JP2019096476A - Series laminate type all-solid battery - Google Patents

Abstract

To provide a series laminate type all-solid battery including a sulfide solid electrolyte and having a negative electrode current collector layer containing copper as a conductive material, which can reduce a battery energy density per unit weight and which can suppress the degradation of a battery.SOLUTION: A series laminate type all-solid battery 10 has two or more unit cells (e.g. V, Vand V) which are laminated in series, and comprises a sulfide solid electrolyte. In the series laminate type all-solid battery, the unit cell Vhas an insulating layer 6 on the side face of a positive electrode collector layer 1 and a positive electrode active material layer 2. One side of the insulating layer extends from the side face of the positive electrode active material layer to a part of a surface of the positive electrode collector layer on a side opposed to a negative electrode current collector layer 5 of the unit cell V. The other side of the insulating layer extends from the side face of the positive electrode active material layer to or beyond an end of a surface of a solid electrolyte layer 3 on a side opposed to the positive electrode active material layer.SELECTED DRAWING: Figure 2

Description

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

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

  In addition, as an all-solid-state battery, a series-stacked all-solid-state battery capable of achieving high energy density and high power density has attracted attention. For example, in Patent Document 1, a bipolar electrode in which a positive electrode active material layer is formed on one side of a current collector and a negative electrode active material layer is formed on the other side is serially connected at least two layers sandwiching an electrolyte layer. U.S. Pat.

  For the production of series-stacked all-solid-state batteries, Patent Document 2 discloses covering the side of the battery element completely or partially with an insulating layer.

JP 2008-140663 A JP 2008-186595 A

  In the series-stacked all solid-state battery as described in Patent Document 2, when the side of the battery element is completely covered with the 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 that On the other hand, when the side of the battery element is partially covered with the insulating layer, the battery is particularly effective in the all solid battery using a sulfide solid electrolyte and a copper current collector such as copper foil as the negative electrode current collector layer. There is a problem that the deterioration is quick.

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

The present inventor has found that the above-mentioned problems can be solved by the following means.
In a series-stacked all-solid-state battery in which two or more unit cells are stacked in series,
The unit battery is formed by laminating 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 in this order,
The positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer include a sulfide solid electrolyte,
The negative electrode current collector layer contains copper as a conductive material,
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, and one side of the insulating layer is a side surface of the positive electrode active material layer, the other side of the positive electrode current collector layer It extends to a part of the surface of the unit battery on the side facing the negative electrode current collector layer, and the other side of the insulating layer is the side surface of the positive electrode active material layer, the positive electrode of the solid electrolyte layer Extends to or beyond the edge of the surface opposite to the active material layer,
Series stacked all solid battery.

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

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 an area difference between a positive electrode active material layer and a solid electrolyte layer of the series-stacked all-solid 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 a 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 after charging and leaving the serially stacked all solid battery of Example 1 and Comparative Example 1 in charge.

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that, for convenience of explanation, in the respective drawings, the same or corresponding parts will be denoted by the same reference symbols, and redundant description will be omitted. Not all of the components of the embodiment are necessarily required, and some components may be omitted. Mostly, 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 bipolar battery in which two or more unit cells are stacked in series,
The unit battery is formed by laminating 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 in this order,
The positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer include a sulfide solid electrolyte,
The negative electrode current collector layer contains copper as a conductive material,
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 on side surfaces 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 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 the end of the surface of the solid electrolyte layer opposite to the positive electrode active material layer or beyond the end.
It is a series-stacked all-solid-state battery.

  In the present disclosure, “serially stacked all solid state battery” is an all solid state battery in which two or more unit cells are stacked in series.

  As described above, in general, the series-stacked all-solid-state battery including a sulfide solid electrolyte and the negative electrode current collector layer containing copper as a conductive material only has a partial insulating layer on the side surface of the cell element. In the case of having a configuration to be coated, a problem was found that the battery deteriorated quickly.

  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. Unit cell Va, a unit cell Vb similarly stacked, and a unit cell Vc similarly stacked, the conventional series-stacked all-solid-state battery 100 performs a charging process by performing a charging process. The negative electrode collector layer 5 of Va has a higher potential (positive electrode potential) than the solid electrolyte layer 3 of the unit battery Vb. By this, the copper contained in the negative electrode current collector layer 5 of the unit battery Va forms copper sulfide when contacted with the sulfide solid electrolyte contained in the solid electrolyte layer 3 of the unit battery Vb, whereby the unit battery Vb is produced Self-discharge occurs, resulting in deterioration of the battery. The inventors of the present invention have found that the negative electrode current collector layer 5 of the unit cell Va is particularly likely to form copper sulfide when in contact with a sulfide solid electrolyte having a potential about 2-3 V lower than that of the unit battery Va. The Deterioration of the battery due to self-discharge can be considered between the unit battery Vb and the unit battery Vc by the same mechanism, but the description is omitted here.

  In the present disclosure, (i) 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, and (ii) the positive electrode current collector layer And 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 collector layer of another unit battery of the positive electrode collector layer from the side surface of the positive electrode active material layer It extends to a part of the side surface, 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 opposite to the positive electrode active material layer or It has two features of extending beyond the end.

  By combining this feature (i) and feature (ii), the copper contained in the negative electrode current collector layer of the unit cell is in contact with the sulfide solid electrolyte contained in the solid electrolyte layer of the unit cell adjacent to this unit cell. As a result, generation of copper sulfide can be suppressed, and 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 cell, 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 effects of the present disclosure can be achieved. Furthermore, 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, and insulated at specific locations on the side of the unit cell. By providing the layer, a short circuit between the electrodes can also be suppressed.

  Hereinafter, 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. Serially stacked all-solid-state battery 10 of the present disclosure, at least the unit cell V _1, the unit battery V _2, are stacked in series. In addition, other unit cells (for example, unit cell V ₃ ) may be stacked in series in a necessary number in the stacking direction of the unit cell V ₂ as necessary. Furthermore, 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 layer The area may be smaller than the area of the conductive 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 1 and the area of the positive electrode active material layer 2.

  In addition, the positive electrode current collector layer 1 and the positive electrode active material layer 2 may not necessarily be laminated on the central portions 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 stacked on the solid electrolyte layer 3, the solid electrolyte layer 3 may have a protrusion with a width r (r> 0). In FIG. 3, the unit cell is drawn in the form of a square, but the form is not limited to the square but may be any form according to the form of the series-stacked all solid battery.

<Feature (ii)>
An insulating layer is provided at a specific location on the side of the unit cell according to the present disclosure. When the unit battery V ₂ in FIG. 2 will be described as an example, the insulating layer 6 is provided on a side surface of the positive electrode collector layer 1 and the cathode active material layer 2. One side of the insulating layer 6 extends from the side surface of the positive electrode active material layer 2 to a part of the surface of the positive electrode current collector layer 1 facing the negative electrode current collector layer 5 of the unit battery V ₁ As shown in FIG. 4, it has a width a (a> 0) on this surface. Also, the other side of the insulating layer 6 extends from the side surface of the positive electrode active material layer 2 to the end of the surface of the solid electrolyte layer 3 on the side facing the positive electrode active material layer 2 or beyond the end And has a width c (c> 0) on this surface, as shown in FIG.

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

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

  In FIG. 4, b (b> 0) is the height of the portion of the insulating layer 6 stacked 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 viewpoint to imparting the durability of the unit cell or the series-stacked all solid battery, and a short circuit by contact of adjacent layers in the stack direction of the unit cell or the series stacked all-solid battery It is preferable to be in a range of 1 μm to 100 μm, more preferable to be in a range of 5 μm to 50 μm, and particularly preferable to be in a range of 10 μm to 30 μm from the viewpoint of preventing the

<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, It is stacked in order.

  In addition, as a type (type of all solid battery) of the series laminated type all solid battery of the present disclosure, all solid lithium battery, all solid sodium battery, all solid magnesium battery, all solid calcium battery and the like can be mentioned. Preferred are all solid lithium batteries and all solid sodium batteries, and particularly preferred are all solid lithium batteries. 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, for example, as a vehicle-mounted battery. Examples of the shape of the all-solid-state battery of the present disclosure include coin-type, laminate-type, cylindrical-type and square-type.

  Below, each structure of each layer is demonstrated, when the series-stacked all-solid-state battery of this indication 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 any known material that can be used for the 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 in view of corrosion resistance, easiness of production, economy and the like.

  It does not specifically limit as a shape of the positive electrode collector layer concerning this indication, For example, foil shape, plate shape, mesh shape etc. can be mentioned. Of these, foils are preferred.

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

(Positive electrode active material layer)
The positive electrode active material layer essentially contains a positive electrode active material. The positive electrode active material layer also contains a sulfide solid electrolyte. In addition, according to a use application, a use purpose, etc., the additive used for the positive electrode active material layer of all the solid batteries, such as a conductive support agent or a binder, can be included.

In the present disclosure, the positive electrode active material to be used is not particularly limited, and known materials can be 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- y} M _y O ₄ (M is, Al, Mg, Co, Fe, Ni, and one or more metal elements selected from Zn) such heterogeneous element substituted Li-Mn spinel composition represented by the can be mentioned, It is 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 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 can also include other solid electrolytes other than the sulfide solid electrolyte. As another solid electrolyte, what is demonstrated by the item of the "solid electrolyte layer" mentioned later can be employ | adopted suitably.

  The conductive aid is not particularly limited, and known ones may be used. Examples thereof include, but are not limited to, carbon materials such as VGCF (vapor grown carbon fiber) and carbon nanofibers and metal materials such as carbon nanofibers.

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

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

(Solid electrolyte layer)
In the present disclosure, the solid electrolyte layer essentially includes a sulfide solid electrolyte. The sulfide solid electrolyte is not particularly limited, and materials usable as the sulfide-based solid electrolyte of the all solid 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 —LiI—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 And sulfide-based solid electrolytes such as Li ₂ S-P ₂ O ₅ , LiI-Li ₃ PO ₄ -P ₂ S ₅ , or Li ₂ S-P ₂ S ₅ . Further, glass ceramics obtained by heat treatment of an amorphous sulfide-based solid electrolyte can also be used as a solid electrolyte.

In addition to the sulfide solid electrolyte described above, other solid electrolytes can also be further included. It does not specifically limit as another solid electrolyte, The material which can be utilized as a solid electrolyte of an 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 include a support salt (lithium salt) for securing ion 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 and the like as needed, in addition to the solid electrolyte described above. As a specific example, it is the same as the "binder" listed in the above-mentioned "positive electrode active material layer", and the description is omitted here.

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

(Anode active material layer)
The negative electrode active material layer essentially contains a negative electrode active material. The negative electrode active material layer also contains a sulfide solid electrolyte. In addition, according to the use application, the purpose of use, etc., the additive used for the negative electrode active material layer of all the solid batteries, such as a conductive support agent or a binder, can be included, for example.

  In the present disclosure, the negative electrode active material to be used is not particularly limited, and it may be capable of absorbing and releasing 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, hard carbon, soft carbon, carbon materials such as graphite, and the like.

  With regard to other additives such as a sulfide solid electrolyte, a conductive auxiliary agent, and a 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" It can be adopted appropriately.

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

(Anode current collector layer)
Since the present disclosure solves the problem in the negative electrode current collector layer containing copper as the conductive material, copper is essentially included as the conductive material of the negative electrode current collector layer. In addition, an alloy containing copper may be used.

  It does not specifically limit as a shape of the negative electrode collector layer concerning this indication, For example, foil shape, plate shape, mesh shape etc. can be mentioned. Of these, foils are preferred.

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

(Insulating 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 similar to the material used for a general all-solid-state battery. Among them, a resin material is preferable. Since the resin material has high durability and elasticity, for example, even if the unit cell is broken in the region where the insulating layer is formed, it is preferable that the short circuit occurs due to the extension of the insulating layer. It is possible to prevent

  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, polycarbonate and the like.

  Further, the insulating layer according to the present disclosure may have an adhesive layer on the side surface of the unit cell. This is because the adhesion between the insulating layer and the unit cell can be improved. In addition, about the material used for an adhesion layer, since it can be set as a general adhesive, description here is abbreviate | omitted.

  In the present disclosure, as a method of forming the insulating layer, an insulating layer having a desired thickness in a desired region (for example, a region having a width a shown in FIG. 4) of 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, for example, a method of forming by applying the above-described resin material, a film of the above-described resin material using a pressure-sensitive adhesive layer or the like, a positive electrode current collector layer And the method of affixing on the surface of a solid electrolyte layer etc. can be mentioned.

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 of 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 lower direction of the stacking direction Therefore, the conductive paste 7 can be installed to fill the gap. The conductive paste 7 used in the present disclosure is not particularly limited as long as it has a known conductivity, and may be, for example, a carbon paste or a paste containing a conductive metal.

  Examples of the present disclosure will be shown below. In addition, the following examples are for the purpose of illustration only and do not 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 electrode 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 support agent + 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
-Conducting auxiliary: Vapor grown 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 collector layer 5: Copper collector foil (thickness: 10 μm)
Insulating 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 described above, as shown in FIG. 6, the conductive paste 7 was not used, and the insulating layer 6 was provided only on a part of the solid electrolyte layer 3. A series-stacked all-solid-state battery 20 'for Comparative Example 1 was produced in the same manner as Example 1 except for the above.

<Evaluation>
The series-stacked all-solid-state batteries 20 and 20 'of the above-described Examples and Comparative Examples are charged at constant current up to 8 V at 1/3 (3 hour rate), and the termination current at 8 V is 1/100 C (100 The battery was charged at a constant voltage to a 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 standing. The results for the series-stacked all-solid-state battery 20 of the example are shown in FIG. 7A, and the results for the series-stacked all-solid-state battery 20 ′ of the comparative example are shown in FIG.

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 unit cell (V ₁ and V ₂ ) are substantially It was comparable. On the other hand, as shown in FIG. 7B, in the series-stacked all-solid-state battery 20 ′ of the comparative example, the unit battery V _{2 ′} positioned on the lower side (negative electrode potential side) in the stacking direction The voltage after standing was found to be much lower than the voltage after standing. This is because the sulfide contained in the solid electrolyte layer 3 of the unit battery V _{2 ′} is copper contained in the negative electrode current collector layer 5 of the unit battery V ₁ in the series laminated all solid battery 20 ′ of the comparative example. It is considered that this causes copper sulfide to be generated in contact therewith, thereby causing self-discharge of unit cell 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 of the battery due to self-discharge.

DESCRIPTION OF SYMBOLS 1 positive electrode collector layer 2 positive electrode active material layer 3 solid electrolyte layer 4 negative electrode active material layer 5 negative electrode collector layer 6 insulating 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 cell

Claims (1)

In a series-stacked all-solid-state battery in which two or more unit cells are stacked in series,
The unit battery is formed by laminating 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 in this order,
The positive electrode active material layer, the solid electrolyte layer, and the negative electrode active material layer include a sulfide solid electrolyte,
The negative electrode current collector layer contains copper as a conductive material,
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 on side surfaces 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 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 the end of the surface of the solid electrolyte layer opposite to the positive electrode active material layer or beyond the end. Series stacked all solid battery.

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