JP2021140892A - Manufacturing method of all-solid battery - Google Patents

Abstract

To provide a manufacturing method of an all-solid-state battery capable of appropriately stacking a plurality of battery units.SOLUTION: A manufacturing method of an all-solid-state battery includes a battery unit manufacturing step (S1), a shape regulation step (S2), and a laminating step (S4). In the battery unit manufacturing step, a plate-shaped battery unit is manufactured by undergoing a pressing step of pressing a laminate including at least one each of a positive electrode active material layer, a solid electrolyte, and a negative electrode active material layer in the thickness direction. In the shape regulation step, the battery unit is restricted to a predetermined curved shape by pressing the battery unit manufactured in the battery unit manufacturing step in the thickness direction in a state of being heated to temperature equal to or higher than temperature at which the battery unit softens and deforms. In the laminating step, the plurality of battery units regulated to have the same curved shape are laminated.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a method for manufacturing an all-solid-state battery.

The secondary battery is widely used as a portable power source for personal computers and mobile terminals, or as a vehicle drive power source for EVs (electric vehicles), HVs (hybrid vehicles), PHVs (plug-in hybrid vehicles), and the like. As an example of a secondary battery, the development of an all-solid-state battery using a solid electrolyte instead of a liquid electrolyte is underway. For example, in the method for manufacturing an all-solid-state battery described in Patent Document 1, a plurality of layers are laminated so that a solid electrolyte layer is sandwiched between a layer containing a negative electrode active material and a layer containing a positive electrode active material. Then, a laminated body is obtained. After that, the laminate is heat-pressed.

Japanese Unexamined Patent Publication No. 2015-8073

An all-solid-state battery may be manufactured by laminating a plurality of battery units after producing a flat plate-shaped battery unit containing at least one positive electrode active material layer, a solid electrolyte, and a negative electrode active material layer. .. Here, the surface state and flatness of each of the plurality of battery units are likely to vary. Therefore, when a plurality of battery units are stacked, the positional relationship between adjacent battery units may shift, resulting in deterioration of battery performance or the like. On the other hand, if a jig or the like is brought into contact with the end of the battery unit in order to suppress the misalignment of the plurality of stacked battery units, the end of the low-strength battery unit may be damaged. Therefore, with the conventional technique, it has been difficult to properly stack a plurality of battery units.

A typical object of the present invention is to provide a method for manufacturing an all-solid-state battery capable of appropriately stacking a plurality of battery units.

One aspect of the method for manufacturing an all-solid-state battery disclosed herein goes through a pressing step of pressing a laminate containing at least one each of a positive electrode active material layer, a solid electrolyte, and a negative electrode active material layer in the thickness direction. By doing so, the battery unit manufacturing step of manufacturing the plate-shaped battery unit and the battery unit manufactured in the battery unit manufacturing step are pressed in the thickness direction in a state of being heated to a temperature equal to or higher than the softening and deforming temperature. A shape regulating step of restricting the battery unit to a predetermined curved shape, and a laminating step of laminating a plurality of the battery units regulated to the same curved shape by the shape regulating step are included.

According to the manufacturing method in the present disclosure, a plurality of battery units regulated to have the same curved shape are laminated. Therefore, the positional relationship between the adjacent battery units is less likely to shift as compared with the case where a plurality of flat battery units are stacked. Further, in the shape regulation step in the present embodiment, the shape of the battery unit is restricted to a curved shape at a temperature equal to or higher than the temperature at which the battery unit softens and deforms. Therefore, unlike the case where the shape is regulated at a temperature lower than the temperature at which the battery unit is softened and deformed, the battery unit is less likely to be damaged during the shape regulating process. Therefore, a plurality of battery units are appropriately stacked.

In the shape regulation step, the shape of the battery unit may be restricted to a curved shape having a radius of curvature R ≧ 50 mm. In this case, since the amount of curvature of each battery unit is small, even if the plurality of stacked battery units are flattened, the battery units are unlikely to be damaged. Therefore, it becomes easy to flatten and use a plurality of battery units.

When the pressure in the press process in the battery unit manufacturing process is P1 and the pressure in the press process in the shape regulation process is P2, P2 ≦ P1 may be satisfied. The pressure P1 in the press (hereinafter referred to as “high pressure press”) in the battery unit manufacturing process is set so that the powder in the laminate has an appropriate density. Therefore, by setting P2 ≦ P1, the battery unit is defined to have a predetermined curved shape in a state where the change in the structure of the electrodes in the battery unit is suppressed.

The pressure P2 may be 0.0005 MPa ≦ P2 ≦ 1500 MPa. By setting the pressure P2 to 1500 MPa or less, changes in the structure of the electrodes in the battery unit are appropriately suppressed. Further, by setting the pressure P2 to 0.0005 MPa or more, the shape of the battery unit is appropriately defined as a curved shape.

A cooling step of heating and cooling the shape-regulated battery unit while the shape is regulated in the shape-regulating step may be further performed. In this case, the springback phenomenon caused by the release of the shape regulation while the battery unit is heated is less likely to occur. Therefore, the shape of each battery unit is more appropriately regulated.

It is sectional drawing of the flat plate-shaped battery unit 1. FIG. It is a flowchart which shows an example of the manufacturing method of an all-solid-state battery. It is explanatory drawing for demonstrating the shape regulation process and the cooling process. It is explanatory drawing for demonstrating the laminating process.

Hereinafter, one of the typical embodiments in the present disclosure will be described in detail with reference to the drawings. Matters other than those specifically mentioned in the present specification and necessary for implementation (for example, the configuration of an all-solid-state battery) can be grasped as design matters of a person skilled in the art based on the prior art in the art. The present invention can be carried out based on the contents disclosed in the present specification and common general technical knowledge in the art. In the following drawings, members / parts having the same action are described with the same reference numerals. Further, the dimensional relations (length, width, thickness, etc.) in each drawing do not reflect the actual dimensional relations.

First, a schematic configuration of an all-solid-state lithium-ion secondary battery (hereinafter, may be simply referred to as an “all-solid-state battery”), which is an example of an all-solid-state battery manufactured by the manufacturing method exemplified in the present disclosure, will be described. However, the all-solid-state battery to which the manufacturing method in the present disclosure is applied is not limited to the all-solid-state lithium ion secondary battery. That is, the all-solid-state battery may be one in which a metal ion other than lithium ion is used as an electric carrier, for example, a sodium ion secondary battery, a magnesium ion secondary battery, or the like.

The battery unit 1 constituting the all-solid-state battery will be described with reference to FIG. The battery unit 1 illustrated in FIG. 1 has a flat plate shape before being manufactured by a battery unit manufacturing step (see S1 and FIG. 2) described later and being restricted to a curved shape by a shape regulating step (see S2 and FIG. 2). Battery unit 1. The all-solid-state battery in the present disclosure is manufactured by stacking a plurality of battery units 1 regulated in a curved shape. The battery unit 1 illustrated in FIG. 1 includes a first current collector 11, a first active material layer 21, a solid electrolyte layer 30, a second active material layer 22, and a second current collector 12. Each of the first current collector 11 and the second current collector 12 is either a positive electrode current collector or a negative electrode current collector. When the first current collector 11 is a positive electrode current collector, the second current collector 12 is a negative electrode current collector. When the first current collector 11 is a negative electrode current collector, the second current collector 12 is a positive electrode current collector. Further, each of the first active material layer 21 and the second active material layer 22 is either a positive electrode active material layer or a negative electrode active material layer. When the first current collector 11 is a positive electrode current collector and the first active material layer 21 is a positive electrode active material layer, the second active material layer 22 is a negative electrode active material layer. When the first current collector 11 is the negative electrode current collector and the first active material layer 21 is the negative electrode active material layer, the second active material layer 22 is the positive electrode active material layer.

In the battery unit 1 of the present embodiment, the first active material layer 21, the solid electrolyte layer 30, the second active material layer 22, and the second current collector 12 are formed on both sides of the sheet-shaped first current collector 11. They are stacked in order. However, the first active material layer 21, the solid electrolyte layer 30, the second active material layer 22, and the second current collector 12 may be laminated in this order on one side of the first current collector 11.

The solid electrolyte layer 30 contains at least a solid electrolyte. Examples of the solid electrolyte include a sulfide-based solid electrolyte and an oxide-based solid electrolyte. Examples of the sulfide-based solid _electrolyte, Li ₂ S-SiS 2 _{system, Li 2 S-P 2 S} 3 _{system, Li 2 S-P 2 S} 5 _based, Li ₂ S-GeS 2 system, _Li 2 S- Examples include glass or glass ceramics such as B ₂ S _{3 series.} Examples of oxide-based electrolytes include various oxides having a NASICON structure, a garnet-type structure, or a perovskite-type structure. The solid electrolyte is, for example, in the form of particles. The solid electrolyte layer 30 contains a binder (binding material) such as butadiene rubber.

The positive electrode active material layer contains at least the positive electrode active material. The positive electrode active material layer preferably further contains a solid electrolyte, and may further contain a conductive material, a binder, and the like. As the conductive material of the positive electrode active material layer, for example, a known conductive material such as VGCF or acetylene black can be used. For the binder of the positive electrode active material layer, for example, a fluorine-containing resin such as polyvinylidene fluoride can be used. As the positive electrode active material, various compounds conventionally used in this type of battery can be used. Examples of positive electrode active materials include _{layered composite oxides such as LiCoO 2} and LiNiO ₂ , spinel-structured composite oxides such as Li ₂ Nimn ₃ O ₈ and LiMn ₂ O ₄ , and olivine-structured composite compounds such as _{LiFePO 4.} , Etc. can be mentioned. As the solid electrolyte in the positive electrode active material layer, the same kind of material as the solid electrolyte contained in the solid electrolyte layer 30 can be used. The positive electrode active material is, for example, in the form of particles.

The negative electrode active material layer contains at least the negative electrode active material. The negative electrode active material layer preferably further contains a solid electrolyte, and may further contain a conductive material, a binder, and the like. As the conductive material of the negative electrode active material layer, for example, a known conductive material such as acetylene black can be used. For the binder of the negative electrode active material layer, for example, a fluorine-containing resin such as polyvinylidene fluoride can be used. As the negative electrode active material, various compounds conventionally used in this type of battery can be used. Examples of the negative electrode active material include carbon-based negative electrode active materials such as graphite, mesocarbon microbeads, and carbon black. Further, as an example of the negative electrode active material, a negative electrode active material containing silicon (Si) or tin (Sn) as a constituent element can be mentioned. As the solid electrolyte in the negative electrode active material layer, the same kind of material as the solid electrolyte contained in the solid electrolyte layer 30 can be used. The negative electrode active material is, for example, in the form of particles.

As the positive electrode current collector, those used as the positive electrode current collector of this type of battery can be used without particular limitation. Typically, the positive electrode current collector is preferably made of a metal having good conductivity. The positive electrode current collector may be made of a metal material such as aluminum, nickel, chromium, gold, platinum, titanium, zinc, or stainless steel. As the negative electrode current collector, those used as the negative electrode current collector of this type of battery can be used without particular limitation. Typically, the negative electrode current collector is preferably made of a metal having good conductivity. As the negative electrode current collector, for example, copper (copper foil), an alloy mainly composed of copper, aluminum, nickel, iron, titanium, zinc, or the like can be used.

A method for manufacturing an all-solid-state battery according to the present embodiment will be described with reference to FIGS. 2 to 4. As shown in FIG. 2, the manufacturing method of the all-solid-state battery exemplified in this embodiment includes a battery unit manufacturing step (S1), a shape regulating step (S2), a cooling step (S3), a laminating step (S4), and a sealing step. The stopping step (S5) is included.

In the battery unit manufacturing step (S1), a laminated body containing at least one each of a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer is pressed at a high pressure in the thickness direction to form a plate. Battery unit 1 (see FIG. 1) is manufactured. The process of pressing the laminate in the battery unit manufacturing process is hereinafter referred to as a high-pressure pressing process.

An example of the battery unit manufacturing process will be described in detail. First, the first active material layer 21 is arranged on both sides of the first current collector 11. As a method for arranging the first active material layer 21 on the first current collector 11, a slurry coating process, a blast method, an aerosol position method, a cold spray method, a sputtering method, a vapor phase growth method, a thermal spraying method, or the like is used. Can be used. For example, in the slurry coating process, a slurry containing the active material contained in the first active material layer 21 is prepared, and the prepared slurry is applied to the surface of the first current collector 11 and dried. Will be done. Further, by coating and drying the prepared slurry on the base material, a first active material film is formed on the base material, and the formed first active material film is a first current collector from the base material. The first active material layer 21 may be arranged by being transferred to 11 by a press.

Next, the solid electrolyte layer 30 is arranged on the surface of each of the first active material layers 21 arranged on both sides of the first current collector 11. For example, a slurry containing a solid electrolyte is coated and dried on a base material to form a solid electrolyte film on the base material, and the formed solid electrolyte film is formed on the surface of the first active material layer 21. The solid electrolyte layer 30 may be arranged by press transfer.

Next, on the surface of each solid electrolyte layer 30, a layer containing the second active material layer 22 and the second current collector 12 is arranged so that the second active material layer 22 is in contact with the solid electrolyte layer 30. As a method of arranging the second active material layer 22 on the solid electrolyte layer 30, various methods can be used in the same manner as the method of arranging the first active material layer 21 on the first current collector 11. After the second active material layer 22 is arranged on the second current collector 12, the second active material layer 22 may be arranged on the solid electrolyte layer 30. Further, after the second active material layer 22 is arranged on the solid electrolyte layer 33, the second current collector 12 may be arranged on the surface of the second active material layer 22.

Next, the second current collector 12, the second active material layer 22, the solid electrolyte layer 30, the first active material layer 21, the first current collector 11, the first active material layer 21, the solid electrolyte layer 30, the second active material. A plate-shaped battery unit 1 is produced by pressing the laminated body in which the material layer 22 and the second current collector 12 are laminated in this order at a high pressure (pressure P1) in the thickness direction. By executing the high-pressure pressing step, powders such as solid electrolytes contained in the laminate and between the layers are brought into close contact with each other, and the voids are reduced. The high pressure press process is sometimes referred to as a densification press process.

The pressure P1 in the high-pressure press may be appropriately set so that the powder in the battery unit 1 is densified to an appropriate density and the layers are in close contact with each other. In this embodiment, the pressure P1 is set to 50 to 1500 MPa. Further, as the high pressure press method, for example, various methods such as a uniaxial press, a cold hydrostatic isotropic press, a mechanical press, and a gas pressurization press can be used.

Needless to say, the battery unit manufacturing process described above is only an example. For example, it is possible to change the timing and number of times the high-pressure pressing process is executed.

When the press of the battery unit 1 by the high-pressure pressing process is released, the flat plate-shaped battery unit 1 is produced. Here, the surface state and flatness of each of the plurality of battery units 1 are likely to vary. Therefore, when a plurality of battery units 1 are stacked, the positional relationship between the adjacent battery units 1 may be displaced, resulting in deterioration of battery performance or the like. The shape regulation step (S2), the cooling step (S3), and the stacking step (S3) described below are executed in order to appropriately stack the plurality of battery units 1.

In the shape regulation step (S2), the battery unit 1 manufactured in the battery unit manufacturing step (S1) is pressed at a pressure P2 in the thickness direction in a state of being heated to a temperature equal to or higher than the softening deformation temperature T described later. Therefore, the battery unit 1 is restricted to a predetermined curved shape.

The shape regulation process of the battery unit 1 in the present embodiment will be described with reference to FIG. In the shape regulating step of the present embodiment, the shape of the battery unit 1 is regulated (deformed) into a predetermined curved shape by the shape regulating jig 40 and the pressing portion 50. A pressed curved surface 41 formed in a predetermined curved shape is formed on the upper surface of the shape regulating jig 40. Further, on the lower surface of the pressing portion 50, a pressing curved surface 51 formed in the same curved shape as the pressed curved surface 41 of the shape regulating jig 40 is formed. In the present embodiment, the pressed curved surface 41 and the pressed curved surface 51 are formed in a curved shape along a cylindrical surface centered on a cylindrical axis extending in a direction perpendicular to the paper surface in FIG. Therefore, in the laminating step (S4) described later, even if the laminating positions of the plurality of battery units 1 are slightly deviated, a gap is unlikely to occur between the plurality of battery units 1.

Further, at least one of the shape regulating jig 40 and the pressing portion 50 (in the present embodiment, the shape regulating jig 40) is provided with a temperature adjusting portion 43 for adjusting the temperature of the battery unit 1. The configuration of the temperature adjusting unit 40 can be appropriately selected. For example, the temperature adjusting unit may be at least one of an oven that adjusts the temperature of the environment in which the shape regulating step for the battery unit 1 is executed, a refrigerator, and the like.

In the shape regulating step of the present embodiment, first, the battery unit 1 produced in a flat plate shape is arranged on the pressed curved surface 41 of the shape regulating jig 40, and the temperature of the battery unit 1 is determined by the temperature adjusting unit 43. Is heated to a temperature equal to or higher than the softening deformation temperature T (FIG. 3 (A)). Next, with the battery unit 1 arranged between the pressing curved surface 51 of the pressing portion 50 and the pressed curved surface 41 of the shape regulating jig 40, the pressing portion 50 is placed on the shape regulating jig 40 side at a predetermined pressure. Press (Fig. 3 (B)). As a result, the shape of the battery unit 1 is restricted to a predetermined curved shape along the pressed curved surface 41 and the pressed curved surface 51. As a method of pressing the pressing portion 50, various methods (for example, a mechanical press, a gas pressurizing press, etc.) can be adopted.

In the present embodiment, the curved shapes of the pressed curved surface 41 and the pressed curved surface 51 are adjusted so that the radius of curvature R ≧ 50 mm. As a result, the radius of curvature of the curved shape of the battery unit 1 whose shape is restricted is also R ≧ 50 mm. In this case, since the amount of curvature of the battery unit 51 is small, even if the battery unit 1 is subsequently flattened, the battery unit 1 is less likely to be damaged.

The shape regulation step is executed in a state where the temperature of the battery unit 1 is adjusted to a temperature equal to or higher than the softening deformation temperature T in which the battery unit 1 softens and deforms. That is, the temperature of the battery unit 1 during the shape regulation process is set to a temperature at which at least a part of the material of the battery unit 1 is softened (preferably liquefied). Therefore, unlike the case where the shape regulation step is executed at a temperature lower than the softening deformation temperature T, it is difficult for the shape of the battery unit 1 to return to its original shape after the press is released. In this embodiment, the softening deformation temperature T is set to 100 ° C. based on the result of the evaluation test. Therefore, the flattening step of the present embodiment is executed in a state where the temperature of the battery unit 1 is adjusted to 100 ° C. or higher (for example, 170 ° C. ± 10 ° C.).

The press pressure P2 in the shape regulation step is adjusted to a pressure equal to or lower than the pressure P1 of the high-pressure press described above. Therefore, unlike the case where the press is performed during the shape regulation process at a pressure higher than the pressure P1 during the high-pressure press, the battery unit 1 is in a state where the change in the electrode structure in the battery unit 1 is suppressed. The shape is properly regulated. As described above, the pressure P1 of the high pressure press is set to 1500 MPa. Therefore, the pressure P2 is set to 1500 MPa or less.

Further, the press pressure P2 in the shape regulating step is set to a pressure equal to or higher than a pressure that can regulate (deform) the shape of the battery unit 1 to a curved shape. Experiments have shown that the shape of the battery unit 1 of the present embodiment is appropriately regulated by being pressed at a pressure of 0.0005 MPa or more. Therefore, the pressure P2 is set to 0.0005 Mpa or less.

In the cooling step (S3), the battery unit 1 regulated to have a curved shape in the shape regulating step (see S2 in FIG. 2 and FIGS. 3A and 3B) is cooled while the shape is regulated. If the press is released while the battery unit 1 is in a heated state, the battery unit 1 is softened, so that a springback phenomenon is likely to occur. On the other hand, in the present embodiment, by executing the cooling step (S3), the shape of the battery unit 1 is less likely to change due to the springback phenomenon. When the cooling step 1 is completed, the press is released to obtain the battery unit 1 (see FIG. 3C) regulated in a curved shape.

In this embodiment, the battery unit 1 is cooled by the temperature adjusting unit 40. However, it is also possible to change the way the cooling process is performed. For example, the cooling step may be executed by arranging the battery unit 1 for which the shape regulation step has been completed in the refrigerator. The cooling step may be executed by flowing the gas toward the battery unit 1 by a fan or the like. Further, by leaving the battery unit 1 pressed in the thickness direction (that is, without using a cooling source, a fan, etc.) until the temperature of the battery unit 1 heated in the shape regulation step drops, the cooling step May be executed.

In the laminating step (S4), a plurality of battery units 1 regulated to have the same curved shape are laminated in the thickness direction. As a result, the plurality of battery units 1 are appropriately stacked. As shown in FIG. 4, the laminating stage 60 is used in the laminating step of the present embodiment. The upper surface of the stacking stage 60 has the same curved shape as the pressed curved surface 51 of the pressing portion 50 and the pressed curved surface 41 of the shape regulating jig 40 (that is, the same curved shape as the shape-regulated battery unit 1). A curved surface formed in a curved shape) is provided. By laminating a plurality of battery units 1 on the curved surface of the laminating stage 60, the curved shape of each battery unit 1 is maintained during the laminating process. Therefore, a plurality of battery units 1 are more appropriately stacked.

Further, in the laminating step of the present embodiment, first, the laminating outer body 8 for sealing the plurality of battery units 1 inside is arranged on the curved surface of the laminating stage 60. The laminated exterior body 8 is in the form of a sheet and has flexibility. The shape of the laminated exterior body 8 may be deformed by pressing, suction, or the like so as to match the shape of the curved surface of the laminated stage 60 before the plurality of battery units 1 are laminated. Next, the plurality of battery units 1 are laminated on the laminated exterior body 8 arranged on the curved surface of the laminated stage 60. After that, the laminated exterior body 8 is further arranged on the upper part of the plurality of battery units 1.

In the sealing step (S9), the plurality of stacked battery units 1 are sealed inside the laminated exterior body 8. As an example, in the present embodiment, a plurality of battery units 1 are sealed inside the laminated exterior body 8 by welding the outer peripheral portions of the pair of laminated exterior bodies 8 to each other.

The shape of the all-solid-state battery manufactured by the above steps is a curved shape. However, the radius of curvature of the curved shape of the battery unit 1 and the entire all-solid-state battery is R ≧ 50 mm. Therefore, the manufactured all-solid-state battery can be used in a state of being on a flat plate compressed in the thickness direction. Of course, an all-solid-state battery may be used in a curved shape.

The techniques disclosed in the above embodiments are merely examples. Therefore, it is possible to modify the techniques exemplified in the above embodiments. For example, in the above embodiment, the pressed curved surface 41 and the pressed curved surface 51 (see FIG. 3) are formed in a curved shape along a cylindrical surface. As a result, the shape of the battery unit 1 that has undergone the shape regulation step also becomes a curved shape along the cylindrical surface. However, the curved shape of the battery unit 1 is not limited to the shape along the cylindrical surface. For example, the radius of curvature of the pressed curved surface 41 and the pressed curved surface 51 may change depending on the position of the curved surface. In this case, when the plurality of battery units 1 are stacked, the positions of the plurality of battery units 1 (positions in the left-right direction in FIG. 3) easily match due to the difference in the radius of curvature depending on the position. As an example, the radius of curvature of the central portion of the pressed curved surface 41 and the pressed curved surface 51 may be smaller than the radius of curvature of the peripheral portion.

Although the detailed description has been given with reference to specific embodiments, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the above-described embodiments.

1 Battery unit 8 Laminated exterior body 11 1st current collector 12 2nd current collector 21 1st active material layer 22 2nd active material layer 30 Solid electrolyte layer

Claims (1)

It is a manufacturing method of all-solid-state batteries.
A battery unit manufacturing step of manufacturing a plate-shaped battery unit by undergoing a pressing step of pressing a laminate containing at least one each of a positive electrode active material layer, a solid electrolyte, and a negative electrode active material layer in the thickness direction. ,
A shape regulating step of regulating the battery unit into a predetermined curved shape by pressing the battery unit manufactured in the battery unit manufacturing step in a thickness direction in a state of being heated to a temperature equal to or higher than a temperature at which it softens and deforms.
A laminating step of laminating a plurality of the battery units regulated to the same curved shape by the shape regulating step, and a laminating step.
A method for manufacturing an all-solid-state battery, which comprises.

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