model representing the outside of the battery 202 from the upper opening of the battery 202 as the "second model". The first model corresponds to FIG. 13(a), and the second model corresponds to FIG. 13(b). Also, an intermediate region 274 is arranged between the first model and the second model. The pressure changes abruptly in the intermediate region 274. The processing unit 132 excludes the intermediate region 274 from the object of the simulation.

[0051] In the first model, if the boundary on the opening side is designated as "Surface 1", the area of ​​Surface 1 is S1, the average flow velocity of the gas passing through Surface 1 is v1, and the average temperature of the gas passing through Surface 1 is T1. In the second model, if the boundary on the opening side is designated as "Surface 2", the area of ​​Surface 2 is S2, the average flow velocity of the gas passing through Surface 2 is v2, and the average temperature of the gas passing through Surface 2 is T2.

[0052] Under these assumptions, T2 and v2 are derived as follows: T2 = T1 and v2 = S1 × v1 / S2.

[0053] In this embodiment, since simulations are performed both inside and outside the battery 202, the intermediate region 274 where the pressure changes rapidly can be excluded from the simulation. Furthermore, by excluding the intermediate region 274 where the pressure changes rapidly from the simulation, the processing can be simplified. In addition, since the mesh size of the finite element method in the first model is made smaller than the mesh size of the finite element method in the second model, the computational load can be reduced while suppressing a decrease in accuracy.

[0054] An outline of one aspect of the present disclosure is as follows: (Item 1) A simulation method comprising: inputting information about the shape of a battery, information about the physical properties of the electrode body of the battery, and information about the conditions for heating the battery; obtaining the time change of the heat distribution of the battery by calculating the heat conduction and gas advection due to heating in the battery by simulation based on the information about the shape of the battery, the information about the physical properties of the electrode body, and the information about the heating conditions; and outputting the time change of the heat distribution of the battery.

[0055] (Item 2) The information relating to the shape of the battery is the simulation method described in Item 1, which includes gas-permeable and gas-non-permeable portions.

[0056] (Item 3) The simulation method according to Item 1 or 2, wherein the information relating to the physical properties of the electrode body includes the heat generation rate of the electrode body and the gas generation rate of the electrode body, the heat generation rate and the gas generation rate being temperature-dependent, and the simulation is performed by first reflecting the temperature-dependent heat generation rate and the temperature-dependent gas generation rate in the governing equations, and then using the information relating to the shape of the battery and the information relating to the heating conditions to calculate the governing equations by the finite element method.

[0057] (Item 4) The simulation method according to Item 3, wherein the simulation is performed on both the inside and outside of the battery, and the mesh size of the finite element method in the simulation inside the battery is smaller than the mesh size of the finite element method in the simulation outside the battery.

[0058] (Item 5) The simulation method according to Item 1, further comprising the step of displaying a first screen for inputting information relating to the shape of the battery, information relating to the physical properties of the electrode body, and information relating to the heating conditions, wherein the output step is to display a second screen showing the time change of the heat distribution of the battery.

[0059] (Item 6) A program for causing a computer to perform the following steps: inputting information about the shape of a battery, information about the physical properties of the electrode body of the battery, and information about the conditions for heating the battery; obtaining the time change of the heat distribution of the battery by calculating the heat conduction and gas advection due to heating in the battery by simulation based on the information about the shape of the battery, the information about the physical properties of the electrode body, and the information about the heating conditions; and outputting the time change of the heat distribution of the battery.

[0060] (Item 7) A storage medium for storing a program that causes a computer to perform the following steps: inputting information about the shape of a battery, information about the physical properties of the electrode body of the battery, and information about the conditions for heating the battery; obtaining the time change of the heat distribution of the battery by calculating the heat conduction and gas advection due to heating in the battery by simulation based on the information about the shape of the battery, the information about the physical properties of the electrode body, and the information about the heating conditions; and outputting the time change of the heat distribution of the battery.

[0061] (Item 8) A simulation device comprising: an input unit for inputting information about the shape of a battery, information about the physical properties of the electrode body of the battery, and information about the conditions for heating the battery; a processing unit for obtaining the time change of the heat distribution of the battery by calculating the heat conduction and gas advection due to heating in the battery through simulation based on the information about the shape of the battery, the information about the physical properties of the electrode body, and the information about the heating conditions; and an output unit for outputting the time change of the heat distribution of the battery.

[0062] (Item 9) A data structure comprising: (Item 9) Time change of the heat distribution of the battery obtained by a computer simulating and calculating the heat conduction and gas advection due to heating in the battery based on information about the shape of the battery, information about the physical properties of the electrode body of the battery, and information about the conditions for heating the battery; and a message indicating that heat conduction and gas advection have been calculated by the simulation.

[0063] 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.

[0064] According to this disclosure, it is possible to predict battery overheating with high accuracy.

[0065] 2 Battery, 10 Positive electrode, 20 Negative electrode, 30 Separator, 40 Electrode body, 50 Positive electrode terminal, 52 Negative electrode terminal, 54 Sealing body, 56 Gasket, 58 Gas discharge valve, 72 Gas advection, 100 Simulation device, 110 Operating device, 120 Display device, 130 Input unit, 132 Processing unit, 134 Memory unit, 136 Output unit, 150 Simulation system, 160 Terminal device, 170 Network, 180 Server, 202 Battery, 210 Positive electrode, 220 Negative electrode, 230 Separator, 240 Electrode body, 258 Gas discharge valve, 260 Nail, 262 Central part, 264 Can bottom part, 270 Heat conduction, 272 Gas advection, 274 Intermediate region, 280 Time change of heat distribution, 282 Message, 284 Short circuit section, 286 Heating section, 288 Graph of time change of average temperature.

Claims

1. A simulation method comprising: inputting information about the shape of a battery, information about the physical properties of the electrode body of the battery, and information about the conditions for heating the battery; obtaining the time change of the heat distribution of the battery by calculating the heat conduction and gas advection due to heating in the battery by simulation based on the information about the shape of the battery, the information about the physical properties of the electrode body, and the information about the heating conditions; and outputting the time change of the heat distribution of the battery.

2. The simulation method according to claim 1, wherein the information relating to the shape of the battery includes a portion through which gas can pass and a portion through which gas cannot pass.

3. The simulation method according to claim 1 or 2, wherein the information relating to the physical properties of the electrode body includes the heat generation rate of the electrode body and the gas generation rate of the electrode body, the heat generation rate and the gas generation rate being temperature-dependent, and the simulation calculates the governing equations by the finite element method using information relating to the shape of the battery and information relating to the heating conditions, after reflecting the temperature-dependent heat generation rate and the temperature-dependent gas generation rate in the governing equations.

4. The simulation method according to claim 3, wherein the simulation is performed on both the inside and outside of the battery, and the mesh size of the finite element method in the simulation inside the battery is smaller than the mesh size of the finite element method in the simulation outside the battery.

5. The simulation method according to any one of claims 1 to 4, further comprising the step of displaying a first screen for inputting information relating to the shape of the battery, information relating to the physical properties of the electrode body, and information relating to the heating conditions, wherein the output step is to display a second screen showing the time change of the heat distribution of the battery.

6. A program for causing a computer to perform the following steps: inputting information about the shape of a battery, information about the physical properties of the electrode body of the battery, and information about the conditions for heating the battery; obtaining the time change of the heat distribution of the battery by calculating the heat conduction and gas advection due to heating in the battery by simulation based on the information about the shape of the battery, the information about the physical properties of the electrode body, and the information about the heating conditions; and outputting the time change of the heat distribution of the battery.

7. A storage medium for storing a program that causes a computer to perform the following steps: inputting information about the shape of a battery, information about the physical properties of the electrode body of the battery, and information about the conditions for heating the battery; obtaining the time change of the heat distribution of the battery by calculating the heat conduction and gas advection due to heating in the battery by simulation based on the information about the shape of the battery, the information about the physical properties of the electrode body, and the information about the heating conditions; and outputting the time change of the heat distribution of the battery.

8. A simulation device comprising: an input unit for inputting information regarding the shape of a battery, information regarding the physical properties of the electrode body of the battery, and information regarding the conditions for heating the battery; a processing unit for obtaining the time change of the heat distribution of the battery by calculating the heat conduction and gas advection due to heating in the battery through simulation based on the information regarding the shape of the battery, the information regarding the physical properties of the electrode body, and the information regarding the heating conditions; and an output unit for outputting the time change of the heat distribution of the battery.

9. A data structure comprising: information about the shape of the battery, information about the physical properties of the electrode body of the battery, and information about the conditions for heating the battery, obtained by a computer simulating and calculating the heat conduction and gas advection due to heating in the battery; and a message indicating that heat conduction and gas advection have been calculated by the simulation.

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