JP2017059444A - Electrode simulation method and device for all-solid battery, and method of manufacturing electrode for all-solid battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To analyze the contact state of powder bodies in consideration of compression/relaxation, expansion/contraction and breaking of plural kinds of powder bodies.SOLUTION: A simulation method for analyzing the contact state of powder bodies in an electrode for an all-solid battery which is formed by performing compression molding on plural kinds of powder bodies containing powder bodies of an active material and solid electrolyte, a step of modeling each of the plural kinds of powder bodies into a powder model of an aggregate of a finite number of elementary particles for which a motion equation is defined, and a step of analyzing the contact state of the plural kinds of powder bodies when the plural kinds of powder bodies are compressed or expanded/contracted by charging/discharging, on the basis of a DEM-SPH coupled analysis method by using plural types of powder body models corresponding to the plural kinds of powder bodies. In the analysis step, on the basis of a stress strain characteristic under load application of each powder body and a volume expansion characteristic under charging/discharging, when a strain exceeding a predetermined strain occurs in the powder body model under the expansion/contraction caused by charging/discharging, it is determined that some of the powder bodies corresponding to the powder model are broken.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an electrode simulation method and apparatus for an all solid state battery, and a method for manufacturing an electrode for an all solid state battery.

  All-solid-state batteries have characteristics such as high output voltage and energy density and high safety, and their use is being promoted, and research and development are being conducted to further improve the characteristics. In order to improve the characteristics of an all-solid-state battery, for example, a prototype of an all-solid-state battery is actually manufactured by changing design specifications and manufacturing conditions, and the state and characteristics of the battery inside are checked using the prototype. It is necessary to measure. In this way, the method of measuring the internal state of the battery using the prototype takes enormous time and cost. Therefore, in order to reduce the production of prototypes and efficiently conduct research and development, a method for predicting the internal state of the all-solid-state battery by simulation is desired.

  On the other hand, a simulation method for simulating the state of powder is known. For example, Patent Document 1 discloses a simulation method for simulating powder compression molding, in which a powder model in a DEM (Discrete Element Method) method and an SPH method (Particle Method) is used, and a powder in the DEM method is used as a spring. -The first step of expressing the powder by a dashpot model and defining the powder in the SPH method with a powder model in which a plurality of particles are joined by an elastic-plastic spring force, and compressing the powder by applying pressure to the powder In addition, in the process, the second step of calculating the powder density by weakly coupling the DEM method and the SPH method, and the weak coupling of the DEM method and the SPH method when the initial particles are in complete contact with each other The third step of performing the interpolation process by the moving least square approximation and performing interpolation is performed, and the DEM method and the SPH method are weakly coupled until pressure is applied to a plurality of powders to achieve a predetermined powder density. Powder Simulation method characterized by comprising a fourth step of performing the calculation of the density, is disclosed.

  According to Patent Document 1, the method of weakly coupling the DEM method and the SPH method used in this simulation method (hereinafter, also referred to as “DEM-SPH coupled analysis method”) greatly deforms the powder. In the compression molding process, the powder density distribution, residual stress distribution, and residual strain distribution can be obtained accurately.

JP 2014-67329 A

  In order to improve the characteristics of an all-solid battery, an electrode for an all-solid battery (hereinafter simply referred to as “battery electrode”) may be improved. In order to improve the battery electrode, it is important to grasp the contact state between the powders constituting the electrode from the viewpoint of conduction of ions and electrons. In particular, at the time of charge / discharge of the all-solid battery, the battery electrode expands / contracts by absorbing / releasing ions. Therefore, when a battery electrode expand | swells, powder may raise | generate a fracture | rupture (break) by strongly pressing each other mutually. Therefore, a technique capable of grasping the contact state between the powders including whether or not the powder of the battery electrode is crushed is desired.

  Here, as a method of grasping the contact state between the powders of the battery electrodes, the simulation method of Patent Document 1 capable of handling the compression of the powders can be considered, but it has also been found that the following problems exist.

  The battery electrode powder greatly expands / contracts due to the absorption / release of ions during charge / discharge. In addition, the battery electrode powder may be very strained by compression molding or expansion / contraction, and may be crushed (broken) depending on the magnitude of the strain. However, the simulation method does not support expansion / contraction and compression molding or crushing (destruction) due to expansion / contraction distortion like the powder of a battery electrode. Therefore, the battery electrode powder cannot be simulated if the simulation method is used as it is.

  In addition, a plurality of types of powders are collectively formed by compression molding in the battery electrode, and the characteristics of the plurality of types of powders are different from each other, and thus the behavior against compression is also different. However, the simulation method can be used only when a single type of powder is compression molded. Therefore, the battery electrode powder cannot be simulated if the simulation method is used as it is.

  As described above, the simulation method cannot analyze the contact state between powders in consideration of expansion / contraction and destruction of plural kinds of powders.

  According to the present invention, the plurality of types of powders in an electrode for an all-solid battery formed by compression molding a plurality of types of powders including a positive electrode active material or negative electrode active material powder and a solid electrolyte powder. The electrode simulation method for an all-solid-state battery for analyzing the contact state of each of the above, wherein each of the plurality of types of powders is individually modeled into a powder model that is an assembly of a finite number of basic particles with a defined equation of motion A plurality of types of powder models corresponding to the plurality of types of powders, and the plurality of types of powders are compressed based on a DEM (Discrete Element Method) -SPH (Particle Method) coupled analysis method. Or the step of analyzing the contact state of the plurality of types of powders when expanding or contracting due to charge / discharge. Release Based on the volume expansion characteristics at the time, when a strain exceeding a predetermined strain occurs during expansion or contraction due to charge / discharge, all or part of the powder corresponding to the powder model is broken An electrode simulation method for an all-solid-state battery including a determining step is provided.

  According to the present invention, the plurality of types of powders in an electrode for an all-solid battery formed by compression molding a plurality of types of powders including a positive electrode active material or negative electrode active material powder and a solid electrolyte powder. An all-solid-state electrode simulation device for analyzing the contact state of each of the above, wherein each of the plurality of types of powders is individually modeled into a powder model that is an aggregate of a finite number of basic particles with a defined equation of motion The plurality of types of powders based on a DEM (Discrete Element Method) -SPH (Particle Method) coupled analysis method using a model definition unit that performs and a plurality of types of the powder models corresponding to the plurality of types of powders And a DEM-SPH analysis unit that analyzes a contact state of the plurality of types of powders when compressed or expanded or contracted by charge / discharge, and the DEM-SPH analysis unit includes the DEM-SPH analysis unit Under load Based on the stress strain characteristics and the volume expansion characteristics during charging / discharging, when a strain exceeding a predetermined strain is generated in the powder model during expansion or contraction due to charging / discharging, all of the powder corresponding to the powder model or An electrode simulation apparatus for an all-solid-state battery is provided that includes a destruction determination unit that determines that a part of the electrode is broken.

  According to the present invention, a plurality of types of powders including a positive electrode active material or negative electrode active material powder and a solid electrolyte powder are placed on a substrate and compression molded to produce an electrode for an all solid state battery. A method for producing an electrode for an all-solid battery, wherein the load for compression molding and the plurality of types of the powder when the plurality of types of powders are compression-molded by executing the electrode simulation method for an all-solid-state battery of the present invention. The step of determining the relationship with the contact state of the powder, and the compression molding load when the predetermined contact state is reached in the simulation method based on the determined relationship, in the actual production of the all-solid-state battery electrode There is provided a method for producing an electrode for an all-solid-state battery, comprising a step of setting a compression molding load and a step of compression molding the plurality of types of powders by the set load.

  According to the all-solid-state battery electrode simulation apparatus and all-solid-state battery electrode simulation method of the present invention, it is possible to analyze a contact state (void state) between powders in consideration of expansion / contraction and destruction of plural kinds of powders. I can do it.

The fragmentary sectional view which shows the structural example of an all-solid-state battery. The flowchart which shows an example of the manufacturing method of a general all-solid-state battery. Powder model. Compression molding machine model. A compression molding machine model after compression molding. Electrode model. The graph which shows the stress-strain characteristic of a general material. The graph which shows the stress-strain characteristic of the negative electrode active material and solid electrolyte by experiment. The figure explaining the contact rate between powder. The functional block diagram which shows the structural example of the electrode simulation apparatus for all-solid-state batteries. The flowchart which shows the electrode simulation method for all-solid-state batteries. The flowchart which shows the method of judging the fracture | rupture of powder. FIG. 13 is a flowchart showing a method for manufacturing an electrode for an all-solid-state battery. The graph which compared the simulation result and the experimental result about the contact rate in the active material layer after the cycle durability test of an all-solid-state battery. The graph which shows the influence which the mechanical material characteristic of an active material and a solid electrolyte has on the contact rate after completion of an all-solid-state battery by comparing with an experimental result and a simulation result. The table | surface which shows typically the result of having examined by the simulation the change of the internal structure of the negative electrode active material layer at the time of completion of an all-solid-state battery when only an initial press load was changed. The graph which compared the simulation result and the experimental result about the relationship between the cycle number of the cycle durability test of an all-solid-state battery, and the contact rate in a negative electrode active material layer. The table | surface which shows typically the result of having examined by the simulation the change of the internal structure of the negative electrode active material layer from completion of an all-solid-state battery to a cycle durability test.

  Hereinafter, an electrode simulation method for an all solid state battery (hereinafter also simply referred to as “the present simulation method”), an electrode simulation device for an all solid state battery (hereinafter, also simply referred to as “the present simulation device”) according to the present embodiment, and The manufacturing method of the electrode for all-solid-state batteries is demonstrated.

  First, the all-solid-state battery that is the object of simulation analysis will be described.

  FIG. 1 is a partial cross-sectional view showing a configuration example of an all-solid battery to be analyzed. The all solid state battery 1 is a chargeable / dischargeable battery, and includes a positive electrode 11, a negative electrode 12, and a solid electrolyte layer 13 disposed between the positive electrode 11 and the negative electrode 12.

The material of the solid electrolyte layer 13 is not particularly limited, and examples thereof include sulfide-based glass bodies / sulfide-based crystals and oxide-based electrolytes that can be used as solid electrolytes for lithium secondary batteries. Examples of sulfide-based electrolyte glass bodies and sulfide-based crystals include Li ₂ S—P ₂ S _{5 and} Li ₂ S—SiS ₂ containing Li atoms, and specific examples of oxide electrolytes include Li _2. such as _{O-B 2 O 3 -P 2} O 5 and the like.

The positive electrode 11 includes a positive electrode active material layer 14 containing a positive electrode active material, and a positive electrode current collector layer 16 that collects current from the positive electrode active material layer 14. As a material of the positive electrode active material layer 14, for example, a material obtained by mixing a positive electrode active material such as LiNi _1/3 Co _1/3 Mn _1/3 O ₂ and a solid electrolyte such as a material of the solid electrolyte layer 13 is used. Can be mentioned. The positive electrode active material layer 14 may further include a conductive additive and a binder. In addition, lithium nickel cobalt manganate (LiNi _x Co _{1-y x} Mn _y O ₂ , where x · y · z is an integer or a real number), lithium cobaltate (LiCoO ₂ ), and the like can be given. Examples of the material of the positive electrode current collector layer 16 include aluminum.

  The negative electrode 12 includes a negative electrode active material layer 15 containing a negative electrode active material and a negative electrode current collector layer 17 that collects current from the negative electrode active material layer 15. Examples of the material of the negative electrode active material layer 15 include a material in which a negative electrode active material such as natural graphite or artificial graphite and a solid electrolyte such as a material of the solid electrolyte layer 13 are mixed. The negative electrode active material layer 15 may further include a conductive additive and a binder. An example of the material for the negative electrode current collector layer 17 is copper.

  When there is no need to distinguish between the positive electrode and the negative electrode, it is simply referred to as an electrode, and when it is not necessary to distinguish between the negative electrode active material layer and the positive electrode active material layer, it is referred to as an active material layer. When it is not necessary to divide, it is referred to as an active material, and when it is not necessary to separate the negative electrode current collector layer and the positive electrode current collector layer, it is referred to as a current collector layer.

  Next, a method for manufacturing an all-solid battery that is an analysis target of simulation will be described.

  FIG. 2 is a flowchart showing an example of a general method for manufacturing an all-solid battery. First, in step 100, each of the positive electrode active material / negative electrode active material and the solid electrolyte material is produced by chemical synthesis from raw materials. Each material is a generally spherical powder.

  Next, in step 101, the prepared material and other materials such as a binder and a solvent are mixed to prepare a slurry for the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer. Each slurry is spread and dried into a sheet, and then compression molded to form the positive electrode active material layer 14, the negative electrode active material layer 15, and the solid electrolyte layer 13, respectively.

  In subsequent step 102, the positive electrode 11 including the positive electrode current collector layer 16 and the positive electrode active material layer 14, the solid electrolyte layer 13, the negative electrode active material layer 15 and the negative electrode 12 including the negative electrode current collector layer 17 are laminated to form an all solid. A battery is produced.

  Thereafter, in step 103, a cycle endurance test of the produced all solid state battery is performed. In the cycle endurance test, for example, electricity of a predetermined amount of power is charged in an all-solid battery per cycle, and then discharged, and N cycles are performed (N is a natural number of 2 or more). For example, the negative electrode 12 expands by charging and contracts by discharging.

  By the way, it takes time and cost to make a prototype and confirm the change in the internal state of the all-solid-state battery due to changes in design specifications and manufacturing conditions. Therefore, the change of the state is predicted by simulation. For example, the simulation method of Patent Document 1 can simulate the compression molding of powder, and can analyze the density distribution, residual stress distribution, and residual strain distribution generated by compression molding. However, in the simulation method of Patent Document 1, as described above, it is possible to analyze the state of occurrence of a contact state (gap state) between powders in consideration of expansion / contraction and crushing of a plurality of types of powders. No.

  Therefore, the simulation apparatus and the simulation method handle a material including a plurality of types of powders using the simulation method of Patent Document 1, that is, the DEM (Discrete Element Method) -SPH (Particle Method) coupled analysis method. In addition, it is possible to handle large expansion / contraction of the powder and crushing (breaking) due to distortion caused by compression molding and expansion / contraction. Thereby, the simulation apparatus and the simulation method can simulate not only the compression molding process in the manufacturing method of the all solid state battery shown in FIG. 2 but also the cycle durability test process. That is, the manufacturing method of an all-solid battery can be reproduced by simulation. As a result, the time and cost can be reduced, such as reducing the number of experiments with prototypes in research and development.

  Hereinafter, the simulation apparatus and the simulation method will be described in detail.

  First, a model used in the simulation will be described.

  First, a powder model for simulating the powder used for the active material layer used through simulation will be described. FIG. 3 shows a powder model. As a powder model, a basic model of the DEM method shown in FIG. 3A, a solid electrolyte powder model Ae simulating one powder of the solid electrolyte shown in FIG. 3B, and FIG. A negative electrode active material powder model Aa that simulates one powder of the negative electrode active material shown in FIG. 3 and a positive electrode active material powder model Ac that simulates one powder of the positive electrode active material shown in FIG. Defined. In any of the solid electrolyte powder model Ae, the negative electrode active material powder model Aa, and the positive electrode active material powder model Ac, one powder model is defined using a plurality of basic particles bp. However, FIG. 3 (A) shows that the exchange of force between the rigid elements A is expressed by two types of springs, and the figure on the right side is between the elements A due to the parallel arrangement of the elastic springs and dashpots in the normal direction. The left diagram shows the exchange of force between the elements A by the parallel arrangement of the tangential elastic spring and the dashpot. Force is transmitted when the elements A are in contact with each other, and no force is transmitted when they are separated. The element A corresponds to the solid electrolyte powder model Ae, the negative electrode active material powder model Aa, and the positive electrode active material powder model Ac.

  The basic particles bp are all spherical particles having the same dimensions and the same mass. The basic particles bp are coupled together by a spring to form the entire shape of one powder. The spring connecting the basic particles bp is elastically plastically deformed. The combination method of the basic particles bp is arbitrary, and a powder having a desired shape and size can be modeled. However, in the DEM method, the relationship between the basic particles bp is expressed by a spring-dashpot model.

  The solid electrolyte powder particle model Ae, the negative electrode active material powder particle model Aa, and the positive electrode active material powder particle model Ac are preliminarily considered in consideration of the closest packing of powder in a three-dimensional space. The specification of each powder diameter is tentatively determined.

  The solid electrolyte powder model Ae and the negative electrode active material powder model Aa are used for the simulation on the negative electrode active material layer, and the solid electrolyte powder model Ae and the positive electrode active material powder model Ac are used for the simulation on the positive electrode active material layer. The positive electrode active material powder model Ac is used for the simulation related to the solid electrolyte layer.

  In addition to each powder model, material characteristic data indicating the characteristics of each powder includes not only the above particle diameter but also mechanical characteristic data such as Young's modulus, yield stress, material strength, and Poisson's ratio. , Given for each type of powder, that is, for each negative electrode active material / positive electrode active material and solid electrolyte. As mentioned above in paragraph 0008, since the simulation method of Patent Document 1 is in a state where only “single type” particle powder can be handled, this is referred to as “multiple material type” particle powder. In order to be able to handle it, we introduced the idea that “designers can give initial condition settings with different material properties in specific powders” in the simulation program structure, and succeeded in establishing the calculation analysis. As a result, the types such as the negative electrode active material powder model Aa, the positive electrode active material powder model Ac, and the solid electrolyte powder model Ae are different, and thus the shape and material characteristics are different, and thus the behavior against compression is different. Simulation is possible even if powder models are mixed.

  Next, a compression molder model for simulating a compression molder that compresses and molds powder used for compression molding in simulation will be described. FIG. 4 shows a compression molder model. The compression molding machine model 20 is composed of a space 23 having boundary layers 21 and 22 facing each other. For example, the space 23 corresponds to the space in the mold of the compression molding machine, the boundary layer 21 corresponds to the surface for pressing the powder in the press machine of the compression molding machine, and the boundary layer 22 corresponds to the powder in the mold of the compression molding machine. Corresponds to the surface against which the body is pressed (or substrate, current collector layer, etc.). A plurality of powder models A are arranged in the space 23.

  However, in this figure, the powder model A shows a combination of the solid electrolyte powder model Ae and the negative electrode active material powder model Aa when the negative electrode active material layer is compression-molded. When compression molding is performed, a combination of the solid electrolyte powder model Ae and the positive electrode active material powder model Ac is shown (hereinafter the same in FIGS. 5 and 6).

  As an initial state, the powder model A is arranged in a state where they are slightly separated from each other or are in light contact with each other in the space 23. Further, the solid electrolyte powder model Ae that is the powder model A and the negative electrode active material powder model Aa (or the positive electrode active material powder model Ac) are randomly dispersed and arranged in the space 23. However, the ratio of the solid electrolyte powder model Ae and the negative electrode active material powder model Aa (or positive electrode active material powder model Ac) in the space 23 is the solid in the actual negative electrode active material layer (or positive electrode active material layer). The ratio between the electrolyte and the negative electrode active material (or the positive electrode active material) is the same.

  For example, in the case of a compression molding model of the negative electrode active material layer, the actual mixing ratio of the negative electrode active material and the solid electrolyte in the negative electrode active material layer is a: b (note: a + b = 100 [unit:%], a> In the case of 0.0 (%) and b> 0.0 (%)), the ratio of the negative electrode active material powder model Aa and the solid electrolyte powder model Ae in the space 23 is also a: b. In the example of this figure, the powder model A in the region 24 indicated by the broken line is analyzed in the compression molder model 20.

  FIG. 5 shows the compression molding machine model 20 after compression molding. After completion of the compression molding process, a plurality of powder models A are compressed and integrated in the compression molding machine model 20 to form a sheet-like active material layer model 35.

  Next, an electrode model that simulates an electrode (negative electrode or positive electrode) in which an active material layer and a current collector layer are stacked, which is used in a cycle endurance test in simulation, will be described. FIG. 6 shows an electrode model. The electrode model 30 is configured by arranging the active material layer model 35 of FIG. 5 formed of a plurality of powder models A in a space 33 having boundary layers 31 and 32 facing each other. For example, when the electrode model 30 is a negative electrode model, the active material layer model 35 corresponds to the powder sheet of the negative electrode active material layer, the space 33 corresponds to the negative electrode region, and the boundary layer 31 is the adjacent solid electrolyte layer. The boundary layer 32 corresponds to the negative electrode current collector layer.

  The boundary layers 31, 32, the space 33, and the powder model A of the electrode model 30 in FIG. 6 correspond to the boundary layers 21, 22, the space 23, and the powder model A of the compression molding machine model 20 in FIG. In other words, after the state of FIG. 5 is obtained by the simulation of the compression molding process using the model of FIG. 4, the cycle durability test process of the model of FIG. 6 can be continuously performed.

  Next, functions added to the simulation will be described.

  First, a relaxation function for expressing a stable state in which residual stress remains after compression of powder, which is used in simulation compression molding and cycle durability test will be described.

FIG. 7 is a graph showing stress-strain characteristics of a general material. The horizontal axis indicates the strain ε, and the vertical axis indicates the stress σ. In the stress-strain curve S, when the load is unloaded in the state P of the plastic region (after the state A) past the elastic region (from the origin 0 to the state A) where the stress σ increases linearly with respect to the strain ε, Energy release, shape relaxation and residual stress occur. In order to express it, the state Q (strain ε _Q ) when the stress becomes zero with a straight line having the same inclination as the elastic region from the state P (strain ε _H , stress σ _P ) is defined as a stable state after unloading. To do. As a result, in the stable state Q reached by unloading, it can be expressed that the residual stress corresponding to the strain ε _Q is generated while the relaxation of the shape corresponding to the decrease in strain (ε _H −ε _Q ) occurs.

  Specifically, the above relaxation function is incorporated using the stress-strain characteristics of the negative electrode active material / positive electrode active material and solid electrolyte measured by experiments. FIG. 8 is a graph showing stress-strain characteristics of the negative electrode active material and the solid electrolyte obtained by experiments. The horizontal axis indicates the strain ε, and the vertical axis indicates the stress σ. The broken line indicates the negative electrode active material, and the solid line indicates the solid electrolyte. That is, in this simulation, the stress-strain characteristic graph of FIG. 8 is used as a specific example of the graph shown in FIG. Regarding the stress-strain characteristics, different data are input for each type of powder, that is, for the negative electrode active material, the positive electrode active material, and the solid electrolyte. In addition, illustration is abbreviate | omitted about the stress-strain characteristic of a positive electrode active material.

  Next, the calculation function of the contact state (contact rate) between the active material and the solid electrolyte, which is used for the evaluation of the active material layer after the compression molding in the simulation and the cycle durability test, will be described.

  The contact rate is calculated by the following method. FIG. 9 is a diagram for explaining the contact ratio between powders. The contact ratio R (%) is an index indicating how many basic particles bp1 on the surface of the powder model A1 are in contact with the surrounding powder model A2. In this example, the powder model A1 is an active material, and the powder model A2 is a solid electrolyte. The higher the contact ratio, the easier the conduction of ions and batteries, so the performance as an all-solid battery increases. Accordingly, it is preferable that the active material layer has a high contact rate.

The contact rate is calculated by the following formula (A).
R (%) = _NA1-A2 / _NA1 * 100 (A)
N _A1 : Total number of particles bp1 on the outermost surface of the active material A1 N _A1-A2 : Particles on the outermost surface of the solid electrolyte A2 surrounding the outer periphery among the total number of particles bp1 on the outermost surface of the N _A1 active materials A1 The total number that bp2 contacts

However, for the contact, the contact state is determined when the center-to-center distance X between the basic particle bp1 of the active material A1 and the basic particle bp2 of the solid electrolyte A2 is within the range defined by the following formula (B). It was set to do.
X−φ <K [μm] (B)
φ: Diameter of basic particle K: In the experiment, when the phenomenon that electrons or Li ions hop between powders was confirmed, the value confirmed with an electron microscope or the like was substituted for this coefficient as the distance between powders

  Next, an expansion / contraction function that reproduces the expansion / contraction of the powder that occurs during charge / discharge, which is used in a cycle endurance test in simulation, will be described.

  It has been experimentally confirmed that the expansion / contraction of the electrode during charging / discharging of the all-solid-state battery is “the expansion / contraction of the active material due to Li ions entering / exiting the electrode” as an actual phenomenon. Yes. In order to model the actual phenomenon, expansion / contraction due to the entry / exit of Li ions is simulated by expansion / contraction due to heat, that is, replaced with “thermal expansion analysis technology”. In FEM, the expansion and contraction calculation can be performed using the index of the linear expansion coefficient, and can be applied to this simulation method.

First, the volume expansion coefficient β in the expansion / contraction of the volume due to the entry / exit of Li ions is measured by experiments in advance using an actual battery electrode. Here, it is known that the following relationship exists between the volume expansion coefficient β and the linear expansion coefficient α.
α≈β / 3 (C)
Accordingly, the expansion / contraction of the volume due to the entry / exit of Li ions is regarded as the thermal expansion / contraction of the linear expansion coefficient α, and the thermal expansion analysis is performed to simulate the expansion / contraction due to the entry / exit of Li ions.

  In the cycle durability test of an all-solid battery, charging / discharging with a predetermined amount of electricity is performed per cycle, and N cycles are performed (N is a natural number of 2 or more). Therefore, in order to simulate charging / discharging for one cycle, the active material layer is formed so as to cause expansion / contraction by heat so as to cause the same expansion / contraction as the expansion / contraction by charging / discharging of a predetermined amount of electricity. Heat / cool virtually by a predetermined temperature.

  However, the actual negative electrode active material layer is composed of a negative electrode current collector layer, a negative electrode active material layer, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode current collector layer that are stacked in that order in the assembled configuration, and a cycle durability test. Sometimes it is restrained from the positive electrode side under the condition of constant load and constant dimension. For this reason, when performing simulation calculation, it is necessary to set appropriate conditions according to the range of analytical modeling of parts and how to apply durability test conditions (load restraint direction, part restraint freedom setting). is there.

  In this way, this simulation method targets powder that expands / contracts greatly due to absorption / release of ions during charge / discharge, such as powder of an active material layer, by making the volume expansion coefficient correspond to the thermal expansion coefficient. The above simulation can be executed.

  Next, a description will be given of a powder breaking function for reproducing powder breakage, which is used in simulation compression molding and cycle durability testing.

In order to make the fracture of the powder reproducible, the stress-strain characteristic itself as shown in FIG. 8 is used as the mechanical characteristic of each powder. Assuming that the stress-strain characteristics shown in FIG. 8 are used,
Breaking strain of negative electrode active material = Breaking strain of solid electrolyte x 3.0 (D)
Breaking stress of negative electrode active material = Breaking stress of solid electrolyte × 4.6 (E)
It can be seen that there is a relationship. It can be determined that the respective materials are broken when the above-described fracture strain or stress is generated in both powders by the combined calculation by SPH and DEM.

  Therefore, there are two types of rupture modes: (i) rupture based on strain generated between particles and (ii) rupture based on stress generated in the particles themselves. In this case, when the phenomenon is visually analyzed, in the case of the above (i), one powder is changed to two powders having no change in the number of elements, and in the case of the above (ii), one powder is changed. However, since the disappearance of particles occurs, the sum of the number of particles of the two powders after the rupture is smaller than the number of particles of the original powder. Specifically, in the simulation, when a distortion exceeding the fracture strain occurs in a basic particle in the powder model, the bond between the basic particle and surrounding basic particles is released to support the powder model. It expresses pulverization (breaking) of the powder.

  In this way, since this simulation method can determine the breakage of the powder, it is possible to evaluate the possibility of the powder being crushed (broken) according to design specifications and manufacturing conditions. In particular, since this simulation method makes it possible to reproduce the expansion / contraction of the powder as described above, the expansion / contraction of the powder and the powder in the cycle endurance test as well as the crushing of the powder by compression molding. You can evaluate the relationship with body crushing.

  Next, the simulation apparatus will be described. FIG. 10 is a functional block diagram illustrating a configuration example of the simulation apparatus 60. The simulation apparatus 60 executes a simulation using a DEM-SPH coupled analysis technique, and analyzes the contact state between powders at the electrodes of an all-solid battery.

  The simulation apparatus 60 is an information processing apparatus exemplified by a computer. The simulation apparatus 60 includes a CPU, a storage device, a removable memory drive, a communication device, an input device, an output device, and an interface (not shown). The CPU executes a computer program installed in the simulation apparatus 60 and controls these storage devices and the like. The storage device stores a computer program, and further stores information used by the CPU and generated information. The removable memory drive is used when a computer program is installed in the simulation apparatus 60 from a storage medium in which the computer program is stored. The communication device is used when a computer program is downloaded / installed into the simulation device 60 from another computer via a communication line network. The input device outputs information generated by a user operation to the CPU. The output device outputs the information generated by the CPU so that the user can recognize it. The interface outputs information generated by an external device connected to the simulation apparatus 60 to the CPU, and outputs information generated by the CPU to the external device. The external device includes another computer. Examples of the storage device include ROM, RAM, HDD, and nonvolatile memory. Examples of the removable memory drive include a CD-ROM drive and a DVD drive. Examples of the input device include a keyboard and a mouse. Examples of the output device include a display and a printer.

  The computer program installed in the simulation apparatus 60 includes a plurality of computer programs for causing the simulation apparatus 60 to realize a plurality of functions. The plurality of functions are realized by cooperation of a computer program (software) and a simulation device 60 (hardware), and include a storage unit 63, a model definition unit 61, and a DEM-SPH analysis unit 62.

  The storage unit 63 stores material property data 75 used in the simulation of the DEM-SPH analysis unit 62. The material property data 75 includes, for example, data on stress-strain properties, volume expansion coefficient β, particle size, and mechanical property data such as Young's modulus, yield stress, material strength, and Poisson's ratio shown in FIG. 8 for each powder. . The material property data 75 is input in advance by the user, for example.

  The model definition unit 61 uses the material property data 75 to define a model used for the simulation. The DEM-SPH analysis unit 62 analyzes the contact state between a plurality of types of powders by a simulation based on the DEM-SPH coupled analysis method using the defined model. The DEM-SPH analysis unit 62 includes the relaxation function and the expansion / contraction function described above, and further includes a DEM analysis unit 71 that analyzes powder by the DEM method, an SPH analysis unit 72 that analyzes powder by the SPH method, A contact rate calculation unit 73 that calculates the degree of contact between each other, that is, a contact rate, and a destruction determination unit 74 that determines breakage of the powder are included.

  Next, the simulation method (operation of the simulation apparatus 60) will be described. FIG. 11 is a flowchart showing this simulation method.

(1) Step 200
In step 200, the model definition unit 61 reads material property data 76 related to the material properties and shape of the active material layer from the storage unit 63, and defines a model to be used for simulation based on the material property data 76. Examples of the model include the models shown in FIGS. 3 and 4.

(2) Step 201
In step 201, the DEM analysis unit 71 and the SPH analysis unit 72 of the DEM-SPH analysis unit 62 perform compression molding by the DEM-SPH coupled analysis method using the model defined in step 200 (FIGS. 3 and 4). The process is simulated.

  Initially, the DEM analysis unit 71 performs a simulation related to the compression molding of the powder using the DEM method. The basic particles bp shown in FIG. 3 correspond to basic particles in the DEM method, that is, DEM particles. In the DEM method, a motion equation for translational motion and a motion equation for rotational motion of a DEM particle are defined, and the motion of the particle is obtained over time. The motion equation of translational motion in the DEM method is, for example, ma + Cv + F = 0, m: mass, a: acceleration, C: damping constant, v: velocity, F: external force, and the motion equation of rotational motion is, for example, Iα + Dω + M = 0, I: Moment of inertia, α: angular acceleration, D: damping constant, M: moment acting from outside (FIG. 3A). Based on the models shown in FIG. 3 and FIG. 4, it is possible to obtain a state in which the powder is gradually compressed by the compression calculation by the DEM method, and the powder is greatly deformed by receiving pressure from the surrounding powder.

  When the powder comes into close contact with the surrounding powder and the mutual movements become integrated, the powders coalesce and cause an integrated movement. When the integration of the powders proceeds in a wide range, the DEM method that requires the movement of individual powders cannot be applied. In that case, it can be considered that the powders are integrated and close to one continuous solid (continuum). Therefore, the subsequent simulation is performed by the SPH analysis unit 72 using the SPH method. The change from the DEM method to the SPH method, that is, the transition from the discontinuous material to the continuous material is performed when the powders are completely in contact with each other.

  However, when shifting from the DEM method to the SPH method, the basic particles of the DEM method are transferred as the basic particles of the SPH method. That is, it can be said that the basic particles bp shown in FIG. 3 correspond to the basic particles in the SPH method, that is, SPH particles.

  In the SPH method, a partial differential equation representing the law of conservation of momentum and the law of conservation of energy is approximately solved by the Kernel integral method. In the elastic analysis, the Newtonian equation of motion of the elastic body is defined as the elastic motion of the SPH particle. Then, the motion of the particles is obtained with time. Newton's equation of motion is, for example, a = (1 / ρ) ∇ · σ, a: acceleration, ρ: density, and σ: Cauchy's stress tensor.

  The compression molding of the powder using the compression molding machine model 20 of FIG. 4 is performed by a constant pressure press or a constant size press. In the constant pressure press, the simulation of compression molding is terminated when the pressure between the boundary layer 21 or the boundary layer 22 and the powder model A (pressure in the Y direction) reaches a preset designated pressure. On the other hand, in the fixed-size press, the compression molding simulation is terminated when the distance between the boundary layer 21 and the boundary layer 22 (the distance in the Y direction) reaches a preset specified dimension.

  After completion of the compression molding process, the compression molding machine model 20 has a shape after compression molding as shown in FIG. 5. In the compression molding machine model 20, a plurality of powder models A are compressed and integrated, A sheet-like active material layer model 35 is formed.

  In the compression molding step, the state of the active material of the active material layer to be compression molded and the powder of the solid electrolyte is calculated by the DEM-SPH coupled analysis method. That is, the acceleration, velocity, and displacement of each basic particle in each powder are calculated over time, and the strain is calculated from them. The stress can be obtained based on the calculated strain with reference to the actually measured stress-strain characteristics as shown in FIG. Thereby, the stress distribution and strain distribution in each powder model A can be obtained.

(3) Step 202
In step 202, the contact rate calculation unit 73 of the DEM-SPH analysis unit 62 contacts the solid electrolyte powder with the active material powder after compression molding based on the state of the active material layer calculated in step 201. The state, that is, the contact rate R is calculated. The contact rate R is calculated by the above formula (A). The calculation of the contact rate R in this step may be performed together with the calculation of the acceleration, velocity, displacement, strain, and stress of each basic particle in each powder over time in step 201.

(4) Step 203
In step 203, the SPH analysis unit 72 of the DEM-SPH analysis unit 62 performs the cycle durability test process of the all solid state battery based on the state of the plurality of types of powders of the active material layer calculated in step 201, that is, Simulate the discharge process. Specifically, based on the electrode model 30 shown in FIG. 6, the charge / discharge in the cycle durability test process is expressed by the expansion / contraction of the powder model A due to heat, and after the cycle durability test, that is, after the charge / discharge. The state of multiple types of powders in the active material layer is calculated. Thereby, the acceleration, velocity, and displacement of each basic particle in each powder are calculated over time, and the strain is calculated therefrom. The stress can be obtained based on the calculated strain with reference to the actually measured stress-strain characteristics as shown in FIG.

(5) Step 204
In step 204, the contact rate calculation unit 73 of the DEM-SPH analysis unit 62 determines the solid electrolyte powder to the active material powder after charge / discharge based on the state of the negative electrode active material layer calculated in step 203. Calculate the contact rate. This step is the same as step 202. Note that the calculation of the contact rate R in this step may also be performed when the acceleration, velocity, displacement, strain, and stress of each basic particle in each powder are calculated over time in step 203.

(6) Step 205
In step 205, the destruction determination unit 74 of the DEM-SPH analysis unit 62 determines the active material and solid electrolyte after charging / discharging, that is, expanded and contracted, based on the state of the active material layer calculated in step 203. It is determined whether or not the powder is broken. That is, when a strain exceeding the breaking strain occurs in a certain basic particle, the pulverization (breaking) of the powder corresponding to the powder model is expressed by releasing the bond between the basic particle and the surrounding basic particles. . The determination of destruction in this step may be performed at the same time when the acceleration, velocity, displacement, strain, and stress of each basic particle in each powder are calculated in step 203 as time elapses.

  As described above, this simulation method makes it possible to grasp the contact state of the active material layer when the active material layer is formed by compression molding or when it is expanded / contracted by a cycle durability test.

  However, the powder breakage determination (step 205) may be performed in step 201 or between step 201 and step 203.

FIG. 12 is a flowchart showing a method of determining breakage of powder.
First, in step 300, one powder model A is selected from a plurality of powder models A to be evaluated. For example, when evaluating the negative electrode active material layer, one negative electrode active material powder model Aa is selected.

  In the subsequent step 301, one basic particle is selected from a plurality of basic particles of the selected powder model A. For example, one is selected from a plurality of basic particles of the negative electrode active material powder model Aa.

  In the subsequent step 302, it is determined whether or not the strain ε between the selected basic particles themselves or the particles adjacent to the basic particles is equal to or greater than the fracture strain εth of the material. If the strain ε is equal to or greater than the breaking strain εth, the process proceeds to step 303. If the strain ε is not equal to or greater than the breaking strain εth, the process proceeds to step 304.

  In step 303, the particle itself is deleted from the particle determined to be broken, or the bond with the adjacent neighboring basic particle is released. For example, if the strain of the selected basic particle of the negative electrode active material powder model Aa is equal to or greater than the fracture strain, the basic particle is determined to be broken, and the bond with the adjacent neighboring basic particles is released. It should be noted that if the selected basic particles of the negative electrode active material have a strain less than the fracture strain, it is determined that the fracture is not the fracture, and the bond with the adjacent neighboring basic particles is maintained.

  The above steps 301 to 303 are executed for all the basic particles of the selected powder model A (step 304). For example, it is executed for all basic particles of the negative electrode active material powder model Aa.

  Further, the above steps 300 to 304 are executed for all powder models A of the active material (step 305). For example, it is executed for all negative electrode active material powder models Aa in the negative electrode active material layer.

  As described above, in this simulation method, it is possible to evaluate and analyze by simulation from at least the compression molding of the active material layer to the cycle durability test of the all solid state battery incorporating the active material layer.

  Next, a method for manufacturing the all-solid-state battery electrode according to the present embodiment using the simulation method will be described.

  If the good contact rate of the above simulation results is regarded as the target performance, the design parameters such as the particle size ratio and fracture strain that give the target performance, and the manufacturing conditions such as the initial press load of compression molding are the setting conditions for the simulation. It can be grasped from. Therefore, a battery having the target performance can be manufactured by using design specifications and manufacturing conditions grasped from the setting conditions of the simulation for actual battery manufacturing. The manufacturing method of such an electrode for an all solid state battery is as follows.

  FIG. 13 is a flowchart showing a method for manufacturing an electrode for an all solid state battery. First, in step 400, as shown in FIG. 11, the positive electrode active material / negative electrode active material and the solid electrolyte powder stress strain characteristics under load and volume expansion characteristics during charge / discharge obtained in advance by experiments are shown. This simulation method (battery electrode simulation) is executed. Thereby, the relationship between the contact state of a plurality of types of powders and the design conditions (example: particle size ratio and fracture strain) or manufacturing conditions (example: initial press load) of the active material layer is grasped by simulation. For example, the relationship between the contact rate R of a plurality of types of powder and the initial press load of the compression molding when a plurality of types of powder is compression molded is obtained.

  In the subsequent step 401, based on the obtained relationship, the design conditions and / or manufacturing conditions of the active material layer showing a good contact state are set to the actual design conditions and / or manufacturing conditions of the active material layer. For example, the initial press load in the simulation when a good contact rate R is shown in the simulation is set to the initial press load when the electrode (active material layer) is actually compression-molded.

  In subsequent step 402, an electrode for an all-solid-state battery is manufactured based on the set design and manufacturing conditions as shown in FIG. For example, an electrode (active material layer) is manufactured by compressing and molding a plurality of types of powder with an actually set initial press load.

  By manufacturing an all-solid battery as described above, an all-solid battery having a good contact rate similar to the simulation result can be obtained.

  The simulation method can be applied in both two-dimensional analysis and three-dimensional analysis.

1. Confirmation of program certainty We confirmed the certainty of the program that implements this simulation method. Specifically, the simulation results were compared with the evaluation results (experimental results) of the prototype of the all-solid-state battery.

  FIG. 14 is a graph comparing a simulation result and an experimental result regarding the contact ratio in the active material layer after the cycle durability test of the all-solid-state battery. The horizontal axis is the particle size ratio, and the vertical axis is the contact ratio (%). The particle size ratio indicates the ratio of the particle size of the solid electrolyte powder to the particle size of the negative electrode active material or the positive electrode active material powder. The solid line is the case of the negative electrode active material layer, and the white circle indicates the simulation result and the black circle indicates the experimental result. On the other hand, a broken line is a case of a positive electrode active material layer, and a white rhombus mark shows a simulation result and a black rhombus mark shows an experimental result.

  In either case, the simulation results and the experimental results show almost the same gentle downward trend, and it can be confirmed that they are within the range with little variation, and the accuracy of the simulation program can be confirmed. It was. From the above results, it was confirmed that the simulation method qualitatively captures the contact phenomenon after completion of the all solid state battery.

2. Design study of all-solid-state battery Design study of all-solid-state battery was conducted using this simulation program.

FIG. 14 described above shows the influence of the particle size ratio on the contact rate after completion of the all-solid battery in the negative electrode active material layer and the positive electrode active material layer in comparison with the experimental result and the simulation result. However, each of r ₁ and r ₂ in the figure indicate the size ratio of the negative electrode active material layer and the positive electrode active material layer, the contact ratio at R ₁ and R ₂ each negative electrode active material layer and the positive electrode active material layer Show.

In experimental results, the particle size ratio in the anode active material layer is a maximum value R ₁ contact ratio when r _1, contact ratio when the particle size ratio is r ₂ in the positive electrode active material layer is the maximum value R ₂ I knew what to show. On the other hand, in the simulation results, as in the experimental results, the contact ratios showed the maximum when the particle size ratios were r ₁ and r ₂ . From the above results, the contact ratio can be maximized even in an actual active material layer by using, for example, the particle size ratio showing the maximum contact ratio in the simulation method.

  FIG. 15 shows the comparison between the experimental results and the simulation results on the effect of the mechanical material properties (stress-strain properties) of the active material layer and the solid electrolyte on the contact rate after the completion of the all-solid battery in the active material layer. It is a graph shown. However, this graph shows the result in the negative electrode active material layer, the horizontal axis is the fracture strain of the negative electrode active material, and the vertical axis is the contact ratio (%). Black square marks indicate experimental results, and black diamond marks indicate simulation results.

According to the experimental results, the contact rate is low (example: R ₃ ) when the fracture strain of the negative electrode active material powder is small (example: ε ₁ ). However, contact ratio him to break strain of the powder of the negative electrode active material is larger rises, when breaking strain of epsilon ₂ were found to exhibit a high value of the contact ratio is R _4.

  On the other hand, in the simulation results, as in the experimental results, the contact rate is low when the fracture strain of the negative electrode active material powder is small, and the contact rate increases as the fracture strain increases, and the maximum when the fracture strain is ε2. The result which shows a contact rate was able to be obtained. From the above results, the contact rate can be maximized even in an actual active material layer by using, for example, an active material having a fracture strain exhibiting the maximum contact rate in the simulation method.

  Therefore, when the simulation result is regarded as a target value, it is possible to determine how to set the design requirement specification by considering the direction from the target value to the direction of the design requirement specification. .

For example, considering the simulation results of FIG. 14, in order to enable maintaining the contact ratio of the positive electrode active material layer in R2 can predict that the particle size ratio of the positive electrode active material layer may be set to r ₂ . Further, when it is desired to maintain the contact ratio in the positive electrode active material layer in the range from the maximum value to 90% of the maximum value, the range of the particle size ratio obtained by reversely tracing the data of the positive electrode active material layer in FIG. It can be predicted that this should be set. In this way, in the examples of FIGS. 14 and 15, if the contact ratio of the simulation result is regarded as a target value, the particle size ratio and the fracture strain can be determined from the target value as the design request specifications.

  The method for determining the design requirement specifications from the simulation result can be applied to the determination of the manufacturing conditions.

  As an example, the initial press load at the time of compression molding that must be determined when producing an all-solid battery will be described. The compressive load is an important parameter that determines the contact rate in the all-solid battery after completion and determines the durability performance for the usage of the all-solid battery thereafter.

FIG. 16 is a table schematically showing the results of examining the change in the internal structure of the negative electrode active material layer when the all solid state battery is completed when only the initial press load is changed, by simulation. However, no cycle durability test was conducted. Each frame in the table shows a cross-sectional view of the negative electrode active material layer. The upper side of the cross-sectional view is a surface in contact with the solid electrolyte, and the lower side is a surface in contact with the negative electrode current collector layer. The respective distributions of relative density (ρ ₁₀ <ρ ₂₀ ), Mises stress (σ ₁₀ <σ ₂₀ ) and strain (ε ₁₀ <ε ₂₀ ) are shown for each case. The magnitude of the initial press load is Case 1> Case 2> Case 3> Case 4. Further, in the cross-sectional views of the respective frames, the horizontally elongated one is the negative electrode active material, and the one filling the periphery is the solid electrolyte.

  As shown in this figure, when the initial press load is very large, that is, in the case 1, compared with the other cases, (i) the powder of the negative electrode active material layer shows non-uniform deformation, and (ii) ) The distribution of the relative density in the negative electrode active material layer increases (the upper part is high), (iii) Mises stress concentration occurs on the surface in contact with the negative electrode current collector, and (iv) the surface in contact with the solid electrolyte. It turns out that extreme distortion occurs in the vicinity.

  On the other hand, as the initial press load decreases, that is, as the case number increases, (i) the deformation of the powder in the negative electrode active material layer becomes uniform, and (ii) the relative density difference in the negative electrode active material layer decreases. Thus, it was found that (iii) Mises stress concentration disappeared on the surface in contact with the negative electrode current collector layer, and (iv) extreme distortion disappeared in the vicinity of the surface in contact with the solid electrolyte.

  Therefore, by setting the initial press load in the compression molding step to be equal to or lower than the press load in case 3 of the simulation method, it is expected that an electrode having a good internal structure can be obtained even in actual manufacture.

3. Cycle Durability Test FIG. 17 is a graph comparing the simulation results and the experimental results regarding the relationship between the number of cycles and the contact ratio in the negative electrode active material layer in the cycle durability test of the all-solid battery. The horizontal axis represents the number of cycles (times), and the vertical axis represents the contact rate (%). The experimental results for the initial press load under the conditions of Case 1 in FIG. 16 are indicated by solid lines and black circles, and the simulation results are indicated by broken lines and white circles. On the other hand, as for the initial press load, the experimental result under the condition of case 3 in FIG. 16 is indicated by a solid line and a black triangle mark, and the simulation result is indicated by a broken line and a white triangle mark.

  From the comparison between the experimental results and the simulation results, the following were found. (I) The simulation result shows the same tendency of the contact ratio as the experimental result, that is, the tendency of the contact ratio to decrease as the number of cycles increases. (Ii) When the output value of the contact rate is evaluated, the case of the case 3 shows a better tendency than the case of the case 1 of the initial press load. Therefore, in carrying out the cycle durability test, it is estimated that the magnitude of the initial press load affects the contact ratio between powders.

  From the results shown in FIGS. 14 to 17, at least the specifications of the particle size ratio, material characteristics (breaking strain), and initial press load are important for designing an all-solid battery that does not cause a decrease in contact rate. It is possible to grasp that.

FIG. 18 is a table schematically showing the results of examining the change in the internal structure of the negative electrode active material layer from the completion of the all-solid battery to the cycle durability test by simulation. Each frame in the table shows a cross-sectional view of the negative electrode active material layer. The cross-sectional view is a surface in contact with the solid electrolyte, and the lower side is a surface in contact with the negative electrode current collector layer. The initial press load is the same as Case 1 in FIG. The horizontal axis shows the time when the negative electrode active material layer is pressed (compression completion), the time when internal stress relaxation is completed after the press is completed, the first cycle is completed, the third cycle is completed, the sixth cycle is completed, It shows the passage of time such as the completion of the 10th cycle, and the relative density (ρ ₁₀ <ρ ₂₀ ), Mises stress (σ ₁₀ <σ ₂₀ ), strain (ε ₁₀ <ε ₂₀ ), and breakage point relative thereto. The distribution of is shown. Further, in the cross-sectional views of each frame, the horizontally elongated shape is the negative electrode active material, the surrounding material is the solid electrolyte, and the dotted (crushed) portion is the broken portion.

  As for the relative density, it was found that the relative density distribution was substantially uniform at the completion of the relaxation of the internal stress after the press was completed, but the relative density distribution state changed greatly when the cycle durability test was performed. It was found that the Mises stress was relatively low for the negative electrode active material and relatively high for the solid electrolyte. Regarding strain, it was found that the strain distribution becomes smaller as the number of cycles increases. Regarding the fracture, it was found that as the number of cycles increased, the number of breaks increased. Since the fracture location is a non-contact location, it is predicted that the contact rate decreases as the number of fracture locations increases, that is, as the number of cycles increases.

  As described above, it can be confirmed that the present simulation method plays a very important role in the design and manufacture of an all-solid battery, and an all-solid battery having an appropriate specification according to the purpose can be manufactured.

DESCRIPTION OF SYMBOLS 1 All-solid-state battery 11 Positive electrode 12 Negative electrode 13 Solid electrolyte layer 14 Positive electrode active material layer 15 Negative electrode active material layer 16 Positive electrode collector layer 17 Negative electrode collector layer 60 Electrode simulation apparatus for all-solid-state battery 61 Model definition part 62 DEM-SPH Analysis unit 63 Storage unit 71 DEM analysis unit 72 SPH analysis unit 73 Contact rate calculation unit 74 Destruction determination unit 75 Material property data

Claims (5)

Analyzes the contact state between the plurality of types of powders in an electrode for an all solid state battery formed by compression molding a plurality of types of powders including a positive electrode active material or negative electrode active material powder and a solid electrolyte powder. An electrode simulation method for an all-solid battery,
Individually modeling each of the plurality of types of powders into a powder model that is an assembly of a finite number of elementary particles with a defined equation of motion;
When the plurality of types of powders corresponding to the plurality of types of powders are compressed using the DEM (Discrete Element Method) -SPH (Particle Method) coupled analysis method Or analyzing the contact state of the plurality of types of powders when expanding or contracting due to charge and discharge,
With
The analyzing step includes:
Based on the stress strain characteristics under load and the volume expansion characteristics at the time of charge and discharge in the plurality of types of powders, when a strain that exceeds a predetermined strain at the time of expansion or contraction due to charge and discharge occurs in the powder model, Determining that all or part of the powder corresponding to the powder model is broken,
Electrode simulation method for all solid state batteries. The analyzing step includes:
Considering expansion and contraction due to charge and discharge as expansion and contraction due to heat based on a linear expansion coefficient calculated from the volume expansion characteristic, calculating distortions of the plurality of types of powder models;
A step of determining that all or a part of the powder corresponding to the powder model is broken when the calculated strain of the plurality of types of powder models exceeds a predetermined strain with reference to the stress strain characteristics. When,
including,
The electrode simulation method for all-solid-state batteries according to claim 1. Analyzes the contact state between the plurality of types of powders in an electrode for an all solid state battery formed by compression molding a plurality of types of powders including a positive electrode active material or negative electrode active material powder and a solid electrolyte powder. An electrode simulation device for an all-solid-state battery,
A model definition unit that individually models each of the plurality of types of powders into a powder model that is an aggregate of a finite number of basic particles in which equations of motion are defined;
When the plurality of types of powders corresponding to the plurality of types of powders are compressed using the DEM (Discrete Element Method) -SPH (Particle Method) coupled analysis method Or a DEM-SPH analysis unit for analyzing the contact state of the plurality of types of powders when expanding or contracting due to charge / discharge,
With
The DEM-SPH analysis unit is
Based on the stress strain characteristics under load and the volume expansion characteristics at the time of charge and discharge in the plurality of types of powders, when a strain that exceeds a predetermined strain at the time of expansion or contraction due to charge and discharge occurs in the powder model, Including a destruction determination unit that determines that all or part of the powder corresponding to the powder model is broken,
Electrode simulation device for all solid state battery. The DEM-SPH analysis unit is
The expansion and contraction due to charge / discharge is regarded as the expansion and contraction due to heat based on the linear expansion coefficient calculated from the volume expansion characteristic, and the distortion of the multiple types of powder models is calculated,
With reference to the stress strain characteristics, when the calculated strain of the plurality of types of powder models exceeds a predetermined strain, it is determined that all or part of the powder corresponding to the powder model is broken,
The electrode simulation apparatus for all-solid-state batteries according to claim 3. An electrode for an all solid state battery in which an electrode for an all solid state battery is manufactured by placing a plurality of types of powders including a positive electrode active material or a negative electrode active material powder and a solid electrolyte powder on a substrate and compression molding the same. A manufacturing method comprising:
The electrode simulation method for an all-solid-state battery according to claim 1 or 2 is executed, and the compression molding load and the contact state of the plurality of types of powders when the plurality of types of powders are compression molded. A process of seeking a relationship;
Based on the obtained relationship, the step of setting the compression molding load when the predetermined contact state is established in the simulation method to the compression molding load in the actual production of an electrode for an all solid state battery;
A step of compression-molding the plurality of types of powders with the set load;
Comprising
Manufacturing method of electrode for all solid state battery.