JP6885309B2 - Series stacked all-solid-state battery - Google Patents

Description

The present disclosure relates to a series-stacked all-solid-state battery, and more particularly to a series-stacked all-solid-state battery containing a sulfide solid electrolyte and a negative electrode current collector layer containing copper as a conductive material.

In recent years, lithium batteries having a high energy density have been put into practical use. In particular, a lithium battery in which the electrolyte is changed to a solid electrolyte layer and the battery is completely solidified does not use a flammable organic solvent in the battery, so that the safety device can be simplified and the manufacturing cost and productivity are excellent. It is believed that.

Further, as an all-solid-state battery, a series-stacked all-solid-state battery capable of achieving high energy density and high output density is attracting attention. For example, in Patent Document 1, at least two or more bipolar electrodes having a positive electrode active material layer formed on one surface of a current collector and a negative electrode active material layer formed on the other surface are connected in series with an electrolyte layer interposed therebetween. The all-solid-state bipolar battery laminated in the above is disclosed.

Regarding the manufacture of a series-stacked all-solid-state battery, Patent Document 2 discloses that the side surface of a battery element is completely or partially covered with an insulating layer.

Japanese Unexamined Patent Publication No. 2008-140663 Japanese Unexamined Patent Publication No. 2008-186595

In a series-stacked all-solid-state battery as in Patent Document 2, when the side surface of the battery element is completely covered with an insulating layer, the ratio of the insulating layer to the weight of the entire battery pack increases, and the energy density per weight decreases. There was a problem to end up. On the other hand, if the side surface of the battery element is partially covered with an insulating layer, especially in an all-solid-state battery in which a sulfide solid electrolyte and a copper current collector such as copper foil are used together as the negative electrode current collector layer, the battery There was a problem that it deteriorated quickly.

Therefore, the present disclosure has been made in view of the above circumstances, and is a series-laminated all-solid-state battery containing a sulfide solid electrolyte and having a negative electrode current collector layer containing copper as a conductive material, per weight. It is an object of the present invention to provide a series-stacked all-solid-state battery capable of suppressing a decrease in energy density and deterioration of a battery.

The present inventor has found that the above problems can be solved by the following means.
In a series-stacked all-solid-state battery in which two or more unit batteries are stacked in series,
The unit battery comprises a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer laminated in this order.
The positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer contain a sulfide solid electrolyte.
The negative electrode current collector layer contains copper as a conductive material and contains copper.
The areas of the positive electrode current collector layer and the positive electrode active material layer are smaller than the areas of the solid electrolyte layer, the negative electrode active material layer, and the negative electrode current collector layer.
The positive electrode current collector layer and the positive electrode active material layer have an insulating layer on the side surface, and one side of the insulating layer is from the side surface of the positive electrode active material layer to the other positive electrode current collector layer. The positive electrode of the solid electrolyte layer extends from the side surface of the positive electrode active material layer so as to extend to a part of the surface of the unit battery facing the negative electrode current collector layer and the other side of the insulating layer. Extends to or beyond the edge of the surface opposite the active material layer,
Series stacked all-solid-state battery.

According to the present disclosure, it is possible to suppress a decrease in energy density per weight and deterioration of a battery of a series-laminated all-solid-state battery containing a sulfide solid electrolyte and a negative electrode current collector layer containing copper as a conductive material. Can be done.

FIG. 1 is a schematic cross-sectional view showing an example of a conventional series-stacked all-solid-state battery. FIG. 2 is a schematic cross-sectional view showing an example of the series-stacked all-solid-state battery of the present disclosure. FIG. 3 is a schematic view showing the area difference between the positive electrode active material layer and the solid electrolyte layer of the series-stacked all-solid-state battery of the present disclosure. FIG. 4 is a schematic cross-sectional view showing a part of the series-stacked all-solid-state battery of the present disclosure. FIG. 5 is a schematic view showing the series-stacked all-solid-state battery of Example 1. FIG. 6 is a schematic view showing a series-stacked all-solid-state battery of Comparative Example 1. FIG. 7 is a graph showing the results of the series-stacked all-solid-state batteries of Example 1 and Comparative Example 1 after being charged and left to stand.

Hereinafter, embodiments for carrying out the present disclosure will be described in detail with reference to the drawings. For convenience of explanation, the same or corresponding parts are designated by the same reference numerals in each figure, and duplicate description will be omitted. Not all of the components of the embodiment are essential, and some components may be omitted. Most of all, the forms shown in the following figures are examples of the present disclosure and do not limit the present disclosure.

<< Series-stacked all-solid-state battery >>
The all-solid-state battery of the present disclosure is
In a series-stacked all-solid-state bipolar battery in which two or more unit batteries are stacked in series,
The unit battery comprises a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer laminated in this order.
The positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer contain a sulfide solid electrolyte.
The negative electrode current collector layer contains copper as a conductive material and contains copper.
The areas of the positive electrode current collector layer and the positive electrode active material layer are smaller than the areas of the solid electrolyte layer, the negative electrode active material layer, and the negative electrode current collector layer.
An insulating layer is provided on the side surface of the positive electrode current collector layer and the positive electrode active material layer.
One side of the insulating layer extends from the side surface of the positive electrode active material layer to a part of the surface of the positive electrode current collector layer on the side facing the negative electrode current collector layer of the other unit battery. The other side of the insulating layer extends from the side surface of the positive electrode active material layer to or beyond the end of the surface of the solid electrolyte layer on the side facing the positive electrode active material layer.
It is a series-stacked all-solid-state battery.

In the present disclosure, the "series-stacked all-solid-state battery" is an all-solid-state battery in which two or more unit batteries are stacked in series.

As described above, in general, a series laminated all-solid-state battery containing a sulfide solid electrolyte and having a negative electrode current collector layer containing copper as a conductive material has an insulating layer only partially on the side surface of the battery element. It has been found that the battery deteriorates quickly when it has a covering configuration.

The cause of this "deterioration" is considered to be due to the following mechanism. That is, as shown in FIG. 1, the positive electrode current collector layer 1, the positive electrode active material layer 2, the solid electrolyte layer 3, the negative electrode active material layer 4, and the negative electrode current collector layer 5 are laminated in this order. In a conventional series-stacked all-solid-state battery 100 having a unit battery Va, a unit battery Vb similarly laminated, and a unit battery Vc similarly laminated, the unit battery is charged by performing a charging process. The negative electrode current collector layer 5 of Va has a higher potential (positive electrode potential) than the solid electrolyte layer 3 of the unit battery Vb. As a result, when the copper contained in the negative electrode current collector layer 5 of the unit battery Va comes into contact with the sulfide solid electrolyte contained in the solid electrolyte layer 3 of the unit battery Vb, copper sulfide is generated, thereby producing copper sulfide of the unit battery Vb. Self-discharge occurs, resulting in deterioration of the battery. According to the diligent research of the present inventor, it has been found that the negative electrode current collector layer 5 of the unit battery Va is particularly likely to generate copper sulfide when it comes into contact with a sulfide solid electrolyte having a potential lower than that of the negative electrode current collector layer 5. It was. It should be noted that the deterioration of the battery due to self-discharge is considered between the unit battery Vb and the unit battery Vc by the same mechanism, but the description thereof will be omitted here.

In the present disclosure, (i) the area of the positive electrode current collector layer and the positive electrode active material layer is smaller than the area of the solid electrolyte layer, the negative electrode active material layer and the negative electrode current collector layer, and (ii) the positive electrode current collector layer. And has an insulating layer on the side surface of the positive electrode active material layer, and one side of the insulating layer faces the negative electrode current collector layer of the other unit battery of the positive electrode current collector layer from the side surface of the positive electrode active material layer. It extends to a part of the surface on the side, and the other side of the insulating layer extends from the side surface of the positive electrode active material layer to the end of the surface of the solid electrolyte layer on the side facing the positive electrode active material layer or. It has two characteristics: it extends beyond the ends.

By combining the feature (i) and the feature (ii), the copper contained in the negative electrode current collector layer of the unit battery comes into contact with the sulfide solid electrolyte contained in the solid electrolyte layer of the unit battery adjacent to the unit battery. Therefore, the formation of copper sulfide can be suppressed, and the deterioration of the battery can be suppressed. Further, as described above, since the insulating layer of the present disclosure does not cover the entire side surface of the unit battery, the ratio of the insulating layer to the weight of the entire battery pack is reduced, and the energy density per weight is improved. You can also. That is, the effect of the present disclosure can be achieved. Further, the areas of the positive electrode current collector layer and the positive electrode active material layer are made smaller than the areas of the solid electrolyte layer, the negative electrode active material layer, and the negative electrode current collector layer, and are insulated at a specific location on the side surface of the unit battery. By providing the layer, a short circuit between the electrodes can be suppressed.

In the following, each of the feature (i) and the feature (ii) will be described in detail.

Here, FIG. 2 is a schematic cross-sectional view showing an example of the series-stacked all-solid-state battery of the present disclosure. In the series-stacked all-solid-state battery 10 of the present disclosure, at least the unit battery V ₁ and the unit battery V ₂ are stacked in series. Further, in the stacking direction of the unit battery V ₂ , other unit batteries (for example, the unit battery V ₃ ) may be stacked in series in a required number as required. Further, the series-stacked all-solid-state battery of the present disclosure may have a battery case and a restraint jig in addition to the above configuration (not shown).

<Feature (i)>
In the present disclosure, the areas of the positive electrode current collector layer and the positive electrode active material layer are smaller than the areas of the solid electrolyte layer, the negative electrode active material layer, and the negative electrode current collector layer. When the unit cell V ₁ of the FIG. 2 will be described as an example, the area of the positive electrode collector layer 1 and the cathode active material layer 2 is smaller than the area of the solid electrolyte layer 3, the anode active material layer 4 and the negative electrode collector layer 5 It is shown that. At this time, the area of the positive electrode current collector layer 1 and the area of the positive electrode active material layer 2 may be the same or different, but the solid electrolyte layer 3, the negative electrode active material layer 4, and the negative electrode collection It may be smaller than the area of the electric body layer 5. Similarly, the area of the solid electrolyte layer 3, the area of the negative electrode active material layer 4, and the area of the negative electrode current collector layer 5 may be the same or different, but the positive electrode current collector layer It may be larger than the area of 1 and the positive electrode active material layer 2.

Further, the positive electrode current collector layer 1 and the positive electrode active material layer 2 do not necessarily have to be laminated on the central portion of the solid electrolyte layer 3, the negative electrode active material layer 4, and the negative electrode current collector layer 5. For example, as shown in FIG. 3, when the positive electrode active material layer 2 is laminated on the solid electrolyte layer 3, the solid electrolyte layer 3 may have a protruding portion having a width r (r> 0). Although the unit battery is drawn in a square shape in FIG. 3, the unit battery is not limited to a square shape and may be in any shape according to the shape of the series-stacked all-solid-state battery.

<Features (ii)>
An insulating layer is provided at a specific location on the side surface of the unit battery according to the present disclosure. Taking the unit battery V ₂ of FIG. 2 as an example, the insulating layer 6 is provided on the side surfaces of the positive electrode current collector layer 1 and the positive electrode active material layer 2. One side of the insulating layer 6 extends from the side surface of the positive electrode active material layer 2, the positive electrode collector layer 1, to a part of the negative electrode collector layer 5 opposite to the side surface of the unit battery V ₁ , Has a width a (a> 0) on this surface, as shown in FIG. Further, the other side of the insulating layer 6 extends from the side surface of the positive electrode active material layer 2 to or beyond the end of the surface of the solid electrolyte layer 3 on the side facing the positive electrode active material layer 2. However, as shown in FIG. 4, it has a width c (c> 0) on this surface.

The width c may be the same length as the end portion of the solid electrolyte layer 3, or may protrude from the end portion of the solid electrolyte layer 3. In other words, the size of the width c is the width r of the protruding portion in the solid electrolyte layer 3 when the positive electrode active material layer 2 is laminated on the solid electrolyte layer 3, as shown in FIG. It is preferable that the size is the same as (r> 0) or larger than the width r because the effects of the present disclosure can be more exerted.

Further, the width a may be 0 or more, and may be appropriately set in consideration of the convenience of construction. The upper limit (maximum value) of the width a is not particularly limited as long as the current can be supplied from the positive electrode current collector layer 1 to the positive electrode active material layer 2, and may be appropriately set.

In FIG. 4, b (b> 0) is the height of the portion of the insulating layer 6 laminated on the positive electrode current collector layer 1, that is, the thickness of the insulating layer 6. Here, the thickness of the insulating layer 6 is a short circuit due to contact between layers adjacent to each other in the stacking direction of the unit battery or the series-stacked all-solid-state battery from the viewpoint of imparting durability of the unit battery or the series-stacked all-solid-state battery. From the viewpoint of preventing the above, it is preferably in the range of 1 μm to 100 μm, more preferably in the range of 5 μm to 50 μm, and particularly preferably in the range of 10 μm to 30 μm.

<Unit battery>
In the present disclosure, a stack of a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer is referred to as a "unit battery". When the unit cell V ₁ shown in FIG. 2 will be described as an example, the positive electrode collector layer 1, the positive electrode active material layer 2, solid electrolyte layer 3, the anode active material layer 4, and the negative electrode collector layer 5, They are stacked in order.

Examples of the type of the series-stacked all-solid-state battery (type of the all-solid-state battery) of the present disclosure include an all-solid-state lithium battery, an all-solid-state sodium battery, an all-solid-state magnesium battery, and an all-solid-state calcium battery. , All-solid-state lithium battery and all-solid-state sodium battery are preferable, and all-solid-state lithium battery is particularly preferable. Further, the all-solid-state battery of the present disclosure may be a primary battery or a secondary battery, but among them, a secondary battery is preferable. This is because it can be repeatedly charged and discharged, and is useful as, for example, an in-vehicle battery. Examples of the shape of the all-solid-state battery of the present disclosure include a coin type, a laminated type, a cylindrical type, and a square type.

In the following, each configuration of each layer will be described in the case where the series-stacked all-solid-state battery of the present disclosure is an all-solid-state lithium battery.

(Positive current collector layer)
In the present disclosure, the conductive material used for the positive electrode current collector layer is not particularly limited, and a known material that can be used for an all-solid-state battery can be appropriately adopted. For example, SUS, aluminum, copper, nickel, iron, titanium, carbon and the like can be mentioned. Among these, aluminum is preferably used from the viewpoint of corrosion resistance, ease of production, economy, and the like.

The shape of the positive electrode current collector layer according to the present disclosure is not particularly limited, and examples thereof include a foil shape, a plate shape, and a mesh shape. Of these, foil-like is preferable.

The thickness of the positive electrode current collector layer according to the present disclosure is not particularly limited, and may be, for example, about 1 to 500 μm.

(Positive electrode active material layer)
The positive electrode active material layer essentially contains the positive electrode active material. The positive electrode active material layer also contains a sulfide solid electrolyte. In addition, additives used in the positive electrode active material layer of an all-solid-state battery, such as a conductive auxiliary agent or a binder, can be included according to the intended use and purpose of use.

In the present disclosure, the positive electrode active material used is not particularly limited, and known materials are used. For example, lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , Li _{1 + x} Mn _{2-x- Examples thereof include dissimilar element-substituted Li-Mn spinels having a composition represented by y My} O ₄ (M is one or more metal elements selected from Al, Mg, Co, Fe, Ni, and Zn). Not limited to these.

In the present disclosure, the sulfide solid electrolyte used is not particularly limited, and a material that can be used as a sulfide-based solid electrolyte of an all-solid-state battery can be used. As a specific example, those listed in the item of "solid electrolyte layer" described later can be appropriately adopted.

The positive electrode active material layer according to the present disclosure may also contain other solid electrolytes other than the sulfide solid electrolyte. As the other solid electrolyte, those described in the item of "solid electrolyte layer" described later can be appropriately adopted.

The conductive auxiliary agent is not particularly limited, and known ones are used. Examples thereof include, but are not limited to, carbon materials such as VGCF (gas phase growth method carbon fiber, Vapor Green Carbon Fiber) and carbon nanofibers, and metal materials.

The binder is not particularly limited, and known binders are used. Examples include, but are not limited to, materials such as polyvinylidene fluoride (PVdF) or carboxymethyl cellulose (CMC) or combinations thereof.

The thickness of the positive electrode active material layer according to the present disclosure is not particularly limited, and can be, for example, about 0.1 to 1000 μm.

(Solid electrolyte layer)
In the present disclosure, the solid electrolyte layer essentially comprises a sulfide solid electrolyte. The sulfide solid electrolyte is not particularly limited, and a material that can be used as a sulfide-based solid electrolyte for an all-solid-state battery can be used. For example, Li ₂ S-SiS ₂ , LiI-Li ₂ S-SiS ₂ , LiI-Li ₂ S-P ₂ S ₅ , Li ₂ S-P ₂ S ₅ -Li I-LiBr, Li ₂ S-P ₂ S _{5 -GeS 2, LiI-Li 2 S} -B 2 S 3, Li 3 PO 4 -Li 2 S-Si 2 S, Li 3 PO 4 -Li 2 S-SiS 2, LiPO 4 -Li 2 S-SiS, LiI _{-Li 2 S-P 2 O 5} , LiI-Li 3 PO 4 -P 2 S 5, or _Li 2 _S-P 2 _{S 5} the sulfide-based solid electrolyte and the like. Further, glass ceramics obtained by heat-treating an amorphous sulfide-based solid electrolyte can also be used as the solid electrolyte.

In addition to the above-mentioned sulfide solid electrolyte, other solid electrolytes can be further included. The other solid electrolyte is not particularly limited, and a material that can be used as the solid electrolyte of the all-solid-state battery can be used. For example, solid polymer electrolytes such as polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof can be used. The solid electrolyte can contain a supporting salt (lithium salt) for ensuring ionic conductivity. Such supporting salts include LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , and mixtures thereof.

The solid electrolyte layer according to the present disclosure may contain a binder or the like, if necessary, in addition to the above-mentioned solid electrolyte. As a specific example, it is the same as the “binder” listed in the above-mentioned “cathode active material layer”, and the description thereof will be omitted here.

The thickness of the solid electrolyte layer according to the present disclosure is not particularly limited, and can be, for example, about 0.1 to 1000 μm.

(Negative electrode active material layer)
The negative electrode active material layer essentially contains the negative electrode active material. The negative electrode active material layer also contains a sulfide solid electrolyte. In addition, additives used in the negative electrode active material layer of an all-solid-state battery, such as a conductive auxiliary agent or a binder, can be included according to the intended use and purpose of use.

In the present disclosure, the negative electrode active material used is not particularly limited as long as it can occlude and release metal ions such as lithium ions. Examples thereof include, but are not limited to, metals such as Li, Sn, Si or In, alloys of lithium and titanium, and carbon materials such as hard carbon, soft carbon and graphite.

Regarding other additives such as the sulfide solid electrolyte, the conductive auxiliary agent, and the binder used for the negative electrode active material layer according to the present disclosure, those described in the above-mentioned "Positive electrode active material layer" and "Solid electrolyte layer" are used. It can be adopted as appropriate.

The thickness of the negative electrode active material layer according to the present disclosure is not particularly limited, and can be, for example, about 0.1 to 1000 μm.

(Negative electrode current collector layer)
Since the present disclosure solves a problem in a negative electrode current collector layer containing copper as a conductive material, copper is indispensably included as a conductive material in the negative electrode current collector layer. It may be an alloy containing copper.

The shape of the negative electrode current collector layer according to the present disclosure is not particularly limited, and examples thereof include a foil shape, a plate shape, and a mesh shape. Of these, foil-like is preferable.

The thickness of the negative electrode current collector layer according to the present disclosure is not particularly limited, and may be, for example, about 1 to 500 μm.

(Insulation layer)
In the present disclosure, the material of the insulating layer is not particularly limited as long as it has a desired insulating property, and may be the same as the material used for a general all-solid-state battery. Above all, a resin material is preferable. Since the resin material has high durability and elasticity, it is preferable that a short circuit occurs due to the elongation of the insulating layer even if the unit battery is torn, for example, in the region where the insulating layer is formed. It is possible to prevent it.

Examples of the resin material used for the insulating layer according to the present disclosure include, but are not limited to, polyimide, polyester, polypropylene, polyamide, polystyrene, polyvinyl chloride, and polycarbonate.

Further, the insulating layer according to the present disclosure may have an adhesive layer on the side surface of the unit battery. This is because it is possible to improve the adhesion between the insulating layer and the unit battery. The material used for the pressure-sensitive adhesive layer can be a general pressure-sensitive adhesive, and thus the description thereof is omitted here.

In the present disclosure, as a method for forming the insulating layer, an insulating layer having a desired thickness is provided in a desired region (for example, a region having a width a shown in FIG. 4) on the surface of the positive electrode current collector layer or the solid electrolyte layer. The method is not particularly limited as long as it can be formed, and for example, a method of forming by applying the above-mentioned resin material, a film of the above-mentioned resin material, using an adhesive layer or the like, a positive electrode current collector layer. And the method of sticking to the surface of the solid electrolyte layer.

Further, in the present disclosure, the unit battery V ₁ to place the most positive potential side shown in FIG. 2, for example, it may have an insulating layer 6 as shown in FIG. 4, may not be provided ..

(Conductive paste)
As shown in FIG. 4, a gap having a thickness b (that is, the thickness of the insulating layer) between the negative electrode current collector layer 5 and the positive electrode current collector layer 1 located in the downward direction in the stacking direction. Therefore, the conductive paste 7 for filling the gap can be installed. The conductive paste 7 used in the present disclosure is not particularly limited as long as it has known conductivity, and may be, for example, a carbon paste or a paste containing a conductive metal.

Hereinafter, examples of the present disclosure will be shown. It should be noted that the following examples are merely for explanation purposes and are not intended to limit the present disclosure.

<Example 1>
Using the following materials, a press pressure of 4 ton / cm ^2, as shown in Figure 5, to produce a series stacked all-solid-state battery 20 and a unit cell V ₁ and V _2.

-Positive current collector layer 1: Aluminum current collector foil (thickness: 15 μm)
-Positive electrode active material layer 2: Positive electrode active material + sulfide solid electrolyte + conductive additive + binder (thickness: 40 μm)
− Positive electrode active material: LiNi _1/3 Mn _1/3 Co _1/3 O ₂
-Sulfide solid electrolyte: 75Li ₂ S-25P ₂ S ₅
-Conductive aid: Vapor Deposition Carbon Fiber (VGCF)
-Binder: Polyvinylidene fluoride (PVdF)
-Solid electrolyte layer 3: Sulfide solid electrolyte + binder (thickness: 30 μm)
-Sulfide solid electrolyte: 75Li ₂ S-25P ₂ S ₅
-Binder: Polyvinylidene fluoride (PVdF)
-Negative electrode active material layer 4: Carbon material + sulfide solid electrolyte + binder (thickness: 60 μm)
-Carbon material: Carbon-Sulfide solid electrolyte: 75Li ₂ S-25P ₂ S ₅
-Binder: Polyvinylidene fluoride (PVdF)
-Negative electrode current collector layer 5: Copper current collector foil (thickness: 10 μm)
-Insulation layer 6: Polyimide tape (thickness: 50 μm)
-Conductive paste 7: Carbon paste (thickness: 50 μm)

<Comparative example 1>
In the production of the series-stacked all-solid-state battery 20 of Example 1, as shown in FIG. 6, the conductive paste 7 was not used, and the insulating layer 6 was provided only partially on the solid electrolyte layer 3. A series-stacked all-solid-state battery 20'for Comparative Example 1 was produced in the same manner as in Example 1 except for the above.

<Evaluation>
The series-stacked all-solid-state batteries 20 and 20'of the above-produced examples and comparative examples are constantly charged to 8 V at 1/3 (3 hour rate), and the termination current is 1/100 C (100) at 8 V. The battery was charged to a constant voltage (time rate), and then left at 25 ° C. for 100 hours. The voltage was measured for each series-stacked all-solid-state battery before and after leaving. The results for the series-stacked all-solid-state battery 20 of the examples are shown in FIG. 7 (a), and the results for the series-stacked all-solid-state battery 20'of the comparative example are shown in FIG. 7 (b).

As shown in FIG. 7A, in the series-stacked all-solid-state battery 20 of the embodiment, the voltage before leaving and the voltage after leaving _{each of the unit batteries (V 1} and V _{2) are substantially the same.} It was about the same. In contrast, as shown in FIG. 7 (b), 'the unit batteries V ₂ located on the lower side of the stacking direction (the negative potential _side)' series stacked all-solid-state cell 20 of the comparative example It was found that the voltage after leaving was much lower than the voltage after leaving. This, 'in the copper contained in the negative electrode collector layer 5 of the unit cell V ₁ is the unit cell V _2' serial stacked type all-solid-state cell 20 of Comparative Example sulfide solid electrolyte contained in the solid electrolyte layer 3 It is probable that this was due to the fact that copper sulfide was produced in contact with the battery, which _{caused self-discharge of the unit battery V 2'.}

As is clear from the results of FIG. 7, the series-stacked all-solid-state battery 20 of the example was able to suppress deterioration due to self-discharge of the battery.

1 Positive electrode current collector layer 2 Positive electrode active material layer 3 Solid electrolyte layer 4 Negative electrode active material layer 5 Negative electrode current collector layer 6 Insulation layer 7 Conductive paste 10, 20, 20', 100 Series-stacked all-solid-state battery V ₁ , V ₂ , V _3, V _2', V _a , V _b , V _c unit battery

Claims (1)

In a series-stacked all-solid-state battery in which two or more unit batteries are stacked in series,
The unit battery comprises a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer laminated in this order.
The positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer contain a sulfide solid electrolyte.
The negative electrode current collector layer contains copper as a conductive material and contains copper.
The areas of the positive electrode current collector layer and the positive electrode active material layer are smaller than the areas of the solid electrolyte layer, the negative electrode active material layer, and the negative electrode current collector layer.
An insulating layer is provided on the side surface of the positive electrode current collector layer and the positive electrode active material layer.
One side of the insulating layer extends from the side surface of the positive electrode active material layer to a part of the surface of the positive electrode current collector layer on the side facing the negative electrode current collector layer of the other unit battery. The other side of the insulating layer extends from the side surface of the positive electrode active material layer to or beyond the end of the surface of the solid electrolyte layer on the side facing the positive electrode active material layer. Series stacked all-solid-state battery.

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