JP6597172B2 - Electrode composite manufacturing method, electrode composite, and battery - Google Patents

Description

  The present invention relates to an electrode composite manufacturing method, an electrode composite, and a battery.

  A lithium battery is used as a primary battery and a secondary battery for the power source of many electric devices such as portable information devices. In a lithium battery, a positive electrode, an electrolyte layer, and a negative electrode are laminated in this order, and the electrolyte layer mediates conduction of lithium ions. In recent years, all-solid-state lithium batteries that use solid electrolytes instead of liquid electrolytes have been studied as lithium batteries that achieve both high energy density and safety. The all solid-state lithium battery is disclosed in Patent Document 1.

  According to Patent Document 1, in a lithium battery, a porous solid electrolyte is formed using a sol-gel method. In addition to lithium, lanthanum and titanium oxide compounds, aluminum compounds are used for the solid electrolyte. Furthermore, the battery active material is installed in the pores of the solid electrolyte using the sol-gel method. Lithium salt and manganese salt or cobalt salt are used as the battery active material.

  In a lithium battery, a battery active material is placed in a hole of a solid electrolyte that is a porous body, and the solid electrolyte and the battery active material are brought into contact with each other. Then, lithium ions are moved between the solid electrolyte and the battery active material.

JP 2006-260887 A

  Patent Document 1 describes that a battery active material is placed in a pore of a solid electrolyte that is a porous body using a sol-gel method. That is, an active material solution in which a battery active material is dissolved in a solvent is filled in the holes, and then heated and dried to remove the solvent. Since the solvent is removed in the pores, a film of the battery active material is formed on the surface of the solid electrolyte, but not all of the pores can be filled, and a hollow portion is generated. Since lithium ions cannot move in the hollow portion, it is necessary to reduce the number of the hollow portions as much as possible in order to increase the capacity of the battery.

  SUMMARY An advantage of some aspects of the invention is to solve at least one of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
A method for producing an electrode assembly according to this application example, wherein a first step of forming an active material assembly having communication holes, and Li _{2 + X} C _1-X B _X O on the active material assembly ₃ (X represents a real number greater than 0 and less than or equal to 1), a second step of installing a solid material, a third step of melting the solid material, and solidifying and crystallizing the solid melt. And a fourth step, wherein the melt is filled in the communication hole in the third step.

According to this application example, first, an active material aggregate having communication holes is formed in the first step. Then, in the second step, a solid material containing Li _{2 + X} C _1-X B _X O ₃ is placed on the active material aggregate. The solid is for forming a solid electrolyte. X is a substitution rate of boron B, and represents a real number exceeding 0 and 1 or less. Therefore, the solid material for forming the solid electrolyte always contains boron B, and when X is 1, Li ₃ BO ₃ is contained. Next, the solid material for forming the solid electrolyte is melted in the third step. And a molten material is filled in a communicating hole. Next, the melt is gradually cooled to solidify and crystallize. Thereby, the electrode composite body which has the solid electrolyte crystallized in the communicating hole of an active material assembly can be formed.

The solid containing Li _{2 + X} C _1-X B _X O ₃ may be heated and melted. For this reason, since there is little quantity of the substance vaporized when filling the melt filled in the communicating hole, the volume change when solidifying can be made small. Therefore, the ratio of the solid electrolyte in the communication holes can be increased, and the porosity in the communication holes can be reduced. As a result, the solid electrolyte can be installed in the communication hole of the active material assembly with high productivity, and an electrode assembly capable of constituting a battery having a relatively large capacity can be formed.

[Application Example 2]
In the method for producing an electrode assembly according to the application example, it is preferable that in the third step, the solid is heated at a temperature of 650 ° C. or higher and 900 ° C. or lower.

  According to this application example, it is preferable to heat the solid material for forming the solid electrolyte in the range of 650 degrees to 900 degrees. When the heating temperature is set to 650 ° C. or higher, the solid material for forming the solid electrolyte can be melted. Since the composition of the solid electrolyte changes when the heating temperature is set to 900 ° C. or higher, the performance as an electrolyte is lowered. Therefore, by setting the solid matter of the solid electrolyte within the above range, the solid matter of the solid electrolyte can be melted without degrading the performance as the electrolyte.

[Application Example 3]
In the method for manufacturing an electrode assembly according to the application example, _{X in the} Li _{2 + X} C _1-X B _X O ₃ is preferably 0.2 or more and 0.6 or less.

According to this application example, the range of X in Li _{2 + X} C _1-X B _X O ₃ is preferably a real number of 0.2 or more and 0.6 or less. At this time, a preferable Li conductivity of the solid electrolyte can be obtained.

[Application Example 4]
In the method for producing an electrode assembly according to the application example described above, the amount of the solid matter is preferably an amount capable of forming a layer on the active material aggregate after solidification and crystallization.

  According to this application example, the amount of the solid material for forming the solid electrolyte is preferably an amount capable of forming a layer on the active material aggregate after solidification and crystallization. As a result, a solidified and crystallized layer can be formed on the active material aggregate. Thereby, in the electrode assembly, it is possible to form a surface where only the crystallized solid electrolyte is exposed without exposing the active material aggregate. By forming the surface where only the solid electrolyte is exposed, when forming the battery, one electrode is formed on the surface where only the solid electrolyte is exposed, so that the active material aggregate is formed on both the positive electrode side and the negative electrode side. It is possible to suppress a short circuit that occurs upon contact.

[Application Example 5]
An electrode composite according to this application example, in which an active material molded body having communication holes and at least Li _{2 + X} C _1-X B _X O ₃ (X exceeds 0 and 1 formed in the communication holes) And a crystallized solid electrolyte containing the following real number):

According to this application example, the electrode assembly includes an active material assembly having communication holes. A crystallized solid electrolyte is installed in the communication hole, and the solid electrolyte contains Li _{2 + X} C _1-X B _X O ₃ . X is a substitution rate of boron B, and represents a real number exceeding 0 and 1 or less. Accordingly, boron B is necessarily included in the solid electrolyte.

[Application Example 6]
The electrode composite according to the application example, including a first layer including the active material aggregate and a second layer not including the active material aggregate, and the solid electrolyte in the first layer And the solid electrolyte in the second layer is preferably continuous.

  According to this application example, the electrode assembly includes the first layer and the second layer. The first layer has an active material assembly and a solid electrolyte. The second layer does not have an active material aggregate and has a solid electrolyte. The solid electrolyte in the first layer and the solid electrolyte in the second layer are continuous. It is possible to obtain a first layer having an active material assembly and a solid electrolyte by placing a solid material that is a material of the solid electrolyte on the active material assembly, melting the solid material, and then crystallizing the solid material. The second layer of the solid electrolyte is formed on the first layer by setting the amount of the solid material as the material of the solid electrolyte at this time to an amount exceeding the amount charged in the active material assembly. . The thus formed first layer solid electrolyte and second layer solid electrolyte have a continuous crystal structure, and can be made into an electrode composite having a preferable Li ion conductivity.

[Application Example 7]
The battery according to this application example is a battery having the electrode assembly described above, and includes a first electrode installed on the first layer side, and a second electrode installed on the second layer side. It is characterized by having.

  According to this application example, the electrode assembly is sandwiched between the first electrode and the second electrode. Thereby, the battery which can be charged and discharged when Li ion moves inside the solid electrolyte in the 1st layer and the solid electrolyte of the 2nd layer can be constituted. Moreover, the short circuit inside a battery can be prevented because the 2nd layer which does not have an active material assembly exists in a battery between a 1st electrode and a 2nd electrode.

The principal part schematic side sectional view which shows the structure of the electrode composite_body | complex concerning 1st Embodiment. The schematic perspective view which shows the structure of a lithium battery. The schematic cross section which shows the structure of a lithium battery. The schematic side view which shows the structure of a battery unit. The schematic plan view which shows the structure of a battery unit. The flowchart of the manufacturing method of a lithium battery. The schematic diagram for demonstrating the manufacturing method of a lithium battery. The schematic diagram for demonstrating the manufacturing method of a lithium battery. The schematic diagram for demonstrating the manufacturing method of a lithium battery. The schematic diagram for demonstrating the manufacturing method of a lithium battery. The schematic diagram for demonstrating the manufacturing method of a lithium battery. The schematic diagram for demonstrating the manufacturing method of a lithium battery. The schematic diagram for demonstrating the manufacturing method of a lithium battery. The schematic diagram for demonstrating the manufacturing method of a lithium battery. The schematic diagram for demonstrating the manufacturing method of a lithium battery. The schematic diagram for demonstrating the manufacturing method of a lithium battery. The graph which shows the relationship between the boron substitution rate X of a solid electrolyte, and the Li conductivity of an electrode composite. The schematic sectional side view which shows the structure of the electrode composite body concerning 2nd Embodiment.

Hereinafter, embodiments will be described with reference to the drawings.
In addition, each member in each drawing is illustrated with a different scale for each member in order to make the size recognizable on each drawing.

(First embodiment)
In the present embodiment, characteristic examples of a lithium battery having an electrode assembly and a method of manufacturing a lithium battery for manufacturing the lithium battery will be described with reference to the drawings. The method for manufacturing a lithium battery includes an electrode composite. The electrode assembly according to this embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional side view of an essential part showing the structure of an electrode assembly. As shown in FIG. 1, the electrode assembly 9 includes an active material assembly 12. The active material aggregate 12 is a porous molded body in which a plurality of active material particles 13 as a forming material are connected. A communication hole 14 is located between the active material particles 13. In the communication holes 14, the cavities between the active material particles 13 communicate with each other in a mesh shape to form a hole.

  A crystalline solid electrolyte 15 is installed in the communication hole 14. Since the communication holes 14 are arranged in a mesh shape, the active material assembly 12 and the solid electrolyte 15 are in contact with each other over a wide area. For this reason, lithium ions easily move between the active material aggregate 12 and the solid electrolyte 15. The solid electrolyte 15 fills the communication holes 14 between the active material aggregates 12. Accordingly, the solid electrolyte 15 is a continuous network structure. Lithium ions move in the solid electrolyte 15. Since the solid electrolyte 15 is filled in the communication holes 14 in a mesh shape, a path through which lithium ions can move to every corner of the active material assembly 12 is secured. For this reason, lithium ions are easy to move.

A lithium double oxide can be used as a material for forming the active material particles 13. Incidentally, an oxide which always contains lithium and contains two or more kinds of metal ions and which does not contain oxo acid ions is called a lithium double oxide. Examples of the lithium double oxide include LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , Li ₂ Mn ₂ O ₃ , LiFePO ₄ , Li ₂ FeP ₂ O ₇ , LiMnPO ₄ , LiFeBO ₃ , Li ₃ V ₂ (PO ₄ ) ₃ , Li ₂ CuO ₂ , LiFeF ₃ , Li ₂ FeSiO ₄ , Li ₂ MnSiO _{4 and the} like.

In addition, solid solutions in which some atoms in the crystal of these lithium double oxides are substituted with other transition metals, typical metals, alkali metals, alkali rare earths, lanthanoids, chalcogenides, halogens, etc. are also included in lithium double oxides. These solid solutions can also be used as the positive electrode active material. In the present embodiment, for example, LiCoO ₂ is used for the active material particles 13.

  The average particle size of the active material particles 13 is preferably 300 nm to 5 μm, more preferably 450 nm to 3 μm, and further preferably 500 nm to 1 μm. When the active material particles 13 having this average particle diameter are used, the ratio of the communication holes 14 included in the active material aggregate 12 can be set within a preferable range. Thereby, since the surface area of the active material assembly 12 can be relatively increased, the contact area between the active material assembly 12 and the solid electrolyte 15 can be increased.

Li _{2 + X} C _1-X B _X O ₃ is used as the material of the solid electrolyte 15. X is a substitution rate of boron B, and represents a real number exceeding 0 and 1 or less. Therefore, Li ₂ CO ₃ when X is 0 is not included in the solid matter of the solid electrolyte, and Li ₃ BO ₃ when X is 1 is included. The solid electrolyte 15 is crystalline.

  Next, the lithium battery will be described with reference to FIGS. FIG. 2 is a schematic perspective view showing the outer shape of the lithium battery. As shown in FIG. 2, a lithium battery 1 as a battery includes a bottomed cylindrical container portion 2 and a lid portion 3. One of the container part 2 and the lid part 3 is a positive electrode and the other is a negative electrode. The lithium battery 1 is an all-solid-state secondary battery capable of storing electricity, but may be used as a primary battery. An electrode assembly 9 is used inside the lithium battery 1.

  FIG. 3 is a schematic cross-sectional view showing the structure of the lithium battery 1. As shown in FIG. 3, four battery units 4 as disk-shaped batteries are stacked in the container portion 2. The battery unit 4 is stacked in a cylindrical shape. An electrode composite 9 is used for each battery unit 4. The number of each battery unit 4 installed in one lithium battery 1 is not particularly limited. One to three or five or more may be used. The battery unit 4 is used between about 2.8v and about 4.2v. By combining the connections of the plurality of battery units 4 in parallel connection and series connection, the voltage value required for the lithium battery 1 can be adjusted.

  A cylindrical first insulating portion 5 is provided around the stacked battery units 4. The lid unit 3 is installed on the upper side of the battery unit 4 and the first insulating unit 5 in the drawing, and the second insulating unit 6 is installed on the outer peripheral side of the lid unit 3 and the side surface side of the first insulating unit 5. The second insulating portion 6 is located between the container portion 2 and the lid portion 3 and is also located between the container portion 2 and the first insulating portion 5.

  The first insulating portion 5 fixes the battery unit 4 so that the battery unit 4 does not move in the left-right direction in the drawing. Further, the first insulating part 5 insulates the side surface of the battery unit 4 from electrical connection with the container part 2. The second insulating part 6 insulates the container part 2 and the lid part 3. The material of the container part 2 and the lid part 3 is not particularly limited as long as it has conductivity and rigidity. However, a metal having corrosion resistance or a metal subjected to a corrosion-resistant surface treatment on the surface can be used. In this embodiment, for example, stainless steel is used as the material for the container 2 and the lid 3. The material of the first insulating portion 5 and the second insulating portion 6 is not particularly limited as long as it has insulating properties, but it is preferable to use a resin material because it is easy to process. In the present embodiment, for example, an acrylic resin is used as the material of the first insulating portion 5 and the second insulating portion 6.

  FIG. 4 is a schematic side view showing the structure of the battery unit. As shown in FIG. 4, the battery unit 4 includes a lower electrode 7 as a first electrode. On the lower electrode 7, a carbon sheet 8, an electrode composite 9 as a first layer, a separation membrane 10 as a second layer, and an upper electrode 11 as a second electrode are stacked in this order. Although the thickness of each part is not particularly limited, in this embodiment, for example, the lower electrode 7 is about 100 μm, the carbon sheet 8 is about 100 μm, the electrode composite 9 is about 300 μm, the separation membrane 10 is about 2 μm, and the upper electrode 11 is About 2 μm.

  The lower electrode 7 is a positive electrode and functions as a substrate for maintaining the structure. Examples of the material of the lower electrode 7 include one metal selected from the group consisting of copper, magnesium, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, indium, gold, platinum, silver, and palladium, An alloy containing two or more metals selected from the group can be used. In the present embodiment, for example, copper is used as the material of the lower electrode 7. The carbon sheet 8 is a carbon film that allows current to flow efficiently between the lower electrode 7 and the electrode composite 9.

  The separation membrane 10 is a membrane that prevents the electrode assembly 9 and the upper electrode 11 from being short-circuited, and is a membrane composed of LBO (trilithium borate), LCBO (lithium carbon borate), or the like. In the present embodiment, for example, LCBO is used for the separation membrane 10. The upper electrode 11 is a negative electrode, and a lithium film was used.

  When the lithium battery 1 is charged, lithium ions move from the active material assembly 12 of the electrode assembly 9 to the upper electrode 11 in the solid electrolyte 15. The upper electrode 11 is a negative electrode of a lithium film. When discharging, in the solid electrolyte 15, lithium ions move from the upper electrode 11 to the active material assembly 12 of the electrode assembly 9.

  FIG. 5 is a schematic plan view showing the structure of the battery unit. As shown in FIG. 5, the planar shape of the battery unit 4 is circular. In conformity with this, in the present embodiment, the lower electrode 7, the carbon sheet 8, and the electrode assembly 9 are also in a disk shape. Although the diameter of the battery unit 4 is not specifically limited, In this embodiment, it is set to 10 mm-20 mm, for example.

  Next, a method for manufacturing the above-described lithium battery 1 will be described with reference to FIGS. FIG. 6 is a flowchart of a method for manufacturing a lithium battery, and FIGS. 7 to 16 are schematic diagrams for explaining a method for manufacturing a lithium battery. In the flowchart of FIG. 6, step S1 is an active material sheet forming step. This step is a step in which the active material particles 13 and the binder are mixed and processed into a sheet shape. Next, the process proceeds to step S2. Step S2 is an outer shape forming process. This step is a step of forming the outer shape of the intermediate product of the active material assembly 12. An intermediate product refers to a product on the way to completion. Next, the process proceeds to step S3. Step S3 is an active material firing step. This step is a step of removing the binder from the intermediate product of the active material aggregate 12 and sintering the active material particles 13. Next, the process proceeds to step S4.

  Step S4 is an electrolyte supply process. This step is a step of supplying the material of the solid electrolyte 15 onto the active material aggregate 12. Next, the process proceeds to step S5. Step S5 is a filling process. This step is a step of heating the material of the solid electrolyte 15 to fill the communication holes 14 of the active material assembly 12. Next, the process proceeds to step S6. Step S6 is a slow cooling process. This step is a step of slowly cooling the active material assembly 12 filled with the material of the solid electrolyte 15. In step S6, the electrode assembly 9 is completed. Steps S <b> 1 to S <b> 6 show a method for manufacturing the electrode assembly 9. Next, the process proceeds to step S7.

  Step S7 is a separation layer installation process. This step is a step of installing the separation membrane 10 on one surface of the electrode assembly 9. Next, the process proceeds to step S8. Step S8 is an upper electrode installation step. This step is a step in which the upper electrode 11 is placed over the separation membrane 10. Next, the process proceeds to step S9. Step S9 is a lower electrode installation step. This step is a step of installing the carbon sheet 8 and the lower electrode 7 on the other surface of the electrode assembly 9. In step S9, the battery unit 4 is completed. Next, the process proceeds to step S10. Step S10 is a packaging process. This step is a step of installing the battery unit 4, the first insulating portion 5, the second insulating portion 6, and the lid portion 3 in the container portion 2, and fixing the lid portion 3 with the container portion 2. The lithium battery 1 is completed through the above steps. Steps S1 to S3 correspond to the first step, and step S4 corresponds to the second step. Step S5 corresponds to the third step. Step S6 corresponds to the fourth step.

  Next, the manufacturing method will be described in detail with reference to FIGS. 7 to 17 in association with the steps shown in FIG.

  FIG. 7 is a diagram corresponding to the active material sheet forming step of step S1. In step S1, the raw material powder of the active material particles 13 is mixed with a binder or the like to form a paste. Then, it is stretched into a thin sheet on a plastic carrier film and dried. The dried sheet is called a green sheet.

  The binder is not particularly limited as long as the raw material powder of the active material particles 13 can be bonded and removed by heating. Examples of the binder include a cellulose-based binder, an acrylic-based binder, a polyvinyl alcohol-based binder, a polyvinyl butyral-based binder, and the like, in addition to polycarbonate. One or more of these can be used in combination.

  Moreover, you may use a solvent in an active material sheet formation process. Although it does not specifically limit as a solvent used at the said process, For example, aprotic solvents, such as butanol, ethanol, propanol, methyl isobutyl ketone, toluene, xylene, can be used. Thereby, deterioration of the active material particles 13 due to contact with the solvent can be reduced. One or more of these solvents can be used in combination. In this embodiment, for example, the binder is used by adding dioxane to polycarbonate.

  The binder may contain an organic polymer compound such as polyvinylidene fluoride or polyvinyl alcohol. In order to adjust the size of the communication hole 14, a particulate pore former may be added to the binder. Although the average particle diameter of the pore former is not particularly limited, in the present embodiment, for example, it is set to 0.5 μm to 10 μm. In addition, particles made of a material having deliquescent properties such as polyacrylic acid may be added to the binder. Water generated around the particles when the particles are deliquescent joins the particulate lithium double oxide. It functions as a binder that joins particulate lithium complex oxide.

  Next, as shown in FIG. 7, a green sheet 17 is installed in the rolling mill 16. The rolling mill 16 includes a first cylinder 16a and a second cylinder 16b. The central axis of the first cylinder 16a and the central axis of the second cylinder 16b are connected to a rotating shaft of a rotating mechanism (not shown). The rotation mechanism includes a motor, a speed reducer, a control device that controls the rotation speed, and the like. The first cylinder 16a is rotated counterclockwise by the rotation mechanism, and the second cylinder 16b is rotated clockwise. The distance between the outer periphery of the first cylinder 16a and the outer periphery of the second cylinder 16b is adjusted to a predetermined distance.

  A green sheet 17 is sandwiched between the first cylinder 16a and the second cylinder 16b from the right side in the figure. As the first cylinder 16a and the second cylinder 16b rotate, the green sheet 17 is rolled to a predetermined thickness and discharged to the left side in the figure. The surfaces of the first cylinder 16a and the second cylinder 16b are processed into mirror surfaces. And since the surface of the 1st cylinder 16a and the 2nd cylinder 16b is transcribe | transferred to the rolled green sheet 17, the surface of the green sheet 17 becomes a flat surface.

  FIG. 8 is a diagram corresponding to the outer shape forming process of step S2. As shown in FIG. 8, in step S <b> 2, the green sheet 17 is installed in the press machine 18. The press machine 18 includes a die plate 18a and a punch 18b. The die plate 18a is provided with a circular hole 18c, and the punch 18b has a cylindrical shape. The diameter of the hole 18c is substantially the same as the diameter of the punch 18b.

  The operator installs the green sheet 17 on the die plate 18a. Then, the press machine 18 moves the punch 18b in the vertical direction in the figure. At this time, the green sheet 17 is pushed out by the punch 18b and passes through the hole 18c of the die plate 18a. And the active material disk 21 in which the green sheet 17 was formed in disk shape is formed. The pressing machine 18 continuously forms the active material disk 21 by moving the green sheet 17 to the left in the figure and moving the punch 18b up and down.

FIG. 9 is a diagram corresponding to the active material firing step of step S3. In the active material firing step of step S3, first, a degreasing step of removing the binder from the active material disc 21 is performed. The active material disk 21 is placed in a reducing gas and heated in a temperature atmosphere of about 150 to 500 ° C. for about 0.1 to 20 hours. Thereby, the binder can be removed from the active material disk 21. Next, the active material particles 13 are heated to a temperature that does not melt. Since the melting point of LiCoO ₂ is 1100 ° C., it is heated to a temperature of less than 1100 ° C. Although the heating temperature and the heating time are not particularly limited, in this embodiment, for example, the heating temperature is set to 900 to 950 ° C., and the heating time is set to about 4 to 14 hours. As a result, as shown in FIG. 9, the active material particles 13 are combined to complete the active material aggregate 12. A communication hole 14 is provided between the active material particles 13. The communication hole 14 is a cavity formed by removing the binder, and the cavity is connected to form the communication hole 14. Since many active holes 14 are provided in the active material assembly 12, it is also called a porous body or a porous body.

  FIG. 10 is a diagram corresponding to the electrolyte supply step of step S4. As shown in FIG. 10, in step S <b> 4, a solid electrolyte 22 as a solid material that is a material of the solid electrolyte 15 is supplied on the active material assembly 12 so as to be in contact with the active material assembly 12. The solid electrolyte 22 is a material of the solid electrolyte 15 and is a solid substance of the solid electrolyte 15. The solid electrolyte 22 is not particularly limited, and can be supplied in various forms such as powder, sheet, and block. In the present embodiment, for example, the solid electrolyte 22 is supplied in a powder state.

When X, which is the substitution rate of boron B, is a real number greater than 0 and equal to or less than 1, the solid electrolyte 22 contains Li _{2 + X} C _1-X B _X O ₃ . X may be a real number exceeding 0. For example, when X is 0.1, Li _{2 + X} C _1-X B _X O ₃ is Li _2.1 C _0.9 B _0.1 O ₃ , and X is 1 Sometimes Li _{2 + X} C _1-X B _X O ₃ is Li ₃ BO ₃ .

  11 and 12 are diagrams corresponding to the filling step of step S5. As shown in FIG. 11, in step S <b> 5, the active material aggregate 12 is mounted on the mounting table 23. The mounting table 23 is heat resistant and can withstand high temperatures of 1000 degrees or more. A ceramic such as alumina or silicon carbide can be used as the material of the mounting table 23.

  Next, the active material assembly 12 and the solid electrolyte 22 are heated. An active material assembly 12 in which a solid electrolyte 22 is installed is put into a preheated electric furnace. In the electric furnace, the solid electrolyte 22 is heated and melted. A material obtained by melting the solid electrolyte 22 is referred to as a melt. As shown in FIG. 12, since gravity acts on the melt, the melt is filled in the communication holes 14 of the active material assembly 12. Furthermore, capillary action acts and the melt is easily filled into the communication hole 14. The mounting table 23 may be a porous structure such as a porous ceramic. Then, the solid electrolyte 22 overflowed from the active material assembly 12 may be adsorbed on the mounting table 23.

  When the solid electrolyte 22 is filled, it is heated and melted without using a solvent to form a liquid. Since the amount of the material that is vaporized when the melt of the solid electrolyte 22 filled in the communication hole 14 is solidified, the volume change of the solid electrolyte 22 can be reduced. Accordingly, it is possible to reduce the porosity in the communication hole 14 after the melt of the solid electrolyte 22 is solidified.

  When the solid electrolyte 22 is melted, the solid electrolyte 22 is heated in the range of 650 degrees to 900 degrees. By setting the heating temperature to 650 ° C. or higher, the solid matter of the solid electrolyte 22 can be melted. When the heating temperature is set to 900 ° C. or higher, the composition of the solid electrolyte 22 changes, so that the performance as an electrolyte is lowered. Therefore, by setting the heating temperature of the solid electrolyte 22 in the range of 650 ° C. or more and 900 ° C. or less, the solid electrolyte 22 can be melted without deteriorating the performance as the electrolyte.

Furthermore, the heating temperature when melting the solid electrolyte 22 is preferably 700 ° C. or higher and 850 ° C. or lower. The heating temperature of the solid electrolyte 22 is preferably changed according to the composition of the solid electrolyte 22. In order to dissolve the solid electrolyte 22, it is preferable to change the heating temperature because the melting point changes depending on the value of the boron substitution rate X in Li _{2 + X} C _1-X B _X O ₃ .

  The heating time of the solid electrolyte 22 is not limited because it varies depending on the amount of the solid electrolyte 22. Since the composition of the solid electrolyte 22 changes when the heating time is long, it is preferable that the heating time is short. The heating time when the solid electrolyte 22 is 20 mg is preferably 4 minutes or more and 6 minutes or less. In this embodiment, for example, the heating time when the solid electrolyte 22 is 20 mg is set to 5 minutes.

  In the slow cooling step of step S6, the active material assembly 12 filled with the solid electrolyte 22 is slowly cooled. Thereby, the melt of the solid electrolyte 22 is solidified and crystallized. When the atmospheric temperature during slow cooling is high, the crystal grain size becomes large, and when the atmospheric temperature is low, the crystal grain size becomes small. The crystal grain size can be controlled by adjusting the atmospheric temperature. The melt of the solid electrolyte 22 is solidified to become the solid electrolyte 15, and the electrode assembly 9 is completed. Note that both surfaces of the electrode composite 9 may be polished and flattened. The contact resistance with the electrode can be lowered.

  FIG. 13 is a diagram corresponding to the separation layer installation step of step S7. As shown in FIG. 13, in step S <b> 7, the separation membrane 10 is installed on the active material aggregate 12. The separation membrane 10 is an LCBO membrane. The film formation method of the separation film 10 is not particularly limited, and a liquid phase film formation method such as a coating method or a spray method can be used in addition to a vapor phase film formation method such as a sputtering method or a vacuum evaporation method. In the present embodiment, for example, the separation film 10 is formed using a sputtering method. A configuration in which the separation membrane 10 is installed on the electrode assembly 9 is referred to as an electrode assembly 25 with a separation membrane.

  FIG. 14 is a diagram corresponding to the upper electrode installation step in step S8. As shown in FIG. 14, the upper electrode 11 is installed on the separation membrane 10 in step S8. The upper electrode 11 is a lithium film. A method for forming the upper electrode 11 can be the same as the method for forming the separation film 10. The method for forming the upper electrode 11 is not particularly limited, but in the present embodiment, for example, the upper electrode 11 is formed using a vacuum evaporation method.

  FIG. 15 is a diagram corresponding to the lower electrode installation step in step S9. As shown in FIG. 15, in step S <b> 9, the carbon sheet 8 is installed on the lower electrode 7. The lower electrode 7 and the carbon sheet 8 may be in contact with each other without being bonded. Furthermore, the electrode composite 9 is placed on the carbon sheet 8 in an overlapping manner. The carbon sheet 8 and the electrode assembly 9 may be in contact with each other without being bonded. The battery unit 4 is completed through the above steps.

  FIG. 16 is a diagram corresponding to the packaging process in step S10. As shown in FIG. 16, in step S10, four battery units 4 are stacked. When the battery units 4 are coupled in parallel, an insulating sheet is installed between the battery units 4 and wirings for connecting the battery units 4 are installed. Next, the battery unit 4 is disposed in the central hole of the first insulating portion 5. Further, the lid 3 is installed on the battery unit 4. Then, the lid 3 is brought into contact with the battery unit 4.

  Next, the second insulating portion 6 is inserted along the outer periphery of the lid portion 3 and the side surface of the first insulating portion 5. Subsequently, the lid portion 3, the battery unit 4, and the first insulating portion 5 in which the second insulating portion 6 is inserted are installed in the container portion 2. Next, the open end of the container part 2 is bent toward the lid part 3 side, and is tightly adhered. Thereby, since each battery unit 4 is pressurized, the lower electrode 7, the carbon sheet 8, and the electrode assembly 9 are electrically connected. The lithium battery 1 is completed through the above steps.

FIG. 17 is a graph showing the relationship between the boron substitution rate X of the solid electrolyte and the Li conductivity of the electrode assembly. In FIG. 17, the horizontal axis represents the boron substitution rate X of the solid electrolyte 22 installed in the electrolyte supply process of step S4. The boron substitution rate X is X in Li _{2 + X} C _1-X B _X O ₃ . A vertical axis | shaft shows Li conductivity of the electrode composite 9 completed through the slow cooling process of step S6. The Li conductivity transition line 24 indicates the Li conductivity with respect to the boron substitution rate X.

  As indicated by the Li conductivity transition line 24, when the boron substitution rate X is lower than 0.2, the change in Li conductivity with respect to the boron substitution rate X is large. The Li conductivity is lower than when the boron substitution rate X is 0.2. Since the performance of the lithium battery 1 is better when the Li conductivity is higher, it is better not to set the boron substitution rate X to less than 0.2.

  Similarly, when the boron substitution rate X is greater than 0.6, the change in Li conductivity with respect to the boron substitution rate X is large. The Li conductivity is lower than when the boron substitution rate X is 0.6. Since the performance of the lithium battery 1 is better when the Li conductivity is higher, the boron substitution rate X should not be set to a value exceeding 0.6. Therefore, the boron substitution rate X is preferably set to a real number of 0.2 to 0.6. At this time, even if the boron substitution rate X varies, the state where the Li conductivity is high can be maintained. A battery having a high Li conductivity can be charged in a shorter time than a battery having a low Li conductivity. And since internal resistance becomes low at the time of discharge, a voltage drop can be made low.

As described above, this embodiment has the following effects.
(1) According to this embodiment, when Li _{2 + X} C _1-X B _X O ₃ is used as the solid electrolyte 15, it is heated and melted without using a solvent to form a liquid. For this reason, since the quantity of the substance vaporized when the melt of the solid electrolyte 22 filled in the communication hole 14 is solidified, the change in the volume of the solid electrolyte 22 can be reduced. Therefore, the porosity of the communication hole 14 after solidification can be reduced. Therefore, since the melt can be filled into the communication holes 14 in one step, the solid electrolyte 15 can be installed in the communication holes 14 of the active material assembly 12 with high productivity.

  (2) According to this embodiment, the solid electrolyte 22 is heated in the range of 650 degrees or more and 900 degrees or less. When the heating temperature is set to 650 ° C. or higher, the solid electrolyte 22 can be melted. When the heating temperature is set to 900 ° C. or higher, the composition of the solid electrolyte 22 changes, so that the performance as an electrolyte is lowered. Therefore, by setting the heating temperature of the solid electrolyte 22 in the above range, the solid matter of the solid electrolyte 22 can be melted without degrading the performance as the electrolyte.

(3) According to the present embodiment, the range of X in Li _{2 + X} C _1-X B _X O ₃ is a real number of 0.2 or more and 0.6 or less. At this time, even if the boron substitution rate X varies, the Li conductivity of the solid electrolyte can be stably maintained at a high level.

  (4) According to this embodiment, in the battery unit 4, the electrode assembly 9 is sandwiched between the lower electrode 7 and the upper electrode 11. Since the electrode assembly 9 is an electrode assembly 9 that can be manufactured with high productivity, the battery unit 4 can be a battery including the electrode assembly 9 that can be manufactured with high productivity.

  (5) According to the present embodiment, the lithium battery 1 includes four battery units 4. The battery unit 4 includes an electrode assembly 9 that can be manufactured with high productivity. Therefore, the lithium battery 1 of the present embodiment can be a battery including the electrode assembly 9 that can be manufactured with high productivity.

(Second Embodiment)
Next, an embodiment of an electrode assembly embodying the present invention will be described with reference to a schematic side sectional view showing the structure of the electrode assembly of FIG. This embodiment is different from the first embodiment in that the separation membrane 10 shown in FIG. 13 is made of the same material as the solid electrolyte 15 and is continuous. Note that description of the same points as in the first embodiment is omitted.

  That is, in this embodiment, as shown in FIG. 18, the electrode composite 27 with a separation membrane as an electrode composite is composed of a layer of the electrode composite 9 as a first layer and a separation membrane 28 as a second layer. The solid electrolyte 15 in the electrode assembly 9 and the solid electrolyte in the separation membrane 28 are continuous. The solid electrolyte 15 and the separation membrane 28 thus formed have a continuous crystal structure, and can be made into an electrode assembly 27 with a separation membrane having a preferable Li ion conductivity.

  In the first embodiment, the solid electrolyte 15 is filled in the communication holes 14 of the active material particles 13 in steps S3 to S5. Next, the separation membrane 10 was installed in step S7. In step S4, the amount of the solid electrolyte 22 installed on the active material assembly 12 is set to an amount capable of forming the separation membrane 10 on the active material assembly 12 after solidification and crystallization. Thereby, the separation membrane 28 is formed on the active material aggregate 12 in the slow cooling step of Step S6. In this embodiment, step S7 is omitted, and step S8 is performed after step S6. Therefore, the electrode assembly 9 in which the separation membrane 28 is installed can be manufactured with a small number of steps. In this embodiment, Steps S1 to S6 are the electrode assembly manufacturing method.

  The active material assembly 12 in the electrode assembly 9 is filled with the material of the solid electrolyte 15, and then the solid electrolyte 22 is placed on the electrode assembly 9. In this method, the electrode assembly 9 and the separation membrane 28 can be continuously installed. Therefore, the electrode assembly 27 with a separation membrane can be the electrode assembly 27 with a separation membrane having a structure capable of producing the electrode assembly 9 and the separation membrane 28 with high productivity.

Note that the present embodiment is not limited to the above-described embodiment, and various changes and improvements can be added by those having ordinary knowledge in the art within the technical idea of the present invention.
(Modification 1)
In the embodiment, the active material disk 21 is formed from the green sheet 17. The active material disk 21 may be molded by putting a material into a mold and pressing it.

(Modification 2)
In the said embodiment, the solid electrolyte 22 was heated using the electric furnace in the filling process of step S5. The solid electrolyte 22 may be heated by other methods. For example, you may irradiate a laser beam and a high frequency electromagnetic wave. Alternatively, the solid electrolyte 22 may be melted and dropped onto the active material assembly 12.

(Modification 3)
In the embodiment, the electrode assembly 9 is formed by filling the communication holes 14 of the active material particles 13 with the solid electrolyte 15. Furthermore, the state in which the separation membrane 10 is installed may be the electrode assembly 25 with a separation membrane as the electrode assembly shown in FIG.

(Modification 4)
In the above embodiment, the separation membrane 10 is installed on the electrode assembly 9 in the battery unit 4 of the lithium battery 1. A battery unit in which the electrode assembly 25 with a separation membrane shown in Modification 3 is sandwiched between the upper electrode 11 and the lower electrode 7 may be used. Further, this battery unit may be used as a lithium battery. Furthermore, the lithium battery can be manufactured with high productivity.

  DESCRIPTION OF SYMBOLS 1 ... Lithium battery as a battery, 4 ... Battery unit as a battery, 7 ... Lower electrode as 1st electrode, 9 ... Electrode complex as 1st layer, 10 ... Separation membrane as 2nd layer, 11 ... upper electrode as second electrode, 12 ... active material aggregate, 13 ... active material particles, 14 ... communication hole, 15 ... solid electrolyte, 22 ... solid electrolyte as solid, 25, 27 ... as electrode composite Electrode assembly with a separation membrane, 28... And a separation membrane as a second layer.

Claims (4)

A first step of forming an active material assembly having communication holes;
A second step of installing a solid material containing Li _{2 + X} C _1-X B _X O ₃ (X represents a real number of more than 0 and 1 or less) on the active material aggregate;
A third step of melting the solid,
A fourth step of solidifying and crystallizing the melt of the solid matter,
The method for producing an electrode assembly, wherein the melt is filled in the communication hole in the third step.   The method for producing an electrode assembly according to claim 1, wherein in the third step, the solid is heated at a temperature of 650 ° C or higher and 900 ° C or lower. _3. The method for producing an electrode composite according to claim 1, wherein _{X in the} Li _{2 + X} C _1-X B _X O ₃ is 0.2 or more and 0.6 or less. 4. The electrode composite according to claim 1, wherein the amount of the solid matter is an amount capable of forming a layer on the active material aggregate after solidifying and crystallizing. 5. Body manufacturing method.

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