CN113646947A - Development support device, development support method, and computer program - Google Patents

Abstract

The invention provides a development support device, a development support method, and a computer program. The development support device includes: a receiving unit that receives, from a terminal apparatus, selection information relating to a degradation mechanism of an electric storage device after user authentication of the terminal apparatus; a simulation execution unit that simulates degradation of the power storage device by the selected degradation mechanism based on the received selection information; and a transmission unit that transmits a simulation result simulated by the simulation execution unit or a simulation program executed when the degradation of the power storage device is simulated, to the terminal device.

Description

Development support device, development support method, and computer program

Technical Field

The present invention relates to a development support device, a development support method, and a computer program installed in a computer.

Background

In recent years, MBD (model-based development) has been actively introduced into various industries including the automobile industry, and product development by simulation has been pervasive (for example, see patent document 1).

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 11-14507

Disclosure of Invention

Problems to be solved by the invention

In order to predict the degradation of a battery, which is one of the elements of development, it is important for enterprises such as automobile manufacturers and power storage system manufacturers who purchase and assemble batteries, from the viewpoints of strength design, life cycle design, cooling device design, maintenance management, and the like of battery cases. However, it is difficult for an expert other than the experts to grasp the deterioration behavior of the battery.

The yield of elements used in the electrodes of the battery is low, and it is considered that the elements will be reused in the future. However, depending on the state of degradation, reuse may be difficult, and it is important to grasp the degradation behavior based on the degradation mechanism in order to perform appropriate reuse for grasping the recovery rate.

An object of the present invention is to provide a development support apparatus, a development support method, and a computer program that can provide a result of a degradation simulation of an electric storage device or a simulation program in which a degradation mechanism is considered to a user via a network.

Means for solving the problems

A development support device according to an aspect of the present invention includes: a receiving unit that receives, from a terminal apparatus, selection information relating to a degradation mechanism of an electric storage device after user authentication of the terminal apparatus; a simulation execution unit that simulates degradation of the power storage device by the selected degradation mechanism based on the received selection information; and a transmission unit that transmits a simulation result simulated by the simulation execution unit or a simulation program executed when the degradation of the power storage device is simulated, to the terminal device.

A development support method according to another aspect of the present invention is a development support method that presents a plurality of options related to a degradation mechanism of an electric storage device by using a development support apparatus connected so as to be able to communicate with a terminal apparatus, receives selection information related to the selected degradation mechanism from the terminal apparatus, simulates degradation of the electric storage device by using the selected degradation mechanism based on the received selection information, and transmits a simulation result or a simulation program executed when the degradation of the electric storage device is simulated to the terminal apparatus.

Another aspect of the present invention relates to a computer program for causing a computer to execute: a plurality of options related to the degradation mechanism of the power storage device are presented, a selection related to the degradation mechanism of the power storage device is accepted based on the presented options, the degradation of the power storage device is simulated by using the selected degradation mechanism, and a simulation result or a simulation program executed when the degradation of the power storage device is simulated is output.

Effects of the invention

According to the above configuration, the result of the degradation simulation of the power storage device in which the degradation mechanism is considered can be provided to the user via the network.

Drawings

Fig. 1 is a block diagram illustrating an overall configuration of a simulation system according to an embodiment.

Fig. 2 is a block diagram illustrating an internal configuration of the server apparatus.

Fig. 3 is a conceptual diagram illustrating an example of a battery table.

Fig. 4 is a block diagram illustrating an internal structure of a client device.

Fig. 5 is a schematic diagram showing an example of an interface screen.

Fig. 6 is a graph showing the relationship between the charge carrier concentration in the solid phase and the Open Circuit Potential (OCP) in a typical cathode material.

Fig. 7 is a graph showing the relationship of the dimensionless charge carrier concentration θ and the open circuit potential OCP of the electrode material having a high energy density.

Fig. 8 is an explanatory view explaining peeling between the collector foil and the electrode.

Fig. 9 is an explanatory view illustrating interruption of the conduction path of the conductive aid.

Fig. 10 is an explanatory view for explaining formation of a resistor film.

Fig. 11 is a graph showing the relationship between the lithium ion concentration and the ionic conductivity in the electrolytic solution.

Fig. 12 is a flowchart illustrating a procedure of processing performed by the server apparatus and the client apparatus.

Fig. 13 is a graph showing a change in expansion ratio with time.

Detailed Description

The development support device includes: a receiving unit that receives, from a terminal apparatus, selection information relating to a degradation mechanism of an electric storage device after user authentication of the terminal apparatus; a simulation execution unit that simulates degradation of the power storage device by the selected degradation mechanism based on the received selection information; and a transmission unit that transmits a simulation result simulated by the simulation execution unit or a simulation program executed when the degradation of the power storage device is simulated, to the terminal device.

Therefore, even when the user is not proficient in the degradation mechanism of the power storage device, the development support device can provide the user with the result of the degradation simulation of the power storage device by simply receiving selection information on the degradation mechanism. The user can grasp the life cycle prediction, replacement timing prediction, recovery rate prediction for reuse purpose, heat generation amount, and the like of the product based on the provided result of the degradation simulation. The development support device may also provide a simulation program executed when simulating degradation of the power storage device. The user executes the simulation program in the terminal device, thereby being able to acquire the result of the degradation simulation of the power storage device.

The simulation execution unit may execute a simulation using a physical model representing the power storage device. According to this configuration, since the simulation is executed using the physical model of the power storage device, a simulation result in which a physical phenomenon inside the power storage device is accurately reflected can be obtained.

The degradation mechanism may include at least one of an increase in resistance among the elements constituting the electric storage device, an isolation of active material particles (the isolation is described later), a decrease in conductivity in the electrolyte, and a decrease in charge carriers involved in charge and discharge. According to this configuration, the deterioration of the electric storage device can be simulated by using, as a deterioration mechanism, an increase in resistance, isolation of active material particles, a decrease in conductivity in the electrolyte, and a decrease in charge carriers in each element. In the present specification, the active material particles refer to secondary particles formed by aggregating primary particles, particles composed of only primary particles, and the like. The active material is a material that transfers electrons, and typical active materials of lithium ion batteries are lithium metal composite oxides and carbon materials. In the present specification, the charge carrier refers to a carrier of a charge existing in a solid phase or a liquid phase, and for example, in the case of a lithium ion battery, refers to a lithium ion Li⁺。

The increase in resistance may include an increase in resistance at the bonding portion between the current collecting foil and the porous electrode, an increase in resistance due to a decrease in the conductive path in the active material particle, or an increase in resistance due to an increase in the resistor coating on the particle surface. According to this configuration, deterioration of the electric storage device can be simulated in consideration of an increase in resistance at the bonding portion between the current collecting foil and the porous electrode, an increase in resistance due to a decrease in the conductive path in the active material particle, or an increase in resistance due to an increase in the resistor film on the particle surface.

The increase in resistance, isolation of the active material particles, and decrease in conductivity may also be expressed as a function of the upper limit and the lower limit of the SOC during discharge. According to this configuration, the deterioration of the power storage device can be simulated in consideration of the usage state of the device on which the power storage device is mounted. SOC is an abbreviation of State of charge (State off charge), and represents a fully charged State as 100% and a fully discharged State as 0%.

The increase in resistance, the isolation of the active material particles, the decrease in conductivity, and the decrease in charge carriers may also be represented as a function of at least one of elapsed time, cycle number, and temperature. With this configuration, the deterioration of the power storage device can be presented as a function of elapsed time, cycle count, or temperature. In this specification, the number of cycles indicates the number of times charge and discharge are performed.

The reduction of charge carriers can also be represented by a metric of charge movement processes in the surface of the negative electrode upon charging. According to this configuration, the decrease in charge carriers can be represented by the metering coefficient.

The simulation result may include a temporal change or a periodic change in any one of a value of resistance, a volume ratio of an isolated region of the active material particles, a diffusion coefficient or ionic conductivity of the electrolyte, an amount of charge carriers, and an expansion rate of the power storage device among the elements constituting the power storage device. According to this configuration, the value of the resistance, the volume ratio of the isolated region of the active material particles, the diffusion coefficient or ionic conductivity of the electrolyte, the amount of charge carriers, and the expansion rate of the electric storage device can be presented as a function of the elapsed time or the cycle number.

The development support device includes: a reception unit that receives selection information relating to a degradation mechanism of the power storage device; a simulation execution unit that simulates degradation of the power storage device by the selected degradation mechanism based on the received selection information; and an output unit that outputs a simulation result simulated by the simulation execution unit or a simulation program executed when the degradation of the power storage device is simulated. With this configuration, even when the user is not proficient in the degradation mechanism of the power storage device, the development support device can provide the user with the result of the degradation simulation of the power storage device by simply receiving selection information on the degradation mechanism. According to the above configuration, the development support apparatus can provide the simulation program to the user, and therefore the user can obtain the result of the degradation simulation of the power storage device by executing the simulation program using the terminal apparatus.

A development support method presents a plurality of options related to a degradation mechanism of an electric storage device by using a development support apparatus connected so as to be communicable with a terminal apparatus, receives selection information related to the selected degradation mechanism from the terminal apparatus, simulates degradation of the electric storage device by using the selected degradation mechanism based on the received selection information, and transmits a simulation result or a simulation program executed when simulating degradation of the electric storage device to the terminal apparatus. With this configuration, even when the user is not proficient in the degradation mechanism of the power storage device, the development support device can provide the user with the result of the degradation simulation of the power storage device by simply receiving selection information on the degradation mechanism. According to the above configuration, the development support apparatus can provide the simulation program to the user, and therefore the user can obtain the result of the degradation simulation of the power storage device by executing the simulation program using the terminal apparatus.

The development support method includes presenting, by a computer, a plurality of options related to a degradation mechanism of an electric storage device, accepting a selection related to the degradation mechanism of the electric storage device based on the presented options, simulating the degradation of the electric storage device by using the selected degradation mechanism, and outputting a simulation result or a simulation program executed when simulating the degradation of the electric storage device. With this configuration, even when the user is not proficient in the degradation mechanism of the power storage device, the development support device can provide the user with the result of the degradation simulation of the power storage device by simply receiving selection information on the degradation mechanism. According to the above configuration, the development support apparatus can provide the simulation program to the user, and therefore the user can obtain the result of the degradation simulation of the power storage device by executing the simulation program using the terminal apparatus.

The computer program causes a computer to execute: a plurality of options related to the degradation mechanism of the electric storage device are presented, selection information related to the selected degradation mechanism is received from a terminal device, degradation of the electric storage device is simulated using the selected degradation mechanism based on the received selection information, and a simulation result or a simulation program executed when the degradation of the electric storage device is simulated is transmitted to the terminal device. With this configuration, even when the user is not proficient in the degradation mechanism of the power storage device, the development support device can provide the user with the result of the degradation simulation of the power storage device by simply receiving selection information on the degradation mechanism. According to the above configuration, the development support apparatus can provide the simulation program to the user, and therefore the user can obtain the result of the degradation simulation of the power storage device by executing the simulation program using the terminal apparatus.

The computer program causes a computer to execute: a plurality of options related to the degradation mechanism of the power storage device are presented, a selection related to the degradation mechanism of the power storage device is accepted based on the presented options, the degradation of the power storage device is simulated by using the selected degradation mechanism, and a simulation result or a simulation program executed when the degradation of the power storage device is simulated is output. With this configuration, even when the user is not proficient in the degradation mechanism of the power storage device, the development support device can provide the user with the result of the degradation simulation of the power storage device by simply receiving selection information on the degradation mechanism. According to the above configuration, the development support apparatus can provide the simulation program to the user, and therefore the user can obtain the result of the degradation simulation of the power storage device by executing the simulation program using the terminal apparatus.

The computer program causes a computer to execute: a plurality of options relating to a degradation mechanism of an electric storage device are presented, a selection relating to the degradation mechanism of the electric storage device is accepted based on the presented options, and selection information of the degradation mechanism is transmitted to a server apparatus in order to cause the server apparatus to simulate the degradation of the electric storage device by the selected degradation mechanism. According to this configuration, since the selection information of the degradation mechanism is transmitted to the server device that simulates degradation of the power storage device based on the degradation mechanism, the simulation result based on the selected degradation mechanism can be obtained.

The simulation program provided to the user may include not only a calculation program for calculating the deterioration but also a calculation program based on an electrochemical model, which will be described later.

The present invention will be described in detail below with reference to the accompanying drawings showing embodiments thereof.

Fig. 1 is a block diagram illustrating an overall configuration of a simulation system according to an embodiment. The simulation system according to the embodiment includes a server device 10 and a client device 20 connected to be able to communicate with each other via a communication network N. The server apparatus 10 simulates degradation of the power storage device in accordance with a request from the client apparatus 20, and provides the simulation result to the client apparatus 20. Here, the deterioration of the electric storage device means, for example, a phenomenon that the charge/discharge capacity is reduced and the discharge does not last for a long time when the electric storage device is repeatedly used. The deterioration is classified into deterioration with time that occurs as long as time passes, and cycle deterioration that occurs according to the number of uses (the number of times charge and discharge has been performed).

In an embodiment, the electric storage device to be simulated is a wound lithium ion battery whose electrolyte is liquid. Alternatively, the electric storage device to be simulated may be any battery such as a laminated lithium ion battery, a lithium ion battery whose electrolyte is an ionic liquid, a lithium ion battery whose electrolyte is a gel, an all-solid lithium ion battery, a bipolar lithium ion battery (a battery in which electrodes are electrically connected in series), a zinc-air battery, a sodium ion battery, or a lead battery. The power storage device may include a module in which a plurality of cells are connected in series, a group in which a plurality of modules are connected in series, a domain in which a plurality of groups are connected in parallel, or the like. In the following description, the power storage device is also referred to simply as a battery.

The client device 20 is a terminal device used by a user, such as a personal computer, a smart phone, or a tablet terminal. The client device 20 is installed with software (application program) for accessing the server device 10. The server device 10 performs user authentication based on, for example, a user ID and a password when receiving an access from the client device 20, and provides an appropriate service to the client device 20 when the user authentication is successful. The user may be a technician of a manufacturer who designs a product of the electric storage device, or may be an end user who uses a product on which the electric storage device is mounted.

After the user authentication, the server device 10 according to the embodiment transmits an interface screen 100 (see fig. 5) for accepting various inputs by the user of the client device 20 to the client device 20. The interface screen 100 is configured to receive conditions necessary for simulating degradation of the power storage device. Details of the interface screen 100 will be described later. The server device 10 executes a simulation based on the conditions received through the interface screen 100, and transmits a simulation result as an execution result to the client device 20. The simulation result transmitted from the server device 10 to the client device 20 includes data such as numerical data and graphs obtained as a result of execution of the simulation. The simulation result transmitted from the server device 10 to the client device 20 may include a mathematical model obtained as a result of execution of the simulation, or may include a simulation model. The mathematical model or simulation model provided by the server device 10 may be provided in a state that can be edited by the user. In this case, the user can change parameters (for example, ion conductivity of the electrolyte, a coefficient relating to deterioration rate, and the like described later) in the mathematical model or the simulation model, and perform the simulation using the mathematical model or the simulation model after the change. Alternatively, the mathematical model or the simulation model may be provided in a state in which editing is not possible or in a state in which some parameters can be edited, depending on the meaning of the provider.

Alternatively, the client apparatus 20 may also have an application program for displaying the interface screen 100 shown in fig. 5. The client device 20 may receive the conditions necessary to simulate the deterioration of the power storage device on the interface screen 100 displayed by executing the application program, and may transmit the received conditions to the server device 10.

Fig. 2 is a block diagram illustrating the internal configuration of the server apparatus 10. The server device 10 includes a control unit 11, a storage unit 12, a communication unit 13, an operation unit 14, and a display unit 15.

The control Unit 11 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The CPU of the control unit 11 expands and executes various computer programs stored in the ROM or the storage unit 12 on the RAM, thereby causing the entire apparatus to function as the development support apparatus of the present application. The server apparatus 10 is merely an embodiment of the development support apparatus, and any information processing apparatus connected to be communicable with the client apparatus 20 may be used.

The control Unit 11 is not limited to the above configuration, and may be any Processing circuit or arithmetic circuit including a plurality of CPUs, a multi-core CPU, a GPU (Graphics Processing Unit), a microcomputer, a volatile or nonvolatile memory, and the like. The control unit 11 may have a function of a timer for measuring an elapsed time from the time when the measurement start instruction is given to the time when the measurement end instruction is given, a counter for counting the number of times, a clock for outputting date and time information, and the like.

The storage unit 12 includes a storage device using an HDD (Hard Disk Drive), an SSD (Solid State Drive), or the like. The storage unit 12 stores various computer programs executed by the control unit 11, data necessary for executing the computer programs, and the like. The computer program stored in the storage unit 12 includes a simulation program simulating the behavior of the power storage device. The simulation program is, for example, executing a binary. The theoretical expression that forms the basis of the simulation program is described by an algebraic equation or a differential equation that represents the degradation mechanism of the power storage device. The simulation program may be prepared for each degradation mechanism, or may be prepared as one computer program. The simulation program may be described by commercially available numerical analysis software or programming language such as MATLAB (registered trademark), Amesim (registered trademark), Twin Builder (registered trademark), MATLAB & Simulink (registered trademark), simlorer (registered trademark), ANSYS (registered trademark), Abaqus (registered trademark), Modelica (registered trademark), VHDL-AMS (registered trademark), C language, C + +, Java (registered trademark), or the like. The numerical analysis software may be a circuit simulator called 1D-CAE, or a simulator such as a finite element method or a finite volume method that is performed in a 3D shape. Instead, a degradation Model (ROM: Reduced-Order Model) based on them can also be used.

The program stored in the storage unit 12 may be provided by a nonvolatile recording medium M1 in which the program is recorded in a readable manner. The recording medium M1 is a portable memory such as a CD-ROM, a USB (Universal Serial Bus) memory, an SD (Secure Digital) card, a micro SD card, or a compact flash (registered trademark). In this case, the control unit 11 reads the program from the recording medium M1 by a reading device not shown, and installs the read program in the storage unit 12. The program stored in the storage unit 12 may be provided by communication via the communication unit 13. In this case, the control unit 11 acquires the program through the communication unit 13, and installs the acquired program in the storage unit 12.

The storage unit 12 may store a mathematical model obtained as a result of the simulation. The mathematical model is, for example, execution code executed by a programming language or numerical analysis software. The mathematical model may also be a library file or definition information referenced by a programming language or numerical analysis software.

The storage unit 12 may have a battery table in which information of a power storage device (also simply referred to as a battery) is stored in association with a user ID. Fig. 3 is a conceptual diagram illustrating an example of a battery table. The battery table stores, for example, a battery ID for identifying a battery, a user ID for identifying a user, and battery information in association with each other. The battery information registered in the battery table includes, for example, information on the positive electrode and the negative electrode, information on the electrolyte, information on the label, and the like. The information on the positive electrode and the negative electrode is information on the material names, thicknesses, widths, depths, open circuit potentials, and the like of the positive electrode and the negative electrode. The information of the electrolyte and the label is information of ion species, mobility, diffusion coefficient, conductivity, and the like. The battery table may include a link for referring to information such as physical properties, operating states, and circuit configurations of the power storage device. The information stored in the battery table may be registered by the administrator of the server apparatus 10 or may be registered by the user via the client apparatus 20. The information stored in the battery table is used as part of the simulation conditions when simulating the deterioration of the power storage device.

The communication unit 13 includes an interface for communicating with the client device 20 via the communication network N. When information to be transmitted to the client device 20 is input from the control unit 11, the communication unit 13 transmits the input information to the client device 20, and outputs the received information from the client device 20 to the control unit 11 via the communication network N.

The operation unit 14 includes an input interface such as a keyboard and a mouse, and receives an operation performed by a user. The display unit 15 includes a liquid crystal display device and the like, and displays information to be notified to the user. In the embodiment, the server device 10 is configured to include the operation unit 14 and the display unit 15, but the operation unit 14 and the display unit 15 are not essential, and a configuration may be adopted in which an operation is received by a computer connected to the outside of the server device 10 and information to be notified is output to the outside computer.

Fig. 4 is a block diagram illustrating the internal structure of the client device 20. The client device 20 is a personal computer, a smartphone, a tablet terminal, or the like, and includes a control unit 21, a storage unit 22, a communication unit 23, an operation unit 24, and a display unit 25.

The control unit 21 includes a CPU, ROM, RAM, and the like. The CPU of the control unit 21 expands and executes various computer programs stored in the ROM or the storage unit 22 on the RAM, thereby causing the entire device to function as the terminal device of the present application.

The control unit 21 is not limited to the above configuration, and may be any processing circuit or arithmetic circuit including a plurality of CPUs, a multicore CPU, a microcomputer, or the like. The control unit 21 may have a function of a timer for measuring an elapsed time from the time when the measurement start instruction is given to the time when the measurement end instruction is given, a counter for counting the number of times, a clock for outputting date and time information, and the like.

The storage unit 22 is configured by a nonvolatile Memory such as an EEPROM (electrically Erasable Programmable Read Only Memory), and stores various computer programs and data. The computer program stored in the storage unit 22 includes a dedicated or general-purpose application used for the purpose of providing and receiving information to and from the server device 10. An example of the dedicated application program is a computer program for causing the client device 20 to present a plurality of options related to the degradation mechanism of the power storage device to a user, receive a selection related to the degradation mechanism of the power storage device, and transmit selection information of the degradation mechanism to the server device 10 in order to cause the server device 10 to simulate degradation of the power storage device by the selected degradation mechanism. An example of a general-purpose application is a web browser. When the server apparatus 10 is accessed by using a web browser, user authentication using a user ID and an authentication code is preferably performed, and communication between the server apparatus 10 and the client apparatus 20 may be permitted only when the user authentication is successful.

The program stored in the storage unit 22 may be provided by a nonvolatile recording medium M2 in which the program is recorded in a readable manner. The recording medium M2 is a portable memory such as a CD-ROM, a USB memory, an SD card, a micro SD card, a compact flash (registered trademark), or the like. In this case, the control unit 21 reads the program from the recording medium M2 by a reading device not shown, and installs the read program in the storage unit 22. The program stored in the storage unit 22 may be provided by communication via the communication unit 23. In this case, the control unit 21 acquires various programs via the communication unit 23, and installs the acquired various programs in the storage unit 22.

The communication unit 23 includes an interface for communicating with the server device 10 via the communication network N. When information to be transmitted to the server device 10 is input from the control unit 21, the communication unit 23 transmits the input information to the server device 10, and outputs the received information from the server device 10 to the control unit 21 via the communication network N.

The operation unit 24 includes an input interface such as a keyboard, a mouse, and a touch panel, and receives an operation performed by a user. The display unit 25 includes a liquid crystal display device and the like, and displays information to be notified to the user. In the embodiment, the client device 20 is configured to include the operation unit 24, but an input interface such as a keyboard or a mouse may be connected to the client device 20.

The operation of the simulation system according to the embodiment will be described below with reference to the interface screen 100 displayed on the display unit 25 of the client device 20.

Fig. 5 is a schematic diagram showing an example of the interface screen 100. The interface screen 100 shown in fig. 5 shows an example of a screen displayed on the display unit 25 of the client apparatus 20 after the client apparatus 20 accesses the server apparatus 10 and authenticates a valid user. The client device 20 communicates with the server device 10, and acquires data for a display screen from the server device 10, thereby causing the display unit 25 to display an interface screen 100 as shown in fig. 5.

The Interface screen 100 is a screen including various display fields and operation buttons arranged as components of a UI (User Interface), and is configured to receive an operation performed by a User via the operation unit 24.

The interface screen 100 shown as an example in fig. 5 includes: a selection field 110 for accepting selection of cycle degradation or degradation over time, a selection field 120 for accepting selection of a degradation mechanism, a display field 130 for displaying a calculation procedure in a simulation, and an input field 140 for accepting input of battery information.

The selection field 110 includes a radio button 111 selected when giving an instruction to execute a simulation for cycle degradation and a radio button 112 selected when giving an instruction to execute a simulation for chronological degradation. In the example of fig. 5, a state in which the radio button 111 indicating the simulation of cycle deterioration is selected is shown. Alternatively, the radio button 112 may be selected, or both the radio buttons 111 and 112 may be selected.

The selection column 120 includes radio buttons 121 to 124 selected when an increase in the designated resistance, an isolation of the active material particles, a decrease in the conductivity of the electrolyte, and a decrease in the charge carriers are used as a degradation mechanism of the electric storage device. In the example of fig. 5, a state is shown in which the radio button 124 that specifies the reduction of the charge carriers as the degradation mechanism is selected. Alternatively, any one of the radio buttons 121 to 123 may be selected, or two or more of the radio buttons 121 to 124 may be selected. In the selection field 120, edit buttons 121a to 124a are arranged corresponding to the radio buttons 121 to 124. When the edit buttons 121a to 124a are operated, a setting screen for accepting setting changes of various parameters is displayed in association with the corresponding degradation mechanism.

In the display column 130, the calculation process in the simulation is displayed. In the example of fig. 5, the calculation procedure for the case where the reduction of charge carriers simulates cycle degradation and degradation over time is shown by a graph. Instead, numerical data representing the calculation process may also be displayed. A download button 131 is disposed in the display field 130, and configured to enable downloading of simulation results. The simulation results may be graphs or numerical data. Alternatively, the simulation results may also be provided by a mathematical model. Here, the mathematical model is a model in which the deterioration process of the electric storage device is described mathematically by an algebraic equation, a differential equation, and a characteristic parameter, and is obtained by performing a simulation. The mathematical model is provided in the form of, for example, commercially available numerical analysis software such as MATLAB (registered trademark), Amesim (registered trademark), Twin Builder (registered trademark), MATLAB & Simulink (registered trademark), simlorer (registered trademark), ANSYS (registered trademark), Abaqus (registered trademark), Modelica (registered trademark), VHDL-AMS (registered trademark), C language, C + +, Java (registered trademark), or libraries, modules used in programming languages.

An edit button 141 for editing information (battery information) of the power storage device is disposed in the input field 140. When the edit button 141 is operated by the operation unit 24, the client device 20 causes the display unit 25 to display a reception screen for receiving battery information. When the reception of the battery information is completed, the client device 20 transmits the received battery information to the server device 10. The server device 10 registers the battery information received from the client device 20 in the battery table of the storage unit 12.

In the example of fig. 5, the battery information is received in the input field 140. Alternatively, the battery information may be prepared in advance for each type and model of the power storage device, and the battery information may be automatically set by receiving a selection of the type and model of the power storage device.

When various conditions are set on the interface screen displayed on the display unit 25 of the client apparatus 20, the simulation of degradation of the power storage device is started in the server apparatus 10. The server device 10 according to the embodiment performs a degradation simulation using a physical model of a battery. The physical model is a model that represents a phenomenon inside the power storage device by a mathematical expression or the like, following a predetermined natural phenomenon (physical law or chemical law). The physical model is also referred to as a white box. Since it is considered difficult for those skilled in the art to express the degradation mechanism of the power storage device by a physical model, a degradation simulation using a physical model has not been performed so far.

An example of the physical model will be described below.

The physical model used for the simulation of deterioration is a physical model represented by a Newman model. The Newman model assumes that homogeneous and single diameter spheres are closely arranged in each of the positive and negative electrodes. The Newman model is described by Nernst-Planck equation, charge storage equation, diffusion equation, Butler-Volmer equation, and Nernst equation described below.

The Nernst-Planck formula is an equation for solving the electrolyte, the ion electrophoresis in the porous electrode, and the ion diffusion, and is represented by the following formula.

[ mathematical formula 1]

Here, i₁Is liquid phase current density (A/m)²)，σ_l，effIs the effective conductivity (S/m) of the liquid phase,

is the liquid phase potential (V), R is the gas constant (J/(K.mol)), T is the temperature (K), F is the Faraday constant (C/mol), F is the activity coefficient, C₁Is the ion concentration (mol/m) of the electrolyte³)，t₊For cation mobility, i_totReaction Current Density per volume (A/m)³). Effective conductivity of liquid phase σ_l，effThe apparent conductivity of the porous body is usually the ratio ε of the liquid phase volume to the solid phase volume_sIs expressed as a function of (c).

The charge retention formula is a formula representing electron conduction in the active material particles and the collector foil, and is represented by the following formula.

[ mathematical formula 2]

Here, i_sIs in solid phase and has a current density (A/m)²)，

Is the solid phase potential (v), σ_sIs solid phase conductivity (S/m), i_totReaction Current Density per volume (A/m)³)。

The diffusion equation is an equation representing diffusion of the active material in the active material particles, and is represented by the following formula.

[ mathematical formula 3]

Here, c_sIs the concentration of charge carriers in the solid phase (mol/m)³) T is time(s), D_sIs the diffusion coefficient (m) in the solid phase²/s)。

The Butler-Volmer formula is a formula representing an activation overvoltage in a charge transfer reaction at an interface between a solid phase and a liquid phase, and the Nernst formula is a formula defining an open circuit potential, and is represented by the following formula.

[ mathematical formula 4]

η＝φ_s-φ_l-E_eq

Here, i_locTo reflect the current density (A/m)²)，i_oFor exchanging the current density (A/m)²)，α_a、α_cEta is activation overvoltage (V), E is transition coefficient of oxidation reaction and reduction reaction respectively_eqTo balance the potentials (V), E⁰Is a standard equilibrium potential (V), z is a valence number, a_0xAs oxidant concentration (mol/m)³)，a_RedIs the concentration (mol/m) of the reducing agent³). The Butler-Volmer and Nernst formulas instead tend to use formulas that vary based on experimental values. For example, the exchange current density may be changed as appropriate as a function of the charge carrier concentration and the ion concentration, or as an open circuit potential using SOC and actual measurement data of the open circuit potential. In particular, in the lithium ion secondary battery, actually measured data of SOC and open circuit potential are often used, and therefore, the following description will be made. Each parameter in the above equations 1 to 4 may be a function of another physical value.

Mathematical formula 5 shows a relational expression between the charge carrier concentration in the solid phase on the surface of the active material particle and the charge carrier flux involved in the charge transfer reaction. r is₀Represents the radius (m), J of the active material particle_sIs the flux (mol/m) of the charge carrier²s). In other words, J_sIs generated by charge transfer reaction and is extinguished per unit area per unit timeThe amount of charge carriers of (a).

[ math figure 5]

Equation 6 is a flux J representing a charge carrier_sAnd reaction current density i_locThe equation of (a).

[ mathematical formula 6]

i_loc＝ZFJ_s

The formula 7 represents the reaction current density i_locAnd reaction current density per unit volume i_totThe equation of (a). S_vMeans a surface area per unit volume, i.e., a specific surface area (m)²/m³)。S_vOr from the radius r of the active substance particles₀Is expressed as a function of (c).

[ math figure 7]

i_tot＝S_vi_loc

Fig. 6 is a graph showing the relationship between the charge carrier concentration in the solid phase and the Open Circuit Potential (OCP) of a typical cathode material. The abscissa of the graph represents the dimensionless charge carrier concentration θ defined by equation 8, and represents the charge carrier concentration c_sAs a function of (c). The vertical axis of the graph is the Open Circuit Potential (OCP).

[ mathematical formula 8]

Here, c_smaxThe charge carrier concentration (mol/m) in the solid phase at the end stage of discharge (at the lower limit voltage) at the time of 0 cycle (for example, at the time of battery production) at which the battery is not deteriorated at all³). On the other hand, c_sminCharge carriers (mol/m) in the solid phase at the initial discharge (at the time of the upper limit voltage or at the time of full charge) at the time of 0 cycle (for example, at the time of battery production) at which the battery is not deteriorated at all³). When fully charged is c_s＝c_sminTherefore, θ is 0.0 and c is the end of discharge_s＝c_smaxTherefore, θ is 1.0. As the battery was discharged, θ changed from 0.0 to 1.0 on average. In this way, the open circuit potential OCP of the positive electrode is expressed as a function of the dimensionless charge carrier concentration θ in the positive electrode. Likewise, the open circuit potential OCP of the negative electrode is expressed as a function of the dimensionless charge carrier concentration θ in the negative electrode. In the negative electrode, C_smaxThe charge carrier concentration (mol/m) in the solid phase at the initial discharge (at the time of the upper limit voltage or at the time of full charge) at the time of 0 cycle (for example, at the time of battery production) at which the battery is not deteriorated at all³). On the other hand, C_sminThe charge carrier concentration (mol/m) in the solid phase at the end stage of discharge (at the lower limit voltage) at the time of 0 cycle (for example, at the time of battery production) at which the battery is not deteriorated at all³). The control unit 11 of the server device 10 calculates the OCP of the positive electrode and the OCP of the negative electrode individually, and can simulate the deterioration due to isolation described later in a fine manner.

Alternatively, the control unit 11 may use different values of the open circuit potential OCP at the time of discharge and at the time of charge. For example, in an electrode material having a high energy density, it is confirmed that the open circuit potential OCP has hysteresis with respect to the dimensionless charge carrier concentration θ. Fig. 7 is a graph showing the relationship of the dimensionless charge carrier concentration θ and the open circuit potential OCP of the electrode material having a high energy density. The abscissa of the graph represents the dimensionless charge carrier concentration θ, and the ordinate represents the open circuit potential OCP. As shown in the graph of fig. 7, even with the same dimensionless charge carrier concentration θ, the value of the open circuit potential OCP differs between the time of charge and the time of discharge. Such a characteristic is called OCP hysteresis or OCP history and is often recognized in an electrode material having a high energy density. When calculating such an electrode material, the control unit 11 can realize a fine simulation by using different values of the open circuit potential OCP at the time of discharge and at the time of charge.

In the embodiment, the Newman model is shown as an example of a physical model of a lithium ion battery. Alternatively, a single particle model may be utilized in which the electrodes are represented by a single active material particle. For the Single Particle Model, for example, refer to non-patent document "Single-Particle Model for a Lithium-Ion Cell: thermal Behavior, Meng Guo, Godfrey Sikha, and Ralph E.white, Journal of The Electrochemical Society, 158(2), 122-. As long as the charge/discharge characteristics are expressed, a model other than a physical model such as an equivalent circuit model or a polynomial model may be used instead. That is, system discrimination for estimating a model from actually measured input/output data may be used. The system discrimination may be black box modeling in which the model is estimated from only the input/output data, or gray box modeling in which the model is estimated based on the input/output data by reflecting a known system configuration when a part of the system configuration is known. As The polynomial model, for example, a model disclosed in non-patent document "Modeling The dependency of The Discharge Behavior of a Lithium-Ion Battery on The Environmental test, Ui Seong Kim, a Jaeshin Yi, a Chee Burm Shin, Taeyoung Han, band Seingpark Park, Journal of The Electrochemical Society, 158(5) 611-.

The deterioration mechanism of the power storage device will be described below.

As the 1 st degradation mechanism, an increase in resistance among the respective elements constituting the electric storage device will be described. The deterioration mechanism by the increase in resistance is a phenomenon in which the resistivity of the electrolyte and the electron conductive member increases, the internal resistance of the battery increases, and the capacity of the battery decreases.

The server device 10 according to the embodiment executes 6 types of simulations including (positive electrode, negative electrode) × (peeling between the collector foil and the electrode, interruption of the conduction path of the conductive auxiliary agent, formation of the resistor body film) as a factor of increasing the resistance.

Fig. 8 is an explanatory view explaining peeling between the collector foil and the electrode. In an electric storage device that has just started to be used, the current collecting foil and the electrode (positive electrode or negative electrode) are in a state of being in close contact with each other, and the resistance between the current collecting foil and the electrode is relatively small. However, since the current collecting foil and the electrode are not well bonded, cracks are generated in the middle due to expansion and contraction of particles (active material particles constituting the electrode) accompanying charge and discharge, the adhesion is reduced, and peeling occurs. As a result, the path through which the current flows decreases, and the resistance increases.

Fig. 9 is an explanatory view illustrating interruption of the conduction path of the conductive aid. Since an electrode material in an electric storage device is often poor in electron conductivity, conductivity is ensured by adding a small amount of a conductive additive such as acetylene black. However, the conductive auxiliary agent itself may be cut off or contact between the conductive auxiliary agent and another conductive auxiliary agent or active material particles may not be ensured due to expansion and contraction of particles (active material particles constituting an electrode) accompanying charge and discharge. Alternatively, the conductive aid may disappear due to a chemical reaction. As a result, the path through which the current flows decreases, and the resistance increases.

Fig. 10 is an explanatory view for explaining formation of a resistor film. A coating of the resistor is formed on the surface of the active material particles in accordance with charging and discharging. For example, in the case of a lithium ion battery, a coating film based on a compound composed of an organic material and lithium ions in an electrolyte solution is formed. Such a film has poor conductivity, and therefore, has an increased resistance.

The control unit 11 of the server device 10 calculates the rate of increase in resistance, that is, the rate of decrease in conductivity, based on, for example, the following expression 9 or expression 10.

[ mathematical formula 9]

Herein, r is_cycle，resIndicating the rate of conductivity decrease according to the number of cycles (S/m/number of cycles). Is typically r_cycle，res＜0。k_0，resIs a reaction rate constant, for example, as a function of cycle number. E_a0，resThe activation energy (J/mol) indicating cycle deterioration is a coefficient indicating the influence of temperature. i is the current density (A/m)²) And | represents an absolute value. The magnitude of the current density i is related to the expansion and contraction speed of the electrode, and is a coefficient indicating a strain rate-dependent failure phenomenon such as creep. Alpha is alpha_resIs a constant. k is a radical of_0，res、E_a0，res、α_resThe value of (b) may be input by the user or may be set in advance in the server device 10. In most cases, the decrease in conductivity is faster as the temperature decreases, so E is preferred_a0，resIs less than 0.0. When the decrease in conductivity is not to be considered, such as when the expansion and contraction of the active material particles are extremely small, when the active material particles are composed of only primary particles, when the adhesive strength by the binder is extremely high, or when the specific resistance of the resistor coating film is negligibly small, it is also possible to set k to be_0，resAnd (3) invalidation is appropriately performed when the value is 0.0.

[ mathematical formula 10]

Herein, r is_t，resIndicates the rate of decrease in conductivity (S/m/S) with the passage of time. Is typically r_t，res＜0。k_l，resIs a reaction rate constant, for example, as a function of time. Instead, k_l，resOr may be defined by any function based on experimental data. E_a1，resThe activation energy (J/mol) showing the deterioration with time is a coefficient showing the influence of temperature. Δ t is the elapsed time(s). k is a radical of_1，res、E_a1，resThe value of (b) may be input by the user or may be set in advance in the server device 10.

If the conductivity at the time point of N period is set as σ_s(N) then σ_s(N +1) by_s(N) is added to the equation of equation 11 representing the cycle deterioration rate and the 1-cycle deterioration rate with time. If note that r_cycle，res< 0 and r_t，res< 0, then typically σ_s(N+1)<σ_s(N), the conductivity decreases with an increase in the number of cycles and a lapse of time.

[ mathematical formula 11]

σ_s(N+1)＝σ_s(N)+r_cycle，res+r_t，res

In the embodiment, the structure of calculating the rate of decrease in conductivity by the expressions of expressions 9 and 10 has been described, but the expressions are merely exemplary and may be freely changed based on experimental results, literature data, and the like.

In the embodiment, a configuration in which the rate of decrease in conductivity is calculated as a function of the number of cycles or elapsed time is described. Alternatively, control unit 11 may calculate the rate of increase in resistance using equation 12, which is a function of the upper limit and the lower limit of the SOC. Here, the upper limit and the lower limit of the SOC mean the upper limit and the lower limit in the usage range of the battery.

[ mathematical formula 12]

The progress of deterioration such as an increase in resistance can be said to be caused by stress due to expansion and contraction caused by charge and discharge. It is known that the magnitude of expansion and contraction has a relationship with the use range of the SOC, and in particular, it is known that expansion and contraction become large by using the lower limit of the SOC. Therefore, it is preferable to apply the deterioration rate as a function of the upper limit and the lower limit of the SOC. In the case of no energization, expansion and contraction do not occur, and therefore it is often sufficient to consider only cycle deterioration. Control unit 11 controls the upper limit value SOC of the SOC_maxAnd a lower limit value SOC_minThe speed of the resistance increase according to the cycle number can be calculated by equation 12, which is a multiplication of a function of an independent variable as a factor. Upper limit value SOC_maxAnd lower limit value SOC_minThe value of (b) may be input by the user or may be set in advance in the server device 10. In most cases, known as (SOC)_max-SOC_min) Since the rate of increase of the resistance increases as the value of (A) is larger, it is preferable to use the following equation (SOC)_max-SOC_min) Becomes larger and the reaction speed becomes faster.

In the velocity equation for determining the increase of the resistance, k is used_0，res、E_a0，res、α_res、k_1，res、E_al，res、SOC_max、SOC_minBut for these valuesThe positive electrode and the negative electrode may have different values with respect to separation between the collector foil and the electrode, interruption of the conduction path of the conductive auxiliary agent, and formation of the resistor film. Alternatively, some or all of these values may be set to the same value as necessary. These values may also be different values during the charging process and the discharging process.

As the 2 nd degradation mechanism, isolation of active material particles will be described. The degradation mechanism based on isolation of the active material particles is a phenomenon in which the active material particles are broken due to repetition of expansion and contraction caused by charge and discharge, a region in which charge carriers cannot be inserted is gradually increased, a region in which charge carriers can be occluded/released in the active material particles is decreased, and the amount of electricity that can be stored, that is, the battery capacity is decreased. Occlusion is a phenomenon in which charge carriers are held in a solid phase, that is, in active material particles. The discharge is a phenomenon in which charge carriers are discharged to the outside of the active material particles.

The control unit 11 of the server device 10 calculates the speed at which the active material particles are isolated from each other by the expression of formula 13 or formula 14.

[ mathematical formula 13]

Herein, r is_cycle，isoThe rate of progress of isolation of the active material particles according to the cycle number (1/cycle number) is shown. Is typically r_cycle，iso＜0。k_0，isoIs a reaction rate constant, for example, as a function of the number of cycles. E_a0，isoThe activation energy (J/mol) indicating cycle deterioration is a coefficient indicating the influence of temperature. I is the current density (A/m)²). The magnitude of the current density i is related to the expansion/contraction speed of the electrode, and is a coefficient indicating a failure phenomenon depending on the strain rate, such as creep and crack progression. Alpha is alpha_isoIs a constant. k is a radical of_0，iso、E_a0，iso、α_isoThe value of (b) may be input by the user or may be set in advance in the server device 10.

[ mathematical formula 14]

Here, f_t，isoThis shows the rate (1/s) at which the active material particles are isolated with time. Is typically r_t，iso<0。k_1，isoIs a reaction rate constant, for example, as a function of time. Instead, k_1，isoOr may be defined by any function based on experimental data. E_a1，isoThe activation energy (J/mol) showing the deterioration with time is a coefficient showing the influence of temperature. Δ t is the elapsed time(s). When the stress in the battery is low, the isolation is rarely developed only with time, but it is difficult to ignore the case where the battery is strongly restrained from the outside and is in a high stress state. k is a radical of_1，iso、E_a1，isoThe value of (b) may be input by the user or may be set in advance in the server device 10.

Let the solid phase volume ratio of the active material particles at the N cycle time be ε_s(N) then ε_s(N +1) by a reaction at ε_s(N) is added to the equation of equation 15 representing the cycle deterioration rate and the 1-cycle deterioration rate with time.

[ mathematical formula 15]

ε_s(N+1)＝ε_s(N)+r_cycle，iso+r_t，iso

Here, the solid phase volume ratio ε to F/O ratio of the active material particles_sThe reason why the electric storage device is deteriorated when the electric storage device is lowered, that is, the place where the electric storage device can store the charge carrier is reduced, and the electric storage device can store the electric energy, that is, the electric capacity is reduced will be described.

By means of the minimum concentration c of occluded charge carriers_sminAnd maximum concentration c_smaxThe reduction in capacitance will be explained. In the case of the positive electrode, the end of discharge is the maximum concentration, and the full charge is the minimum concentration. The volume required for calculating these charge carrier concentrations is that of the phase in which occluded charge carriers can existVolume. When the apparent volume (for example, coating area × coating thickness) of the electrode is V_app(m³) The volume ratio of the solid phase occupied by the active material particles in the electrode during production is represented by ∈_s0The volume of the phase in which the occluded charge carrier can exist is V_appε_s0. When the battery capacity at the time of manufacture is defined as Q₀(C or Ah), equation 16 holds.

[ mathematical formula 16]

When the battery is deteriorated and the electrodes are isolated, the solid phase volume ratio epsilon of the active material particles contributing to the electric storage increases_sThan epsilon_s0And (4) descending. When the solid phase volume ratio of the active material particles is ∈_sWhen the battery capacity is Q, equation 17 holds.

[ mathematical formula 17]

Q＝zFV_appε_s(c_smax-c_smin)

Unnecessary characters are removed from the expressions 16 and 17, and an expression 18 is obtained.

[ mathematical formula 18]

I.e. show if_sLess than epsilon_s0Q is less than Q₀. This is the reason why the battery capacity is decreased due to the isolation.

In the embodiment, the description has been given of the structure for calculating the speed of the progress of the isolation of the active material particles by the expressions of expressions 13 and 14, but the expressions are merely exemplary and may be freely changed based on the experimental results, the literature data, and the like.

In an embodiment, the structure is calculated by calculating the speed of the isolation progress of the active material particles as a function of the number of cycles or elapsed timeThe description is given. Alternatively or additionally, the control unit 11 may calculate the speed at which the active material particles are isolated using the same expression as expression 12 having a function of the upper limit and the lower limit of the SOC when the switching of the energization direction occurs as a factor. Upper limit value SOC_maxAnd lower limit value SOC_minThe value of (b) may be input by the user or may be set in advance in the server device 10. In most cases, known as (SOC)_max-SOC_min) Since the larger the value of (A) is, the faster the isolation progresses, it is preferable to use the value of (SOC)_max-SOC_min) Becomes larger and the reaction speed becomes faster. Instead of the cycle number, the total energization power amount may be used.

[ math figure 19]

In the velocity formula for determining the progress of the isolation, k is used_0，iso、E_a0，iso、α_iso、k_1，iso、E_a1，iso、SOC_max、SOC_minHowever, it is preferable to use different values for the positive electrode and the negative electrode. Therefore, the contribution amount of the positive electrode and the contribution amount of the negative electrode among the causes of isolation of the entire battery can be simulated separately. When isolation is not considered, for example, when expansion and contraction of the active material particles are extremely small, or when the active material particles are composed of only primary particles, k may be set to_0，isoAnd (3) invalidation is appropriately performed when the value is 0.0. The above values may also be different values during the charging process and the discharging process.

As the 3 rd deterioration mechanism, a decrease in conductivity in the electrolytic solution will be described. The deterioration mechanism based on the decrease in conductivity in the electrolyte is a phenomenon in which the resistivity of the electrolyte increases due to decrease in conductivity caused by charge carrier disappearance, decrease in conductivity caused by generation of fine bubbles in the electrode body, change in solvated molecular structure, clogging of the separator, or the like, and the internal resistance of the battery increases, thereby decreasing the capacity. Charge carrier disappearance occurs mainly when a resistor coating film is formed on the surface of the active material particles.

It is known that the lithium ions in the electrolyte decrease when charging and discharging are repeated. The conductivity of the electrolyte is a function of the lithium ion concentration and is known to be generally greatest at initial manufacture, but to decrease as the lithium ion concentration decreases. Fig. 11 is a graph showing the relationship between the lithium ion concentration and the ionic conductivity in the electrolytic solution. The horizontal axis of the graph shown in fig. 11 represents the lithium ion concentration in the electrolyte, and the vertical axis represents the ionic conductivity. The relationship between the lithium ion concentration and the ionic conductivity in the electrolytic solution is often as shown in fig. 11. The control unit 11 of the server device 10 can calculate the rate of decrease in conductivity by the same function as that of expression 5 and expression 6. Alternatively, the control unit 11 may calculate the rate of decrease in conductivity using the same expression as expression 8, which takes a function of the upper limit and the lower limit of the SOC as a factor. Instead, not only the conductivity of ions but also the diffusion coefficient may be changed.

The reason why the lithium ion concentration of the electrolytic solution is reduced is considered to be that the electrolyte salt is precipitated as insoluble substances due to a very small amount of products of the oxidation reaction of the electrolytic solution at the positive electrode, and the like. As a result, a reaction occurs in which more lithium ions are captured than the number of electrons consumed by reductive decomposition of the electrolyte in the negative electrode. As this reaction progresses, the lithium ion concentration in the electrolyte gradually decreases, resulting in a decrease in conductivity.

As the 4 th deterioration mechanism, reduction of charge carriers involved in charge and discharge will be described. The degradation mechanism based on the reduction of charge carriers is a phenomenon in which ions in the electrolyte disappear due to a side reaction in the surface of the electrode at the time of charging.

For example, in the case of a lithium ion battery, when lithium ions in the electrolyte enter graphite (i.e., at the time of charging), the main reaction (Li) is excluded⁺+e^-+6C→LiC₆) In addition, LiC also occurs₆And a side reaction in which the resist film is adhered to the surface of the electrode active material particles as a resistor by reaction with an organic substance or the like. The main reaction is a reversible reaction, which is caused if a voltage is applied in a reverse directionLi→Li⁺+e^-But the side reactions are irreversible. That is, once lithium ions that have become the resistor coating film become unable to participate in charging and discharging, and the capacity decreases. This mechanism is referred to as a reduction in charge carriers (or a shift in capacity balance) involved in charge and discharge. With regard to the 4 th deterioration mechanism, the lithium ion concentration of the electrolytic solution is decreased due to not deterioration of the electrode material. That is, the 4 th deterioration mechanism may be reused after disintegration washing.

Regarding the 4 th degradation mechanism, it is known that in the case of a lithium ion battery, acceleration is caused by both passage of time and a cycle. On charging, e.g. Li⁺+e^-+6C+P→xLiC₆+(1-x)Li_SEIIn addition to the main reaction (ideally, x is 1) for producing Li, as shown in the reaction formula (ii), Li is also produced_SEISuch by-products. P is a substance which is a source of a by-product. Here, x: (1-x) is the main reaction: the stoichiometric ratio of the side reaction, but usually (1-x)/x < 1, is very small. The lithium ions, which have been multiplied by the current density and the surface area of the electrode and divided by the faraday constant, of the side reaction, disappear from the electrolyte. To demonstrate the mechanism, Li in the liquid phase⁺The disappearance amount of (1) is J_Li+(mol/m²s), the amount J of Li to be introduced into the solid phase_Li(mol/m²s) is set to J_Li＝xJ_Li+And (4) finishing.

x may be set as an upper limit value SOC as appropriate_maxAnd lower limit value SOC_minTemperature T, current density i. For example, a function described in equation 20 may be used. H is an arbitrary function specified as appropriate to the experimental data. Note that 0.0. ltoreq. x.ltoreq.1.0.

[ mathematical formula 20]

x＝h(SOC_max，SOC_min，T，|i|)

The side reactions occur not only during charging but also when no electricity is applied, but they change the disappearance rate r of lithium ions based on measured data_LiAs a function of time (r)_LiPreferably, the compound is given as g (t). As function g, the square root of time t is often usedA proportional function. The function g may also further comprise a temperature dependent factor.

The decrease in charge carriers involved in charge and discharge in the 4 th deterioration mechanism is related to the formation of the resistor film in the 1 st deterioration mechanism and the decrease in conductivity in the electrolyte in the 3 rd deterioration mechanism. That is, the reason is that lithium ions in the electrolytic solution become unusable due to irreversible reaction and are deposited on the electrode surface. In the simulation of the present application, it is possible to calculate by correlating these phenomena, which have been dealt with sporadically in the past.

For example, the thickness of the resistor coating is δ (m), and the mass density is ρ_film(kg/m³) In the case of (2), the equation (21) is expressed. M is the molecular weight (kg/mol) of the coating material.

[ mathematical formula 21]

The expression shown in the formula 22 represents the surface area S (m) of the electrode active material particles until the time t (S)²) The total amount (mol) of lithium ions that have formed a coating and have disappeared from the electrolyte solution. When this expression is correlated with the decrease in the lithium ion concentration in the electrolyte solution described in the deterioration mechanism of the 3 rd embodiment, the growth of the resistor coating film, the decrease in the conductivity in the electrolyte solution, and the decrease in the charge carriers can be calculated by correlating them with each other.

[ mathematical formula 22]

The ohmic overvoltage generated by the resistor film is expressed by equation 23. Herein, r is_filmThe resistivity (omega m) of the resistor body coating film²)。

[ mathematical formula 23]

η_film＝r_filmδi_loc

The following describes operations of the server apparatus 10 and the client apparatus 20.

Fig. 12 is a flowchart illustrating a procedure of processing performed by the server apparatus 10 and the client apparatus 20. After the user authentication, the control unit 21 of the client device 20 receives the data for the display screen transmitted from the server device 10, and displays the interface screen 100 on the display unit 25 (step S101). The control unit 21 receives the simulation conditions through the interface screen 100 displayed on the display unit 25 (step S102). The interface screen 100 receives, for example, selection of cycle deterioration or deterioration with time, selection of a deterioration mechanism, and input of battery information.

The control unit 21 transmits the simulation conditions received through the interface screen 100 to the server device 10 through the communication unit 23 (step S103).

The server device 10 receives the simulation conditions transmitted from the client device 20 by the communication unit 13 (step S104).

The control unit 11 of the server device 10 executes a simulation based on the simulation conditions received through the communication unit 13 (step S105). At this time, the control unit 11 selects a simulation program corresponding to the simulation condition, and applies the simulation condition to the selected simulation program, thereby simulating the deterioration of the power storage device. The control unit 11 may store the simulation condition received in step S104 in the storage unit 12 in association with the user ID input at the time of user authentication. When the simulation is executed, the control unit 11 transmits the calculation result to the client device 20 through the communication unit 13 (step S106). In step S106, the calculation result may be transmitted to the client device 20 as needed each time a value of the calculation target (the resistance of each component, the volume ratio of the isolated region, the diffusion coefficient or ionic conductivity of the electrolyte, the expansion ratio of the battery, and the like) in a certain time step or a certain period is obtained.

The client device 20 receives the calculation result transmitted from the server device 10 by the communication unit 23 (step S107). The control unit 21 of the client device 20 displays the received calculation result in the display field 130 of the interface screen 100 as a calculation procedure in the simulation (step S108). The user can grasp whether or not the simulation performed by the server device 10 is completed by referring to the calculation procedure displayed in the display field 130.

Next, when the download button 131 is operated on the interface screen 100, the control unit 21 transmits a download request of the simulation result to the server device 10 via the communication unit 23 (step S109).

When receiving the download request from the client device 20 (step S110), the server device 10 transmits the simulation result to the client device 20 (step S111). The simulation result transmitted from the server device 10 in step S111 is data indicating how the resistance value of each component, the volume ratio of the isolated region, the diffusion coefficient or ionic conductivity of the electrolyte, the reduced amount of the electric charge, the expansion rate of the battery compared with the initial state, and the like change together with the elapsed time and the cycle number. The simulation result may also be 3 columns of numerical data of elapsed time, cycle number, and physical value. Alternatively, a graph, a contour map, or an animation generated from numerical data may be used. Alternatively, it may be in the form of a library conforming to the form of commercial simulation software. Alternatively, a simulation program for degradation simulation including electrochemistry may be included. The downloaded file format may also be based on the numerical analysis software, programming language used by the user to enable the desired format to be selected by the user.

The client device 20 receives the simulation result transmitted from the server device 10 by the communication unit 23 (step S112). The control unit 21 of the client device 20 causes the display unit 25 to display the received simulation result (step S113). If the value of the resistance of each component and the diffusion coefficient or ionic conductivity of the electrolyte are known, the amount of heat generated during energization can be calculated, and therefore, the client can perform a simulation of the temperature, for example. Therefore, a cooling design and a heat management design can be performed. Since the degradation of the electrode material is known when the volume ratio of the isolated region and the amount of the reduced charge carriers are known, the client can predict the life cycle and the recycling rate, for example. If the expansion rate of the battery is known in comparison with the initial state, the client can design the strength of, for example, a module case, a can case of the battery, and the like.

The expansion of the battery accompanying the deterioration includes expansion due to gas generation in the battery, volume expansion due to rupture of the electrode, and expansion and contraction of the electrode accompanying charge and discharge. Among them, expansion by gas generation and volume expansion by rupture of an electrode are irreversible expansion and contraction which become larger than the original volume as by one charge and discharge. On the other hand, the expansion and contraction of the electrode accompanying charge and discharge is reversible such as to return to the original volume after the charge and discharge are performed once.

For example, equations 24 to 26 can be considered as equations representing expansion.

[ mathematical formula 24]

α_gas＝k₀(T)

Herein, α is_gasThe resulting linear expansion coefficient relative to the original volume is generated for the gas. Mathematical expression 24 is an expression representing the expansion caused by gas generation as a function of temperature T. That is, the higher the temperature, the higher the vapor pressure increases, and therefore evaporation of the electrolyte and separation of the gas from the electrode are likely to occur.

[ mathematical formula 25]

α_crack＝f(ε_s0-ε_s)

Herein, α is_crackCoefficient of linear expansion, epsilon, relative to the original volume, resulting from electrode rupture_s0Is the effective active material particle volume ratio of the electrode during manufacture, epsilon_sIs the effective active species particle volume fraction of the electrode at any point in time. The volume ratio of the effective active material particles is a volume ratio of a portion not isolated among the volumes of the solid portions of the electrode. If the active material particles are broken and the volume ratio epsilon of the active material particles is effective_sDecrease then (epsilon)_s0-ε_s) And (4) increasing. The numerical expression 25 represents the amount of electrode rupture (ε) by taking the expansion due to electrode rupture_s0-ε_s) Is expressed as a function of (a).

[ mathematical formula 26]

α＝g(α_gas，α_crack)

Equation 26 represents the bus expansion coefficient as a function of the independent variables of the expansion caused by gas generation and the expansion caused by electrode rupture.

The expansion formula may be appropriately changed depending on the type of battery and the battery material, and is not limited to the above formulas 24 to 26.

Fig. 13 is a graph showing a change in expansion ratio with time. The horizontal axis of the graph shown in fig. 13 represents time (or cycle number), and the vertical axis represents expansion rate. As shown in the graph of fig. 13, the expansion ratio of the battery is the sum of a component that decreases and monotonously increases and a component that expands and contracts with charge and discharge. The former is irreversible (plastic) expansion and the latter is reversible (elastic) expansion. The irreversible expansion is imparted so as to increase as a function of time and cycle number, and the relationship between the expansion rate and the elapsed time and cycle number is preferably obtained in advance by experiments. In the case of performing the expansion ratio simply without directly using experimental data, the expansion ratio can be defined by an equal ratio sequence in which the elapsed time and the cycle number are independent variables. For example, if the increase amount of the expansion ratio in 1 cycle is r (typically 0 < r < 1), the expansion ratio after N cycles is α₀Is expressed by equation 27 as a constant.

[ mathematical formula 27]

The degradation simulation model may include a stress-strain model and a fatigue model. It is known that most electrode materials cause volume change with charge and discharge. In particular, in an electrode material of a lithium ion battery, a volume change accompanying the desorption and insertion of lithium of a charge carrier is significant. In general, since a battery is constrained by a resin material, a metal material, high-strength steel, and the like, a large internal stress is generated when an electrode material expands, and minute cracks (cracks) may be generated in active material particles. The cracks cause the isolation of the active material particles. Therefore, a design that does not increase the stress in the active material particles is desired.

Therefore, in the structural simulation, strain is applied to the stress-strain relational expression as a function of the charge carrier concentration in the active material particles, and calculation of stress strain due to expansion and contraction of the electrode in consideration of charge and discharge can be performed. The functional form of the charge carrier concentration and strain may also be proportional, or may be any other function.

For example, the part of the model for calculating the electrochemistry may be connected to a circuit network of numerical analysis software, and the part for calculating the stress strain may be connected to commercially available numerical analysis software (structural analysis simulation software of a finite element method, etc.). Thereby, the deterioration and the stress strain of the battery can be simultaneously calculated in a linked manner.

The degradation simulation model may also include a thermal conductivity model. Among the batteries whose deterioration progresses, the batteries whose resistance increases and whose conductivity in the electrolyte decreases tend to generate a large amount of heat. In general, the higher the temperature, the more rapid the deterioration progresses, and temperature management is also an important factor in suppressing deterioration of the battery.

The calorific value can be calculated by the following equation.

(heat generation amount) (current) × (ohmic overvoltage + activated overvoltage) × (current) × (open circuit voltage between terminals-voltage between terminals)

For example, the part for calculating the electrochemistry in the present model may be connected to a circuit network of numerical analysis software, and the part for calculating the heat may be connected to a thermal circuit network calculating part of commercially available numerical analysis software. This makes it possible to calculate the deterioration and heat generation of the battery simultaneously in a linked manner.

As described above, in the embodiment, it is possible to simulate the deterioration of the power storage device in consideration of the deterioration mechanism and provide the simulation result to the user. Since the mathematical model obtained as a result of simulating the deterioration of the power storage device can be provided to the user as needed, the client device 20 can obtain a simulation result of the power storage device or the system including the power storage device under a desired condition using the mathematical model downloaded from the server device 10. The client device 20 may download a simulation program used for calculating a simulation result from the server device 10.

When the simulation program downloaded to the client device 20 is used, it may be necessary to communicate with the server device 10 and receive user authentication. At this time, the simulated conditions input to the client device 20 may be transmitted to the server device 10.

The disclosed embodiments are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the scope of the claims, and includes all modifications equivalent in meaning to the scope of the claims and within the scope.

For example, in the present embodiment, a wound lithium ion battery in which the electrolyte is a liquid is exemplified. Alternatively, the simulation method of the present application may be applied to all-solid lithium ion batteries, bipolar lithium ion batteries (batteries in which electrodes are electrically connected in series), zinc-air batteries, sodium ion batteries, lead batteries, and the like, without limiting the types of batteries.

In the present specification, a mode in which the simulation is implemented by communication between the server apparatus 10 and the client apparatus 20 is exemplified. Alternatively, the server administrator may provide the simulation program to the client user by means of a storage medium such as a DVD-ROM, and perform the simulation locally at the client terminal. As the providing means, a download form via communication is possible. That is, when the control unit 21 of the client device 20 executes the simulation program, the client device 20 is configured to function as a development support device of the present application that receives selection information on a degradation mechanism of the electric storage device, executes a degradation simulation of the electric storage device using the selected mechanism, and outputs a simulation result.

Description of the symbols

10 a server device;

11 a control unit;

12 a storage section;

13 a communication unit;

14 an operation part;

15 a display unit;

20 a client device;

21a control unit;

22 a storage section;

23 a communication unit;

24 an operation section;

25 a display unit;

n communication network.

Claims (14)

1. A development support device is characterized by comprising:

a receiving unit that receives, from a terminal apparatus, selection information relating to a degradation mechanism of an electric storage device after user authentication of the terminal apparatus;

a simulation execution unit that simulates degradation of the power storage device by the selected degradation mechanism based on the received selection information; and

and a transmission unit that transmits a simulation result simulated by the simulation execution unit or a simulation program executed when the degradation of the power storage device is simulated, to the terminal device.

2. The development support apparatus according to claim 1,

the simulation execution unit executes a simulation using a physical model representing the power storage device.

3. The development support apparatus according to claim 1 or 2,

the degradation mechanism includes at least one of an increase in resistance, an isolation of active material particles, a decrease in conductivity in an electrolyte, and a decrease in charge carriers involved in charge and discharge in each element constituting the electric storage device.

4. The development support apparatus according to claim 3,

the increase in resistance includes an increase in resistance at the bonding portion between the current collecting foil and the porous electrode, an increase in resistance due to a decrease in the conductive path in the active material particle, or an increase in resistance due to an increase in the resistor coating on the particle surface.

5. The development support apparatus according to claim 3,

the increase in the resistance, the isolation of the active material particles, and the decrease in the conductivity are expressed as a function of the upper limit and the lower limit of the SOC during discharge.

6. The development support apparatus according to claim 3,

the increase in resistance, the isolation of the active material particles, the decrease in conductivity, and the decrease in charge carriers are expressed as a function of at least one of elapsed time, cycle number, and temperature.

7. The development support apparatus according to claim 3,

the reduction of the charge carriers is represented by a metering factor of the charge transfer process in the surface of the negative electrode upon charging.

8. The development support apparatus according to any one of claims 1 to 7,

the simulation result includes a temporal change or a periodic change in any one of a value of resistance, a volume ratio of an isolated region of the active material particles, a diffusion coefficient or ionic conductivity of the electrolyte, an amount of charge carriers, and an expansion rate of the power storage device among the elements constituting the power storage device.

9. A development support device is characterized by comprising:

a reception unit that receives selection information relating to a degradation mechanism of the power storage device;

a simulation execution unit that simulates degradation of the power storage device by the selected degradation mechanism based on the received selection information; and

and an output unit that outputs a simulation result simulated by the simulation execution unit or a simulation program executed when the degradation of the power storage device is simulated.

10. A development support method is characterized in that,

by using a development support device connected to be able to communicate with a terminal device,

presenting a plurality of options regarding a degradation mechanism of the electric storage device, and receiving selection information regarding the selected degradation mechanism from the terminal apparatus,

simulating degradation of the power storage device using the selected degradation mechanism based on the received selection information,

the simulation result or a simulation program executed when the degradation of the power storage device is simulated is transmitted to the terminal device.

11. A development support method is characterized in that,

by means of the computer, it is possible to,

a plurality of options relating to the degradation mechanism of the power storage device are presented,

receiving a selection regarding a degradation mechanism of the electric storage device based on the presented selection items,

simulating degradation of the power storage device using the selected degradation mechanism,

outputting a simulation result or a simulation program executed when simulating degradation of the electric storage device.

12. A computer program for causing a computer to execute:

presenting a plurality of options regarding a degradation mechanism of the electric storage device, and receiving selection information regarding the selected degradation mechanism from the terminal apparatus,

simulating degradation of the power storage device using the selected degradation mechanism based on the received selection information,

the simulation result or a simulation program executed when the degradation of the power storage device is simulated is transmitted to the terminal device.

13. A computer program for causing a computer to execute:

a plurality of options relating to the degradation mechanism of the power storage device are presented,

receiving a selection regarding a degradation mechanism of the electric storage device based on the presented selection items,

simulating degradation of the power storage device using the selected degradation mechanism,

outputting a simulation result or a simulation program executed when simulating degradation of the electric storage device.

14. A computer program for causing a computer to execute:

a plurality of options relating to the degradation mechanism of the power storage device are presented,

receiving a selection regarding a degradation mechanism of the electric storage device based on the presented selection items,

in order for the server apparatus to simulate the deterioration of the electric storage device using the selected deterioration mechanism, selection information of the deterioration mechanism is transmitted to the server apparatus.

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