JP7042059B2 - All solid state battery - Google Patents

Description

The present invention relates to an all-solid-state battery.

In recent years, secondary batteries have been used in various fields. A secondary battery using an electrolytic solution has a problem such as leakage of the electrolytic solution. Therefore, an all-solid-state battery having a solid electrolyte and having other components made of solid is being developed. Further, in order to improve the capacity density, it is desired to increase the number of battery units. A technique for providing cover layers above and below the all-solid-state battery in the stacking direction in the case of multiple stacking is disclosed (see, for example, Patent Documents 1 to 4).

Japanese Unexamined Patent Publication No. 2007-80812 Japanese Unexamined Patent Publication No. 2011-198692 Japanese Unexamined Patent Publication No. 2008-198402 Japanese Unexamined Patent Publication No. 2016-207540

The cover layer is preferably composed of a solid electrolyte layer and a material that does not interdiffuse during firing. Therefore, it is conceivable to use a material having the same composition as the solid electrolyte layer as the cover layer. However, when a plurality of the above-mentioned all-solid-state batteries are stacked to form a battery module, ionic conduction in the cover layer may cause an unexpected battery reaction via the cover layer.

The present invention has been made in view of the above problems, and provides an all-solid-state battery in which mutual diffusion between the solid electrolyte layer and the cover layer during firing is suppressed, and unexpected battery reaction via the cover layer is suppressed. The purpose is.

The all-solid battery according to the present invention includes a solid electrolyte layer, a positive electrode layer formed on one surface of the solid electrolyte layer, a negative electrode layer formed on the other surface of the solid electrolyte layer, and the solid. In the laminated structure including the electrolyte layer, the positive electrode layer and the negative electrode layer, the first cover layer laminated on the first outermost layer in the laminating direction and the second layer on the opposite side of the first outermost layer in the laminated structure. A second cover layer laminated on the outermost layer is provided, and the first cover layer and the second cover layer have lower ionic conductivity than the solid electrolyte layer and have a Zr ratio higher than that of the solid electrolyte layer. The total ionic conductivity of the first cover layer and the second cover layer is two orders of magnitude or more lower than the total ionic conductivity of the solid electrolyte layer at the same temperature. And.

In the all-solid-state battery, the solid electrolyte layer may be composed of a solid electrolyte having a NASICON type crystal structure.

In the all-solid-state battery, the first cover layer and the second cover layer are composed of a Li-Al-Zr-PO-based material, and the solid electrolyte layer is a Li-Al-Ge-PO-based material. It may be composed of .

According to the present invention, it is possible to provide an all-solid-state battery in which mutual diffusion between the solid electrolyte layer and the cover layer during firing is suppressed, and an unexpected battery reaction via the cover layer is suppressed.

It is a schematic sectional view of the all-solid-state battery which concerns on embodiment. It is an exploded view which shows the laminated structure of a positive electrode and a negative electrode. It is a schematic sectional view of the all-solid-state battery which concerns on embodiment. It is an exploded view which shows the laminated structure of a positive electrode and a negative electrode. (A) to (c) are diagrams illustrating a battery module. It is a figure which illustrates the total ionic conductivity of LAZP. It is a figure which illustrates the total ionic conductivity of LAGP. It is a figure which illustrates the flow of the manufacturing method of an all-solid-state battery.

Hereinafter, embodiments will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a schematic cross-sectional view of the all-solid-state battery 100 according to the embodiment. FIG. 2 is an exploded view showing a laminated structure of a positive electrode 20 and a negative electrode 40, which will be described later. FIG. 1 corresponds to the cross section taken along line AA of FIG. In FIG. 2, the solid electrolyte layer 30 described later is omitted.

The all-solid-state battery 100 has a substantially rectangular parallelepiped shape. As illustrated in FIG. 1, in the all-solid-state battery 100, the solid electrolyte layer 30 is laminated on the positive electrode 20 and the solid electrolyte layer 30 is laminated on the negative electrode 40 on the first cover layer 10. It has a structure in which the second laminated unit is alternately laminated. When the uppermost laminated unit is the first laminated unit, the negative electrode 40 and the second cover layer 50 are laminated in this order on the uppermost first laminated unit. When the uppermost laminated unit is the second laminated unit, the positive electrode 20 and the second cover layer 50 are laminated in this order on the uppermost second laminated unit. Each solid electrolyte layer 30 has substantially the same shape. The two adjacent solid electrolyte layers 30 face each other with the positive electrode 20 or the negative electrode 40 interposed therebetween.

As illustrated in FIGS. 1 and 2, in the first laminated unit, the positive electrode 20 reaches the first edge portion 25, which is a part of one end surface of the solid electrolyte layer 30, on the lower surface of the solid electrolyte layer 30. There is. On the lower surface of the solid electrolyte layer 30, a first margin layer 60 having substantially the same thickness as the positive electrode 20 is provided in a peripheral portion where the positive electrode 20 is not provided.

In the second laminated unit, the negative electrode 40 reaches the second edge portion 45, which is a part of the other end surface of the solid electrolyte layer 30, on the lower surface of the solid electrolyte layer 30. Both end faces of the solid electrolyte layer 30 have a positional relationship facing each other. On the lower surface of the solid electrolyte layer 30, a second margin layer 70 having substantially the same thickness as the negative electrode 40 is provided in the peripheral portion where the negative electrode 40 is not provided.

The positive electrode 20 includes a positive electrode layer 21 and a current collector layer 22. As an example, the positive electrode 20 has a structure in which the current collector layer 22 is sandwiched between the two positive electrode layers 21. At the first edge portion, a first external electrode 80 connected to each current collector layer 22 is provided. The negative electrode 40 includes a negative electrode layer 41 and a current collector layer 42. As an example, the negative electrode 40 has a structure in which the current collector layer 42 is sandwiched between the two negative electrode layers 41. At the second edge portion, a second external electrode 90 connected to each current collector layer 42 is provided. The thickness of each layer is not particularly limited. However, if the electrode layer is too thin, it may be difficult to increase the capacitance density, and if it is too thick, the responsiveness (output characteristics) of the all-solid-state battery 100 may deteriorate. Therefore, the layer thicknesses of the positive electrode layer 21 and the negative electrode layer 41 are preferably 1 μm to 100 μm, and more preferably 2 μm to 50 μm. If the current collector layer is too thin, the continuous rate of the current collector may decrease, that is, the effective area of the all-solid-state battery 100 may decrease. Since the current collector layer itself is a portion that does not contribute to the battery capacity, if the current collector layer is too thick, the capacity density may decrease. Therefore, the layer thicknesses of the current collector layer 22 and the current collector layer 42 are preferably 0.1 μm to 5 μm, and more preferably 1 μm to 3 μm.

The cross section of FIG. 1 is a cross section passing through a portion where the positive electrode 20 reaches the first edge portion 25 and a portion where the negative electrode 40 reaches the second edge portion 45. Therefore, in the stacking direction of FIG. 1, the negative electrode 40 is interposed between the first margin layer 60 and the other first margin layer 60. Further, in the stacking direction of FIG. 1, the positive electrode 20 is interposed between the second margin layer 70 and the other second margin layer 70.

FIG. 3 is a schematic cross-sectional view of the all-solid-state battery 100. FIG. 4 is an exploded view showing a laminated structure of a positive electrode 20 and a negative electrode 40. FIG. 3 corresponds to the BB line cross section of FIG. The BB line cross section is a cross section that does not pass through the portion where the positive electrode 20 reaches the first edge portion 25 and the portion where the negative electrode 40 reaches the second edge portion 45. Therefore, in the stacking direction of FIG. 3, the second margin layer 70, not the negative electrode 40, is interposed between the first margin layer 60 and the other first margin layer 60. Further, in the stacking direction of FIG. 3, the first margin layer 60, not the positive electrode 20, is interposed between the second margin layer 70 and the other second margin layer 70.

The battery module including the all-solid-state battery 100 has a configuration in which a plurality of all-solid-state batteries 100 are connected in parallel. For example, as illustrated in FIG. 5A, the first cover layer 10 of the second all-solid-state battery 100 faces the second cover layer 50 of the first all-solid-state battery 100. The all-solid-state battery 100 and the second all-solid-state battery 100 are laminated. Further, as illustrated in FIG. 5B, the second external electrode 90 of the first all-solid-state battery 100 and the second external electrode 90 of the second all-solid-state battery 100 form the same plane. The all-solid-state battery 100 of 1 and the second all-solid-state battery 100 are laminated. The first external electrode 80 of the first all-solid-state battery 100 and the first external electrode 80 of the second all-solid-state battery 100 are connected, and the second external electrode 90 and the second whole of the first all-solid-state battery 100 are connected. By connecting the second external electrode 90 of the solid-state battery, the first all-solid-state battery 100 and the second all-solid-state battery 100 can be connected in parallel.

A similar laminate may be further laminated on the laminate of the first all-solid-state battery 100 and the second all-solid-state battery 100. By connecting the second external electrode 90 of the other all-solid-state battery 100 to the first external electrode 80, the two all-solid-state batteries 100 can be connected in series.

In the present embodiment, as illustrated in FIG. 5C, as an example, in the battery module 200, a pair of all-solid-state batteries 100 are connected in series, and eight sets of the pair of all-solid-state batteries 100 are connected in parallel. It has a solid-state structure. These all-solid-state batteries 100 are housed in, for example, the outer can 300.

The solid electrolyte layer 30 is not particularly limited as long as it is an oxide-based solid electrolyte, but for example, the solid electrolyte layer 30 contains an oxide-based solid electrolyte having a NASICON structure as a main component. The oxide-based solid electrolyte having a NASICON structure has a property of having high ionic conductivity and being stable in the atmosphere. The oxide-based solid electrolyte having a NASICON structure is, for example, a phosphate containing lithium. The phosphate is not particularly limited, and examples thereof include a lithium complex phosphate salt with Ti (for example, Li _{1 + x} Al _x Ti _2-x (PO ₄ ) ₃ ). Hereinafter, Li _{1 + x} Al _x Ti _2-x (PO ₄ ) ₃ may be referred to as LATP. Alternatively, Ti can be partially or wholly replaced with a tetravalent transition metal such as Ge, Sn, Hf, Zr or the like. Further, in order to increase the Li content, it may be partially replaced with a trivalent transition metal such as Al, Ga, In, Y or La. More specifically, the phosphate containing lithium and having a NASICON structure includes, for example, Li-Al-Ge-PO-based materials (Li _{1 + x} Al _x Ge _2-x (PO ₄ ) ₃ ) and Li-. Al-Zr-PO-based materials (Li _{1 + x} Al _x Zr _2-x (PO ₄ ) ₃ ) and Li-Al-Ti-PO-based materials (Li _{1 + x} Al _x Ti _2-x (PO ₄ )) ₃ ) and the like. Hereinafter, Li _{1 + x} Al _x Ge _2-x (PO ₄ ) ₃ may be referred to as LAGP, and Li _{1 + x} Al _x Zr _2-x (PO ₄ ) ₃ may be referred to as LAZP. For example, a LAGP-based material to which the same transition metal as the transition metal contained in the phosphate having an olivine crystal structure contained in the positive electrode layer 21 and the negative electrode layer 41 is added in advance is preferable. For example, when the positive electrode layer 21 and the negative electrode layer 41 contain a phosphate containing Co and Li, it is preferable that the LAGP-based material to which Co is added in advance is contained in the solid electrolyte layer 30. In this case, the effect of suppressing the elution of the transition metal contained in the electrode active material into the electrolyte can be obtained.

The positive electrode layer 21 contains a substance having an olivine-type crystal structure as an electrode active material. It is preferable that the negative electrode layer 41 also contains the electrode active material. Examples of such an electrode active material include phosphates containing a transition metal and lithium. The olivine-type crystal structure is a crystal of natural olivine and can be discriminated by X-ray diffraction.

As a typical example of the electrode active material having an olivine type crystal structure, LiCoPO ₄ containing Co can be used. Phosphate in which the transition metal Co is replaced in the chemical formula can also be used. Here, the ratio of Li and PO ₄ may fluctuate depending on the valence. It is preferable to use Co, Mn, Fe, Ni or the like as the transition metal.

The electrode active material having an olivine type crystal structure acts as a positive electrode active material in the positive electrode layer 21. For example, when the positive electrode layer 21 contains an electrode active material having an olivine type crystal structure, the electrode active material acts as a positive electrode active material. When the negative electrode layer 41 also contains an electrode active material having an olivine crystal structure, the mechanism of action of the negative electrode layer 41 is not completely understood, but it is partially dissolved with the negative electrode active material. The effects of increasing the discharge capacity and increasing the operating potential associated with the discharge, which are presumed to be based on the formation of the state, are exhibited.

When both the positive electrode layer 21 and the negative electrode layer 41 contain an electrode active material having an olivine type crystal structure, each electrode active material preferably contains a transition metal that may be the same as or different from each other. included. The fact that "they may be the same or different from each other" means that the electrode active materials contained in the positive electrode layer 21 and the negative electrode layer 41 may contain the same type of transition metal, or different types of transition metals may be used. It means that it may be included. The positive electrode layer 21 and the negative electrode layer 41 may contain only one type of transition metal, or may contain two or more types of transition metals. Preferably, the positive electrode layer 21 and the negative electrode layer 41 contain the same kind of transition metal. More preferably, the electrode active materials contained in both electrode layers have the same chemical composition. Since the positive electrode layer 21 and the negative electrode layer 41 contain the same type of transition metal or the electrode active material having the same composition, the similarity in composition between the two electrode layers is enhanced. Even if the mounting is reversed, it has the effect of being able to withstand actual use without malfunction depending on the application.

Of the positive electrode layer 21 and the negative electrode layer 41, the negative electrode layer 41 may further contain a substance known as a negative electrode active material. By containing the negative electrode active material only in one electrolytic layer, it becomes clear that the one electrode layer acts as a negative electrode and the other electrode layer acts as a positive electrode. When only one electrode layer contains the negative electrode active material, it is preferable that the one electrode layer is the negative electrode layer 41. In addition, both electrolytic layers may contain a substance known as a negative electrode active material. As the negative electrode active material of the electrode, the prior art in a secondary battery can be appropriately referred to, and for example, compounds such as titanium oxide, lithium titanium composite oxide, carbon, lithium titanium composite phosphate, and vanadium lithium phosphate. Can be mentioned.

In the production of the positive electrode layer 21 and the negative electrode layer 41, an oxide-based solid electrolyte material, a conductive material (conductive aid) such as carbon or metal, or the like may be further added in addition to these active materials. For these members, a paste for the electrode layer can be obtained by uniformly dispersing the binder and the plasticizer in water or an organic solvent. Examples of the metal of the conductive auxiliary agent include Pd, Ni, Cu, Fe, and alloys containing these.

Conductive materials such as carbon and metal can also be applied to the current collector layers 22 and 42. As the conductive metal, simple substances, alloys or oxides of metals such as Ni, Cu, Pd, Ag, Pt, Au, Al and Fe can be used.

In order to suppress the composition change of the solid electrolyte layer 30, it is preferable that the first cover layer 10 and the second cover layer 50 do not mutually diffuse with the solid electrolyte layer 30 at the time of firing. Therefore, it is conceivable that the first cover layer 10 and the second cover layer 50 have a composition similar to that of the solid electrolyte layer 30. Therefore, in the present embodiment, the first cover layer 10 and the second cover layer 50 contain an oxide-based solid electrolyte as a main component.

However, if the first cover layer 10 and the second cover layer 50 contain an oxide-based solid electrolyte as a main component, the ionic conductivity of the first cover layer 10 and the second cover layer 50 may increase. If the ionic conductivity of the first cover layer 10 and the second cover layer 50 is high, ionic conductivity will occur in the first cover layer 10 and the second cover layer 50. In this case, for example, in the battery module 200 illustrated in FIGS. 5A to 5C, the positive electrode 20 and the negative electrode 40 are sandwiched between the first cover layer 10 and the second cover layer 50 facing each other. There is a risk of unexpected battery reaction. In particular, when a plurality of all-solid-state batteries 100 are laminated as in the battery module 200, the first cover layer 10 and the second cover layer 50 are formed as thin as possible (for example, a thickness of 30 μm or less) in order to improve the capacity density. ), Since the gap between all-solid-state batteries is reduced, unexpected battery reactions are likely to occur. Therefore, in the present embodiment, the first cover layer 10 and the second cover layer 50 have lower ionic conductivity than the solid electrolyte layer 30.

According to this configuration, it is possible to suppress an unexpected battery reaction while suppressing mutual diffusion during firing between the first cover layer 10 and the second cover layer 50 and the solid electrolyte layer 30. The high or low of ionic conductivity is determined by comparing the total ionic conductivity, which is the conductivity calculated from the total resistance value of bulk resistance and grain boundary resistance measured by the AC impedance method, at the same temperature. do.

Subsequently, the specific material composition of the first cover layer 10 and the second cover layer 50 will be described. When the solid electrolyte layer 30 has a NASICON-type Li—XYP—O composition, the first cover layer 10 and the second cover layer 50 also have a NASICON-type Li—XY—. It preferably has a PO composition. X-site is a trivalent metal element such as Al or Ga. The Y site is a transition metal such as Ti, Ge, Zr. For example, by increasing the composition ratio of Zr in the first cover layer 10 and the second cover layer 50 to the composition ratio of Zr in the solid electrolyte layer 30, the ion conduction of the first cover layer 10 and the second cover layer 50 It is preferable to lower the sex. For example, the proportion of Zr in the transition metal entering the Y site is preferably 50% or less, more preferably 30% or less, still more preferably 10% or less in the solid electrolyte layer 30. Further, for example, in the ratio of Zr to the transition metal entering the Y site, the ratio of the first cover layer 10 and the second cover layer 50 is preferably 50% or more, more preferably 70% or more, and more preferably 90% or more. It is more preferable to have.

A Zr-containing NASICON-type crystal structure solid electrolyte can be applied to the solid electrolyte layer 30, but the Li-Zr-PO (for example, triclinic structure), which is a low ion conductive phase, has an internal resistance of the battery. Is not preferable because it becomes expensive. Therefore, it is preferable that a large amount of Li-Zr-PO having a rhombohedral structure is contained. On the other hand, it is preferable to mainly use Li-Zr-PO, which is a low ion conductive phase, as the solid electrolyte applied to the first cover layer 10 and the second cover layer 50, and there is a concern about unexpected battery reaction. Li-Zr-PO of the ionic conduction phase (rhombohedral crystal structure) is not very preferable. Hereinafter, Li-Zr-PO may be referred to as LZP. The structure is not particularly limited, but for example, when the solid electrolyte applied to the solid electrolyte layer 30 is LAGP (Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) ₃ ), it is used during firing. From the viewpoint of suppressing mutual diffusion, the solid electrolyte applied to the first margin layer 60 and the second margin layer 70 is also preferably LAZP (Li _1.5 Al _0.5 Zr _1.5 (PO ₄ ) ₃ ) having the same composition.

Here, the definitions of high ionic conduction and low ionic conduction in ionic conductors will be examined. High ionic conductivity can be defined, for example, as a total ionic conductivity of 1 × 10 ^-5 S / cm or more at room temperature. Low ionic conductivity can be defined, for example, as a total ionic conductivity of less than 1 × 10 ^-6 S / cm at room temperature. As described above, there is a difference of one digit or more between high ionic conduction and low ionic conduction in the ionic conductor. In the present embodiment, since it does not have to function as an ionic conductor, the total ionic conductivity of the first cover layer 10 and the second cover layer 50 is the total of the solid electrolyte layer 30 at the same temperature (for example, room temperature). It is preferably two orders of magnitude or more lower than the ion conductivity.

FIG. 6 is a diagram illustrating the total ionic conductivity of LAZP. FIG. 7 is a diagram illustrating the total ionic conductivity of LAGP. For example, at room temperature (25 ° C.), the total ionic conductivity of LAZP is 3.5 × 10 ^-9 S / cm, and the total ionic conductivity of LAGP is 1.1 × 10 ^-4 S / cm. As described above, at room temperature, the total ionic conductivity of LAZP is about 4 digits lower than the total ionic conductivity of LAGP. Similar results have been obtained at other temperatures. Therefore, it is preferable to use LAZP for the first cover layer 10 and the second cover layer 50, and LAGP for the solid electrolyte layer 30.

In the present embodiment, since the first cover layer 10 and the second cover layer 50 contain an oxide-based solid electrolyte as a main component, the first cover layer 10 and the second cover layer 50 and the solid electrolyte layer 30 are formed. It will have a similar composition. Thereby, mutual diffusion during firing between the first cover layer 10 and the second cover layer 50 and the solid electrolyte layer 30 can be suppressed. Further, since the first cover layer 10 and the second cover layer 50 have lower ionic conductivity than the solid electrolyte layer 30, it is possible to suppress an unexpected battery reaction mediated by them.

It is preferable that the first margin layer 60 and the second margin layer 70 do not mutually diffuse with the solid electrolyte layer 30 at the time of firing. Therefore, in the present embodiment, it is preferable that the first margin layer 60 and the second margin layer 70 contain an oxide-based solid electrolyte as a main component. However, if the first margin layer 60 and the second margin layer 70 contain an oxide-based solid electrolyte as a main component, the ionic conductivity of the first margin layer 60 and the second margin layer 70 may increase. When the ionic conductivity of the first margin layer 60 and the second margin layer 70 is high, the electrode layer at a certain position is separated from the adjacent electrodes (electrodes having different polarities) via the margin layer and the solid electrolyte layer 30. Battery reaction may occur with the counter electrode in the above position. For example, as shown by the arrow in FIG. 3, other than the battery reaction between the positive electrode 20 and the negative electrode layer 41 in the adjacent negative electrode 40 facing each other via the solid electrolyte layer 30 in contact with the positive electrode layer 21. A battery reaction may occur with the negative electrode layer 41 in the negative electrode 40 which is not the closest adjacent electrode 40. Therefore, it is preferable that the first margin layer 60 and the second margin layer 70 have lower ionic conductivity than the solid electrolyte layer 30. For example, it is preferable that the first margin layer 60 and the second margin layer 70 have substantially the same composition as the first cover layer 10 and the second cover layer 50.

Subsequently, a method for manufacturing the all-solid-state battery 100 will be described. FIG. 8 is a diagram illustrating a flow of a manufacturing method of the all-solid-state battery 100.

(Green sheet manufacturing process)
The powder of the oxide-based solid electrolyte constituting the above-mentioned solid electrolyte layer 30 is prepared so as to have an appropriate particle size distribution, and is uniformly dispersed in water or an organic solvent together with a binder, a dispersant, a plasticizer, and the like to form a slurry. To get. At this time, a bead mill, a wet jet mill, various kneaders, a high-pressure homogenizer, or the like can be used, and it is preferable to use the bead mill from the viewpoint that the particle size distribution can be adjusted and dispersed at the same time. The obtained slurry can be applied to obtain a green sheet having a desired thickness. The coating method is not particularly limited, and a slot die method, a reverse coat method, a gravure coat method, a bar coat method, a doctor blade method and the like can be used.

(Cover sheet manufacturing process)
The powder of the oxide-based solid electrolyte constituting the first cover layer 10 described above is prepared so as to have an appropriate particle size distribution, and is uniformly dispersed in water or an organic solvent together with a binder, a binder, a plasticizer, and the like. , Obtain a slurry. At this time, a bead mill, a wet jet mill, various kneaders, a high-pressure homogenizer, or the like can be used, and it is preferable to use the bead mill from the viewpoint that the particle size distribution can be adjusted and dispersed at the same time. The obtained slurry can be applied to obtain a green sheet having a desired thickness. The coating method is not particularly limited, and a slot die method, a reverse coat method, a gravure coat method, a bar coat method, a doctor blade method and the like can be used. A cover sheet for forming the second cover layer 50 can also be manufactured by the same method.

(Paste preparation process for electrode layer)
A paste for an electrode layer can be obtained by uniformly dispersing a conductive auxiliary agent, an active material, a solid electrolyte material, a binder, a plasticizer, etc. in water or an organic solvent. The electrode layer paste is used for forming the positive electrode layer 21 and the negative electrode layer 41. As the conductive auxiliary agent, carbon, Pd, Ni, Cu, Fe, or an alloy containing these may be used. A printed layer of the conductive metal paste for forming the current collector layers 22 and 42 is formed on one surface of the paste for the electrode layer, and a printed layer of the paste for the electrode layer is further formed on the printed layer of the conductive metal paste.

(Laminating process)
A pattern of the paste for the electrode layer and the conductive metal paste for the current collector is placed on the green sheet. Next, the powder of the oxide-based solid electrolyte constituting the first margin layer 60 and the second margin layer 70 is prepared so as to have an appropriate particle size distribution, and water or an organic solvent is prepared together with a binder, a dispersant, a plasticizer, and the like. A paste for forming a margin layer is obtained by uniformly dispersing the mixture. Next, this margin layer forming paste is printed on the margin portion on the green sheet. The printing method is not particularly limited, and a screen printing method, an intaglio printing method, a letterpress printing method, a calendar roll method, or the like can be used. While screen printing is considered to be the most common method for producing thin and highly laminated laminated devices, it may be preferable to apply inkjet printing when very fine electrode patterns or special shapes are required. A laminated body can be obtained by laminating a required number of green sheets, arranging a cover sheet on the outermost layer, and crimping.

(Baking process)
Next, the obtained laminate is fired. The firing conditions are an oxidizing atmosphere or a non-oxidizing atmosphere, and the maximum temperature is preferably 400 ° C. to 1000 ° C., more preferably 500 ° C. to 900 ° C., and the like is not particularly limited. In order to sufficiently remove the binder until the maximum temperature is reached, a step of holding the binder at a temperature lower than the maximum temperature in an oxidizing atmosphere may be provided. In order to reduce the process cost, it is desirable to bake at the lowest possible temperature. After firing, a reoxidation treatment may be performed. In this way, the all-solid-state battery 100 is manufactured.

Although the examples of the present invention have been described in detail above, the present invention is not limited to the specific examples thereof, and various modifications and variations are made within the scope of the gist of the present invention described in the claims. It can be changed.

10 1st cover layer 20 Positive electrode 21 Positive electrode layer 22 Current collector layer 25 1st edge 30 Solid electrolyte layer 40 Negative electrode 41 Negative electrode layer 42 Collector layer 45 2nd edge 50 2nd cover layer 60 1st margin layer 70 2nd margin layer 80 1st external electrode 90 2nd external electrode 100 All-solid-state battery 200 Battery module 300 Exterior can

Claims (3)

With a solid electrolyte layer,
A positive electrode layer formed on one surface of the solid electrolyte layer and
A negative electrode layer formed on the other surface of the solid electrolyte layer and
In a laminated structure including the solid electrolyte layer, the positive electrode layer, and the negative electrode layer, a first cover layer laminated on the first outermost layer in the stacking direction, and
In the laminated structure, a second cover layer laminated on a second outermost layer opposite to the first outermost layer is provided.
The first cover layer and the second cover layer are composed of a solid electrolyte having a lower ion conductivity than the solid electrolyte layer and a higher proportion of Zr than the solid electrolyte layer.
An all-solid-state battery characterized in that , at the same temperature, the total ionic conductivity of the first cover layer and the second cover layer is two orders of magnitude or more lower than the total ionic conductivity of the solid electrolyte layer . The all-solid-state battery according to claim 1, wherein the solid electrolyte layer is composed of a solid electrolyte having a NASICON type crystal structure. The first cover layer and the second cover layer are made of a Li-Al-Zr-PO-based material, and the solid electrolyte layer is made of a Li-Al-Ge-PO-based material. The all-solid-state battery according to claim 1 or 2 .

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