JP2021108258A - All-solid battery - Google Patents

Abstract

To provide an all-solid battery which enables the increase in battery capacity.SOLUTION: An all-solid battery comprises: a laminate chip in which a plurality of solid electrolyte layers containing a solid electrolyte and a plurality of internal electrodes containing an electrode active substance are laminated alternately, which has an almost rectangular parallelepiped shape, and in which the plurality of internal electrodes are exposed from two side faces other than two faces at its ends in a lamination direction alternately; and a pair of external electrodes formed so as to be in contact with the two side faces. At least one of the pair of external electrodes contains an electrode active substance which is the same, in polarity, as the electrode active substance included in the internal electrode connected thereto.SELECTED DRAWING: Figure 2

Description

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

In recent years, secondary batteries have been used in various fields. Secondary batteries using an electrolytic solution have problems such as leakage of the electrolytic solution. Therefore, an all-solid-state battery having a solid electrolyte and having other components made of solid is being developed.

In the field of all-solid-state batteries, in order to achieve high energy density, two or more sets of battery units (also referred to as single cells) consisting of a positive electrode, a solid electrolyte, and a negative electrode are laminated and integrated. A laminated all-solid-state battery including a laminated body has been proposed (see, for example, Patent Documents 1 and 2).

Japanese Unexamined Patent Publication No. 2007-80812 International Publication No. 2018/181379

In a stacked all-solid-state battery, it is desired to improve the battery capacity. However, it is difficult to sufficiently improve the battery capacity with the techniques of Patent Documents 1 and 2.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an all-solid-state battery capable of improving the battery capacity.

The all-solid battery according to the present invention has a substantially rectangular shape in which a plurality of solid electrolyte layers containing a solid electrolyte and a plurality of internal electrodes containing an electrode active material are alternately laminated, and other than the two surfaces at the ends in the stacking direction. A laminated chip in which a plurality of the internal electrodes are alternately exposed on the two side surfaces thereof and a pair of external electrodes formed so as to be in contact with the two side surfaces are provided, and at least one of the pair of external electrodes is connected. It is characterized by containing an electrode active material having the same electrode as the electrode active material contained in the internal electrode.

In the all-solid-state battery, in at least one of the pair of external electrodes, the region containing the electrode active material may be between the two adjacent layers of the internal electrodes.

In the all-solid-state battery, the first internal electrode containing the positive electrode active material and the second internal electrode containing the negative electrode active material are alternately exposed on the two side surfaces of the laminated chip, and the pair of external electrodes Of these, the one connected to the first internal electrode may contain a positive electrode active material, and the one connected to the second internal electrode of the pair of external electrodes may contain a negative electrode active material.

In the all-solid-state battery, the first internal electrode containing the positive electrode active material and the negative electrode active material and the second internal electrode containing the positive electrode active material and the negative electrode active material are alternately exposed on the two side surfaces of the laminated chip. , The pair of external electrodes may contain a positive electrode active material and a negative electrode active material.

In the all-solid-state battery, the first internal electrode containing the positive electrode active material and the negative electrode active material and the second internal electrode containing the positive electrode active material and the negative electrode active material are alternately exposed on the two side surfaces of the laminated chip. The one of the pair of external electrodes connected to the first internal electrode contains either a positive electrode active material or a negative electrode active material, and is connected to the second internal electrode of the pair of external electrodes. Those who are subjected to may include the other of the positive electrode active material and the negative electrode active material.

In the all-solid-state battery, at least one of the pair of external electrodes may contain a solid electrolyte together with the electrode active material.

In the all-solid-state battery, the solid electrolyte contained in at least one of the pair of external electrodes may have the same crystal structure as the solid electrolyte contained in the solid electrolyte layer.

In the all-solid-state battery, the solid electrolyte contained in at least one of the pair of external electrodes and the solid electrolyte contained in the solid electrolyte layer may have a NASICON type crystal structure.

In the all-solid-state battery, the pair of external electrodes may contain a carbon material, a metal material, or an alloy as a conductive material.

In the other all-solid-state battery according to the present invention, a plurality of solid electrolyte layers containing a solid electrolyte and a plurality of internal electrodes containing an electrode active material are alternately laminated to have a substantially rectangular shape, and the two at the end in the stacking direction. A laminated chip in which a plurality of the internal electrodes are alternately exposed on two side surfaces other than the surface and a pair of external electrodes formed so as to be in contact with the two side surfaces are provided, and at least one of the pair of external electrodes is provided. It is characterized in that the battery capacity is developed during charging and discharging.

According to the present invention, it is possible to provide an all-solid-state battery capable of improving the battery capacity.

It is a schematic cross-sectional view which shows the basic structure of an all-solid-state battery. It is a schematic cross-sectional view of the all-solid-state battery which concerns on embodiment. It is a schematic sectional view of another all-solid-state battery. It is a schematic sectional view of another all-solid-state battery. It is a figure which illustrates the flow of the manufacturing method of an all-solid-state battery. (A) and (b) are diagrams illustrating the laminating process. It is a figure which illustrates the flow of the other manufacturing method of an all-solid-state battery.

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

(Embodiment)
FIG. 1 is a schematic cross-sectional view showing the basic structure of the all-solid-state battery 100. As illustrated in FIG. 1, the all-solid-state battery 100 has a structure in which the solid electrolyte layer 30 is sandwiched between the first internal electrode 10 and the second internal electrode 20. The first internal electrode 10 is formed on the first main surface of the solid electrolyte layer 30, has a structure in which the first internal electrode layer 11 and the first current collector layer 12 are laminated, and the solid electrolyte layer 30. A first internal electrode layer 11 is provided on the side. The second internal electrode 20 is formed on the second main surface of the solid electrolyte layer 30, has a structure in which the second internal electrode layer 21 and the second current collector layer 22 are laminated, and the solid electrolyte layer 30. A second internal electrode layer 21 is provided on the side.

When the all-solid-state battery 100 is used as a secondary battery, one of the first internal electrode 10 and the second internal electrode 20 is used as a positive electrode, and the other is used as a negative electrode. In the present embodiment, as an example, the first internal electrode 10 is used as the positive electrode, and the second internal electrode 20 is used as the negative electrode.

The solid electrolyte layer 30 contains a solid electrolyte having ionic conductivity as a main component. The solid electrolyte of the solid electrolyte layer 30 is, for example, an oxide-based solid electrolyte having lithium ion conductivity. The solid electrolyte is, for example, a phosphate-based solid electrolyte having a NASICON structure. The phosphate-based solid electrolyte having a NASICON structure has a property of having high conductivity and being stable in the atmosphere. The phosphate-based solid electrolyte is, for example, a phosphate containing lithium. The phosphate is not particularly limited, and examples thereof include a lithium complex phosphate salt with Ti (for example, LiTi ₂ (PO ₄ ) ₃ ). Alternatively, Ti can be partially or wholly replaced with a tetravalent transition metal such as Ge, Sn, Hf, Zr or the like. Further, in order to increase the Li content, it may be partially replaced with a trivalent transition metal such as Al, Ga, In, Y or La. More specifically, for example, Li _{1 + x} Al _x Ge _2-x (PO ₄ ) ₃ , Li _{1 + x} Al _x Zr _2-x (PO ₄ ) ₃ , Li _{1 + x} Al _x Ti _2-x (PO ₄ ) ₃ And so on. _{For example, the Li-Al-Ge-PO 4} system to which the same transition metal as the transition metal contained in the phosphate having an olivine crystal structure contained in the first internal electrode layer 11 and the second internal electrode layer 21 is added in advance. The material is preferred. For example, if the phosphate containing Co and Li are contained in the first internal electrode layer 11 and the second internal electrode layer 21, Co added in advance the Li-Al-Ge-PO ₄ based material solid electrolyte It is preferably contained in the layer 30. In this case, the effect of suppressing the elution of the transition metal contained in the electrode active material into the electrolyte can be obtained. When the first internal electrode layer 11 and the second internal electrode layer 21 contain a phosphate containing a transition element other than Co and Li, the Li-Al-Ge-PO ₄ system to which the transition metal is added in advance is used. The material is preferably contained in the solid electrolyte layer 30.

Of the first internal electrode layer 11 and the second internal electrode layer 21, at least the first internal electrode layer 11 used as a positive electrode contains a substance having an olivine type crystal structure as an electrode active material. The second internal electrode layer 21 also preferably contains the electrode active material. Examples of such an electrode active material include phosphates containing a transition metal and lithium. The olivine-type crystal structure is a crystal possessed by natural olivine and can be discriminated by X-ray diffraction.

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

The electrode active material having an olivine type crystal structure acts as a positive electrode active material in the first internal electrode layer 11 that acts as a positive electrode. For example, when the first internal electrode layer 11 contains an electrode active material having an olivine type crystal structure, the electrode active material acts as a positive electrode active material. When the second internal electrode layer 21 also contains an electrode active material having an olivine type crystal structure, the mechanism of action of the second internal electrode layer 21 that acts as a negative electrode has not been completely clarified. The effects of increasing the discharge capacity and increasing the operating potential due to the discharge, which are presumed to be based on the formation of a partially solidified state with the negative electrode active material, are exhibited.

When both the first internal electrode layer 11 and the second internal electrode layer 21 contain an electrode active material having an olivine type crystal structure, the respective electrode active materials are preferably different from each other even if they are the same. May include transition metals. The fact that "they may be the same or different from each other" means that the electrode active materials contained in the first internal electrode layer 11 and the second internal electrode layer 21 may contain the same kind of transition metal, or may be mutually exclusive. It means that different types of transition metals may be included. The first internal electrode layer 11 and the second internal electrode layer 21 may contain only one type of transition metal, or may contain two or more types of transition metals. Preferably, the first internal electrode layer 11 and the second internal electrode layer 21 contain the same type of transition metal. More preferably, the electrode active materials contained in both internal electrode layers have the same chemical composition. When the first internal electrode layer 11 and the second internal electrode layer 21 contain the same kind of transition metal or an electrode active material having the same composition, the composition similarity between the two internal electrode layers is enhanced. Therefore, even if the terminals of the all-solid-state battery 100 are attached in the opposite direction, it has the effect of being able to withstand actual use without malfunction depending on the application.

Of the first internal electrode layer 11 and the second internal electrode layer 21, the second internal electrode layer 21 may further contain a substance known as a negative electrode active material. By containing the negative electrode active material only in one internal electrode layer, it becomes clear that the one internal electrode layer acts as a negative electrode and the other internal electrode layer acts as a positive electrode. When the negative electrode active material is contained only in one internal electrode layer, the one internal electrode layer is preferably the second internal electrode layer 21. In addition, both internal electrode layers may contain a substance known as a negative electrode active material. For the negative electrode active material of the electrode, the prior art in the secondary battery can be appropriately referred to, and for example, compounds such as titanium oxide, lithium titanium composite oxide, lithium titanium composite phosphate, carbon, and vanadium lithium phosphate. Can be mentioned.

In the production of the first internal electrode layer 11 and the second internal electrode layer 21, in addition to these electrode active materials, a solid electrolyte having ionic conductivity, a conductive material (conductive auxiliary agent) such as carbon or metal, or the like is further added. It may be added. For these members, a paste for the electrode layer can be obtained by uniformly dispersing the binder and the plasticizer in water or an organic solvent. Examples of the metal of the conductive auxiliary agent include Pd, Ni, Cu, Fe, and alloys containing these.

The first current collector layer 12 and the second current collector layer 22 contain a conductive material as a main component. For example, as the conductive material of the first current collector layer 12 and the second current collector layer 22, metal, carbon, or the like can be used.

FIG. 2 is a schematic cross-sectional view of a laminated all-solid-state battery 100a in which a plurality of battery units are laminated. The all-solid-state battery 100a includes a laminated chip 60 having a substantially rectangular parallelepiped shape. In the laminated chip 60, the first external electrode 40a and the second external electrode 40b are provided so as to be in contact with two side surfaces, which are two of the four surfaces other than the upper surface and the lower surface of the end in the stacking direction. The two side surfaces may be two adjacent side surfaces or two side surfaces facing each other. In the present embodiment, it is assumed that the first external electrode 40a and the second external electrode 40b are provided so as to be in contact with two side surfaces (hereinafter, referred to as two end surfaces) facing each other.

In the following description, those having the same composition range, the same thickness range, and the same particle size distribution range as the all-solid-state battery 100 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the all-solid-state battery 100a, a plurality of first current collector layers 12 and a plurality of second current collector layers 22 are alternately laminated. The edge edges of the plurality of first current collector layers 12 are exposed on the first end face of the laminated chip 60 and not on the second end face. The edge edges of the plurality of second current collector layers 22 are exposed on the second end face of the laminated chip 60 and not on the first end face. As a result, the first current collector layer 12 and the second current collector layer 22 are alternately conducted to the first external electrode 40a and the second external electrode 40b.

The first internal electrode layer 11 is laminated on the first current collector layer 12. A solid electrolyte layer 30 is laminated on the first internal electrode layer 11. The solid electrolyte layer 30 extends from the first external electrode 40a to the second external electrode 40b. The second internal electrode layer 21 is laminated on the solid electrolyte layer 30. A second current collector layer 22 is laminated on the second internal electrode layer 21. Another second internal electrode layer 21 is laminated on the second current collector layer 22. Another solid electrolyte layer 30 is laminated on the second internal electrode layer 21. The solid electrolyte layer 30 extends from the first external electrode 40a to the second external electrode 40b. The first internal electrode layer 11 is laminated on the solid electrolyte layer 30. In the all-solid-state battery 100a, these stacking units are repeated. As a result, the all-solid-state battery 100a has a structure in which a plurality of battery units are stacked.

The first current collector layer 12 and the two layers of the first internal electrode layer 11 sandwiching the first current collector layer 12 are regarded as one internal electrode, and the second current collector layer 22 and the two layers of the second internal electrode sandwiching the first current collector layer 22 are regarded as one internal electrode. Considering the layer 21 as one internal electrode, it can be said that the laminated chip 60 has a structure in which a plurality of internal electrodes and a plurality of solid electrolyte layers are alternately laminated.

In such a laminated all-solid-state battery 100a, further improvement in battery capacity is required. Therefore, the first external electrode 40a and the second external electrode 40b have a configuration in which the battery capacity is developed when the all-solid-state battery 100a is charged and discharged.

Specifically, at least one of the first external electrode 40a and the second external electrode 40b contains an electrode active material together with the conductive material. The conductive material is a carbon material, a metal material, an alloy or the like.

The electrode active material contained in the first external electrode 40a is an electrode active material having the same electrode as the electrode active material contained in the first internal electrode layer 11, and the electrode active material contained in the second external electrode 40b is the electrode active material contained in the second internal electrode layer 21. It is an electrode active material having the same electrode as the containing electrode active material. For example, when the first internal electrode layer 11 contains only the positive electrode active material among the positive electrode active material and the negative electrode active material, and the second internal electrode layer 21 contains only the negative electrode active material among the positive electrode active material and the negative electrode active material. The first external electrode 40a contains a positive electrode active material, and the second external electrode 40b contains a negative electrode active material. When the first internal electrode layer 11 and the second internal electrode layer 21 contain both the negative electrode active material and the positive electrode active material, the first external electrode 40a and the second external electrode 40b are also both the negative electrode active material and the positive electrode active material. including. Alternatively, when the first internal electrode layer 11 and the second internal electrode layer 21 contain both the negative electrode active material and the positive electrode active material, the first external electrode 40a contains only the positive electrode active material among the positive electrode active material and the negative electrode active material. The second external electrode 40b may contain only the negative electrode active material.

In this configuration, when the all-solid-state battery 100a is charged and discharged, the first external electrode 40a exhibits the same battery capacity as the first internal electrode layer 11, and the second external electrode 40b is the same as the second internal electrode layer 21. It develops a polar battery capacity. As a result, the battery capacity of the all-solid-state battery 100a is improved.

The first external electrode 40a and the second external electrode 40b preferably contain a solid electrolyte having ionic conductivity. By including the solid electrolyte in the first external electrode 40a and the second external electrode 40b, the path of ion conduction in the first external electrode 40a and the second external electrode 40b is secured, and the first external electrode 40a and the second external electrode 40b are secured. This is because the battery capacity is likely to be developed in the above. It is preferable to use a material that functions as a negative electrode active material and also functions as a solid electrolyte having ionic conductivity, such as a Li-Al-Ti-PO _{4-based material.}

The region of the first external electrode 40a containing the electrode active material is preferably between the two adjacent first internal electrode layers 11. That is, the region of the first external electrode 40a containing the electrode active material is preferably a region in contact with the solid electrolyte layer 30. This is because the solid electrolyte of the solid electrolyte layer 30 secures the path of ionic conduction.

Similarly, the region of the second external electrode 40b containing the electrode active material is preferably between the two adjacent second internal electrode layers 21. That is, the region of the second external electrode 40b containing the electrode active material is preferably a region in contact with the solid electrolyte layer 30.

If the amount of the electrode active material in the first external electrode 40a and the second external electrode 40b is too large, it causes poor continuity between the conductive material of the internal electrode and the external electrode, and when a plating layer is formed on the outside of the external electrode, plating is performed. It may not be formed uniformly and may also cause poor continuity. On the other hand, if the amount of the electrode active material in the first external electrode 40a and the second external electrode 40b is too small, the effect of capacity development may be reduced. Therefore, the concentration of the electrode active material in the first external electrode 40a and the second external electrode 40b is preferably 5% by volume or more and 50% by volume or less, and more preferably 10% by volume or more and 40% by volume or less. It is preferably 15% by volume or more and 30% by volume or less.

Among the electrode active materials contained in the first external electrode 40a and the second external electrode 40b, the positive electrode active material is a phosphate containing, for example, Li, Co, Fe, Mn, and Ni. The negative electrode active material is a compound such as Ti oxide or Ti-containing phosphate. When the first internal electrode 10 contains a positive electrode active material, it is preferable that the first external electrode 40a also contains the same type of positive electrode active material. When the second internal electrode 20 contains a negative electrode active material, it is preferable that the second external electrode 40b also contains the same type of negative electrode active material. Both positive and negative active materials may be contained. The thickness of the first external electrode 40a and the second external electrode 40b is preferably 0.5 μm or more and 50 μm or less, more preferably 1 μm or more and 30 μm or less, and 2 μm or more and 20 μm or less. More preferred.

Further, since the same kind of materials have high adhesion to each other, the first external electrode 40a contains a solid electrolyte, so that the first external electrode 40a realizes good adhesion to the solid electrolyte layer 30. .. In this case, since the first external electrode 40a realizes good adhesion to the first end surface of the laminated chip 60, good continuity can be obtained between the first external electrode 40a and the first internal electrode 10. Further, the second external electrode 40b realizes good adhesion to the solid electrolyte layer 30. As a result, good continuity is obtained between the second external electrode 40b and the second internal electrode 20.

For example, the solid electrolyte contained in the first external electrode 40a and the second external electrode 40b is an oxide-based solid electrolyte. However, from the viewpoint of improving the adhesion between compounds having similar structures, the solid electrolyte contained in the first external electrode 40a and the second external electrode 40b has the same crystal structure as the solid electrolyte contained in the solid electrolyte layer 30. Is preferable. For example, if the solid electrolyte contained in the solid electrolyte layer 30 has a NASICON structure, it is preferable that the solid electrolyte contained in the first external electrode 40a and the second external electrode 40b also has a NASICON structure. Further, in the same crystal structure, it is preferable that at least a part of the constituent elements is common, it is more preferable that all the constituent elements are the same, and it is further preferable that the composition is the same. For example, when the solid electrolyte layer 30 contains a Li-Al-Ge-PO _4- based material as a main component, the first external electrode 40a and the second external electrode 40b also _{contain the Li-Al-Ge-PO 4-} based material. It is preferable to have.

When the first internal electrode layer 11 contains a solid electrolyte, the solid electrolyte contained in the first external electrode 40a may have the same crystal structure as the solid electrolyte contained in the first internal electrode layer 11. In this case, in the same crystal structure, it is preferable that at least a part of the constituent elements is common, it is more preferable that all the constituent elements are the same, and it is further preferable that the composition is the same.

When the second internal electrode layer 21 contains a solid electrolyte, the solid electrolyte contained in the second external electrode 40b may have the same crystal structure as the solid electrolyte contained in the second internal electrode layer 21. In this case, in the same crystal structure, it is preferable that at least a part of the constituent elements is common, it is more preferable that all the constituent elements are the same, and it is further preferable that the composition is the same.

The innermost layer formed on the first end surface of the laminated chip 60 is the first external electrode 40a, and a plating layer may be further provided on the surface of the first external electrode 40a. Similarly, the innermost layer formed on the second end surface of the laminated chip 60 may be the second external electrode 40b, and a plating layer may be further provided on the surface of the second external electrode 40b. For example, as illustrated in FIG. 3, a plating layer 41a may be provided on the surface of the first external electrode 40a. Further, the plating layer 41b may be provided on the surface of the second external electrode 40b. The plating layer 41a and the plating layer 41b have, for example, a double structure in which the first layer is Ni-plated and the second layer is Sn-plated from the inside.

The all-solid-state battery 100a does not have to include a current collector layer. For example, as illustrated in FIG. 4, the first current collector layer 12 and the second current collector layer 22 may not be provided. In this case, the first internal electrode 10 is formed only by the first internal electrode layer 11, and the second internal electrode 20 is formed only by the second internal electrode layer 21.

Subsequently, a method for manufacturing the all-solid-state battery 100a illustrated in FIG. 2 will be described. FIG. 5 is a diagram illustrating a flow of a method for manufacturing the all-solid-state battery 100a.

(Ceramic raw material powder manufacturing process)
First, a powder of the solid electrolyte constituting the above-mentioned solid electrolyte layer 30 is prepared. For example, a powder of a solid electrolyte constituting the solid electrolyte layer 30 can be produced by mixing raw materials, additives and the like and using a solid phase synthesis method or the like. The obtained powder can be adjusted to a desired average particle size by dry pulverization. For example, it is adjusted to a desired average particle size with a planetary ball mill using a _{ZrO 2 ball having a diameter of 5 mm.}

Additives include sintering aids. As a sintering aid, for example, glass such as Li-B-O-based compound, Li-Si-O-based compound, Li-CO-based compound, Li-SO-based compound, Li-PO-based compound and the like. It contains glass components such as one or more of the components.

(Solid electrolyte green sheet manufacturing process)
Next, the obtained powder is uniformly dispersed in an aqueous solvent or an organic solvent together with a binder, a dispersant, a plasticizer, etc., and wet-pulverized to carry out wet pulverization to obtain a solid electrolyte slurry having a desired average particle size. To get. At this time, a bead mill, a wet jet mill, various kneaders, a high-pressure homogenizer, or the like can be used, and it is preferable to use the bead mill from the viewpoint that the particle size distribution can be adjusted and dispersed at the same time. A binder is added to the obtained solid electrolyte slurry to obtain a solid electrolyte paste. By applying the obtained solid electrolyte paste, a solid electrolyte green sheet can be produced. The coating method is not particularly limited, and a slot die method, a reverse coating method, a gravure coating method, a bar coating method, a doctor blade method and the like can be used. The particle size distribution after wet pulverization can be measured, for example, by using a laser diffraction measuring device using a laser diffraction scattering method.

(Paste preparation process for internal power)
Next, an internal electric paste for producing the first internal electrode layer 11 and the second internal electrode layer 21 described above is produced. For example, a paste for internal electric power can be obtained by uniformly dispersing a conductive auxiliary agent, an electrode active material, a solid electrolyte material, a binder, a plasticizer, or the like in water or an organic solvent. As the solid electrolyte material, the above-mentioned solid electrolyte paste may be used. As the conductive auxiliary agent, Pd, Ni, Cu, Fe, alloys containing these, various carbon materials, and the like may be further used. When the composition of the first internal electrode layer 11 and the composition of the second internal electrode layer 21 are different, each internal electric paste may be prepared individually.

(Paste preparation process for current collector)
Next, a current collector paste for producing the first current collector layer 12 and the second current collector layer 22 described above is produced. For example, a paste for a current collector can be obtained by uniformly dispersing Pd powder, carbon black, plate-shaped graphite carbon, binder, dispersant, plasticizer, etc. in water or an organic solvent.

(Paste preparation process for external power)
Next, an external electric paste for producing the first external electrode 40a and the second external electrode 40b described above is produced. For example, a paste for external electricity can be obtained by uniformly dispersing a conductive material, an electrode active material, a solid electrolyte, a binder, a plasticizer, or the like in water or an organic solvent.

(Laminating process)
As illustrated in FIG. 6A, the internal power paste 52 is printed on one surface of the solid electrolyte green sheet 51, the current collector paste 53 is further printed, and the internal power paste 52 is further printed. The reverse pattern 54 is printed on the solid electrolyte green sheet 51 in the area where the internal current paste 52 and the current collector paste 53 are not printed. As the reverse pattern 54, the same one as that of the solid electrolyte green sheet 51 can be used. A plurality of printed solid electrolyte green sheets 51 are laminated by alternately shifting them, and a cover sheet 55 to which the plurality of solid electrolyte green sheets are bonded is pressure-bonded from above and below in the stacking direction to obtain a laminated body. In this case, in the laminated body, a substantially rectangular parallelepiped-shaped laminated body is obtained so that the pair of the internal current paste 52 and the current collector paste 53 are alternately exposed on the two end faces. Next, as illustrated in FIG. 6B, the external electric paste 56 is applied to each of the two end faces by a dip method or the like and dried. As a result, a molded body for forming the all-solid-state battery 100a is obtained.

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

The all-solid-state battery 100a illustrated in FIG. 3 is plated by using the first external electrode 40a and the second external electrode 40b obtained by firing the paste for external power as the base layer and plating the base layer. Layers 41a and 41b can be formed.

For the all-solid-state battery 100a illustrated in FIG. 4, the step of applying the current collector paste 53 may be omitted in the step of FIG. 6A.

The first external electrode 40a and the second external electrode 40b may be baked after the firing step. FIG. 7 is a flow chart illustrating the manufacturing method in this case. For example, the external power paste 56 is not applied in the laminating step, but the external power paste 56 is applied to the two end faces of the laminated chip 60 obtained in the firing step and baked. Thereby, the first external electrode 40a and the second external electrode 40b can be formed.

Hereinafter, an all-solid-state battery was produced according to the embodiment, and its characteristics were investigated.

(Example)
Co ₃ O ₄ , Li ₂ CO ₃ , ammonium dihydrogen phosphate, Al ₂ O ₃ , and GeO ₂ are mixed, and a predetermined amount of Co is contained as a solid electrolyte material powder. Li _1.3 Al _0.3 Ge _1.7 ( PO ₄ ) ₃ was prepared by the solid phase synthesis method. The obtained powder was dry-pulverized with _{ZrO 2 balls.} Further, a solid electrolyte slurry was prepared by wet pulverization (dispersion medium: ion-exchanged water or ethanol). A binder was added to the obtained slurry to obtain a solid electrolyte paste, and a solid electrolyte green sheet was prepared. Li CoPO _{4 and Li 1.3} Al _0.3 Ti _1.7 (PO ₄ ) ₃ containing a predetermined amount of Co were synthesized by the solid phase synthesis method in the same manner as described above.

The electrode active material and the solid electrolyte material were highly dispersed by a wet bead mill or the like to prepare a ceramic paste consisting of only ceramic particles. Next, the ceramic paste and the conductive material were mixed well to prepare a paste for internal electricity. The internal electric paste for the positive electrode contained LiCoPO ₄ and Li-Al-Ge-PO ₄ based materials as the positive electrode active material. The internal electric paste for the negative electrode contained a Li-Al-Ti-PO _4- based material as the negative electrode active material.

As a paste for external electricity for a positive electrode, a paste which is a composite of conductive carbon, a Li-Al-Ge-PO _{4 material that functions as a solid electrolyte, and LiCoPO 4} that functions as a positive electrode active material was prepared. As telex paste for negative electrode, a conductive carbon, to prepare a paste is a composite of the Li-Al-Ti-PO ₄ based material serving as a negative electrode active material. The Li-Al-Ti-PO _4- based material also functions as a solid electrolyte having ionic conductivity.

An internal electric paste for the positive electrode is printed on the solid electrolyte green sheet using a screen having a predetermined pattern, a Pd paste is printed as a paste for the current collector layer, and an internal electric paste for the positive electrode is further printed. I printed it. On another solid electrolyte green sheet, a screen for internal power for the negative electrode is printed using a screen having a predetermined pattern, and then Pd paste is printed as a paste for the current collector layer, and further for internal power for the negative electrode. The paste was printed. The printed sheets are alternately stacked by shifting the electrodes to the left and right so that the electrodes are pulled out, and the solid electrolyte green sheets are stacked one above the other as a cover layer, which is then crimped by a heat-pressurized press to form a dicer. The laminate was cut to a predetermined size. As a result, a laminated body having a substantially rectangular parallelepiped shape was obtained. In the laminated body, the external power paste for the positive electrode was applied to one end face where the internal power paste for the positive electrode was exposed by a dip method and dried. An external electric paste for the negative electrode was applied to the other end face where the internal electric paste for the negative electrode was exposed by a dip method and dried. Then, it was heat-treated at 300 ° C. or higher and 500 ° C. or lower to degreas, and then heat-treated at 900 ° C. or lower and sintered to prepare a sintered body.

(Comparison example)
In the comparative example, the positive electrode for without any distinction between telex paste for telex paste and the negative electrode, conductive carbon and, Li-Al-Ge-PO 4 based material and telex paste paste is a composite of Made as. The electrode active material was not included in the paste for external electricity. This external power paste was applied to the two end faces of the laminate by a dip method and dried. Other conditions were the same as in the examples.

For the samples of Examples and Comparative Examples, the presence or absence of peeling of the external electrodes was confirmed. In addition, the initial capacity was measured. The results are shown in Table 1. For the initial capacity of the examples, the ratio when the measured value of the comparative example is “1” is described. When the battery of the comparative example is constantly charged at room temperature with a current value (0.2C) that is fully charged in 5 hours, and after a rest time of 30 seconds, it is discharged to 0 V with the same current value. The capacity was set as the initial capacity. The examples were charged and discharged with the same current values as those of the comparative examples.

In the comparative example, an initial capacity equivalent to that in the case where the external electrode was formed by Au sputtering after firing the laminate of the solid electrolyte green sheet, the paste for internal electricity and the paste for the current collector was obtained. In the examples, the initial volume was increased by 5% with respect to the sample of the comparative example. It is considered that this is because the electrode active material was contained in the paste for external power, the electrode active material was contained in the external electrode, and the external electrode developed the capacity. Moreover, in the examples, peeling of the external electrode was not confirmed. It is considered that this is because the adhesion between the external electrode and the solid electrolyte layer is improved by including the solid electrolyte in the external electrode.

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

10 1st internal electrode 11 1st internal electrode layer 12 1st current collector layer 20 2nd internal electrode 21 2nd internal electrode layer 22 2nd current collector layer 30 Solid electrolyte layer 40a 1st external electrode 40b 2nd external electrode 41a, 41b Plating layer 51 Solid electrolyte green sheet 52 Internal electrode paste 53 Current collector paste 54 Reverse pattern 55 Cover sheet 56 External electrode paste 100,100a All-solid-state battery

Claims (10)

A plurality of solid electrolyte layers containing a solid electrolyte and a plurality of internal electrodes containing an electrode active material are alternately laminated to have a substantially rectangular parallelepiped shape, and the plurality of internal electrodes are formed on two surfaces other than the two surfaces at the end in the stacking direction. Laminated chips that are exposed alternately and
A pair of external electrodes formed so as to be in contact with the two side surfaces are provided.
An all-solid-state battery characterized in that at least one of the pair of external electrodes contains an electrode active material having the same electrode as the electrode active material contained in the connected internal electrode. The all-solid-state battery according to claim 1, wherein in at least one of the pair of external electrodes, the region containing the electrode active material is between the two adjacent layers of the internal electrodes. The first internal electrode containing the positive electrode active material and the second internal electrode containing the negative electrode active material are alternately exposed on the two side surfaces of the laminated chip.
The pair of external electrodes connected to the first internal electrode contains a positive electrode active material, and the pair of external electrodes connected to the second internal electrode contains a negative electrode active material. The all-solid-state battery according to claim 1 or 2. The first internal electrode containing the positive electrode active material and the negative electrode active material and the second internal electrode containing the positive electrode active material and the negative electrode active material are alternately exposed on the two side surfaces of the laminated chip.
The all-solid-state battery according to claim 1 or 2, wherein the pair of external electrodes contains a positive electrode active material and a negative electrode active material. The first internal electrode containing the positive electrode active material and the negative electrode active material and the second internal electrode containing the positive electrode active material and the negative electrode active material are alternately exposed on the two side surfaces of the laminated chip.
The pair of external electrodes connected to the first internal electrode contains either a positive electrode active material or a negative electrode active material, and is connected to the second internal electrode of the pair of external electrodes. The all-solid-state battery according to claim 1 or 2, wherein the one contains the other of the positive electrode active material and the negative electrode active material. The all-solid-state battery according to any one of claims 1 to 5, wherein at least one of the pair of external electrodes contains a solid electrolyte together with an electrode active material. The all-solid-state battery according to claim 5, wherein the solid electrolyte contained in at least one of the pair of external electrodes has the same crystal structure as the solid electrolyte contained in the solid electrolyte layer. The whole according to claim 6 or 7, wherein the solid electrolyte contained in at least one of the pair of external electrodes and the solid electrolyte contained in the solid electrolyte layer have a NASICON type crystal structure. Solid-state battery. The all-solid-state battery according to any one of claims 1 to 8, wherein the pair of external electrodes contains a carbon material, a metal material, or an alloy as a conductive material. A plurality of solid electrolyte layers containing a solid electrolyte and a plurality of internal electrodes containing an electrode active material are alternately laminated to have a substantially rectangular parallelepiped shape, and the plurality of internal electrodes are formed on two surfaces other than the two surfaces at the end in the stacking direction. Laminated chips that are exposed alternately and
A pair of external electrodes formed so as to be in contact with the two side surfaces are provided.
An all-solid-state battery characterized in that at least one of the pair of external electrodes develops battery capacity during charging and discharging.

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