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

Abstract

A processing unit 132 acquires a variation over time in the temperature of a battery during charging and discharging and a variation over time in the temperature of the battery after charging and discharging by calculating the variation over time in the temperature of the battery by means of a simulation on the basis of information pertaining to the physical properties of the battery, information pertaining to the shape of an electrode body, and information pertaining to charging and discharging conditions. The processing unit 132 subtracts the amount of relaxation heat in the simulation for acquiring the variation over time in the temperature of the battery during charging and discharging, and adds the amount of relaxation heat in the simulation for acquiring the variation over time in the temperature of the battery after charging and discharging. An output unit 136 outputs the variation over time in the temperature of the battery during charging and discharging and the variation over time in the temperature of the battery after charging and discharging.

Description

Simulation methods, programs, storage media, simulation devices, data structures

[0001] This disclosure relates to simulation technology, and more particularly to a simulation method, program, storage medium, simulation device, and data structure for calculating the time change of battery temperature.

[0002] It is necessary to accurately estimate the internal temperature of a secondary battery using a computer. For this reason, an internal resistance map is prepared in advance, which is the relationship between the internal resistance of the secondary battery, the duration since the start of charging or discharging of the secondary battery, the state of charge (SOC) of the secondary battery, and the temperature of the energy storage section. In the simulation, the internal resistance is determined based on the internal resistance map using the time since the start of charging or discharging (hereinafter referred to as "charging and discharging") of the secondary battery, and the amount of heat generated in the energy storage section is calculated using the internal resistance (see, for example, Patent Document 1).

[0003] Japanese Patent Publication No. 2013-101884

[0004] As described in Patent Document 1, the heat generated during charging and discharging is usually calculated based on internal resistance. However, conventional methods that use internal resistance to calculate the heat generation are not capable of accurately predicting the battery temperature or heat generation behavior. Therefore, it is difficult to accurately predict how the battery temperature changes over time due to charging and discharging (hereinafter referred to as "time change") using only internal resistance.

[0005] This disclosure is made in light of these circumstances, and its purpose is to provide a technology for accurately predicting the time change in battery temperature due to charging and discharging.

[0006] To solve the above problems, a simulation method according to one aspect of the present disclosure includes the steps of: inputting information on the physical properties of the battery, information on the shape of the battery electrodes, and information on the charging and discharging conditions of the battery; obtaining the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging by calculating the time change of the battery temperature through simulation based on the information on the physical properties of the battery, the shape of the electrodes, and the charging and discharging conditions; and outputting the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging. In the acquisition step, the relaxation heat is subtracted in the simulation for obtaining the time change of the battery temperature during charging and discharging, and the relaxation heat is added in the simulation for obtaining the time change of the battery temperature after charging and discharging.

[0007] Another aspect of this disclosure is a storage medium. This storage medium includes the steps of: inputting information relating to the physical properties of a battery, information relating to the shape of the battery electrodes, and information relating to the charging and discharging conditions of the battery; obtaining the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging by calculating the time change of the battery temperature through simulation based on the information relating to the physical properties of the battery, the shape of the electrodes, and the charging and discharging conditions; and outputting the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging. The acquisition step stores a program that causes a computer to subtract the relaxation heat in the simulation for obtaining the time change of the battery temperature during charging and discharging, and to add the relaxation heat in the simulation for obtaining the time change of the battery temperature after charging and discharging.

[0008] A further aspect of this disclosure is a simulation device. This device includes an input unit that inputs information on the physical properties of a battery, information on the shape of the battery electrodes, and information on the charging and discharging conditions of the battery; a processing unit that calculates the time change of the battery temperature through simulation based on the information on the physical properties of the battery, the shape of the electrodes, and the charging and discharging conditions, thereby obtaining the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging; and an output unit that outputs the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging. In the simulation for obtaining the time change of the battery temperature during charging and discharging, the processing unit subtracts the amount of relaxation heat, and in the simulation for obtaining the time change of the battery temperature after charging and discharging, it adds the amount of relaxation heat.

[0009] Another aspect of this disclosure is a data structure. This data structure includes the time change of the battery temperature during charging and discharging, the time change of the battery temperature after charging and discharging, and a message indicating that relaxation heat was used in the simulation, obtained by a computer simulating the time change of the battery temperature based on information about the physical properties of the battery, information about the shape of the battery electrodes, and information about the charging and discharging conditions of the battery. This clearly distinguishes the results from those calculated by conventional methods and clearly expresses the reliability of the results calculated by this calculation. In the simulation to obtain the time change of the battery temperature during charging and discharging, relaxation heat is subtracted, and in the simulation to obtain the time change of the battery temperature after charging and discharging, relaxation heat is added.

[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 with high accuracy the time change in battery temperature due to charging and discharging.

[0012] This figure shows the structure of the battery according to this embodiment. This figure shows the change in temperature over time after charging and discharging the battery in Figure 1. This figure shows the configuration of the simulation device according to this embodiment. This figure shows the configuration of the simulation system according to this embodiment. This figure shows the input screen displayed on the display device in Figure 3. This figure shows the correspondence table between the bias of Li+ concentration to the positive electrode and the L+ concentration of the positive electrode electrolyte. Figures 7(a)-7(b) show the data structure of the table stored in the memory unit of Figure 3. This figure shows the results screen displayed on the display device in Figure 3. This is a flowchart showing the simulation procedure by the simulation device in 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 simulating the time change of temperature when charging and discharging batteries such as lithium-ion secondary batteries. As a result of diligent research by the inventors, a phenomenon has been clarified in which some of the heat that should be generated during charging and discharging is not generated and starts to be generated with a delay after charging and discharging is completed. Due to the existence of this delayed heat generation phenomenon, which no one had known before, the inventors have found that, regarding the time change of temperature during charging and discharging, the amount of heat generated during charging and discharging decreases as the charge and discharge rate increases. Conventional simulations take Joule heating into consideration, but do not take into account the decrease in the amount of heat generated during charging and discharging. Therefore, conventional simulation results tended to show that the temperature increased during charging and discharging and decreased after charging and discharging as the charge and discharge rate increased, compared to measured values.

[0014] This embodiment is characterized by clearly identifying the existence of relaxation heat generation, which no one had previously discovered, and by reproducing these behaviors, improving prediction accuracy by incorporating them into simulations that predict the heat generation behavior of batteries during charging and discharging. The relaxation heat generation in this embodiment is a phenomenon that occurs when a battery is charged or discharged, and is caused by the uneven distribution of electrolyte concentration in the electrolyte solution generated by the current flow. Therefore, it applies to all battery systems that use electrolytes (including primary batteries) and is not limited to lithium-ion secondary batteries described in this embodiment.

[0015] 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.

[0016] Figure 1 shows the structure of battery 2, and in particular, it 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.

[0017] 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.

[0018] 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.

[0019] Figure 2 shows the change in temperature over time after charging and discharging of battery 2. The horizontal axis represents the time elapsed since the start of charging and discharging of battery 2. Time "T1" indicates the timing when charging and discharging of battery 2 is completed. Therefore, the period up to time "T1" corresponds to the charging and discharging of battery 2, and the period after time "T1" corresponds to the period after charging and discharging of battery 2. The vertical axis represents the temperature of battery 2, for example, the surface temperature of battery 2.

[0020] The calculated value of 200 represents the temperature calculated by previous simulations that take Joule heating into account. The following heat transfer equations are used in these simulations. Here, "ρ" is the density of battery 2 [kg / m³]. ３ ] indicates, "V ｏｌ " is the volume of battery 2 [m ３ ] indicates "C Ｐ " indicates the specific heat of battery 2 [J / kg / K], "T" indicates the temperature of battery 2 [K], and "h" indicates the heat transfer coefficient [W / m ２ [K] indicates that "S" is the surface area [m²] of battery 2. ２ The equation (1) shows that "T0" represents the ambient temperature [K]. In addition, "q1" represents the heat of electrode reaction (entropy heat), "q2" represents resistance heating (heat generated due to ohmic resistance or reaction resistance), and "q3" represents the heat of side reactions. Therefore, the first to third terms on the right side of equation (1) represent the amount of heat generated. The fourth term on the right side of equation (1) represents the amount of heat dissipated.

[0021] "q1" through "q3" are shown as follows: Here, "I" represents electric current [A], and "V" represents electric current [V]. ＯＣＶ " indicates the open-circuit voltage [V], and "V ＣＣＶ The symbol "" indicates the closed-circuit voltage [V]. The time variation of "I" indicates the charge / discharge rate.

[0022] Furthermore, in the simulation, the heat transfer equations are calculated using the finite element method. In this process, the shape data of the battery 2 is meshed, the amount of heat generated during charging and discharging is calculated in the mesh containing the electrode body 40 of the battery 2, and the amount of heat dissipated is calculated in the mesh containing the outer casing (negative electrode terminal 52) of the battery 2.

[0023] The measured value 202 represents the value measured under the same conditions as when the calculated value 200 was calculated. Comparing the calculated value 200 and the measured value 202, the measured value 202 is smaller than the calculated value 200 during the charging and discharging of battery 2, and larger than the calculated value 200 after the charging and discharging of battery 2. Here, the area of ​​the difference between the calculated value 200 and the measured value 202 during charging and discharging is shown as the first relaxation heat quantity 250a, and the area of ​​the difference between the calculated value 200 and the measured value 202 after charging and discharging is shown as the second relaxation heat quantity 250b. From this, it can be said that the heat generation is reduced by the first relaxation heat quantity 250a in relation to Joule heating. In other words, relaxation heating becomes more pronounced as the charging and discharging current increases. Furthermore, it can be said that there is heat generation of the second relaxation heat quantity 250b after charging and discharging. The first relaxation heat quantity 250a and the second relaxation heat quantity 250b are collectively referred to as relaxation heat quantity 250. In this example, a simulation is performed that reflects a relaxation heat amount of 250.

[0024] Figure 3 shows the configuration of the simulation device 100. The simulation device 100 predicts the time change in the temperature of the battery 2 due to charging and discharging by simulating the thermal phenomena of the battery 2 that generate heat during charging and discharging. 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.

[0025] 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.

[0026] The input unit 130 receives information to be used for the simulation from the operating device 110. The input unit 130 may also receive information to be used for the simulation from the storage unit 134.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] The simulation device 100 may be configured as a system. FIG. 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 operation device 110 and display device 120.

[0031] The network 170 is configured by wireless communication, wired communication, or a combination of wireless communication and wired communication. The terminal device 160 and the server 180 are connected to the network 170, and the terminal device 160 and the server 180 communicate with each other via the network 170. The server 180 corresponds to the aforementioned simulation device 100 and executes the simulation. Hereinafter, this embodiment will be described based on the configuration of FIG. 3, but this embodiment may also be executed in the configuration of FIG. 3.

[0032] The processing unit 132 displays an input screen on the display device 120. While viewing the input screen displayed on the display device 120, the user operates the operation device 110 to input information to be used in the simulation. FIG. 5 shows the input screen displayed on the display device 120. In the "physical properties of battery materials" here, information regarding the physical properties of the battery 2 and information regarding the shape of the battery 2 are input. The "shape of the electrode body" includes information regarding the shape of the electrode body 40 of the battery 2. The "charge / discharge conditions" include information regarding the charge / discharge conditions of the battery 2. Details of this information will be described later.

[0033] Each piece of information input to the operation device 110 as described above is output from the operation device 110 to the simulation device 100. The input unit 130 receives each piece of information from the operation device 110. The input unit 130 may receive each piece of information from the storage unit 134.

[0034] Information on the physical properties of the battery 2 includes electrochemical characteristics such as equilibrium potential, exchange current density, electron conductivity, and ion conductivity, and thermal characteristics such as specific heat, density, and thermal conductivity. Further, information on the shape of the battery 2 is shown, for example, as the three-dimensional shape of the battery 2 shown in FIG. 1, or is shown in a format such as CAD (Computer Aided Design) data. Information on the shape of the electrode body 40 of the battery 2 includes the physical properties, dimensions, porosity, etc. of the constituent material of the electrode body 40. Information on the charge / discharge conditions of the battery 2 includes the charge / discharge rate, limiting voltage, time to end charge / discharge, etc.

[0035] The processing unit 132 receives each piece of information from the input unit 130. The processing unit 132 specifies the relaxation heat quantity 250 based on the charge / discharge rate included in the information on the charge / discharge conditions of the battery 2. Here, the relaxation heat quantity 250 will be described. Assuming that lithium ions Li+ do not disappear during the process of using the battery and the volume of the electrode does not change, the following equation holds. Here, let the initial Li+ concentration of the positive electrode electrolyte and the negative electrode electrolyte be c ０ Let the Li+ concentration of the positive electrode electrolyte be c ｐ and the Li+ concentration of the negative electrode electrolyte be c ｎ Let the volume in which the positive electrode electrolyte can exist be V ｐ and the volume in which the negative electrode electrolyte can exist be V ｎ The volume in which the electrolyte exists is the volume other than the solid part of the porous electrode.

[0036] It is known that when a current flows through the battery, a bias occurs in the Li+ concentration distribution in the electrolyte. For example, during charging, the Li+ ion concentration at the positive electrode 10 decreases, and the Li+ ion concentration at the negative electrode 20 increases. Also, during discharging, the Li+ ion concentration at the positive electrode 10 increases, and the Li+ ion concentration at the negative electrode 20 decreases. Further, the greater the current, the greater the difference in Li+ ion concentration.

[0037] Here, η is introduced as a variable representing the bias of the Li+ concentration to the positive electrode 10. Equation (5) is transformed as follows. Considering that 0 ≦ c ｐ , c ｎ When c ｎ = 0, then cｐ The next maximum value is... On the other hand, c ｐ The minimum value is shown as follows: Therefore, the bias η of the Li+ concentration towards the positive electrode 10 is defined as shown in the correspondence table in Figure 6. When η = 0, it represents a situation where all Li+ ions in the electrolyte are concentrated towards the negative electrode 20, and when η = 1, it represents a situation where all Li+ ions in the electrolyte are concentrated towards the positive electrode 10.

[0038] The following relationships are shown in the correspondence table. Therefore, the bias η and the positive electrode electrolyte Li+ concentration c ｐ The relationship is proportional. From equations (5) and (9), the concentration of the negative electrode electrolyte Li+ can also be expressed using the bias η as follows.

[0039] The total Gibbs free energy G of the positive and negative electrode electrolytes is given by the following equation: Here, μ ０ The formula represents the chemical potential of Li+ in the electrolyte under standard conditions, R represents the gas constant, and T represents the temperature.

[0040] c ｐ and c ｎ Substituting equations (9) and (10) into the equation, we find that G is expressed as η as follows. G is a function of η only. Differentiating G with respect to η shows the following:

[0041] The following equation holds true: The following case: In that case, G will be the following minimum value.

[0042] Equation (16) represents the Gibbs free energy of the electrolyte in an equilibrium state with respect to the concentration distribution, i.e., when there is no bias in the concentration of Li+ ions in the electrolyte, while equation (12) represents the difference in the free energy of the electrolyte in a state with an arbitrary bias in concentration. Therefore, (Equation 12) - (Equation 16) is the difference in Gibbs free energy ΔG due to the bias in the concentration of Li+ ions in the electrolyte. Since the pressure and temperature are kept constant here, the difference in Gibbs free energy corresponds to the difference in entropy. The only variable in equation (17) is the bias η. From this, it follows that in these situations, energy corresponding to the degree of bias is stored in the Li+ ion concentration, and this energy is converted into sensible heat by the homogenization of the Li+ ion concentration. This energy or sensible heat is the relaxation heat of 250. In other words, the relaxation heat of 250 is generated by the concentration distribution of the electrolyte present between the positive electrode 10 and the negative electrode 20 of battery 2. This corresponds to being generated by the concentration distribution of Li+ ions, or more generally, ions or salts in the electrolyte.

[0043] Figures 7(a) and 7(b) show the data structure of the table stored in the memory unit 134. Figure 7(a) shows the correspondence between the charge / discharge rate and the relaxation heat quantity 250. When the charge / discharge rate is "R1", the processing unit 132 refers to the table and identifies q4(1). The same applies to other charge / discharge rates. Figure 7(b) shows the data structure of the identified relaxation heat quantity 250. This corresponds to, for example, q4(1). The relaxation heat quantity 250 has values ​​associated with each time period. A constant value may be included.

[0044] The value of the relaxation heat of 250 is calculated, for example, as a function (electrochemical formula) of the ion concentration between the positive electrode 10 and the negative electrode 20. Specifically, the average electrolyte concentration c of the positive electrode ｐ，ａｖｅ And the average electrolyte concentration c of the negative electrode ｎ，ａｖｅ The logarithmic difference of ln(c ｐ，ａｖｅ / c ｎ，ａｖｅ It is calculated in proportion to ). Alternatively, the value of relaxation heat 250 may be calculated as a function of the polarization voltage generated when energized (equivalent circuit, measured value in actual cell). Furthermore, the value of relaxation heat 250 may be calculated as an empirically based function.

[0045] As mentioned above, relaxation heat generation occurs due to the uneven distribution of electrolyte concentration, and therefore its amount and temporal behavior vary depending on the design of the battery electrode plates (material particle size, porosity, etc.) and the characteristics of the electrolyte (viscosity, electrolyte concentration, type of solvent, etc.). For this reason, the amount and temporal behavior of relaxation heat generation may be calculated from the distribution and temporal behavior of electrolyte unevenness calculated by charge-discharge simulation, or from the difference between the heat generation behavior obtained by simulation and the measured temperature behavior of the actual battery.

[0046] The processing unit 132 calculates the time change in the temperature of the battery 2 by simulation, based on information regarding the physical properties of the battery 2, information regarding the shape of the battery 2, information regarding the shape of the electrode body 40, and information regarding the charge and discharge conditions. The following heat transfer equation is used for the simulation during charge and discharge. This is an example where "-q4" is added to the right-hand side compared to equation (1). q4 represents the relaxation heat of 250. The aforementioned value is input for q4. At that time, the value is also changed as time elapses from the start of charging and discharging.

[0047] In the simulation, the heat transfer equations are calculated using the finite element method. At that time, the shape data of the battery 2 is meshed, and the amount of heat generated and the amount of relaxation heat 250 are calculated in the mesh including the electrode body 40 of the battery 2, and the amount of heat dissipated is calculated in the mesh including the outer casing (negative electrode terminal 52) of the battery 2. In other words, the processing unit 132 uses the amount of heat generated by the battery 2, the heat transfer of the battery 2, and the amount of relaxation heat 250 to calculate the time change in the temperature of the battery through simulation, and in the simulation to obtain the time change in the temperature of the battery 2 during charging and discharging, the amount of relaxation heat 250 is subtracted from the amount of heat generated by the battery 2.

[0048] The following heat transfer equations are used for simulations after charging and discharging. In comparison to equation (1), the "q1 + q2 + q3" term on the right-hand side, i.e., the heat generation term, becomes 0, and "q4" is added to the right-hand side. q4 represents the relaxation heat of 250. The aforementioned value is input for q4. At that time, the value is also changed as time elapses since the end of charging and discharging.

[0049] In the simulation, the heat transfer equations are calculated using methods such as the finite element method. At that time, the relaxation heat amount 250 is calculated in the mesh including the electrode body 40 of the battery 2, and the heat dissipation amount is calculated in the mesh including the outer casing (negative electrode terminal 52) of the battery 2. In other words, the processing unit 132 uses the heat generated by the battery 2, the heat transfer of the battery 2, and the relaxation heat amount 250 to calculate the time change of the battery temperature through simulation, and adds the relaxation heat amount 250 in the simulation to obtain the time change of the battery temperature 2 after charging and discharging. As a result of the above processing, the processing unit 132 obtains the time change of the battery temperature 2 during charging and discharging and the time change of the battery temperature 2 after charging and discharging. The processing unit 132 stores the time change of the battery temperature 2 during charging and discharging and the time change of the battery temperature 2 after charging and discharging as simulation results in the storage unit 134 and outputs them to the output unit 136.

[0050] As described above, the output unit 136 displays the simulation results as a results screen on the display device 120. In other words, the output unit 136 outputs the time change of the temperature of the battery 2 during charging and discharging, and the time change of the temperature of the battery 2 after charging and discharging. Figure 8 shows the results screen displayed on the display device 120. The results screen includes a time change graph of temperature 280 and a message 282. The time change graph of temperature 280 shows the time change of the temperature of the battery 2 during charging and discharging, and the time change of the temperature of the battery 2 after charging and discharging. The message 282 states, "The relaxation heat amount is subtracted during charging and discharging, and the relaxation heat amount is added after charging and discharging," which indicates that the relaxation heat amount 250 is used in the simulation.

[0051] 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.

[0052] The operation of the simulation device 100 with the above configuration will now be explained. Figure 9 is a flowchart showing the simulation procedure by the simulation device 100. The input unit 130 receives information regarding the physical properties of the battery 2, information regarding the shape of the electrode body 40, and information regarding the charge and discharge conditions (S10). The processing unit 132 identifies the amount of relaxation heat based on the charge and discharge rate (S12). The processing unit 132 calculates the temperature time by simulation, subtracting the amount of relaxation heat during charge and discharge and adding the amount of relaxation heat after charge and discharge (S14). The storage unit 134 stores the simulation results (S16). The output unit 136 outputs the simulation results (S18).

[0053] In this embodiment, the relaxation heat amount 250 is subtracted in the simulation to obtain the time change in the temperature of the battery 2 during charging and discharging, and the relaxation heat amount 250 is added in the simulation to obtain the time change in the temperature of the battery 2 after charging and discharging, so the effect of reduced heat generation during charging and discharging can be reflected. Furthermore, since the effect of reduced heat generation during charging and discharging is reflected, the time change in the temperature of the battery 2 due to charging and discharging can be predicted with high accuracy. In addition, the relaxation heat amount 250 is subtracted from the amount of heat generated by the battery 2 in the simulation during charging and discharging, and the relaxation heat amount 250 is added in the simulation after charging and discharging, so the effect of reduced heat generation during charging and discharging can be reflected.

[0054] Furthermore, since the relaxation heat quantity 250 depends on the charge-discharge rate, the time change in the temperature of the battery 2 due to charging and discharging can be predicted with high accuracy. Also, since the relaxation heat quantity 250 is generated by the concentration distribution of the electrolyte present between the positive and negative electrodes of the battery 2, the time change in the temperature of the battery 2 due to charging and discharging can be predicted with high accuracy. In addition, an input screen for inputting information for the simulation is displayed, and a results screen showing the time change in the temperature of the battery 2 during charging and discharging and the time change in the temperature of the battery 2 after charging and discharging is displayed, thereby improving user operability.

[0055] An outline of one aspect of the present disclosure is as follows: (Item 1) A simulation method comprising the steps of: inputting information relating to the physical properties of a battery, information relating to the shape of the electrode body of the battery, and information relating to the charging and discharging conditions of the battery; obtaining the time change of the temperature of the battery during charging and discharging and the time change of the temperature of the battery after charging and discharging by calculating the time change of the temperature of the battery by simulation based on the information relating to the physical properties of the battery, the information relating to the shape of the electrode body, and the information relating to the charging and discharging conditions; and outputting the time change of the temperature of the battery during charging and discharging and the time change of the temperature of the battery after charging and discharging, wherein the acquisition step subtracts the amount of relaxation heat in the simulation for obtaining the time change of the temperature of the battery during charging and discharging, and adds the amount of relaxation heat in the simulation for obtaining the time change of the temperature of the battery after charging and discharging.

[0056] (Item 2) The simulation method described in Item 1, wherein the acquisition step calculates the time change of the battery temperature by simulation using the amount of heat generated by the battery, the heat transfer of the battery, and the relaxation heat amount, and in the simulation for acquiring the time change of the battery temperature during charging and discharging, the relaxation heat amount is subtracted from the amount of heat generated by the battery, and in the simulation for acquiring the time change of the battery temperature after charging and discharging, the relaxation heat amount is added.

[0057] (Item 3) The simulation method according to Item 1 or 2, wherein the information relating to the charge and discharge conditions of the battery includes the charge and discharge rate, and the relaxation heat amount depends on the charge and discharge rate.

[0058] (Item 4) The relaxation heat is generated by the concentration distribution of the electrolyte present between the positive and negative electrodes of the battery, as described in the simulation method of Item 3.

[0059] (Item 5) The simulation method according to any one of Items 1 to 4, further comprising the step of displaying a first screen for inputting information relating to the physical properties of the battery, information relating to the shape of the electrode body of the battery, and information relating to the charging and discharging conditions of the battery, wherein the output step is to display a second screen showing the time change of the temperature of the battery during charging and discharging and the time change of the temperature of the battery after charging and discharging.

[0060] (Item 6) A program comprising the steps of: inputting information relating to the physical properties of a battery, information relating to the shape of the electrode body of the battery, and information relating to the charging and discharging conditions of the battery; obtaining the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging by calculating the time change of the battery temperature through simulation based on the information relating to the physical properties of the battery, the information relating to the shape of the electrode body, and the information relating to the charging and discharging conditions; and outputting the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging, wherein the acquisition step causes a computer to subtract the relaxation heat in the simulation for obtaining the time change of the battery temperature during charging and discharging, and to add the relaxation heat in the simulation for obtaining the time change of the battery temperature after charging and discharging.

[0061] (Item 7) A storage medium that stores a program causing a computer to perform the acquisition step of subtracting the amount of relaxation heat in the simulation for acquiring the amount of relaxation heat in the simulation for acquiring the amount of relaxation heat in the simulation for acquiring the amount of relaxation heat in the simulation for acquiring the amount of relaxation heat in the simulation for acquiring the amount of relaxation heat

[0062] (Item 8) A simulation device comprising: an input unit that inputs information relating to the physical properties of a battery, information relating to the shape of the electrode body of the battery, and information relating to the charging and discharging conditions of the battery; a processing unit that calculates the time change of the temperature of the battery by simulation based on the information relating to the physical properties of the battery, the information relating to the shape of the electrode body, and the information relating to the charging and discharging conditions, thereby obtaining the time change of the temperature of the battery during charging and discharging and the time change of the temperature of the battery after charging and discharging; and an output unit that outputs the time change of the temperature of the battery during charging and discharging and the time change of the temperature of the battery after charging and discharging, wherein the processing unit subtracts the amount of relaxation heat in the simulation for obtaining the time change of the temperature of the battery during charging and discharging, and adds the amount of relaxation heat in the simulation for obtaining the time change of the temperature of the battery after charging and discharging.

[0063] (Item 9) A data structure comprising: information on the physical properties of the battery, information on the shape of the electrode body of the battery, and information on the charging and discharging conditions of the battery, obtained by a computer simulation to calculate the change in the temperature of the battery over time; the change in the temperature of the battery over time after charging and discharging; and a message indicating that relaxation heat is used in the simulation, wherein in the simulation to obtain the change in the temperature of the battery over time during charging and discharging, relaxation heat is subtracted, and in the simulation to obtain the change in the temperature of the battery over time after charging and discharging, relaxation heat is added.

[0064] The present disclosure has been explained 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.

[0065] According to this disclosure, it is possible to predict with high accuracy the time change in battery temperature due to charging and discharging.

[0066] 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, 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, 200 Calculated value, 202 Measured value, 250 Relaxation heat quantity, 280 Time change graph of temperature, 282 Message.

Claims

1. A simulation method comprising the steps of: inputting information relating to the physical properties of a battery, information relating to the shape of the electrode body of the battery, and information relating to the charging and discharging conditions of the battery; obtaining the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging by calculating the time change of the battery temperature through simulation based on the information relating to the physical properties of the battery, the shape of the electrode body, and the charging and discharging conditions; and outputting the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging, wherein the acquisition step subtracts the relaxation heat amount in the simulation for obtaining the time change of the battery temperature during charging and discharging, and adds the relaxation heat amount in the simulation for obtaining the time change of the battery temperature after charging and discharging.

2. The simulation method according to claim 1, wherein the acquisition step calculates the time change of the battery temperature by simulation using the amount of heat generated by the battery, the heat transfer of the battery, and the relaxation heat amount, and in the simulation for acquiring the time change of the battery temperature during charging and discharging, the relaxation heat amount is subtracted from the amount of heat generated by the battery, and in the simulation for acquiring the time change of the battery temperature after charging and discharging, the relaxation heat amount is added.

3. The simulation method according to claim 1 or 2, wherein the information relating to the charge and discharge conditions of the battery includes the charge and discharge rate, and the relaxation heat amount depends on the charge and discharge rate.

4. The simulation method according to claim 3, wherein the relaxation heat is generated by the concentration distribution of the electrolyte present between the positive and negative electrodes of 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 physical properties of the battery, information relating to the shape of the electrode body of the battery, and information relating to the charging and discharging conditions of the battery, wherein the output step is to display a second screen showing the time change of the temperature of the battery during charging and discharging and the time change of the temperature of the battery after charging and discharging.

6. A program comprising the steps of: inputting information relating to the physical properties of a battery, information relating to the shape of the electrode body of the battery, and information relating to the charging and discharging conditions of the battery; obtaining the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging by calculating the time change of the battery temperature through simulation based on the information relating to the physical properties of the battery, the shape of the electrode body, and the charging and discharging conditions; and outputting the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging, wherein the acquisition step causes the computer to subtract the relaxation heat in the simulation for obtaining the time change of the battery temperature during charging and discharging, and to add the relaxation heat in the simulation for obtaining the time change of the battery temperature after charging and discharging.

7. A storage medium that stores a program causing a computer to perform the acquisition step of subtracting the relaxation heat amount in the simulation for acquiring the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging, wherein the acquisition step includes a step of inputting information relating to the physical properties of the battery, information relating to the shape of the electrode body of the battery, and information relating to the charging and discharging conditions, and a step of calculating the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging based on the information relating to the physical properties of the battery, information relating to the shape of the electrode body of the battery, and the information relating to the charging and discharging conditions, and outputting the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging, wherein the acquisition step includes storing a program that causes a computer to perform the action of subtracting the relaxation heat amount in the simulation for acquiring the time change of the battery temperature during charging and discharging and adding the relaxation heat amount in the simulation for acquiring the time change of the battery temperature after charging and discharging.

8. A simulation device comprising: an input unit that inputs information relating to the physical properties of a battery, information relating to the shape of the electrode body of the battery, and information relating to the charging and discharging conditions of the battery; a processing unit that calculates the time change of the battery temperature through simulation based on the information relating to the physical properties of the battery, the shape of the electrode body, and the charging and discharging conditions, thereby acquiring the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging; and an output unit that outputs the time change of the battery temperature during charging and discharging and the time change of the battery temperature after charging and discharging, wherein the processing unit subtracts the relaxation heat amount in the simulation for acquiring the time change of the battery temperature during charging and discharging, and adds the relaxation heat amount in the simulation for acquiring the time change of the battery temperature after charging and discharging.

9. A data structure comprising: information regarding the physical properties of the battery; information regarding the shape of the electrode body of the battery; and information regarding the charging and discharging conditions of the battery, obtained by a computer simulation to calculate the time change of the battery's temperature; the time change of the battery's temperature during charging and discharging; the time change of the battery's temperature after charging and discharging; and a message indicating that relaxation heat is used in the simulation, wherein in the simulation to obtain the time change of the battery's temperature during charging and discharging, relaxation heat is subtracted, and in the simulation to obtain the time change of the battery's temperature after charging and discharging, relaxation heat is added.

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