KR20220032453A - All solid rechargeable battery, multilayer all solid rechargeable battery and method for preparing the same - Google Patents

Abstract

The present invention relates to an all-solid secondary battery in which a crack is rarely generated in a current collector compared to a related art or the current collector is rarely cut while the unevenness of a surface of the all-solid secondary battery is reduced. An all-solid secondary battery includes a first electrode layer that is one of a positive electrode layer and a negative electrode layer, a solid electrolyte layer stacked on each surface of the first electrode layer, a second electrode layer that is the other of the positive electrode layer and the negative electrode layer stacked on each external surface of the solid electrolyte layer, an insulating layer disposed on a side end surface of the first electrode layer, and a foil-shaped current collector part that protrudes to the outside penetrating from the first electrode layer to the insulating layer. At the side end surface of the insulating layer on the side where the current collector part protrudes, a different surface part whose surface roughness is different from that of the other side end surface of the insulating layer is formed.

Description

All-solid-state secondary battery, stacked all-solid-state secondary battery, and manufacturing method thereof

It relates to an all-solid-state secondary battery, a laminated all-solid-state secondary battery, and a manufacturing method thereof.

In order to improve the energy density of the all-solid-state secondary battery, it is considered to use a plurality of stacked all-solid-state secondary batteries. When a plurality of all-solid-state secondary batteries are stacked and used in this way, as described in Patent Document 1, one of the positive electrode layer or the negative electrode layer (hereinafter, The first electrode layer) and the solid electrolyte layer respectively disposed on the surface of the first electrode layer, and the other one (hereinafter, the second electrode layer) of the positive electrode layer or the negative electrode layer respectively laminated on the outer surface of each solid electrolyte layer. It is preferable to reduce the unevenness of the surface of the all-solid-state secondary battery and reduce the physical influence on the adjacent all-solid-state secondary battery.

In Patent Document 1, an all-solid-state secondary battery in which surface irregularities are further reduced by laminating packs in a state where the laminate of the above-described configuration is placed on a support plate and pressing from the lamination direction by an isostatic press is produced.

However, in the all-solid-state secondary battery manufactured by pressurizing from the lamination direction by an isostatic press as described above, it was confirmed that the problem that the charge/discharge capacity cannot be exhibited occurs extremely rarely. As a result of repeated investigations by the present inventors, the cause of this problem is that a part of the current collector, which is a thin protruding portion provided for electrically connecting the first electrode layer to an external wiring, is cracked, or that the current collector is It became clear that the cause was being amputated.

In this way, when a crack occurs in the current collector or the current collector is cut, the electrical connection between the first electrode layer and the external wiring is cut off, so that the current collector is electrically connected to the first electrode layer once more A process is required, and there is a problem in that the manufacturing process of the all-solid-state secondary battery becomes complicated.

Japanese Patent Laid-Open No. 2019-121558

The present invention has been made in view of this problem, and while reducing the unevenness of the surface of the all-solid-state secondary battery, the current collector part is less prone to cracking than before, or the current collector part is less likely to be cut than before, and the all-solid-state secondary battery and An object of the present invention is to provide a method for manufacturing a solid secondary battery.

In other words, the all-solid-state secondary battery according to the present invention is manufactured by the following manufacturing method.

A thin house in which a solid electrolyte layer is laminated on both surfaces of the first electrode layer, each of the second electrode layers is laminated on an outer surface of each solid electrolyte layer, and the first electrode layer is electrically connected to an external wiring A laminate manufacturing process of manufacturing a laminate in which all of them are disposed to protrude outward from the first electrode layer, and a current collector protection member for protecting the current collector is disposed cheaply in the current collector; It provides an all-solid-state secondary battery manufacturing method comprising: a pressing process of pressing in the stacking direction; and a removal process of removing the current collector protection member after the pressing process.

According to the manufacturing method of the all-solid-state secondary battery configured in this way, the protruding portion of the current collector can be protected by wrapping the current collector protection member with the current collector protection member while the laminate is pressed. Alternatively, the problem that the current collector is cut can be suppressed.

Assuming that the laminate further includes an insulating layer disposed to cover the side end surface of the first electrode layer, and the current collector protection member is an excess insulating layer integrally formed on the side end surface of the insulating layer, the insulating layer and Since there is no gap between the current collector and the protection member, cracks and cuts in the current collector can be further reduced.

If a cutout is formed between the surplus insulating layer and the insulating layer, it is preferable because only the surplus insulating layer can be easily removed. In order to make it easier to remove the excess insulating layer, it is preferable that the cutout is formed in a range of 5% or more and 99% or less of the thickness in the lamination direction of the insulating layer.

The all-solid-state secondary battery manufactured by the manufacturing method as described above has the following characteristics. The first electrode layer, the solid electrolyte layer stacked on both surfaces of the first electrode layer, the second electrode layer stacked on the outer surface of each solid electrolyte layer, respectively, and an insulating layer disposed on the side end surface of the first electrode layer and a thin current collector protruding from the first electrode layer to the outside through the insulating layer, wherein the insulation A roughened portion having a surface roughness different from that of the other side end surfaces of the layer is formed. As an example of the roughening part, a roughening part having a rougher surface than that of the other end surfaces of the insulating layer is formed.

More specifically, the roughening part is formed when the excess insulating layer formed on the outside of the side end surface of the insulating layer is removed, and the excess insulating layer is formed by removing the protruding portion of the current collector before the excess insulating layer is removed. to wrap and protect.

It is mentioned that the height of the said lamination direction of the said roughening part formed by removing the said excess insulating layer with the said insulating layer is 1% or more and 95% or less of the thickness of the said lamination|stacking direction of the said insulating layer.

As a specific embodiment of the present invention, a cutout between the insulating layer and the current collector protective member may be formed at a depth of 5% or more and 99% or less of the thickness of the current collector protective part.

In order to simplify the manufacturing process more, it is preferable that the said surplus insulating layer and the said insulating layer are integrally formed.

As a specific embodiment, it is preferable that the said insulating layer consists of resin or contains resin.

If the said insulating layer further contains an insulating filler, the adhesiveness of the materials which form the said insulating layer can be improved by the said insulating filler, and the intensity|strength of the said insulating layer can be improved.

Examples of the insulating filler include at least one substance selected from the group consisting of fibrous resin, resin nonwoven fabric, alumina, magnesium oxide, silica, boehmite, barium titanate, barium carbonate, yttrium oxide and manganese oxide. .

When a part or all of the outer edge of the insulating layer on the side from which the current collector protrudes is positioned outside the outer edge of the second electrode layer, the first electrode layer and the second electrode layer (positive electrode layer and negative electrode layer) Since the short circuit by the physical contact between them can be suppressed, it is preferable.

In order to suppress a short circuit between the first electrode layer and the second electrode layer (anode layer and cathode layer), it is preferable that a part or all of an outer edge of the second electrode layer is disposed on the insulating layer.

In order to improve the structural stability of the entire solid-state secondary battery, the first electrode layer is preferably the positive electrode layer.

When the solid electrolyte layer is an all-solid secondary battery containing at least a sulfide-based solid electrolyte containing lithium, phosphorus, and sulfur, battery performance can be further improved, and thus, it is preferable.

The negative electrode layer includes a negative electrode active material that forms an alloy with lithium and/or a negative electrode active material that forms a compound with lithium, wherein metallic lithium can be deposited in the negative electrode layer during charging, and the charge capacity of the negative electrode layer It is preferable that 80% or more of the metal is exhibited by metallic lithium.

As a specific embodiment of the present invention, the negative electrode layer includes any one or more selected from the group consisting of amorphous carbon, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin and zinc. .

According to the present invention, since the manufacturing method of the all-solid-state battery includes a pressing step, it is possible to planarize the surface irregularities of the all-solid-state secondary battery. In addition, since the protruding portion of the current collector is wrapped and protected with the current collector protection member during pressurization, pressure is directly applied to the current collector to cause cracks at the root of the protruding portion of the current collector, or It can be suppressed more than before that all are cut|disconnected.

1 is a cross-sectional view showing a schematic configuration of an all-solid-state secondary battery according to an embodiment.
2 is an enlarged cross-sectional view illustrating a schematic configuration of an all-solid-state secondary battery according to an embodiment.
3 is an enlarged plan view illustrating a schematic configuration of an all-solid-state secondary battery according to an embodiment.
4 is a schematic diagram illustrating a method of manufacturing an all-solid-state secondary battery according to an embodiment.
5 is a schematic diagram illustrating a method of manufacturing an all-solid-state secondary battery according to an embodiment.
6 is a schematic diagram illustrating a method of manufacturing an all-solid-state secondary battery according to an embodiment.
7 is a schematic view of an excess insulating layer, an insulating layer, and a positive electrode layer of an all-solid-state secondary battery according to an embodiment as viewed in a stacking direction.
Fig. 8 is a schematic view showing a side end surface of an excess insulating layer material.
9 is a schematic diagram illustrating a method of manufacturing an all-solid-state secondary battery according to an embodiment.
10 is an enlarged view illustrating a roughening part of an all-solid-state secondary battery according to an exemplary embodiment.
11 is a graph illustrating a result of charging/discharging evaluation of an all-solid-state secondary battery according to an embodiment.
12 is a graph showing cycle characteristics of an all-solid-state secondary battery according to an embodiment and a comparative example.
13 is a graph showing a result of charging/discharging evaluation of an all-solid-state secondary battery according to an embodiment.
14 is a graph showing a result of charging/discharging evaluation of an all-solid-state secondary battery according to a comparative example.
15 is a graph showing a result of charging/discharging evaluation of an all-solid-state secondary battery according to a comparative example.
16 is a graph showing cycle characteristics of an all-solid-state secondary battery according to an embodiment.

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described in detail, referring an accompanying drawing. In addition, in this specification and drawings, the same code|symbol is attached|subjected to the component which possesses substantially the same functional structure, and duplicate description is abbreviate|omitted. In addition, each component in the drawing is appropriately enlarged or reduced for ease of explanation, and the size and ratio of each component in the drawing may differ from actual ones.

<1. Composition of all-solid-state secondary battery>

First, the configuration of the all-solid-state secondary battery 1 according to an embodiment of the present invention will be described.

The all-solid-state secondary battery 1 according to the present embodiment includes a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30. More specifically, one of the positive electrode layer 10 or the negative electrode layer 20 (hereinafter, the first electrode layer), the solid electrolyte layer 30 respectively laminated on both surfaces of the first electrode layer, and the solid electrolyte layer laminated on the outer surface of each solid electrolyte layer, respectively An all-solid-state lithium secondary battery 1 including the other one of the positive electrode layer 10 and the negative electrode layer 20 (hereinafter, the second electrode layer) and the insulating layer 13 disposed on the side end surface S of the first electrode layer. In this embodiment, as shown in FIG. 1 and FIG. 2, the said 1st electrode layer is the positive electrode layer 10, and the said 2nd electrode layer is the negative electrode layer 20 is demonstrated. On the other hand, the side end surface is an end of the periphery rather than the lamination direction of each layer, and means an end of each layer in a direction perpendicular to the lamination direction of each layer.

(1-1. Anode layer)

The positive electrode layer 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12 as shown in FIG. 2 .

Examples of the positive electrode current collector 11 include a plate-like body or a thin body made of stainless steel, titanium (Ti), nickel (Ni), aluminum (Al), or an alloy thereof.

The positive electrode active material layer 12 is disposed on both surfaces of the positive electrode current collector 11 as shown in FIG. 2 . The positive electrode active material layer 12 contains a positive electrode active material and a solid electrolyte. The solid electrolyte contained in the positive electrode active material layer 12 may or may not be the same as the solid electrolyte contained in the solid electrolyte layer 30 . The details of the solid electrolyte will be described in the section of the solid electrolyte layer 30 to be described later.

The positive electrode active material may be any positive electrode active material capable of reversibly occluding and releasing lithium ions.

The positive active material is, for example, in a powdery or granular form, lithium cobalt acid (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobalt oxide, nickel cobalt aluminum Lithium salts such as lithium acid (hereinafter referred to as NCA), nickel cobalt manganese oxide (hereinafter referred to as NCM), lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, It can be formed using sulfur, iron oxide, or vanadium oxide. These positive electrode active materials may be used individually, respectively, and may be used in combination of 2 or more types.

In addition, the positive active material is preferably formed by including a lithium salt of a transition metal oxide having a layered rock salt structure among the lithium salts described above. Here, "layered" refers to a thin sheet-like shape. In addition, "rock salt structure" refers to a sodium chloride type structure, which is a type of crystal structure, and specifically, the face-centered cubic lattice formed by each of the positive ions and the anions is arranged with a shift of only 1/2 of the corners of the unit lattice from each other. represents the structure.

As a lithium salt of a transition metal oxide possessing such a layered rock salt structure, for example, LiNi _x Co _y Al _z O ₂ (NCA), or LiNi _x Co _y Mn _z O ₂ (NCM) (provided that 0<x and lithium salts of ternary transition metal oxides such as <1, 0<y<1, 0<z<1, and x+y+z=1).

When the positive active material includes a lithium salt of a ternary transition metal oxide having the layered rock salt structure, energy density and thermal stability of the all-solid-state secondary battery 1 may be improved.

The positive electrode active material may be covered with a coating layer. Here, the coating layer of the present embodiment may be any one known as a coating layer of the positive electrode active material of the all-solid-state secondary battery 1. As an example _of a coating layer, Li2O _- ZrO2 etc. are mentioned, for example.

In addition, when the positive electrode active material is formed from a lithium salt of a ternary transition metal oxide such as NCA or NCM, and nickel (Ni) is included as the positive electrode active material, the capacity density of the all-solid-state secondary battery 1 is increased, and the state of charge It is possible to reduce the metal elution from the positive electrode active material in Accordingly, the all-solid-state secondary battery 1 according to the present embodiment can improve long-term reliability and cycle characteristics in a charged state.

Here, as a shape of a positive electrode active material, particle shapes, such as a spherical shape and an ellipsoidal shape, are mentioned, for example. In addition, the particle diameter of the positive electrode active material is not particularly limited, and may be within a range applicable to the positive electrode active material of a conventional all-solid-state secondary battery. On the other hand, the content of the positive electrode active material in the positive electrode layer 10 is also not particularly limited, as long as it is within a range applicable to the positive electrode layer 10 of the conventional all-solid secondary battery 1 .

Further, in the positive electrode active material layer 12, in addition to the above-described positive electrode active material and solid electrolyte, for example, an additive such as a conductive auxiliary agent, a binder material, a filler, a dispersing agent, an ion conductive auxiliary agent may be suitably blended.

Examples of the conductive additive that can be blended into the positive electrode active material layer 12 include graphite, carbon black, acetylene black, ketjen black, carbon fibers, carbon nanotubes, graphene, and metal powder. In addition, examples of the binder that can be incorporated into the positive electrode active material layer 12 include styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, and the like. . Moreover, as a filler, a dispersing agent, an ion conduction auxiliary agent, etc. which can be mix|blended with the positive electrode active material layer 12, well-known materials which can generally be used for the electrode of the all-solid-state secondary battery 1 can be used.

(1-2. Cathode layer)

The negative electrode layer 20 includes, for example, as shown in FIG. 2 , a plate-shaped or thin negative electrode current collector 21 and a negative electrode active material layer 22 formed on the negative electrode current collector 21 .

The negative electrode current collector 21 forms the outermost layer of the all-solid-state secondary battery 1 in this embodiment. The negative electrode current collector 21 is preferably made of a material that does not react with lithium, that is, neither an alloy nor a compound is formed. Examples of the material constituting the negative electrode current collector 21 include, in addition to stainless steel, copper (Cu), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), and the like. The negative electrode current collector 21 may be composed of one of these metals, or may be composed of an alloy of two or more metals or a cladding material.

The negative electrode active material layer 22 includes, for example, at least one of a negative electrode active material that forms an alloy with lithium and a negative electrode active material that forms a compound with lithium. In addition, the negative electrode active material layer 22 may contain such a negative electrode active material so that metallic lithium can be deposited on the surface of one or both sides of the negative electrode active material layer 22 as will be described below.

Examples of the negative active material include amorphous carbon, money, platinum, palladium (Pd), silicon (Si), aluminum (Al), bismuth (Bi), tin, antimony, and zinc. Here, as said amorphous carbon, carbon black, such as acetylene black, furnace black, and Ketjen black, graphene, etc. are mentioned, for example.

The shape of the negative electrode active material is not particularly limited, and may be granular, for example, may be a uniform layer such as a plating layer. In the former case, lithium ions pass through gaps between the anode active materials in the form of granules, and a metal layer mainly made of lithium is formed between the anode active material layer 22 and the anode current collector 21, and some lithium is a metal element in the anode active material. It is present in the negative electrode active material layer 22 by forming an alloy with it. Meanwhile, in the latter case, the metal layer is deposited between the anode active material layer 22 and the solid electrolyte layer 30 .

Among the above-mentioned, the negative electrode active material layer 22 is amorphous carbon, and has a low specific surface area amorphous carbon having a specific surface area of 100 m ² /g or less measured by a nitrogen gas adsorption method, and a specific surface area measured by a nitrogen gas adsorption method of 300 m ² /g It is preferable to include a mixture with the above high specific surface area amorphous carbon.

The negative electrode active material layer 22 may contain any 1 type of these negative electrode active materials, and may contain 2 or more types of negative electrode active materials. For example, the negative electrode active material layer 22 may contain only amorphous carbon as the negative electrode active material, and any one selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, antimony and zinc. You may contain more than that. Further, the negative electrode active material layer 22 may contain a mixture of amorphous carbon and at least one selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, antimony and zinc.

The mixing ratio (mass ratio) of the mixture of amorphous carbon and the aforementioned metal such as gold is preferably about 1:1 to 1:3, and the anode active material is composed of these materials, and the characteristics of the all-solid-state secondary battery 1 This is also improved.

When any one or more selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, antimony and zinc together with amorphous carbon is used as the negative electrode active material, the particle diameter of these negative electrode active materials is 4 μm or less. it is preferable In this case, the characteristics of the all-solid-state secondary battery 1 are further improved.

In addition, as the negative electrode active material, any one or more selected from the group consisting of a material capable of forming an alloy with lithium, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, antimony, and zinc may be used. In this case, the negative electrode active material layer 22 may be a layer made of these metals. For example, a plating layer may be sufficient as this metal layer.

The negative electrode active material layer 22 may further contain a binder as needed. Examples of the binder include styrene butadiene rubber (SBR), polytetrafluoroethylene (PET), polyvinylidene fluoride, and polyethylene oxide. A binder may be comprised by 1 type of these, or may be comprised by 2 or more types. By including the binder in the negative electrode active material layer 22 in this way, especially when the negative electrode active material has a granular shape, it is possible to suppress the separation of the negative electrode active material.

The content of the binder contained in the negative electrode active material layer 22, relative to the total mass of the negative electrode active material layer 22, is, for example, 0.3 mass% or more and 20.0 mass% or less, preferably 1.0 mass% or more and 15.0 mass% or less, more preferably is 3.0 mass % or more and 15.0 mass % or less.

In addition, the negative electrode active material layer 22 may be suitably blended with additives used in the conventional all-solid-state secondary battery 1, for example, a filler, a dispersion material, an ion conductive material, and the like.

The thickness of the negative electrode active material layer 22 is not particularly limited when the negative electrode active material is granular, but for example, 1.0 μm or more and 20.0 μm or less, preferably 1.0 μm or more and 10 μm or less. By setting it as such a thickness, the resistance value of the negative electrode active material layer 22 can fully be reduced while fully acquiring the above-mentioned effect of the negative electrode active material layer 22, and the characteristic of the all-solid-state secondary battery 1 can fully be improved.

On the one hand, the thickness of the negative electrode active material layer 22 is, for example, 1.0 nm or more and 100.0 nm or less when the negative electrode active material forms a uniform layer. The upper limit of the thickness of the negative electrode active material layer 22 in this case is preferably 95 nm, more preferably 90 nm, still more preferably 50 nm.

In addition, this invention is not limited to the above-mentioned embodiment, The negative electrode active material layer 22 can employ|adopt any structure which can be used as the negative electrode active material layer 22 of the all-solid-state secondary battery 1. For example, the negative electrode active material layer 22 may be a layer including the above-described negative electrode active material, a solid electrolyte, and a negative electrode layer conductive aid.

In this case, for example, a metal active material or a carbon active material may be used as the negative electrode active material. As said metal active material, metals, such as lithium (Li), indium (In), aluminum (Al), tin (Sn), and silicon (Si), and alloys thereof, etc. can be used, for example. In addition, as the carbon active material, for example, artificial graphite, graphite carbon fiber, resin plastic carbon, pyrolysis vapor phase growth carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin plastic carbon, Polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon may be used. In addition, these negative electrode active materials may be used independently and may be used in combination of 2 or more types.

As the negative electrode layer conductive aid and the solid electrolyte, the same compound as the conductive agent and solid electrolyte included in the positive electrode active material layer 12 may be used. For this reason, the description here regarding these structures is abbreviate|omitted.

(1-3. Solid electrolyte layer)

The solid electrolyte layer 30 is a layer formed between the positive electrode layer 10 and the negative electrode layer 20, and includes a solid electrolyte.

In this embodiment, the solid electrolyte layer 30 is laminated between the positive electrode layer 10 and the negative electrode layer 20 . The thickness of the solid electrolyte layer 30 may be 5 µm or more and 100 µm or less in a finished state as a battery. It is preferable that they are 8 micrometers or more and 50 micrometers or less, and, as for this thickness, it is more preferable that they are 10 micrometers or more and 30 micrometers or less.

The solid electrolyte is, for example, in a powder form, and is composed of, for example, a sulfide-based solid electrolyte material.

Examples of the sulfide-based solid electrolyte material include Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -LiX (X is a halogen element, for example, I, Br, Cl), Li ₂ SP ₂ S ₅ - Li ₂ O, Li ₂ SP ₂ S ₅ -Li ₂ O-LiI, Li ₂ S-SiS ₂ , Li ₂ S-SiS ₂ -LiI, Li ₂ S-SiS ₂ -LiBr, Li ₂ S-SiS ₂ -LiCl , Li ₂ S-SiS ₂ -B ₂ S ₃ -LiI, Li ₂ S-SiS ₂ -P ₂ S ₅ -LiI, Li ₂ SB ₂ S ₃ , Li ₂ SP ₂ S ₅ -Z _m S _n (m, n is a positive number, Z is either Ge, Zn or Ga), Li ₂ S-GeS ₂ , Li ₂ S-SiS ₂ -Li ₃ PO ₄ , Li ₂ S-SiS ₂ -Li _p MO _q (p , q is a positive number, and M is any of P, Si, Ge, B, Al, Ga or In).

Here, the sulfide-based solid electrolyte material is manufactured by treating a starting material (eg, Li ₂ S, P ₂ S ₅ , etc.) by a melt quenching method or a mechanical milling method. Moreover, you may heat-process further after these processes. The solid electrolyte may be amorphous, may be crystalline, or may be in a mixed state.

Further, as the solid electrolyte, it is preferable to use a material containing at least one element selected from the group consisting of sulfur, silicon, phosphorus and boron among the above sulfide-based solid electrolyte materials. Accordingly, the lithium conductivity of the solid electrolyte layer 30 is improved, and the battery characteristics of the all-solid secondary battery 1 are improved. In particular, it is preferable to use a solid electrolyte containing at least sulfur (S), phosphorus (P) and lithium (Li) as constituent elements, and it is more preferable to use a solid electrolyte containing particularly Li ₂ SP ₂ S ₅ .

Here, when a sulfide-based solid electrolyte material containing Li ₂ SP ₂ S ₅ is used as the sulfide-based solid electrolyte material for forming the solid electrolyte, the mixing molar ratio of Li ₂ S and P ₂ S ₅ is, for example, Li ₂ S:P. ₂ S ₅ =50:50 to 90:10 may be selected.

Further, the solid electrolyte layer 30 may further contain a binder. The binder included in the solid electrolyte layer 30, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene (polytetrafluoroethylene), polyvinylidene fluoride (polyvinylidenefluoride), polyethylene (polyethylene), polyacrylic acid (poly acrylic acid) and the like. The binder contained in the solid electrolyte layer 30 may be of the same type as the binder in the positive electrode active material layer 12 and the negative electrode active material layer 22, or may be of a different type.

(1-4. Insulation layer)

The insulating layer 13 is disposed, for example, in close contact with the side end surface S of the anode layer 10 so as to cover the entire side end surface S of the anode layer 10, which is the first electrode layer in the present embodiment.

The insulating layer 13 may be formed using the insulating layer material 13A, which is a material that does not allow electricity to pass through. As the material constituting the insulating layer material 13A, for example, polypropylene, polyethylene, or a copolymer thereof. A resin film containing resin, such as these, etc. are mentioned. If it is such a resin film, it can be made to adhere to the positive electrode layer 10 by pressure forming, such as isostatic press, for example, and it can make it hard to peel off. Moreover, it is still good if the said insulating layer material 13A mixes these resin with insulating filler, etc. and it is still good.

When the insulating layer material 13A contains an insulating filler, the adhesiveness between the insulating layer materials 13A becomes good, and the strength of the insulating layer 13 can be improved when the insulating layer 13 is formed or used by the insulating layer material 13A. Moreover, when the insulating layer material 13A contains an insulating filler with resin, the fine unevenness|corrugation by mixing an insulating filler on the surface of the insulating layer 13 and being crowded can be formed. According to the concavo-convex shape of the surface of the insulating layer 13, when the solid electrolyte layer 30 is laminated, the solid electrolyte layer 30 can be made difficult to peel off from the insulating layer 13.

As the insulating filler, articles of various shapes such as particulate, fibrous, needle or plate-shaped articles can be used. Among these, it is preferable to use the insulating filler of a fibrous type or a nonwoven fabric type as a thing which plays the said effect especially notably. As said insulating filler, from a viewpoint of suppressing an increase in cost, for example, a fibrous resin, resin nonwoven fabric, alumina, magnesium oxide, silica, boehmite, barium titanate, barium carbonate, yttrium oxide, and manganese oxide. It is preferable to use one made of at least one material selected from

(1-5. Current collector)

The positive electrode current collector 11 and the negative electrode current collector 21 are connected to an external wiring via a current collector.

The current collector includes, for example, as shown in FIGS. 2 and 3 , a positive electrode current collector 111 for electrically connecting the positive electrode current collector 11 to an external wiring or the like, and a negative electrode current collector 21 for connecting the negative current collector 21 to an external wiring. A negative electrode current collector 211 is provided. The positive electrode current collector 111 may have a thin shape formed of, for example, the same material as the positive electrode current collector 11 . The positive electrode current collector 111 extends from the positive electrode current collector 11 and is integrally formed with the positive electrode current collector 11 . In each figure, an imaginary line is drawn between the positive electrode current collector 11 and the positive electrode current collector 111 .

In the present embodiment, the positive electrode current collector 111 connecting the positive electrode current collector 11 included in the positive electrode layer 10 as the first electrode layer to an external wiring is configured to penetrate the insulating layer 13 and protrude to the outside. On the other hand, for convenience of explanation, in FIGS. 1 to 10, the direction in which the positive electrode current collector 111 protrudes is referred to as a protruding direction, and each layer constituting the all-solid-state secondary battery 1 is located in the protruding direction in the plan view viewed from the stacking direction. The direction perpendicular to it is called the width direction.

The negative electrode current collector 211 is, for example, a thin type formed of the same material as the negative electrode current collector 21 . The negative electrode current collector 211 is integrally formed with the negative electrode current collector 21 so as to extend from the negative electrode current collector 21 . In FIG. 3 , an imaginary line is drawn between the negative electrode current collector 21 and the negative electrode current collector 211 .

More specifically, when the all-solid-state secondary battery 1 is used, the positive electrode current collector 11 is wired through the positive electrode current collector 111 attached to one end of the positive electrode current collector 11 and a terminal (collection tab) not shown. is connected to Similarly, when the all-solid-state secondary battery 1 is used, the negative electrode current collector 21 is connected to the wiring via the negative electrode current collector 211 attached to one end of the negative electrode current collector 21 and a terminal (current collector tab) not shown. do.

On the other hand, the thickness of the positive electrode current collector 111 and the negative current collector 211 can be suitably changed depending on the thickness of the positive electrode current collector 11 or the negative electrode current collector 21 integrally formed, for example, 1 µm or more and 50 µm or less, more preferably It is preferably 5 μm or more and 30 μm or less.

<2. Manufacturing method of all-solid-state secondary battery>

Next, an example of a method and a procedure for manufacturing the all-solid-state secondary battery 1 according to the present embodiment will be described with reference to FIGS. 4 to 8 .

The manufacturing method of the all-solid-state secondary battery 1 according to the present embodiment includes the following steps.

(2-1. Preparation of the anode layer)

By adding the material (positive electrode active material, binder, etc.) constituting the positive electrode active material layer 12 to a non-polar solvent, the positive electrode active material layer coating liquid (this positive electrode active material layer coating liquid may be in the form of a slurry or paste. The coating liquid used for forming is also the same). Then, as shown in Fig. 4 (a), the obtained positive electrode active material layer coating solution was applied to both surfaces of the positive electrode current collector 11 and dried, and then the positive electrode current collector 11 and the applied positive electrode active material layer 12 were applied in a rectangular plate shape using a Thompson blade or the like. pierce in The laminate obtained in this way is called a positive electrode structure. This positive electrode structure is placed on an aluminum plate covered with PET film, and an insulating layer material 13A of a substantially rectangular ring shape forming an insulation layer 13 is placed around the positive electrode structure, and another PET film is placed on all of them, and then a laminate pack Then, the anode layer 10A before cutting, as shown in Fig. 4(b) with respect to the pressure from the lamination direction, is produced by performing a pressurization treatment by isostatic pressure (isotropic press).

(2-2. Preparation of cathode layer)

By adding the material (negative electrode active material, binder, etc.) constituting the negative electrode active material layer 22 to a polar solvent or a non-polar solvent, a negative electrode active material layer coating solution is prepared. Then, as shown in Fig. 5 (a), the obtained negative electrode active material layer coating liquid is applied on the negative electrode current collector 21 and dried. The cathode layer 20 is produced by piercing this with a Thompson blade or the like so as to form a rectangular plate.

(2-3. Preparation of solid electrolyte layer)

The solid electrolyte layer 30 can be made of a solid electrolyte formed from a sulfide-based solid electrolyte material. The method for preparing the solid electrolyte is as follows.

First, the starting material is treated by a melt quenching method or a mechanical milling method. For example, when using the melt quenching method, a predetermined amount of starting materials (for example, Li2S, P2S5, etc.) are mixed, and the pelletized product is reacted in a vacuum at a predetermined reaction temperature, and then quenched by quenching to form a sulfide system. A solid electrolyte material can be produced. On the other hand, the reaction temperature of the mixture of Li ₂ S and P ₂ S ₅ is preferably 400°C to 1000°C, more preferably 800°C to 900°C. Moreover, the reaction time becomes like this. Preferably it is 0.1 hour - 12 hours, More preferably, it is 1 hour - 12 hours. In addition, the quenching temperature of the reactant is usually 10 degrees or less, preferably 0 degrees or less, and the quenching rate is usually about 1 degree/sec to 10000 degrees/sec, preferably 1 degree/sec to 1000 degrees/sec. about sec.

In addition, in the case of using the mechanical milling method, a sulfide-based solid electrolyte material can be produced by stirring and reacting the starting material (eg, Li ₂ S, P ₂ S ₅ , etc.) using a ball mill or the like. . On the other hand, although the stirring speed and stirring time in the mechanical milling method are not particularly limited, the production rate of the sulfide-based solid electrolyte material can be increased enough that the stirring speed is high, and the stirring time is long enough to increase the amount of the sulfide-based solid electrolyte material. The conversion ratio of the raw material can be made high.

Thereafter, the mixed raw material obtained by the melt quenching method or the mechanical milling method is heat-treated at a predetermined temperature and then pulverized to produce a particulate solid electrolyte. When the solid electrolyte has a glass transition point, it may change from amorphous to crystalline by heat treatment.

Then, a solid electrolyte layer coating liquid containing the solid electrolyte obtained by the above method and other additives such as a binder and a dispersion medium is prepared. As the dispersion medium, a general-purpose non-polar solvent such as xylene or diethylbenzene can be used. Alternatively, a polar solvent having relatively poor reactivity with the solid electrolyte may be used. The concentration of the solid electrolyte and other additives can be appropriately adjusted according to the composition of the solid electrolyte layer 30 to be formed and the viscosity of the liquid composition.

The liquid composition of the above-described solid electrolyte is applied on a blade on a PET film having a release treatment on the surface, dried, and then a solid electrolyte sheet having a solid electrolyte layer 30 formed on the PET film is manufactured.

(2-4. Lamination process)

On one side of the negative electrode layer 20 prepared as described above, as shown in Fig. 5 (a), a solid electrolyte sheet punched out to have the same shape or a larger shape as the negative electrode layer 20 is laminated, and these are pressed by isostatic pressing. As a result, as shown in Fig. 5(b), the negative electrode layer 20 and the solid electrolyte layer 30 are brought into close contact and integrated. When the solid electrolyte layer 30 has a larger shape than the negative electrode layer 20, a portion of the solid electrolyte layer 30 that protrudes outward when stacked on the negative electrode layer 20 may be removed. This laminate will be referred to as an electrolyte negative electrode structure 20A.

Then, as shown in Fig. 6(a), the above-described positive electrode layer 10A before cutting is laminated so as to be sandwiched by two electrolyte negative electrode structures 20A from both sides. At this time, the electrolyte negative electrode structure 20A is laminated on both surfaces of the positive electrode layer 10 so that the solid electrolyte layer 30 of the electrolyte negative electrode structure 20A is in contact with each other, and the entirety is laminated pack and isostatically pressed, as shown in FIG. 6(b). An untreated all-solid-state secondary battery 1A, which is a laminate as described above, is prepared.

In the present embodiment, in the lamination step described above, as shown in Figs. 2, 3 and 6(b), the outer edge 1E of the insulating layer 13 is outside the outer edge 2E of the cathode layer 20. As shown in Figs. The outer edge 1E of the insulating layer 13 may be displaced outward from the outer edge 2E of the cathode layer 20 in a range of, for example, 1 µm or more and 2 mm or less. It is preferable that they are 0.05 mm or more and 1 mm or less, and, as for the range of this shift|offset|difference, if it is the range of 0.1 mm or more and 0.5 mm or less, it is more preferable.

More specifically, as shown in Figs. 2, 3, and 6(b), in this embodiment, at least a part of the outer edge 2E of the cathode layer 20 is outside the insulating layer 13 provided around the anode layer 10 Inner than edge 1E, preferably laminated over insulating layer 13. With this configuration, for example, in the all-solid-state secondary battery 1 illustrated in FIG. 2 , even when the negative electrode layer 20 can be pressed to the positive electrode layer 10 side by external pressure and is deformed, the positive electrode layer 10 It is possible to suppress the physical short circuit between and the cathode layer 20.

In the all-solid-state secondary battery 1 described in FIG. 2, in particular, the outer edge 2E of the negative electrode layer 20 and the positive electrode layer 10 easily cause a physical short circuit via the positive electrode current collector 111. As shown in Fig. 6(b) , a part of the outer edge 1E of the insulating layer 13 covering the positive electrode layer 10 from the side end surface S thereof is at least on the side from which the positive electrode current collector 111 protrudes, the outside of the negative electrode layer 20 What is necessary is just to exist outside the edge 2E. In this way, the short circuit between the positive electrode layer 10 and the negative electrode layer 20 due to the contact between the negative electrode current collector 21 or the outer edge 2E of the negative electrode active material layer 22 and the positive electrode current collector 111 can be suppressed. One side or electric pole of the outer edge 1E of the insulating layer 13 may be made to be outside the outer edge 2E of the negative electrode layer 20 .

The outer edge 1E of the insulating layer 13 is, as shown in Figs. 2, 3, and 6(b), the outermost edge (outer side) of the side end surfaces of the insulating layer 13 in the direction perpendicular to the lamination direction. edge), more specifically, the outer edge of the insulating layer 13 on the side from which the positive electrode current collector 111 protrudes. Further, the outer edge 2E of the negative electrode layer 20 refers to the outermost edge (outer edge) in the direction perpendicular to the lamination direction among the side end surfaces of the negative electrode layer 20. In this embodiment, for example, the negative electrode The outermost edge of the side end face of the current collector 21 or the negative electrode active material layer 22 in a direction perpendicular to the stacking direction thereof.

(2-5. Isostatic Press)

Below, the pressurization process (pressing process) by the above-mentioned isostatic press is demonstrated. The isostatic press is performed by arranging the support plate 4, such as a SUS plate, on at least one side of the laminate. By this isostatic pressing, the pressure treatment from the lamination direction can be performed on each laminate forming the positive electrode layer 10A, the electrolyte negative electrode structure 20A, or the untreated all-solid-state secondary battery 1A before cutting. Liquids, such as water, oil, and powder, etc. are mentioned as a pressure medium of an isostatic press. It is more preferable to use a liquid as the pressure medium.

Although the pressure in an isostatic press is not specifically limited, For example, 10-1000 Mpa, Preferably it is 100-500 Mpa. Moreover, pressurization time is not specifically limited, For example, it is 1 to 120 minutes, Preferably it is 5 to 30 minutes. Moreover, the temperature of the pressure medium at the time of pressurization is also not specifically limited, For example, it is 20-200 degreeC, Preferably it can be set as 50-100 degreeC.

On the other hand, at the time of isostatic pressure pressing, the laminate constituting the all-solid-state secondary battery 1 is laminated together with the support plate 4 with a resin film or the like, and it is preferable to be in a state blocked by an external atmosphere. Compared with other press methods such as roll press, the isostatic press is advantageous from the viewpoint of suppressing cracking of each layer constituting the all-solid-state secondary battery 1 and preventing warpage of the all-solid-state secondary battery 1.

(2-6. Characteristics of the manufacturing method of the all-solid-state secondary battery according to the present invention)

However, the feature of the method of manufacturing the all-solid-state secondary battery 1 according to the present invention is that the current collector protector 14 protects the protruding portion of the current collector 111 or 211 by at least during the pressing process described above. It covers the whole of (111 or 211) from both sides.

In the present embodiment, the protruding portion of the positive electrode current collector 111 mounted on the positive electrode current collector 11 of the positive electrode layer 10 that is the first electrode layer sandwiched in the center is covered by the current collector protection member 14 . The current collector protection member 14 may have a surface larger than the area of the positive electrode current collector 111 so as to cover the entire positive electrode current collector 111 without a gap at least while lacking isostatic pressure, and the shape is not particularly limited.

The current collector protective member 14 is, for example, formed integrally with the insulating layer 13 as shown in FIG. 7, has the same width and thickness as the insulating layer 13, and in the same direction as the positive electrode current collector 111 from the insulating layer 13 It is preferable from the viewpoint of easiness of manufacture to use the surplus insulating layer 14 in the shape of a rectangular plate that protrudes larger than the positive electrode current collector 111 . On the other hand, an imaginary line is described between the insulating layer 13 and the surplus insulating layer 14 so that it is easy to understand in terms of angles.

In this embodiment, as shown in FIG. 8, this excess insulating layer 14 is formed of the current collector protective member material 14A integrally formed at the edge part of the ring-shaped insulating layer material 13A. In the present embodiment, as shown in Fig. 8, two surplus insulating layer materials 13B including insulating layer material 13A and current collector protection member material 14A are prepared, and these two surplus insulating layer materials 13B are combined with anode collection. 7, the positive electrode current collector 111 is covered with the excess insulating layer 14 by arranging both surfaces of the entire 111 to be sandwiched with the current collector protection member material 14A and then performing pressure treatment by isostatic pressure. In addition, FIG. 8 is a schematic diagram which shows the side end surface of the excess insulating layer material 13B.

The current collector protective member material 14A may be formed independently of the insulating layer material 13A, but as shown in Figs. 7 and 8, it is formed integrally with the insulating layer material 13A at the end of the insulating layer material 13A. It is preferable from a viewpoint of easiness of manufacture. The thickness of the current collector protective member 14 is, for example, preferably 10 μm or more and 500 μm or less, and 50 μm or more and 300 μm or less for one current collector protective member material 14A laminated on one side of the positive electrode current collector 111 More preferably, it is especially preferable that they are 80 micrometers or more and 200 micrometers or less. Moreover, this preferable thickness changes with the thickness of the positive electrode layer 10, and the thing close|similar to the thickness of the positive electrode active material layer 12 is suitable.

The total thickness of the current collector protection member 14 is preferably 20 μm or more and 1000 μm or less, more preferably 100 μm or more and 600 μm or less, more preferably 160 μm or more 400 μm. The following are especially preferable. As described earlier, this desirable total thickness also varies depending on the thickness of the positive electrode layer 10, and a product having a thickness close to the total thickness of the two positive electrode active material layers 12 formed on both surfaces of the positive electrode current collector 11 is suitable.

In this way, since the thickness of the current collector protective member 14 corresponds to the thickness of the positive electrode active material layer 12, the step difference between the current collector protective member 14 and the positive electrode layer 10 covering the positive electrode current collector 111 is reduced, and when the pressure treatment is performed It is possible to more effectively suppress cracks or cuts in the positive electrode current collector 111. The thickness of the two sheets of the current collector protection member material 14A laminated one by one on both surfaces of the positive electrode current collector 111 may be the same as or different from each other. Moreover, the thickness of the insulating layer 13 and the thickness of the current collector protective member 14 may mutually be same, and may differ. Since the manufacturing process can be simplified, the current collector protection member 14 is preferably made of the same material as the insulating layer 13 described above, but is not limited thereto.

The timing for covering the positive electrode current collector 111 with the current collector protection member 14 is not particularly limited, and the positive electrode current collector 111 may be covered with the current collector protection member 14 while the isostatic press is being performed. For example, when the current collector protection member material 14A forming the current collector protection member 14 is not formed integrally with the insulating layer material 13A, before laminating the positive electrode active material layer 12 on the positive electrode current collector 11, the positive electrode collector All 111 may be covered with the current collector protection member 14 .

As described above, an isostatic pressure was applied while the positive electrode current collector 111 was covered with the current collector protection member 14, and all the layers constituting the all-solid-state secondary battery 1 were brought into close contact with each other to form an untreated all-solid-state secondary battery 1A. Thereafter, as shown in FIG. 9 , the all-solid-state secondary battery 1 is completed by a removal process of removing the excess insulating layer 14 that is the current collector protection member 14 from the untreated all-solid-state secondary battery 1A. Meanwhile, in FIG. 9, FIG. 9 (a) shows the untreated all-solid-state secondary battery 1A, and FIG. 9(b) shows the all-solid-state secondary battery 1 after the excess insulating layer 14 is removed. In this FIG. 9, the insulating layer 13 is formed of the insulating layer material 13A of 2 sheets, These insulating layer material 13A can also be heated and integrated at the time of the first assembly|assembly filling, for example.

The excess insulating layer 14 is cut out by hand so that the positive electrode current collector 111 is exposed, for example, in a direction perpendicular to the stacking direction of each layer constituting the all-solid-state secondary battery 1 by hand. At this time, for example, if the cutout 13C is placed in the thickness direction between the insulating layer 13 and the surplus insulating layer 14, the surplus insulating layer 14 is easily removed. The cutout 13C may be formed from the positive electrode current collector 111 side toward the outside in the stacking direction, or may be formed from the outside in the stacking direction toward the positive electrode current collector 111 side. In addition, the cutout 13C may be formed over the entire width of the surplus insulating layer 14, but may be formed, for example, in the shape of a broken line, and one end or both ends in the width direction of the surplus insulating layer 14 as an opportunity to start cutting. The depth cut 13C may be formed only in the range of a predetermined length from the. The depth in the thickness direction of the cutout 13C is preferably in the range of 5% or more and 99% or less of the thickness of the insulating layer 13 in the stacking direction of the all-solid-state secondary battery 1.

If the depth cut 13C is formed at a depth of 5% or more of the thickness of the insulating layer, it is preferable because the excess insulating layer 14 is easily cut out. The cutout 13C having a depth of 99% or less of the thickness of the insulating layer 13 is preferable because cracks or cuts in the positive electrode current collector 111 can be suppressed while the isostatic pressure is insufficient. On the other hand, the method for removing the excess insulating layer 14 is not limited to the above-mentioned article, and for example, it may be removed by a tool or a machine instead of a human hand.

<3. Characteristics of the all-solid-state secondary battery manufactured by the manufacturing method of the present embodiment base>

In the all-solid-state secondary battery 1, in which the excess insulating layer 14 formed integrally with the insulating layer 13 was removed by elongating and cutting the insulating layer 13 by hand, as shown in FIG. 10 , the positive electrode current collector 111 was On the side end face of the insulating layer 13 on the side, a roughened portion 13D having a surface roughness different from that of the other end face of the insulating layer 13 is formed.

The roughened portion 13D is, for example, an irregular cross section formed when the excess insulating layer 14 is removed by stretching the insulating layer 13 by hand. is becoming In this embodiment, since the surplus insulating layer 14 is torn apart, resin is torn at the boundary of the surplus insulating layer 14 and the insulating layer 13, and the roughened part 13D is in a broken state.

When the cutout 13C is formed between the insulating layer 13 and the excess insulating layer 14 like this embodiment, as shown in FIG. 10, it is a part except the part in which the cutout 13C was formed. WHEREIN: This roughening Part 13D is formed. Meanwhile, FIG. 10 is a schematic view of the all-solid-state secondary battery 1 (shown in FIG. 9(b) ) after the excess insulating layer 14 has been removed, as viewed from the side from which the positive electrode current collector 111 protrudes, and the positive electrode current collector The insulating layer 13 and the positive electrode current collector 111 of the all-solid-state secondary battery are shown when the cutout 13C is formed from 111 to about half the thickness of the insulating layer 13 outward.

As mentioned above, other surface parts 13D such as the roughened part 13D are formed in different places depending on, for example, the place where the cutout 13C was formed, and between the insulating layer 13 and the surplus insulating layer 14 as a whole. It may be crazy and may be formed, and may be formed in only a part. It is preferable that the thickness in the lamination direction of the roughening part 13D is 1% or more and 95% or less of the thickness of the insulating layer which is the range except a cutout.

<4. Effects of the all-solid-state secondary battery and the all-solid-state secondary battery manufacturing method according to the present embodiment>

Since the all-solid-state secondary battery 1 forms each layer by solidifying the powder, if it is manufactured without pressure treatment by isostatic pressure, etc., there is a risk that grooves or irregularities may occur on the surface of each layer due to a slight gap between the powder and the powder. . According to the manufacturing method of the all-solid-state secondary battery 1 according to the present embodiment, since the whole is formed by isostatic pressing, the unevenness of the surface of the all-solid-state secondary battery 1 can be suppressed as small as possible. As a result, in the multilayer all-solid-state secondary battery in which a plurality of these all-solid-state secondary batteries 1 are stacked, it is possible to avoid concentrating the current only on the protrusion of the all-solid-state secondary battery 1. If it is possible to avoid concentrating the current on only a part of the surface of the all-solid-state secondary battery 1 in this way, since the entirety of the positive electrode layer 10 and the negative electrode layer 20 contributes to charging and discharging, the charge/discharge capacity of the stacked all-solid-state secondary battery can be improved. there is. Moreover, since the positive electrode layer 10 and the negative electrode layer 20 uniformly contribute to charging and discharging over the whole, it is possible to suppress, for example, concentration of metallic lithium or the like from precipitating in only a part of the place. As a result, the short circuit by precipitation of metallic lithium can also be suppressed.

In addition, since the entire surface of the positive electrode current collector 111 is covered from both sides by the current collector protection member 14 while the isostatic press is being performed, cracks in the positive electrode current collector 111 or cuts in the positive electrode current collector 111 are suppressed. can do. As a result, it is possible to manufacture highly reliable all-solid-state secondary battery 1 and stacked all-solid-state secondary battery without the need to reconnect the positive electrode current collector 111 to the positive electrode current collector 11 again.

<5. Manufacturing method of laminated all-solid-state secondary battery>

A plurality of all-solid-state secondary batteries 1 prepared as described above are laminated to obtain a laminated all-solid-state secondary battery. During lamination, the negative electrode current collector 21 and the negative electrode current collector 21 of the other all-solid-state secondary battery 1 are disposed to face each other with the insulating layer 13 interposed therebetween. Accordingly, even if a relatively large number of, for example, three or four or more all-solid-state secondary batteries 1 are stacked, it is possible to manufacture a stacked all-solid-state secondary battery that sufficiently maintains cycle characteristics and is unlikely to cause a short circuit.

<6. Charging/discharging of the all-solid-state secondary battery according to the present embodiment>

Charging and discharging of the all-solid-state secondary battery 1 according to the present embodiment will be described below.

In the all-solid-state secondary battery 1 according to the present embodiment, in the initial stage of charging, the negative electrode active material forming an alloy or compound with lithium in the negative electrode active material layer 22 forms an alloy or compound with lithium ions, so that in the negative electrode active material layer 22 Lithium is stored. After that, after exceeding the charging capacity exhibited by the negative electrode active material layer 22, metallic lithium is deposited on one or both surfaces of the negative electrode active material layer 22 to form a metallic lithium layer.

Since metallic lithium is formed by diffusion through an anode active material capable of forming an alloy or compound, it is not of several types (dendrite type), but is mainly formed uniformly between the anode active material layer 22 and the anode current collector 21. do. During discharge, metallic lithium is ionized in the anode active material layer 22 and the metallic lithium layer and moves to the cathode active material layer 12 side. Therefore, as a result, since metallic lithium itself can be used as an anode active material, energy density is improved.

In addition, when the metallic lithium layer is formed between the negative electrode active material layer 22 and the negative electrode current collector 21, that is, inside the negative electrode layer 20, the negative electrode active material layer 22 covers the metallic lithium layer. Accordingly, the anode active material layer 22 functions as a protective layer of the metal layer. Thereby, the short circuit and the capacity|capacitance fall of the all-solid-state secondary battery 1 are suppressed, and the characteristic of the all-solid-state secondary battery 1 is improved further.

In the negative electrode active material layer 22, as a method of enabling precipitation of metallic lithium, the method of making the charging capacity of the positive electrode active material layer 12 larger than the charging capacity of the negative electrode active material layer 22 is mentioned, for example. Specifically, the comparison (capacity ratio) between the charge capacity of the positive electrode active material layer 12 and the charge capacity of the negative electrode active material layer 22 satisfies the requirements of the following formula (1).

0.002 <b/a <0.5 (One)

a: the charge capacity of the positive electrode active material layer 12 (mAh)

b: charging capacity of the negative electrode active material layer 22 (mAh)

When the capacity ratio expressed by Equation (1) is greater than 0.002, the anode active material layer 22 can sufficiently mediate the precipitation of metallic lithium from lithium ions, regardless of the configuration of the anode active material layer 22, so that of the metallic lithium layer It becomes easy to perform formation appropriately. Further, when the metallic lithium layer is formed between the negative electrode active material layer 22 and the negative electrode current collector 21, it is preferable in order that the negative electrode active material layer 22 can sufficiently function as a protective layer. For this reason, the capacity ratio is more preferably 0.01 or more, and still more preferably 0.03 or more.

Also, when the capacity ratio is less than 0.5 and there is no case that the negative electrode active material layer 22 stores most of the lithium during charging, it is easy to form the metallic lithium layer uniformly regardless of the configuration of the negative electrode active material layer 22 lose The capacity ratio is more preferably 0.2 or less, and still more preferably 0.1 or less.

More preferably, the capacity ratio is greater than 0.01. This is because, when the capacity ratio is 0.01 or less, the characteristics of the all-solid-state secondary battery 1 may be deteriorated. As this reason, it is mentioned that the negative electrode active material layer 22 does not fully function as a protective layer. For example, when the thickness of the anode active material layer 22 is very thin, the capacity ratio may be 0.01 or less. In this case, there is a possibility that the negative electrode active material layer 22 may collapse due to repeated charging and discharging, and dendrites may precipitate and grow. As a result, there exists a possibility that the characteristic of the all-solid-state secondary battery 1 may fall. Moreover, it is preferable that the said capacity|capacitance ratio is smaller than 0.5. This is because, when the capacity ratio is 0.5 or more, the amount of lithium precipitated in the negative electrode layer 20 decreases, and the battery capacity may decrease. For the same reason, it is considered that the capacity ratio is more preferably less than 0.25. Moreover, when the said capacity ratio is less than 0.25, the output characteristic of a battery can also be improved more.

Here, the charge capacity of the positive electrode active material layer 12 is obtained by multiplying the specific charge capacity (mAh/g) of the positive electrode active material by the mass of the positive electrode active material in the positive electrode active material layer 12 . When a plurality of positive electrode active materials are used, a value of specific charge capacity x mass is calculated for each positive electrode active material, and the sum of these values may be defined as the charge capacity of the positive electrode active material layer 12 . The charging capacity of the negative electrode active material layer 22 is also calculated in the same way. In other words, the charge capacity of the negative electrode active material layer 22 is obtained by multiplying the specific charge capacity (mAh/g) of the negative electrode active material by the mass of the negative electrode active material in the negative electrode active material layer 22 . When a plurality of negative electrode active materials are used, a value of specific charge capacity x mass is calculated for each negative electrode active material, and the sum of these values may be used as the capacity of the negative electrode active material layer 22 . Here, the charge specific capacity of the positive electrode active material and the negative electrode active material is a capacity estimated using an all-solid half cell using lithium metal for the opposite electrode. In practice, the charging capacities of the positive electrode active material layer 12 and the negative electrode active material layer 22 are directly measured by measurement using an all-solid half cell.

As a specific method for directly measuring the charging capacity, the following method is exemplified. First, the charging capacity of the positive electrode active material layer 12 is determined by manufacturing an all-solid-state half cell using the positive electrode active material layer 12 as the working electrode and Li as the opposite electrode, and performing CC-CV charging from the OCV (opening voltage) to the upper limit charging voltage. measure The upper limit charging voltage is determined by the standard of JIS C 8712:2015, and is 4.25V for the positive electrode active material layer 12 using a lithium cobalt acid-based positive electrode active material, and for the positive electrode active material layer 12 using other positive electrode active materials The required voltage is indicated by applying the provisions of JIS C 8712:2015 A. 3.2.3 (safety requirements when other upper limit charging voltage is applied). Regarding the charging capacity of the negative electrode active material layer 22, it is measured by making an all-solid-state half cell using the negative electrode active material layer 22 as the working electrode and Li as the opposite electrode, and performing CC-CV charging from OCV (open voltage) to 0.01 V. do.

By dividing the measured charging capacity by the mass of each active material in this way, the charging specific capacity is calculated. The charging capacity of the positive electrode active material layer 12 may be an initial charging capacity measured at the time of charging in the first cycle.

In the embodiment of the present invention, the charging capacity of the positive electrode active material layer 12 is excessive with respect to the charging capacity of the negative electrode active material layer 22 . As will be described later, in the present embodiment, the all-solid-state secondary battery 1 is charged beyond the charging capacity of the negative electrode active material layer 22 . In other words, the negative electrode active material layer 22 is overcharged. At the initial stage of charging, lithium is occluded in the anode active material layer 22 . In other words, the negative electrode active material forms an alloy or compound with lithium ions that have migrated from the positive electrode layer 10 . When charging is performed beyond the capacity of the negative electrode active material layer 22, lithium is deposited on the back side of the negative electrode active material layer 22, that is, between the negative electrode current collector 21 and the negative electrode active material layer 22, and a metallic lithium layer is formed by this lithium.

This phenomenon occurs when the negative electrode active material is composed of a specific material, that is, a material that forms an alloy or compound with lithium. During discharge, lithium in the negative electrode active material layer 22 and the metallic lithium layer is ionized and moves to the positive electrode layer 10 side. Therefore, in the all-solid-state secondary battery 1, metallic lithium can be used as an anode active material. More specifically, when the charging capacity of the negative electrode layer 20 (the total charging capacity of the charging capacity exerted by the negative electrode active material layer 22 and the metallic lithium layer) is 100%, the charging capacity of 80% or more is the metallic lithium layer. It is desirable to be exhibited by

In addition, since the negative electrode active material layer 22 covers the above-described metallic lithium layer on the solid electrolyte layer 30 side, it functions as a protective layer of the metallic lithium layer and can suppress precipitation and growth of dendrites. Thereby, the short circuit and capacity|capacitance decrease of the all-solid-state secondary battery 1 are suppressed more efficiently, and by extension, the characteristic of the all-solid-state secondary battery 1 is improved.

<7. Another embodiment according to the present invention>

The all-solid-state secondary battery according to the present invention is not limited to the above. For example, the first electrode layer may be a cathode layer, and the second electrode layer may be an anode layer.

In the above embodiment, it has been described that the insulating layer is disposed on the side end face of the first pole layer, but it may also be provided with the insulating layer on the side end face of the second pole layer. At least one solid electrolyte layer 30 provided between the positive electrode layer and the negative electrode layer may be laminated, or may be laminated in two, three, four or more layers.

In the above-described embodiment, the roughened part is described as a specific example of the roughened part to be formed after the excess insulating layer is removed with the insulating layer. It may be smoother than other surfaces. The present invention is not limited to an all-solid-state lithium ion secondary battery, but can be widely applied to an all-solid-state secondary battery having a thin current collector and formed by pressure treatment such as isostatic pressing.

(Example 1)

Next, examples of the above-described embodiment will be described. In Example 1, the all-solid-state secondary battery 1 was produced by the following process, and the produced all-solid-state secondary battery 1 was evaluated.

[Production of anode layer]

LiNi _0.8 Co _0.15 Al _0.05 O ₂ (NCA) ternary powder as a cathode active material, Li ₂ SP ₂ S ₅ (80:20 mol%) amorphous powder as a sulfide-based solid electrolyte, and a cathode layer conductive material (conductive auxiliary) The vapor-grown carbon fiber powder was weighed in a mass % comparison of 60:35:5, and mixed using a rotational revolution mixer. Next, to this mixed powder, a dehydrated xylene solution in which SBR as a binder was dissolved was added so that the SBR was 5.0 mass % with respect to the total mass of the mixed powder, to prepare a primary mixed solution. A secondary liquid mixture was prepared by adding an appropriate amount of dehydrated xylene for viscosity adjustment to this primary liquid mixture.

In addition, in order to improve the dispersibility of the mixed powder, zirconia balls having a diameter of 5 mm were put into the secondary mixture so that the space, the mixing powder, and the zirconia balls occupy 1/3 of the total volume of the kneading vessel, respectively. The resulting tertiary liquid mixture was put into an autorotation mixer and stirred at 3000 rpm for 3 minutes to prepare a positive electrode active material layer coating liquid. Next, an aluminum foil current collector with a thickness of 20 μm was prepared as the positive electrode current collector 11, the positive electrode current collector 11 was mounted on a desktop screen printing machine, and the positive electrode active material layer coating solution was applied onto the sheet using a metal mask having a thickness of 150 μm. .

After that, the sheet coated with the positive electrode active material layer coating solution was dried on a hot plate at 60°C for 30 minutes, then applied to the back side, and dried in a hot plate at 60°C for 30 minutes, and then vacuum dried at 80°C for 12 hours. did. The positive electrode active material layer 12 was formed on both sides of the positive electrode current collector 11 by piercing it into a rectangular plate shape with a Thompson blade. The total thickness of the positive electrode current collector 11 and the positive electrode active material layer 12 after drying was about 330 μm.

The insulating resin film was punched out with a pinnacle die to prepare an surplus insulating layer material 13B in which the current collector protective member material 14A and the insulating layer material 13A were integrated. The shape of the insulating layer material 13A included in the surplus insulating layer material 13B was a ring-shaped article having a size that could accurately surround the positive electrode active material layer 12 around it. The insulating resin film used in this example was made by Dainippon Printing Co., Ltd. containing a resin nonwoven fabric as an insulating filler. A notch of about 70% of the thickness of the film is formed in the thickness direction of the film between this surplus portion (current collector protective member material 14A) and the ring-shaped portion (insulating layer material 13A), and current collector protective member material It has become a structure in which the excess insulating layer 14 formed by 14A can be cut out easily after press-formation.

The positive electrode current collector 11 and the positive electrode active material layer 12 are placed on an aluminum plate (support material) having a thickness of 3 mm to which a PET film (hereinafter referred to as a release film) with a surface release treatment is attached, and the above-described insulating layer material 13A is applied to the positive electrode active material layer 12. After arranging the perimeter, it was further covered with a release film, and further covered with a metal plate (support material) made of SUS having the same shape as the excess insulating layer material 13B with a thickness of 0.3 mm, followed by a vacuum lamination pack including the supporting material. The insulating layer material 13A was integrated with the positive electrode current collector 11 and the positive electrode active material layer 12 by submerging it in a pressurized medium and performing hydrostatic pressure treatment (compression/compression chemical industry degree by isostatic press) at 490 MPa.

A positive electrode active material layer 12 is laminated on both surfaces of this positive electrode current collector 11, and an insulating layer material 13A covering a peripheral surface different from the stacking direction of these positive electrode active material layers 12 is referred to as a positive electrode layer 10A before cutting. .

[Production of cathode layer]

As the negative electrode current collector 21, a nickel foil current collector having a thickness of 10 μm was prepared.

In addition, as an anode active material, CB1 manufactured by Asahi Carbon (Nitrogen adsorption specific surface area is about 339 m2/g, DBP oil supply is about 193 ml/100 g), CB2 manufactured by Asahi Carbon Company (Nitrogen adsorption specific surface area is about 52 m2/g, DBP oil supply amount is about 193 ml/100 g) and silver particles having a particle size of 3 µm were prepared. In addition, as the particle diameter of this silver particle, the median diameter (so-called D50) measured using a laser-type particle size distribution meter can be used, for example. Next, 1.5 g of CB1, 1.5 g of CB2, and 1 g of silver particles were put in a container, and 4 g of an N-methylpyrrolidone (NMP) solution containing 5% by mass of a binder (#9300 manufactured by Kureha Corporation) was added thereto. Next, a negative electrode active material layer coating solution was prepared by gradually adding NMP of a total amount of 30 g to this mixed solution and using the mixed solution in a gaiter.

This negative electrode active material layer coating solution was applied on Ni foil using a blade coater, and dried in the air at 80°C for about 20 minutes to form a negative electrode active material layer 22. The laminate thus obtained was vacuum-dried at 100°C for about 12 hours and pierced with a Pinnacle die. By the above process, the negative electrode layer 20 was produced.

[Production of solid electrolyte layer coating solution]

To Li ₂ SP ₂ S ₅ (80:20 mol%) amorphous powder as a sulfide-based solid electrolyte, an SBR binder dissolved in dehydrated xylene was added so as to be 1% by mass based on the solid electrolyte, to produce a primary mixed slurry. Further, by adding appropriate amounts of dehydrated xylene and dehydrated diethylbenzene for viscosity adjustment to this primary mixed slurry, a secondary mixed slurry was produced. In addition, in order to improve the dispersibility of the mixed powder, zirconia balls having a diameter of 5 mm were introduced into the tertiary mixing slurry such that the space, the mixing powder, and the zirconia balls each occupy 1/3 of the total volume of the kneading vessel. The tertiary liquid mixture thus prepared was put into an autorotation mixer, and stirred at 3000 rpm for 3 minutes to prepare a solid electrolyte layer coating liquid.

[Production of solid electrolyte sheet]

The prepared solid electrolyte layer coating solution was applied with a blade onto a PET film having a release treatment on the surface, dried on a hot plate at 40°C for 10 minutes, and vacuum dried at 40°C for 12 hours to obtain a solid electrolyte sheet.

The thickness of the solid electrolyte layer after drying was around 42 μm. The dry solid electrolyte sheet was punched out with a Thompson blade and processed to a predetermined size.

[Production of Electrolyte Cathode Structure]

A solid electrolyte sheet is placed on the surface of the negative electrode layer 20 so that the solid electrolyte layer 30 and the negative electrode active material layer 22 are in contact, and these are burned on an aluminum plate (support material) with a thickness of 3 mm to which a release film is pasted, and vacuum by including the support material Laminate pack was performed. The solid electrolyte layer in the form of a solid electrolyte sheet was integrated with the negative electrode layer 20 by immersing it in a pressurized medium and performing isostatic treatment (compression/compression chemical industry grade by isostatic press) at 10 MPa. Let this be called electrolyte cathode structure 20A.

[Production of all-solid-state secondary battery]

The prepared positive electrode layer 10A before cutting was arranged so as to be sandwiched by two electrolyte negative electrode structures 20A. At this time, the outer edge 2E on the side from which the positive electrode current collector 111 of the electrolyte negative electrode structure 20A protrudes was disposed between the cutout 13C and the side end surface S of the positive electrode layer 10 . Take out this laminate, put it on an aluminum plate (support material) with a thickness of 3 mm to which a release film is attached, cover with a release film, and a metal plate made of SUS (support material) with a thickness of 0.3 mm and the same shape as the electrolyte cathode structure 20A Moreover, after covering, the vacuum lamination pack was performed by including a support material. It was submerged in a pressurized medium, and hydrostatic treatment (compression-bonding/compression chemical industry grade by an isostatic press) was performed at 490 MPa.

Subsequently, the obtained untreated all-solid-state secondary battery 1A is taken out from the laminate pack, and the surplus insulating layer 14 is cut out from the cutout 13C formed between the insulating layer 13 and the surplus insulating layer 14, the single cell of the all-solid-state secondary battery 1 (cell) was produced. On the other hand, in Examples, an aluminum plate and a metal plate made of SUS are used as the supporting material, but the material of these supporting materials is not particularly limited as long as the material has sufficient strength for pressure processing by isostatic pressure.

[Production of stacked all-solid-state secondary battery]

After the prepared single cell of the all-solid-state secondary battery 1 was laminated in four layers, Al metal tabs and Ni metal tabs were welded to the positive electrode current collector 111 and the negative electrode current collector 211, respectively, and a laminate pack was applied to obtain a laminated all-solid-state secondary battery.

[Evaluation of all-solid-state secondary batteries]

The stacked all-solid-state secondary battery produced in the above procedure is sandwiched between two metal plates from the outside in the stacking direction, and a screw with a disk spring is passed through a hole previously drilled in the metal plate, and the pressure applied to the battery is 1.0. Tighten the screw to MPa.

In the evaluation of the battery characteristics, as described above, the laminated all-solid-state secondary battery in the pressurized state was charged at 45 degrees at a constant current of 0.1C, up to an upper limit voltage of 4.25V, and then charged at a constant voltage until a current of 0.05C. and discharge was evaluated by the charge-discharge evaluation apparatus TOSCAT-3100 under the charge-discharge conditions of discharging 0.1C to a final voltage of 2.5V. This evaluation result is shown in FIG.

In addition, for cycle evaluation of charge and discharge, the stacked all-solid-state secondary battery in the pressurized state as described above is charged at a constant current of 0.33 C at 45 degrees to an upper limit voltage of 4.25 V, and a final voltage of 0.33 C to 2.5 V. The charging/discharging cycle evaluation was performed. The results are shown in FIG. 12 .

Moreover, about this laminated all-solid-state secondary battery, the thickness of the whole including a laminated film was measured with the film thickness measuring device. The measurement evaluated the surface unevenness|corrugation by examining the dispersion|variation in behavior and thickness in 6 other points|pieces. The results are shown in Table 1.

In the graph of Fig. 11, overcharge or spike-shaped charge/discharge curve that exceeds the theoretical capacity is not observed, charging and discharging are performed without any problem, there is no short circuit phenomenon, and cracks or cuts in the positive electrode current collector 111 are observed. It can be seen that there is no In addition, from the graph of Fig. 11, it was confirmed that the multilayer all-solid-state secondary battery produced in Example 1 can be charged and discharged without short circuit. In addition, as a result of FIG. 12 , it was confirmed that the multilayer all-solid-state secondary battery manufactured in Example 1 exhibited stable charge/discharge cycle characteristics.

(Example 2)

In Example 2, the all-solid-state secondary battery 1 and these all-solid-state secondary batteries 1 were stacked in the same manner as in Example 1 except that two layers of the solid electrolyte layer 30 were formed between the positive electrode layer 10 and the negative electrode layer 20. A laminated all-solid-state secondary battery was produced and evaluated. A method of forming two solid electrolyte layers 30 is as follows.

[Production of Electrolyte Anode Structure]

With the positive electrode layer 10A sandwiched between two solid electrolyte sheets, these are placed on an aluminum plate (supporting material) with a thickness of 3 mm pasted with a release film, covered with a release film, and cut to a thickness of 0.3 mm Front positive electrode After covering again with the SUS-made metal plate (support material) of the same shape as layer 10A, the support material was included and the vacuum lamination pack was performed. It was submerged in a pressurized medium and subjected to hydrostatic pressure treatment at 30 MPa (squeezing/compression chemical industry grade by isostatic press), so that the electrolyte layer on the electrolyte sheet was integrated with the positive electrode layer 10A before being cut. Let this be called an electrolyte anode structure.

[Production of all-solid-state secondary batteries and stacked all-solid-state secondary batteries]

After arranging the produced electrolyte positive electrode structure to sandwich the two electrolyte negative electrode structures 20A, an all-solid-state secondary battery 1 and a laminated all-solid-state secondary battery were produced in the same manner as in Example 1.

[Evaluation of all-solid-state secondary batteries]

For the laminated all-solid-state secondary battery produced in Example 2, charge/discharge evaluation and charge/discharge cycle evaluation were performed in the same procedure as in Example 1, the results of the charge/discharge evaluation are shown in FIG. 13, and the results of the charge/discharge cycle evaluation are shown in FIG. 12, respectively. 13 and 12, in the case of using the all-solid-state secondary battery 1 in which two layers of the solid electrolyte layer 30 were laminated between the positive electrode layer 10 and the negative electrode layer 20, the positive electrode current collector 111 was similar to that of Example 1. It was confirmed that the silver was not cracked or cut, and there was no short circuit and stable charging and discharging was possible.

(Comparative Example 1)

Instead of the surplus insulating layer material 13B used in Example 1, the insulating layer material 13A without the cutout 13C and the current collector protective member material 14A was used, except for the all-solid-state secondary battery 1 and stacked in the same order as in Example 1 An all-solid-state secondary battery was produced, and charging/discharging evaluation was performed in the procedure similar to Example 1. This evaluation result is shown in FIG. In the graph of Fig. 14, from the fact that a spike-shaped charge-discharge curve was observed, and the positive electrode current collector 111 was cracked or cut, only a charge-discharge capacity significantly lower than the theoretical capacity could be detected. In the case of the graph of Fig. 14, if calculated from the comparison between the charge/discharge capacity and the theoretical capacity, two or three all-solid-state secondary batteries of the four-layer all-solid-state secondary battery 1 constituting the stacked all-solid-state secondary battery If the positive electrode current collector 111 of Battery 1 is cracked or cut, it is considered.

(Comparative Example 2)

Instead of the surplus insulating layer material 13B used in Example 1, the insulating layer material 13A without the cutout 13C and the current collector protection member material 14A was used, and the [Production of the positive electrode layer] process and the [Production of the all-solid-state secondary battery] In the process, the laminated all-solid-state secondary battery 1 was manufactured in the same manner as in Example 1, except that the all-solid-state secondary battery 1 was manufactured using only an aluminum plate as a support material without using the 0.3 mm SUS metal plate used in Example 1. A battery was produced and this laminated all-solid-state secondary battery was evaluated.

About this laminated all-solid-state secondary battery, it carried out similarly to Example 1, and the thickness of the whole including a laminated film was measured with the film thickness measuring device. The measurement evaluated the surface unevenness|corrugation by examining the dispersion|variation in behavior and thickness in 6 other points|pieces. The results are shown in Table 1. The result of the charge/discharge evaluation was shown in FIG. 15, and the result of the charge/discharge cycle evaluation was shown in FIG. 12, respectively.

As a result of Fig. 15, in the multilayer all-solid-state secondary battery produced in Comparative Example 2, since an excess charge was generated above the theoretical capacity, the positive electrode current collector 111 did not crack or cut, but if a short circuit occurred, are considered Also, from the result of Fig. 12, it can be seen that the charge/discharge capacity deteriorated remarkably due to the short circuit.

(Example 3)

The all-solid-state secondary battery 1 prepared in Example 1 was not laminated as a single cell, and Al metal tabs and Ni metal tabs were welded to the positive electrode current collector 11 and the negative electrode current collector 21, respectively, and a laminate pack was applied to the battery test. 16 shows the results of evaluation of charge/discharge cycle characteristics in the same manner as in Example 1. From the results, it was possible to observe the same good cycle characteristics as the laminated all-solid-state secondary battery of Example 1. About the all-solid-state secondary battery 1 of this Example 3, the thickness was made the same as that of Example 1, and the thickness of 6 points was measured using a film thickness meter over the whole thickness including the laminate film, and the thickness of The variance was evaluated. The results are shown in Table 1.

(Comparative Example 3)

All-solid-state secondary battery 1 prepared in Comparative Example 2 was not laminated, but a single cell, laminated pack, over the entire thickness including the laminate film, and 6-point thickness was measured using a film thickness meter, and the thickness variation evaluated. The measurement method is the same as in Example 1. The results are shown in Table 1.

number of single cells gasket thickness
/μm Average thickness/
μm Standard Deviation Example 1 4 With current collector protection member 1860
1868
1852
1856
1865
1851 1859 6.3 Example 3 One With current collector protection member 627
620
621
635
619
615 623 6.5 Comparative Example 2 4 No protection member for current collector 1793
1810
1799
1812
1817
1809 1807 8.1 Comparative Example 3 One No protection member for current collector 670
652
652
627
625
619 641 18.3

As a result of Table 1, when the variation in thickness is compared with respect to Example 1 and Comparative Example 2, Example 3 and Comparative Example 3, respectively, when performing isostatic pressing, an SUS metal plate having a thickness of 0.3 mm was used. In Examples 1 and 3, Comparative Example 1 (in which a support material was placed on only one side of the positive electrode layer 10 or the all-solid-state secondary battery 1 and subjected to pressure treatment) without using a metal plate made of SUS when performing isostatic pressing And it turns out that the dispersion|variation in thickness is clearly smaller than that of Comparative Example 3, and the surface unevenness|corrugation is suppressed. If the unevenness of the surface can be suppressed small, the concentration of the current by concentrating only on the protrusion is eliminated. When the current is not applied by concentrating only on a portion in this way, the entirety of the positive electrode layer 10 and the negative electrode layer 20 contributes to charging and discharging, so that the charging and discharging capacity of the all-solid-state secondary battery 1 can be improved. In addition, since the positive electrode layer 10 and the negative electrode layer 20 uniformly contribute to charging and discharging over the whole, it is possible to suppress a short circuit due to concentration and deposition in only a part of the lithium metal or the like, for example. As a result, as shown in FIG. 12, in Examples 1 and 2, it is considered that a short circuit did not generate|occur|produce and the stable charging/discharging cycle was implement|achieved. As can be seen from the above results, as in Example 1 or Example 3, in order to make the surface of the all-solid-state secondary battery 1 more flat, the positive electrode layer 10, the negative electrode layer 20, or a laminate forming the all-solid-state secondary battery 1 It is preferable to pressurize in a state sandwiched by two supporting materials on both surfaces in the lamination direction.

However, when a pressure treatment such as isostatic pressing is performed in a state sandwiched by a supporting material from both sides, as can be seen from the comparison between Comparative Example 1 and Comparative Example 2, cracks are formed in the current collector or the current collector is cut or it is more likely to happen Therefore, it is considered that the effect by providing the surplus insulating layer 14 was exhibited more remarkably when the pressurization process was performed in the state which sandwiched the all-solid-state secondary battery 1 from both surfaces as a support material.

In this way, when performing pressure treatment such as isostatic pressing while sandwiching the support material from both sides, the positive electrode layer 10, the negative electrode layer 20, or the all-solid state to be pressurized is the shape viewed from the lamination direction of the one supporting material. It is preferable to make it into the same shape as the shape seen from the lamination direction of the laminated body which forms the secondary battery 1. For example, as a support material, when an article of a shape larger than that of the all-solid-state secondary battery 1 is subjected to pressure treatment by isostatic pressure in a state sandwiched from both sides, it comes into contact with the positive electrode layer 10, the negative electrode layer 20, or the all-solid-state secondary battery 1 of the support body. The part that has not been done is greatly bent in the lamination direction, and the support body cannot be reused. In addition, since a space is created between the support materials due to the thickness of the all-solid-state secondary battery 1 sandwiched between the support and the support, the vacuum lamination-packed laminate material may break at the time of pressurization by isostatic pressure.

In Examples 1 and 2, a stacked all-solid-state secondary battery in which four all-solid-state secondary batteries 1 are stacked was examined, but also in a stacked all-solid-state secondary battery in which five or more layers of all-solid-state secondary battery 1 according to the present invention are stacked Similarly, it can be sufficiently inferred that the positive electrode current collector 111 does not crack or cut, and what can be done with the stacked all-solid-state secondary battery in which a short circuit hardly occurs. In addition, it cannot be overemphasized that this invention is not limited to these Examples.

1 All-solid-state secondary battery
10 anode layer
11 positive electrode current collector
12 cathode active material layer
13 insulating layer
14 Current collector protection member (excess insulating layer)
20 cathode layer
21 Anode current collector
22 Anode active material layer
30 solid electrolyte layer

Claims (20)

A first electrode layer that is either an anode layer or a cathode layer;
A solid electrolyte layer laminated on both sides of the first electrode layer,
a second electrode layer which is the other one of the positive electrode layer and the negative electrode layer laminated on the outer surface of each solid electrolyte layer;
an insulating layer disposed on the side end surface of the first electrode layer to cover the first electrode layer;
An all-solid-state secondary battery having a thin current collector protruding from the first electrode layer through the insulating layer to the outside,
An all-solid-state secondary battery, characterized in that a roughening portion having a surface roughness different from that of another end surface of the insulating layer is formed on a side end surface of the insulating layer on a side from which the current collector protrudes. In claim 1,
The all-solid-state secondary battery, characterized in that the roughened part is a roughened part whose surface is rougher than that of the other side end surfaces of the insulating layer. In claim 2,
The all-solid-state secondary battery, characterized in that the roughening part is formed when the excess insulating layer formed on the outer side of the side end surface of the insulating layer is removed. In claim 3,
The excess insulating layer is an all-solid-state secondary battery to protect the protruding portion of the current collector before removal of the insulating layer. In claim 1,
The thickness of the roughened portion in the stacking direction is 1% or more and 95% or less of the thickness of the insulating layer in the stacking direction. 5. In claim 3 or 4,
The all-solid-state secondary battery, characterized in that the excess insulating layer is integrated with the insulating layer. In claim 1,
The all-solid-state secondary battery, characterized in that the insulating layer contains a resin. In claim 7,
The all-solid-state secondary battery, characterized in that the insulating layer contains an insulating filler. In claim 8,
The insulating filler is made of at least one material selected from the group consisting of fibrous resin, resin nonwoven fabric, alumina, magnesium oxide, silica, boehmite, barium titanate, barium carbonate, yttrium oxide, and manganese oxide, characterized in that All-solid-state secondary battery. In claim 1,
Part or all of the outer edge of the insulating layer on the side from which the current collector protrudes is located outside the outer edge of the second electrode layer. In claim 10,
Part or all of the outer edge of the second electrode layer is an all-solid-state secondary battery, characterized in that disposed on the insulating layer. In claim 1,
The first electrode layer is an all-solid-state secondary battery, characterized in that the positive electrode layer. In claim 1,
The solid electrolyte layer is an all-solid-state secondary battery, characterized in that it contains a sulfide-based solid electrolyte containing at least lithium, phosphorus and sulfur. In claim 1,
The negative electrode layer includes a negative electrode active material forming an alloy with lithium and/or a negative electrode active material forming a compound with lithium,
When charging, metallic lithium can be deposited inside the negative electrode layer,
All-solid-state secondary battery, characterized in that 80% or more of the charging capacity of the negative electrode layer is exhibited by metallic lithium. In claim 1,
The anode layer is an all-solid-state secondary battery, characterized in that it comprises any one or more selected from the group consisting of amorphous carbon, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin and zinc. In claim 1,
A stacked all-solid-state secondary battery, characterized in that two or more all-solid-state secondary batteries are stacked. A solid electrolyte layer is respectively laminated on both sides of the first electrode layer, which is either the positive electrode layer or the negative electrode layer, and the second electrode layer, which is the other one of the positive electrode layer or the negative electrode layer, is laminated on the outer surface of each solid electrolyte layer. and a thin current collector for electrically connecting the first electrode layer to an external wiring is disposed to protrude outward from the first electrode layer, and a current collector protection member for protecting the current collector is inexpensively disposed on the current collector A laminate manufacturing process for manufacturing a laminate with a
A pressing step of pressing the laminate in the lamination direction;
After the pressing step, the all-solid-state secondary battery manufacturing method comprising a removing step of removing the current collector protection member. In claim 17,
The laminate further includes an insulating layer disposed to cover the side end surface of the first electrode layer,
The all-solid-state secondary battery manufacturing method, characterized in that the current collector protection member is an excess insulating layer integrally formed on the side end surface of the insulating layer. In claim 18,
An all-solid-state secondary battery manufacturing method, characterized in that between the insulating layer and the excess insulating layer, to form a cutout for removing the excess insulating layer. In paragraph 19,
The all-solid-state secondary battery manufacturing method, characterized in that the cutout is formed in the range of 5% or more and 99% or less of the thickness of the excess insulating layer.

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