JP2024134923A - Battery and manufacturing method thereof - Google Patents

Abstract

[Problem] To provide a battery or the like capable of suppressing the occurrence of internal short circuits and enabling rapid charging. [Solution] A battery 10 includes a positive electrode layer 11, a negative electrode layer 12 disposed opposite the positive electrode layer 11, and a solid electrolyte layer 20 disposed between the positive electrode layer 11 and the negative electrode layer 12. The solid electrolyte layer 20 includes a first solid electrolyte layer 13 adjacent to the positive electrode layer 11, and a second solid electrolyte layer 14 adjacent to the negative electrode layer 12. The porosity of the first solid electrolyte layer 13 is 16% or more and 40% or less. The porosity of the second solid electrolyte layer 14 is 7% or less. [Selected Figure] Figure 1

Description

This disclosure relates to a battery and a method for manufacturing the same.

A lithium-ion secondary battery is a storage battery that has a negative electrode layer, a positive electrode layer, and an electrolyte sandwiched between the negative electrode layer and the positive electrode layer, and enables charging and discharging by moving lithium ions back and forth between the two electrode layers. Traditionally, organic electrolyte solutions have been used as the electrolyte in lithium-ion secondary batteries. However, organic electrolyte solutions are prone to leakage, and there is also a risk of short circuits occurring inside the battery due to overcharging, so there is a demand for further improvements in reliability and safety.

Under these circumstances, development of all-solid-state lithium-ion secondary batteries using inorganic solid electrolytes instead of organic electrolytes is underway. In the following, batteries using solid electrolytes as electrolytes, such as all-solid-state lithium-ion secondary batteries, are referred to as "all-solid-state batteries." All-solid-state batteries have anode layers, electrolyte layers, and cathode layers all made of solids, and are said to be able to significantly improve the safety and reliability that are issues with batteries using organic electrolytes, and to enable longer life. In addition, due to the characteristics of the solid electrolyte, such as high flame retardancy, high pack energy density due to the absence of a cooling unit, and the ability to charge at high rates, it is expected that they will be put to practical use, for example, in automobile applications.

In solid-state batteries, for example, when charging, lithium ions are released from the lithium metal composite oxide that constitutes the positive electrode layer, and these lithium ions pass through the solid electrolyte to reach the negative electrode layer and are absorbed into the negative electrode active material. At this time, some of the lithium ions absorbed into the negative electrode active material may take up electrons and precipitate as metallic lithium. If this metallic lithium precipitate grows into dendrites (branch-like crystals) through repeated charging and discharging, it will eventually come into contact with the positive electrode layer, causing an internal short circuit and preventing it from functioning as a secondary battery.

To address these issues, Patent Document 1 discloses that by highly filling the solid electrolyte, it is possible to suppress the growth of dendrites and reduce the resistance within the solid electrolyte layer.

Patent Documents 2 and 3 also disclose the use of two or more solid electrolyte layers with different porosities. In Patent Documents 2 and 3, the solid electrolyte layer in contact with the positive electrode layer has a low porosity to suppress the growth of dendrites. Furthermore, in Patent Documents 2 and 3, the solid electrolyte layer in contact with the negative electrode layer or that in contact with neither the positive electrode layer nor the negative electrode layer has a high porosity to prevent cracks from occurring in the solid electrolyte layer even if internal stress generated mainly by the expansion and contraction of the negative electrode layer during firing or charge and discharge is applied to the solid electrolyte layer. As a result, Patent Documents 2 and 3 claim that it is possible to suppress an increase in internal resistance and improve charge and discharge cycle characteristics.

JP 2021-99958 A International Publication No. 2013/175993 JP 2020-107594 A

For automotive applications, batteries are required to be capable of rapid charging. In addition, when the charging load is high, such as during rapid charging, dendrites tend to grow inside the battery, making it easy for an internal short circuit to occur.

Therefore, the present disclosure aims to provide a battery that can suppress the occurrence of internal short circuits and can be rapidly charged.

A battery according to one embodiment of the present disclosure includes a positive electrode layer, a negative electrode layer disposed opposite the positive electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, the solid electrolyte layer having a first solid electrolyte layer adjacent to the positive electrode layer and a second solid electrolyte layer adjacent to the negative electrode layer, the porosity of the first solid electrolyte layer being 16% or more and 40% or less, and the porosity of the second solid electrolyte layer being 7% or less.

In addition, a method for manufacturing a battery according to one embodiment of the present disclosure is a method for manufacturing a battery including a positive electrode layer, a negative electrode layer disposed opposite the positive electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, the solid electrolyte layer having a first solid electrolyte layer adjacent to the positive electrode layer and a second solid electrolyte layer adjacent to the negative electrode layer, and the method includes forming the first solid electrolyte layer having a porosity of 16% or more and 40% or less, and forming the second solid electrolyte layer having a porosity of 7% or less.

This disclosure makes it possible to provide a battery that can suppress the occurrence of internal short circuits and can be rapidly charged.

FIG. 1 is a schematic cross-sectional view showing an example of a battery according to an embodiment. FIG. 2 is a flowchart showing an example of a method for manufacturing a battery according to an embodiment. FIG. 3 is a schematic cross-sectional view showing an example of a positive electrode side laminate according to an embodiment. FIG. 4 is a schematic cross-sectional view showing an example of a negative electrode laminate according to an embodiment.

(How one aspect of the present disclosure was achieved)
As described above, in a battery for use in an automobile, etc., it is required that the battery be capable of rapid charging. However, when rapid charging is performed, an internal short circuit is likely to occur, and it is important to suppress the occurrence of the internal short circuit. Furthermore, when the interfacial resistance between the positive electrode layer, the solid electrolyte layer, and the negative electrode layer is high, the internal resistance of the battery becomes high, making rapid charging difficult. Therefore, it is important to suppress the growth of dendrites made of metallic lithium and the like to suppress the occurrence of an internal short circuit, and to reduce the interfacial resistance between the positive electrode layer, the solid electrolyte layer, and the negative electrode layer in order to enable rapid charging and extend the life of the battery.

In the above Patent Documents 1 to 3, both the positive electrode layer and the solid electrolyte layer in contact with the positive electrode layer have low porosity, and although the internal resistance of the positive electrode layer and the solid electrolyte layer themselves is low, the surface of the positive electrode layer and the surface of the solid electrolyte layer are both hard, and when the positive electrode layer and the solid electrolyte layer are joined after the low porosity is achieved, the contact is insufficient, the interface resistance is high, and the internal resistance of the battery is high, making rapid charging difficult. In addition, although the manufacturing process becomes complicated, when the positive electrode layer and the solid electrolyte layer are joined before the low porosity is achieved, the relatively hard positive electrode layer causes cracks in the solid electrolyte layer during the subsequent processing to reduce the porosity of the positive electrode layer. In particular, when the areas of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer are different from each other, cracks expand from the end of the layer with the smaller area when the positive electrode layer, the solid electrolyte layer, and the negative electrode layer are joined, resulting in a problem of low production yield.

Therefore, in consideration of the above problems, this disclosure provides a battery etc. that can suppress the occurrence of internal short circuits and can be rapidly charged.

(Summary of the Disclosure)
As an outline of the present disclosure, examples of a battery and a method for manufacturing a battery according to the present disclosure are given below.

The battery according to the first aspect of the present disclosure includes a positive electrode layer, a negative electrode layer disposed opposite the positive electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, the solid electrolyte layer having a first solid electrolyte layer adjacent to the positive electrode layer and a second solid electrolyte layer adjacent to the negative electrode layer, the porosity of the first solid electrolyte layer being 16% or more and 40% or less, and the porosity of the second solid electrolyte layer being 7% or less.

As a result, the first solid electrolyte layer, which has a relatively high porosity, increases the contact area between the layer adjacent to the first solid electrolyte layer, reducing reaction unevenness and interfacial resistance, thereby suppressing localized deposition and growth of metallic lithium. In addition, the second solid electrolyte layer, which has a relatively low porosity and is dense, can suppress the growth of dendrites. This makes it possible to suppress the occurrence of internal short circuits in the battery and to enable rapid charging.

For example, the battery according to the second aspect of the present disclosure may be the battery according to the first aspect, in which the first solid electrolyte layer and the second solid electrolyte layer contain an argyrodite-type sulfide-based solid electrolyte as the solid electrolyte.

As a result, the argyrodite-type sulfide-based solid electrolyte has high ionic conductivity and is stable over a wide temperature range, which improves the charge/discharge characteristics of the battery and expands the temperature range over which the battery can be used. In addition, although the argyrodite-type sulfide-based solid electrolyte is relatively hard, the porosity of the first solid electrolyte layer is relatively high as described above, which increases the contact area between the first solid electrolyte layer and the layer adjacent to the first solid electrolyte layer, thereby reducing reaction unevenness and interface resistance, thereby suppressing localized deposition and growth of metallic lithium.

The manufacturing method of a battery according to the third aspect of the present disclosure is a manufacturing method for manufacturing a battery including a positive electrode layer, a negative electrode layer disposed opposite the positive electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, the solid electrolyte layer having a first solid electrolyte layer adjacent to the positive electrode layer and a second solid electrolyte layer adjacent to the negative electrode layer, and the manufacturing method includes forming the first solid electrolyte layer having a porosity of 16% or more and 40% or less, and forming the second solid electrolyte layer having a porosity of 7% or less.

This makes it possible to manufacture a battery that can suppress the occurrence of internal short circuits and enable rapid charging.

The following describes in detail the embodiments of the present disclosure with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection forms, steps, and processes shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components that are not described in an independent claim are described as optional components.

In addition, in this specification, terms indicating the relationship between elements, such as parallel and perpendicular, terms indicating the shape of an element, such as rectangle, and numerical ranges are not expressions that only express a strict meaning, but also expressions that include substantially equivalent ranges.

In addition, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, for example, the scales of the figures do not necessarily match. In addition, in each figure, substantially the same configuration is given the same reference numerals, and duplicate explanations are omitted or simplified.

In this specification, a cross-sectional view is a diagram showing a cross section of a laminate such as a battery cut along the stacking direction at the center of the laminate. In this specification, the stacking direction coincides with the thickness direction of each layer of the battery and the direction perpendicular to the main surface of each layer of the battery.

In addition, in this specification, ordinal numbers such as "first" and "second" do not refer to the number or order of components, unless otherwise specified, but are used for the purpose of avoiding confusion and distinguishing between components of the same type.

(Embodiment)
[1. Configuration]
First, the configuration of the battery according to the present embodiment will be described.

[1-1. Battery]
First, an overview of the battery according to the present embodiment will be described.

Figure 1 is a schematic cross-sectional view showing an example of a battery according to one embodiment of the present invention.

As shown in FIG. 1, the battery 10 includes a positive electrode layer 11 containing a positive electrode active material, a negative electrode layer 12 that is disposed opposite the positive electrode layer 11 and contains a negative electrode active material, a solid electrolyte layer 20 disposed between the positive electrode layer 11 and the negative electrode layer 12, a positive electrode collector layer 15 that collects current from the positive electrode layer 11, and a negative electrode collector layer 16 that collects current from the negative electrode layer 12. The solid electrolyte layer 20 includes a first solid electrolyte layer 13 that is disposed on the positive electrode layer 11 side of the solid electrolyte layer 20 and adjacent to the positive electrode layer 11, and a second solid electrolyte layer 14 that is disposed on the negative electrode layer 12 side of the solid electrolyte layer 20 and adjacent to the negative electrode layer 12. The positive electrode layer 11 and the positive electrode collector layer 15 may be collectively referred to as a positive electrode, and the negative electrode layer 12 and the negative electrode collector layer 16 may be collectively referred to as a negative electrode.

The battery 10 is, for example, an all-solid-state battery in which the positive electrode layer 11, the negative electrode layer 12, and the solid electrolyte layer 20 are all solid. The battery 10 is not particularly limited as long as it has the positive electrode layer 11, the negative electrode layer 12, and the solid electrolyte layer 20. The shape of the battery 10 is, for example, a coin type, a pouch type, a cylindrical type, or a square type. The positive electrode layer 11, the negative electrode layer 12, the solid electrolyte layer 20, the positive electrode collector layer 15, and the negative electrode collector layer 16 may have the same planar shape and area, or at least one of these layers may have a different planar shape and area from the other layers.

The battery 10 according to this embodiment can be used in a variety of applications. There are no particular limitations on the application of the battery 10. For example, when the battery 10 is installed in an electronic device, the electronic device may be a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a mobile phone, a cordless phone handset, a pager, a handheld terminal, a mobile fax machine, a mobile copier, a mobile printer, a headphone stereo, a video movie machine, a liquid crystal television, a handheld cleaner, a portable CD, a mini disc, an electric shaver, a transceiver, an electronic organizer, a calculator, a memory card, a mobile tape recorder, a radio, a backup power source, and the like. Other consumer applications of the battery 10 include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, clocks, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder massagers, and the like), and the like. Furthermore, the battery 10 can be used for space applications. The battery 10 can also be combined with a solar cell.

The components of the battery 10 are described below.

[1-2. Solid electrolyte layer]
First, a description will be given of the solid electrolyte layer 20. The solid electrolyte layer 20 is a layer in which at least two layers including a first solid electrolyte layer 13 and a second solid electrolyte layer 14 are laminated.

The first solid electrolyte layer 13 is a solid electrolyte layer adjacent to the positive electrode layer 11. The first solid electrolyte layer 13 is disposed between the second solid electrolyte layer 14 and the positive electrode layer 11. The first solid electrolyte layer 13 may be in contact with both the second solid electrolyte layer 14 and the positive electrode layer 11.

The second solid electrolyte layer 14 is a solid electrolyte layer adjacent to the negative electrode layer 12. The second solid electrolyte layer 14 is disposed between the first solid electrolyte layer 13 and the negative electrode layer 12. The second solid electrolyte layer 14 may be in contact with both the first solid electrolyte layer 13 and the negative electrode layer 12.

The first solid electrolyte layer 13 and the second solid electrolyte layer 14 contain a solid electrolyte as a main component. Examples of the solid electrolyte include sulfide-based solid electrolytes such as Li ₂ S-P ₂ S ₅ (Li ₇ P ₃ S ₁₁ ), Li ₁₀ GeP ₂ S ₁₂ , Li ₆ PS ₅ Cl, and Li ₆ PS ₅ I, and inorganic solid electrolytes such as oxide-based solid electrolytes such as Li _1.4 Al _0.4 Ti _1.6 (PO ₄ ) ₃ , Li ₇ La ₃ Zr ₂ O ₁₂ , and Li _1.5 Al _0.5 Ge _1.5 (PO ₄ ) _3. The first solid electrolyte layer 13 and the second solid electrolyte layer 14 may contain two or more of these. Among these, from the viewpoint of ion conductivity, the first solid electrolyte layer 13 and the second solid electrolyte layer 14 may contain a sulfide-based solid electrolyte.

The first solid electrolyte layer 13 and the second solid electrolyte layer 14 may also contain an argyrodite-type sulfide-based solid electrolyte as a solid electrolyte. The argyrodite-type sulfide-based solid electrolyte is a type of sulfide-based solid electrolyte, and is a sulfide-based solid electrolyte having an argyrodite-type crystal structure. The argyrodite-type sulfide-based solid electrolyte has high lithium ion conductivity and is stable over a wide temperature range. Therefore, by using the argyrodite-type sulfide-based solid electrolyte, the charge and discharge characteristics of the battery 10 can be improved and the operating temperature range of the battery 10 can be expanded.

At least one of the first solid electrolyte layer 13 and the second solid electrolyte layer 14 may contain a binder as a constituent material. The first solid electrolyte layer 13 and the second solid electrolyte layer 14 contain a binder, thereby improving the strength of the first solid electrolyte layer 13 and the second solid electrolyte layer 14. The binder is not particularly limited as long as it is chemically and electrically stable, and examples of the binder include organic binders such as fluorine-based binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), rubber-based binders such as styrene butadiene rubber (SBR), olefin-based binders such as polypropylene (PP) and polyethylene (PE), and cellulose-based binders such as carboxymethyl cellulose (CMC). At least one of the first solid electrolyte layer 13 and the second solid electrolyte layer 14 may further contain other components other than the solid electrolyte and the binder. The content and type of each constituent material in the first solid electrolyte layer 13 and the second solid electrolyte layer 14 are set appropriately and are not limited. In addition, the content and type of each constituent material in the first solid electrolyte layer 13 and the second solid electrolyte layer 14 may be the same, or at least one of the content and type of each constituent material may be different, or both the content and type of each constituent material may be different.

The thickness of the first solid electrolyte layer 13 and the second solid electrolyte layer 14 is set appropriately and is not limited. The thickness of the first solid electrolyte layer 13 and the second solid electrolyte layer 14 is, for example, 0.01 μm to 1 mm, and may be 0.1 μm to 100 μm, or 1 μm to 25 μm. The thickness of the first solid electrolyte layer 13 and the second solid electrolyte layer 14 may be the same or different.

The ratio of the thickness of the second solid electrolyte layer 14 to the thickness of the first solid electrolyte layer 13 is, for example, 1/100 or more and 100/1 or less, may be 1/50 or more and 50/1 or less, may be 1/30 or more and 30/1 or less, or may be 1/10 or more and 10/1 or less.

Here, the first solid electrolyte layer 13 has a higher porosity than the second solid electrolyte layer 14. The first solid electrolyte layer 13 may also have a higher porosity than the positive electrode layer 11. As a result, even if the positive electrode layer 11 and the second solid electrolyte layer 14 adjacent to the first solid electrolyte layer 13 have a low porosity, when the first solid electrolyte layer 13 is brought into contact with or joined to these layers, the surface of the first solid electrolyte layer 13 undergoes plastic deformation due to the high porosity of the first solid electrolyte layer 13, resulting in good contact between the first solid electrolyte layer 13 and the positive electrode layer 11 and the second solid electrolyte layer 14, respectively. Therefore, the interface resistance between the first solid electrolyte layer 13 and the positive electrode layer 11 and the second solid electrolyte layer 14, respectively, is reduced, and a good lithium ion conduction path is formed, which is thought to suppress local deposition and growth of metallic lithium. The porosity of each layer is the ratio of the volume occupied by voids in the layer to the apparent volume of the layer. The apparent volume is calculated from the area and thickness of the layer, the volume occupied by the constituent material of the layer is calculated from the mass of the layer and the true density of the constituent material of the layer, the difference between the apparent volume and the volume occupied by the constituent material is taken as the volume occupied by voids, and the porosity is calculated by dividing the volume occupied by voids by the apparent volume.

Furthermore, when the layers of the battery 10 are joined, if the positive electrode layer 11 and the first solid electrolyte layer 13 are brought into contact or joined in a state in which the positive electrode layer 11 has a high porosity, the relatively hard positive electrode layer 11 will cause cracks in the first solid electrolyte layer 13 when the positive electrode layer 11 is subsequently processed to have a low porosity. In particular, when the positive electrode layer 11, the second solid electrolyte layer 14, and the negative electrode layer 12 have different areas and shapes, the cracks will expand from the ends of the layers with smaller areas, complicating the manufacturing process and reducing the yield during production. To address this issue, the high porosity of the first solid electrolyte layer 13 makes the first solid electrolyte layer 13 relatively soft and suppresses the occurrence of cracks, thereby suppressing a decrease in the yield during production.

In addition, by reducing the porosity of the second solid electrolyte layer 14 adjacent to the negative electrode layer 12, even if some of the lithium ions absorbed in the negative electrode active material contained in the negative electrode layer 12 take up electrons and precipitate as metallic lithium, the dense second solid electrolyte layer 14 can suppress the growth of dendrites.

Thus, the solid electrolyte layer 20 includes two layers with different roles, the first solid electrolyte layer 13 and the second solid electrolyte layer 14. This increases the contact area between the high-porosity first solid electrolyte layer 13 and the cathode layer 11 and the second solid electrolyte layer 14 adjacent to the first solid electrolyte layer 13, thereby reducing reaction unevenness and interface resistance, and suppressing localized precipitation and growth of metallic lithium. In addition, the dense second solid electrolyte layer 14 can suppress the growth of dendrites. This makes it possible to suppress the occurrence of internal short circuits in the battery 10 and to rapidly charge the battery.

The porosity of the first solid electrolyte layer 13 is 16% or more and 40% or less. If the porosity of the first solid electrolyte layer 13 is less than 16%, the first solid electrolyte layer 13 has little room for plastic deformation, and contact with other layers is insufficient, resulting in high interface resistance with the positive electrode layer 11 and the second solid electrolyte layer 14. As a result, it is believed that the lithium ion conduction path is blocked, resulting in localized precipitation and growth of metallic lithium. In addition, if the porosity of the first solid electrolyte layer 13 exceeds 40%, there are many problems in terms of manufacturing, such as the voids being too large and the solid electrolyte falling off, and the ion conductivity inside the first solid electrolyte layer 13 is reduced, resulting in a deterioration in the characteristics of the battery 10.

The porosity of the second solid electrolyte layer 14 is 7% or less. If the porosity of the second solid electrolyte layer 14 exceeds 7%, when some of the lithium ions absorbed in the negative electrode active material contained in the negative electrode layer 12 take up electrons and precipitate as metallic lithium, dendrites tend to grow in the voids of the second solid electrolyte layer 14, and the occurrence of an internal short circuit cannot be suppressed, making rapid charging difficult.

In addition, when an argyrodite-type sulfide-based solid electrolyte is contained in the first solid electrolyte layer 13 and the second solid electrolyte layer 14, the argyrodite-type sulfide-based solid electrolyte has high ionic conductivity and is hard, so that there is a tendency for the interface resistance to increase and for localized precipitation and growth of metallic lithium to occur easily. However, by having the above-mentioned porosity in the first solid electrolyte layer 13 and the second solid electrolyte layer 14, the occurrence of internal short circuits in the battery 10 can be suppressed and rapid charging is possible.

[1-3. Positive electrode layer]
Next, a description will be given of the positive electrode layer 11. The positive electrode layer 11 is disposed between the positive electrode current collector layer 15 and the solid electrolyte layer 20. The positive electrode layer 11 contains, as main components, a positive electrode active material and a solid electrolyte.

Examples of the positive electrode active material include LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , ternary lithium metal composite oxides of Ni, Co, and Mn, ternary lithium metal composite oxides of Ni, Co, and Al, and LiFePO _4. Two or more of these materials may be used for the positive electrode layer 11.

As the solid electrolyte, for example, the solid electrolytes exemplified in [1-2. Solid electrolyte layer] above can be used.

When a sulfide-based solid electrolyte is used as the solid electrolyte, the surface of the positive electrode active material may be coated with LiNbO ₃ in order to suppress the reaction of the positive electrode active material.

The positive electrode layer 11 may also contain a binder as a constituent material. The strength of the positive electrode layer 11 is improved by the positive electrode layer 11 containing a binder. For example, the binders exemplified in [1-2. Solid electrolyte layer] above can be used as the binder.

The positive electrode layer 11 may also contain a conductive material as a constituent material. When the positive electrode layer 11 contains a conductive material, the electronic conductivity of the positive electrode layer 11 is improved. Examples of conductive materials include carbon materials such as carbon nanofiber, acetylene black, and Ketjen Black (registered trademark), and metal materials such as nickel, aluminum, and stainless steel.

In addition, the positive electrode layer 11 may further contain other components as constituent materials other than the positive electrode active material, solid electrolyte, binder, and conductive material.

The content of each component material in the positive electrode layer 11 and the shape of the positive electrode layer 11 are not particularly limited. The thickness of the positive electrode layer 11 is, for example, 0.1 μm or more and 30 mm or less, and may be 1 μm or more and 1 mm or less, or 2 μm or more and 250 μm or less.

The content of the positive electrode active material in the positive electrode layer 11 is, for example, 50% by mass or more and 99% by mass or less, or may be 70% by mass or more and 98% by mass or less, or may be 90% by mass or more and 97% by mass or less.

In addition, from the viewpoint of improving the energy density and charge/discharge characteristics, the porosity of the positive electrode layer 11 is, for example, 12% or less, and may be 9% or less.

[1-4. Negative electrode layer]
Next, a description will be given of the negative electrode layer 12. The negative electrode layer 12 is disposed between the negative electrode current collector layer 16 and the solid electrolyte layer 20. The negative electrode layer 12 contains, as main components, a negative electrode active material and a solid electrolyte.

Examples of negative electrode active materials include graphite, hard carbon, lithium titanate, titanium oxide, silicon, and silicon oxide. Two or more of these may be used in the negative electrode layer 12.

As the solid electrolyte, for example, the solid electrolytes exemplified in [1-2. Solid electrolyte layer] above can be used.

The negative electrode layer 12 may also contain a binder as a constituent material. The strength of the negative electrode layer 12 is improved by the negative electrode layer 12 containing a binder. For example, the binders exemplified in [1-2. Solid electrolyte layer] above can be used as the binder.

In addition, the negative electrode layer 12 may further contain other components as constituent materials other than the negative electrode active material, solid electrolyte, and binder.

The content of each constituent material in the negative electrode layer 12 and the shape of the negative electrode layer 12 are not particularly limited. The thickness of the negative electrode layer 12 is, for example, 0.1 μm or more and 30 mm or less, and may be 1 μm or more and 1 mm or less, or 2 μm or more and 250 μm or less.

The content of the negative electrode active material in the negative electrode layer 12 is, for example, 50% by mass or more and 99% by mass or less, or may be 70% by mass or more and 98% by mass or less, or may be 90% by mass or more and 97% by mass or less.

[1-5. Current collector layer]
Next, the positive electrode current collector layer 15 and the negative electrode current collector layer 16 will be described. The positive electrode layer 11 is laminated on one main surface of the positive electrode current collector layer 15. The positive electrode current collector layer 15 and the positive electrode layer 11 are in contact with each other. The negative electrode layer 12 is laminated on one main surface of the negative electrode current collector layer 16. The negative electrode current collector layer 16 and the negative electrode layer 12 are in contact with each other.

It is preferable that the material constituting the positive electrode collector layer 15 and the negative electrode collector layer 16 does not react with the solid electrolyte or with charging and discharging at the operating potential, and has low electrical resistivity. The positive electrode collector layer 15 and the negative electrode collector layer 16 are made of, for example, metal foil. Examples of materials used for the positive electrode collector layer 15 and the negative electrode collector layer 16 include aluminum, stainless steel (SUS, austenitic, martensite, ferritic, austenitic-ferritic (two-phase)), nickel, and copper. The positive electrode collector layer 15 and the negative electrode collector layer 16 may contain two or more of these.

In addition, when the positive electrode layer 11 and the negative electrode layer 12 contain a sulfide-based solid electrolyte as the solid electrolyte, depending on the material of the collector layer used, the collector layer may react with the sulfide-based solid electrolyte, and the internal resistance of the battery 10 may increase. In such a case, it is preferable to use a material that has low reactivity with the sulfide-based solid electrolyte as the material for the positive electrode collector layer 15 and the negative electrode collector layer 16. For example, stainless steel or nickel may be used as the material for the negative electrode collector layer 16. Also, for example, aluminum may be used as the material for the positive electrode collector layer 15.

[1-6. Other configurations]
The battery 10 may further include other components in addition to the layers described above. As the other components, any typical components used in batteries can be applied without any particular limitations.

The battery 10 may, for example, have a positive electrode terminal connected to the positive electrode collector layer 15 and a negative electrode terminal connected to the negative electrode collector layer 16. Examples of materials constituting the positive electrode terminal and the negative electrode terminal include aluminum, copper, stainless steel, and nickel. The positive electrode terminal and the negative electrode terminal may contain two or more of these materials. In addition, a sealant film using a thermoplastic resin such as polypropylene may be disposed on the positive electrode terminal and the negative electrode terminal at a location where the terminal comes into contact with the exterior body described below. This makes it possible to strengthen the sealing by thermocompression bonding.

The battery 10 may also include, for example, an exterior body that collectively covers each layer of the battery 10. For example, a metal resin composite film or the like is used for the exterior body. In order to prevent the solid electrolyte in the battery 10 from reacting with moisture contained in the atmospheric environment and deteriorating, the exterior body has, for example, gas barrier properties. The exterior body is also formed, for example, by vacuum sealing. The interface resistance of each layer can be reduced by vacuum sealing.

2. Battery manufacturing method
Next, a method for manufacturing the battery 10 according to the above-described embodiment will be described.

Figure 2 is a flowchart showing an example of a method for manufacturing the battery 10 according to the present embodiment. Note that the manufacturing method described below is just one example, and the manufacturing method for the battery 10 according to the present embodiment is not limited to the following example.

In the manufacturing method of the battery 10, as shown in FIG. 2, first, the positive electrode layer 11 is formed (step S10). For example, a metal foil constituting the positive electrode collector layer 15 is prepared, and a composition such as a slurry containing the constituent material of the positive electrode layer 11 is applied to the surface of the positive electrode collector layer 15, and then dried to form the positive electrode layer 11. Examples of the application method include a doctor blade method, a die coater, a comma coater, etc., or a continuous manufacturing method such as screen printing to form a printed layer. A roll-to-roll method may also be used to apply the constituent material of the positive electrode layer 11.

In addition, in order to increase the packing density, the positive electrode layer 11 may be pressurized. The method of pressurization is not particularly limited, but the positive electrode layer 11 may be pressurized continuously after the above coating, such as a method of pressurizing using a roll-to-roll method, or may be pressurized by a normal method such as flat plate press, roll press, or isostatic press (ISP). Heating may also be performed during pressurization. The various pressurization conditions, such as the pressurizing force, pressurizing temperature, and pressurizing time, are not particularly limited, but the porosity of the positive electrode layer 11 can be adjusted by these pressurization conditions. For example, the porosity can be reduced by increasing the pressurizing force, increasing the pressurizing temperature, or lengthening the pressurizing time. Pressurization may be performed on the positive electrode layer 11 alone, or may be performed on multiple layers at once after other layers are stacked on the positive electrode layer 11.

Next, the first solid electrolyte layer 13 is formed (step S20). For example, a substrate such as a metal foil or a resin film is prepared, and a composition such as a slurry containing the constituent materials of the first solid electrolyte layer 13 is applied onto the surface of the substrate, followed by drying to form the first solid electrolyte layer 13. The application method can be the same as that used in forming the positive electrode layer 11 described above.

Next, the first solid electrolyte layer 13 formed in step S20 is laminated on the cathode layer 11 formed in step S10 to form a cathode side laminate (step S30). FIG. 3 is a schematic cross-sectional view showing an example of a cathode side laminate according to the present embodiment. As shown in FIG. 3, the cathode side laminate 30 has a structure in which the cathode current collector layer 15, the cathode layer 11, and the first solid electrolyte layer 13 are laminated in this order along the thickness direction. For example, the cathode side laminate 30 is formed by transferring the first solid electrolyte layer 13 onto the cathode layer 11 by pressure. The method of pressure application during transfer can be the same as the method of pressure application in the formation of the cathode layer 11 described above. The porosity of the first solid electrolyte layer 13 can be adjusted by the pressure application conditions during this pressure application. For example, the porosity can be reduced by increasing the pressure, increasing the pressure application temperature, or increasing the pressure application time. The porosity of the first solid electrolyte layer 13 can also be adjusted by changing the conditions during application. In addition, the porosity may be adjusted by applying pressure to the first solid electrolyte layer 13 before the transfer of the first solid electrolyte layer 13. In this manner, in the manufacturing method of the battery 10, the porosity of the first solid electrolyte layer 13 is adjusted to form a first solid electrolyte layer 13 having a porosity of 16% or more and 40% or less.

The first solid electrolyte layer 13 may be formed directly on the positive electrode layer 11. In this case, steps S20 and S30 are performed simultaneously. For example, the first solid electrolyte layer 13 is formed by applying a composition such as a slurry containing the constituent materials of the first solid electrolyte layer 13 onto the positive electrode layer 11, and the first solid electrolyte layer 13 is pressurized as necessary to adjust the porosity of the first solid electrolyte layer 13. In this way, the positive electrode side laminate 30 can also be formed by forming the first solid electrolyte layer 13 directly on the positive electrode layer 11.

Next, the negative electrode layer 12 is formed (step S40). For example, a metal foil that constitutes the negative electrode collector layer 16 is prepared, and a composition such as a slurry containing the constituent material of the negative electrode layer 12 is applied to the surface of the negative electrode collector layer 16, and then dried to form the negative electrode layer 12. The application method can be the same as the application method used in forming the positive electrode layer 11 described above.

In order to increase the packing density, the formed negative electrode layer 12 may be pressurized. The pressurization method may be the same as that used in forming the positive electrode layer 11. As with the positive electrode layer 11, the porosity of the negative electrode layer 12 can be adjusted by adjusting the pressurization conditions. Pressurization may be applied to the negative electrode layer 12 alone, or may be applied to multiple layers at once after other layers have been stacked on the negative electrode layer 12.

Next, the second solid electrolyte layer 14 is formed (step S50). For example, a substrate such as a metal foil or a resin film is prepared, and a composition such as a slurry containing the constituent materials of the second solid electrolyte layer 14 is applied to the surface of the substrate, followed by drying to form the second solid electrolyte layer 14. The application method can be the same as that used in forming the positive electrode layer 11 described above.

Next, the second solid electrolyte layer 14 formed in step S40 is laminated on the negative electrode layer 12 formed in step S40 to form a negative electrode side laminate (step S60). FIG. 4 is a schematic cross-sectional view showing an example of a negative electrode side laminate according to the present embodiment. As shown in FIG. 4, the negative electrode side laminate 40 has a structure in which the negative electrode current collector layer 16, the negative electrode layer 12, and the second solid electrolyte layer 14 are laminated in this order along the thickness direction. For example, the negative electrode side laminate 40 is formed by transferring the second solid electrolyte layer 14 onto the negative electrode layer 12 by pressure. The method of pressure application during transfer can be the same as the method of pressure application in the formation of the positive electrode layer 11 described above. Depending on the pressure application conditions during this pressure application, the porosity of the second solid electrolyte layer 14 can be adjusted, as with the first solid electrolyte layer 13. The porosity of the second solid electrolyte layer 14 can also be adjusted by changing the conditions for application. The porosity may also be adjusted by applying pressure to the second solid electrolyte layer 14 before the transfer of the second solid electrolyte layer 14. In this way, in the manufacturing method of the battery 10, the porosity of the second solid electrolyte layer 14 is adjusted to form a second solid electrolyte layer 14 with a porosity of 7% or less.

The second solid electrolyte layer 14 may be formed directly on the anode layer 12. In this case, steps S50 and S60 are performed simultaneously. For example, the second solid electrolyte layer 14 is formed by applying a composition such as a slurry containing the constituent materials of the second solid electrolyte layer 14 onto the anode layer 12, and the second solid electrolyte layer 14 is pressurized as necessary to adjust the porosity of the second solid electrolyte layer 14. In this way, the anode side laminate 40 can also be formed by forming the second solid electrolyte layer 14 directly on the anode layer 12.

Next, the positive electrode side laminate 30 and the negative electrode side laminate 40 are laminated so that the first solid electrolyte layer 13 and the second solid electrolyte layer 14 face each other (step S70). As a result, the first solid electrolyte layer 13 and the second solid electrolyte layer 14 come into contact with each other, and the solid electrolyte layer 20 is formed between the positive electrode layer 11 and the negative electrode layer 12, thereby obtaining the battery 10. In addition, when laminating the positive electrode side laminate 30 and the negative electrode side laminate 40, pressure may be applied as necessary to bond the first solid electrolyte layer 13 and the second solid electrolyte layer 14. The method of pressurization may be the same as the method of pressurization used in forming the positive electrode layer 11 described above.

In addition, terminals may be formed on each of the positive electrode collector layer 15 and the negative electrode collector layer 16 of the obtained battery 10. The terminals may be formed during the manufacturing process of the battery 10.

If necessary, an exterior body may be formed on the battery 10. For example, the obtained battery 10 is vacuum sealed with a metal resin composite film.

The battery 10 may be restrained by a restraining member, so that a restraining pressure is applied to the battery 10 in the thickness direction. The application of the restraining pressure by the restraining member may be a process in place of the pressurization of each layer described above. The type of restraining member is not particularly limited, and a general restraining member such as a member that sandwiches the battery 10 between metal plates may be used.

The order of the manufacturing steps shown in FIG. 2 is an example, and as long as the battery 10 can be manufactured, the steps may be interchanged, or two or more steps may be performed in parallel. For example, steps S10 to S30 and steps S40 to S60 may be performed in parallel, or at least some of steps S40 to S60 may be performed before steps S10 to S30. Also, for example, steps S40 and S50 may be performed before step S30.

In the above manufacturing method, the battery 10 is formed by stacking the positive electrode side laminate 30 and the negative electrode side laminate 40, but the battery 10 may be formed by forming and stacking laminates having configurations other than the positive electrode side laminate 30 and the negative electrode side laminate 40. For example, the battery 10 may be formed by forming a laminate of the positive electrode collector layer 15 and the positive electrode layer 11 and a laminate of the negative electrode collector layer 16, the negative electrode layer 12, and the solid electrolyte layer 20 and stacking them. In addition, the battery 10 may be formed by forming three or more laminates and then stacking these three or more laminates. In addition, the battery 10 may be formed by stacking each layer of the battery 10 in sequence from the positive electrode collector layer 15 side or the negative electrode collector layer 16 side.

Although the above manufacturing method includes a step of forming the negative electrode layer 12 on the negative electrode collector layer 16 by coating, the negative electrode layer 12 may be formed by forming a laminate of the battery 10 without the negative electrode layer 12, and then precipitating lithium metal as the negative electrode active material on the negative electrode collector layer 16 by charging. The negative electrode layer 12 may be a layer formed by depositing or forming lithium metal powder, or a lithium metal layer such as a lithium foil or a lithium vapor deposition film.

The formed battery 10 can also be further stacked as a unit cell to form a stacked battery in which multiple unit cells are connected in parallel or series. The battery according to this embodiment may be a stacked battery in which multiple such unit cells are stacked. In the case of a stacked battery, the exterior body and the restraining member may, for example, seal and restrain the multiple unit cells collectively.

(Example)
Next, the results of evaluating the battery according to the present disclosure will be described in examples. The present disclosure is not limited to the examples. Specifically, batteries in the examples and comparative examples were produced and the produced batteries were evaluated.

[Evaluation method]
First, the method for evaluating the batteries in each of the Examples and Comparative Examples will be described. The batteries were evaluated by evaluating the battery characteristics and porosity.

<Battery characteristic evaluation>
To evaluate the battery characteristics, first, the batteries in each Example and Comparative Example were subjected to CCCV (Constant Current Constant Voltage) charging and discharging at a current of 0.1 C at 25° C. and in a voltage range of 3.00 V to 4.35 V with both sides of the battery sandwiched between restraining members and pressurized. Note that 1 C is the current at which the battery is charged to its full capacity in 1 hour. That is, 0.1 C is the current value at which the battery is charged to its full capacity in 10 hours, and 6 C below is the current value at which the battery is charged to its full capacity in 10 minutes.

Then, constant current (CC) charging was performed at 60°C in the voltage range of 3.00V to 4.35V at a current of 6C, and CCCV discharging was performed at a current of 0.1C to measure the charge and discharge capacity. The coulombic efficiency when charging at a current of 6C (6C coulombic efficiency) was calculated by discharging capacity/charging capacity x 100 (%). Charging at a current of 6C is a rapid charge in which the battery is charged to its full capacity in 10 minutes. When the 6C coulombic efficiency was 99% or more, no signs of an internal short circuit were observed and rapid charging was possible, and the battery was evaluated as "good", whereas when the 6C coulombic efficiency was less than 99%, signs of an internal short circuit were observed and the battery was evaluated as "poor".

<Porosity evaluation>
To evaluate the porosity of each layer of the battery, first, a cross-sectional SEM (Scanning Electron Microscope) image was obtained for the batteries in the examples and comparative examples, and the thickness of each layer was measured from the obtained cross-sectional SEM. Then, the porosity was calculated by the above-mentioned method from the measured layer thickness, layer area, true density of the constituent material of the layer used, mass of the constituent material of the layer used, and content of the constituent material of the layer used.

[Preparation of battery]
The batteries in the examples and comparative examples were fabricated in the following manner.

Example 1
First, an aluminum foil was prepared as a positive electrode collector layer, a ternary lithium metal composite oxide (true density: 4.75 g/cm ³ ) of Ni, Co, and Mn coated with LiNbO ₃ was prepared as a positive electrode active material, an Argyrodite-type sulfide-based solid electrolyte (true density: 1.89 g/cm ³ ) was prepared as a solid electrolyte, carbon nanofiber (true density: 2.1 g/cm ³ ) was prepared as a conductive material, and an organic binder (true density: 0.93 g/cm ³ ) was prepared as a binder. Next, a positive electrode active material slurry, which was a mixture of the prepared positive electrode active material, solid electrolyte, conductive material, and binder, was applied onto the positive electrode collector layer to form a positive electrode layer, and the positive electrode layer was pressed under pressure conditions adjusted so that the porosity of the positive electrode layer was 9%.

Next, a stainless steel foil was prepared as the negative electrode current collector layer, graphite (true density: 2.3 g/ ^cm3 ) was prepared as the negative electrode active material, the same argyrodite-type sulfide-based solid electrolyte as above was prepared as the solid electrolyte, and the same organic binder as above was prepared as the binder. Next, a negative electrode active material slurry, which was a mixture of the prepared negative electrode active material, solid electrolyte, and binder, was applied and pressed onto the negative electrode current collector layer to form a negative electrode layer.

Next, a solid electrolyte slurry containing the same argyrodite-type sulfide-based solid electrolyte as above as the solid electrolyte and the same organic binder as above as the binding material was applied onto a stainless steel foil to form a first solid electrolyte layer and a second solid electrolyte layer that constitute a two-layer solid electrolyte layer.

Next, the first solid electrolyte layer was transferred onto the formed positive electrode layer under pressure conditions adjusted so that the porosity of the first solid electrolyte layer was 18%, and the first solid electrolyte layer was laminated onto the positive electrode layer. This resulted in the formation of a positive electrode side laminate. At this time, there was no change in the porosity of the positive electrode layer. The stainless steel foil used to coat the first solid electrolyte layer was peeled off and removed during the transfer process.

The second solid electrolyte layer was then transferred onto the formed negative electrode layer under pressure conditions adjusted so that the porosity of the second solid electrolyte layer was 4%, and the second solid electrolyte layer was laminated onto the negative electrode layer. This resulted in the formation of a negative electrode-side laminate. The stainless steel foil used to coat the second solid electrolyte layer was peeled off and removed during the transfer process.

Next, terminals were connected to the positive electrode current collector layer and the negative electrode current collector layer. Furthermore, the positive electrode side laminate and the negative electrode side laminate were laminated so that the first solid electrolyte layer and the second solid electrolyte layer faced each other, and vacuum sealed using a metal resin composite film as an exterior body. Finally, the battery sealed with the exterior body was restrained by sandwiching it from both sides using restraining members made of SUS steel plates, and the battery in Example 1 was obtained. The lamination of the positive electrode side laminate and the negative electrode side laminate, the vacuum sealing, and the restraining by the restraining members were carried out so as not to change the porosity of each layer. The porosity of each layer did not change even after the battery characteristics were evaluated.

Example 2
The battery in Example 2 was produced in the same manner as in Example 1, except that in laminating the first solid electrolyte layer onto the positive electrode layer, the first solid electrolyte layer was pressed and transferred under pressure conditions adjusted so that the porosity of the first solid electrolyte layer was 26%. Note that the porosity of each layer did not change after restraint and after evaluation of the battery characteristics.

Example 3
The battery in Example 3 was produced in the same manner as in Example 1, except that in laminating the first solid electrolyte layer onto the positive electrode layer, the first solid electrolyte layer was pressed and transferred under pressure conditions adjusted so that the porosity of the first solid electrolyte layer was 35%. Note that the porosity of each layer did not change after restraint and after evaluation of the battery characteristics.

<Comparative Example 1>
A battery in Comparative Example 1 was produced in the same manner as in Example 1, except that in laminating the first solid electrolyte layer onto the positive electrode layer, the first solid electrolyte layer was pressed and transferred under pressure conditions adjusted so that the porosity of the first solid electrolyte layer was 14%. Note that the porosity of each layer did not change after restraint and after evaluation of the battery characteristics.

<Comparative Example 2>
A battery in Comparative Example 2 was produced in the same manner as in Example 1, except that in the formation of the positive electrode side laminate, the first solid electrolyte layer was formed by coating on the positive electrode layer (i.e., the first solid electrolyte layer was not pressurized). The porosity of the first solid electrolyte layer after the restraint was 41%. The porosity of each layer did not change after the battery characteristics evaluation.

<Comparative Example 3>
A battery in Comparative Example 3 was produced in the same manner as in Example 1, except that in laminating the first solid electrolyte layer onto the positive electrode layer, the first solid electrolyte layer was pressed and transferred under pressure conditions adjusted so that the porosity of the first solid electrolyte layer was 4%. Note that the porosity of each layer did not change after restraint and after evaluation of the battery characteristics.

<Comparative Example 4>
A battery in Comparative Example 4 was produced in the same manner as in Example 1, except that in laminating the first solid electrolyte layer onto the positive electrode layer, the first solid electrolyte layer was pressed and transferred under pressure conditions adjusted so that the porosity of the first solid electrolyte layer was 3%. Note that the porosity of each layer did not change after restraint and after evaluation of the battery characteristics.

<Comparative Example 5>
A battery in Comparative Example 5 was produced in the same manner as in Example 1, except that in laminating the second solid electrolyte layer onto the negative electrode layer, the second solid electrolyte layer was pressed and transferred under pressure conditions adjusted so that the porosity of the second solid electrolyte layer was 8%. Note that the porosity of each layer did not change after restraint and after evaluation of the battery characteristics.

<Comparative Example 6>
A battery in Comparative Example 6 was produced in the same manner as in Example 1, except that a cathode-side laminate without a first solid electrolyte layer was formed on the cathode layer, the solid electrolyte layer was a single layer of the second solid electrolyte layer laminated on the anode layer, and the cathode-side laminate and the anode-side laminate were laminated such that the cathode layer and the second solid electrolyte layer faced each other. Note that the porosity of each layer did not change after restraint and after evaluation of the battery characteristics.

<Comparative Example 7>
The battery in Comparative Example 7 was produced in the same manner as in Comparative Example 6, except that in laminating the second solid electrolyte layer on the negative electrode layer, the second solid electrolyte layer was transferred by pressing under pressure conditions adjusted so that the porosity of the second solid electrolyte layer was 3%. Note that the porosity of each layer did not change after restraint and after evaluation of the battery characteristics.

<Comparative Example 8>
The battery in Comparative Example 8 was produced in the same manner as in Comparative Example 6, except that in laminating the second solid electrolyte layer onto the negative electrode layer, the second solid electrolyte layer was pressed and transferred under pressure conditions adjusted so that the porosity of the second solid electrolyte layer was 12%. Note that the porosity of each layer did not change after restraint and after evaluation of the battery characteristics.

<Comparative Example 9>
The battery in Comparative Example 9 was produced in the same manner as in Comparative Example 6, except that in laminating the second solid electrolyte layer onto the negative electrode layer, the second solid electrolyte layer was pressed and transferred under pressure conditions adjusted so that the porosity of the second solid electrolyte layer was 27%. Note that the porosity of each layer did not change after restraint and after evaluation of the battery characteristics.

[Battery evaluation results]
The results of evaluating the characteristics of the batteries in Examples 1 to 3 and Comparative Examples 1 to 9 are shown in Table 1.

As shown in Table 1, as in the batteries in Examples 1 to 3, when the solid electrolyte layer has a first solid electrolyte layer and a second solid electrolyte layer, and the porosity of the first solid electrolyte layer adjacent to the positive electrode layer is 16% to 40%, and the porosity of the second solid electrolyte layer adjacent to the negative electrode layer is 7% or less, the 6C coulombic efficiency is 99% or more, and a battery with high characteristics that can be rapidly charged is realized.

On the other hand, the batteries in Comparative Examples 1, 3, and 4, in which the porosity of the first solid electrolyte layer is less than 16%, Comparative Example 2, in which the porosity of the first solid electrolyte layer is more than 40%, Comparative Example 5, in which the porosity of the second solid electrolyte layer is more than 7%, and Comparative Examples 6 to 9, in which there is only one solid electrolyte layer, had a 6C coulombic efficiency of less than 99%, showed signs of internal short circuit when rapidly charged, and were inferior in characteristics to the batteries in Examples 1 to 3. In particular, the batteries in Comparative Examples 3 and 4, in which the porosity of the first solid electrolyte layer adjacent to the positive electrode layer is 7% or less and the solid electrolyte is highly filled, and the batteries in Comparative Examples 6 and 7, in which the porosity of only one solid electrolyte layer is 7% or less and the solid electrolyte is highly filled, also had poor characteristics.

As described above, it has become clear that a battery capable of rapid charging and excellent characteristics can be realized by producing a battery under conditions in which the solid electrolyte layer has a first solid electrolyte layer and a second solid electrolyte layer, the porosity of the first solid electrolyte layer adjacent to the positive electrode layer is 16% or more and 40% or less, and the porosity of the second solid electrolyte layer adjacent to the negative electrode layer is 7% or less.

(Other embodiments)
Although the battery according to the present disclosure has been described above based on the embodiments and examples, the present disclosure is not limited to these embodiments and examples. As long as it does not deviate from the gist of the present disclosure, various modifications conceived by a person skilled in the art to the embodiments or examples, as well as other forms constructed by combining some of the components in the embodiments and examples, are also included in the scope of the present disclosure.

For example, in the above embodiment, the ions conducted in the battery 10 are lithium ions, but this is not limiting. The ions conducted in the battery 10 may be ions other than lithium ions, such as sodium ions, magnesium ions, potassium ions, calcium ions, or copper ions.

For example, in the above embodiment, the solid electrolyte layer 20 is composed of two layers, the first solid electrolyte layer 13 and the second solid electrolyte layer 14, but this is not limited to the above. The solid electrolyte layer 20 may be composed of three or more layers. For example, the solid electrolyte layer 20 may have another solid electrolyte layer between the first solid electrolyte layer 13 and the second solid electrolyte layer 14.

The batteries disclosed herein can be used in a variety of applications, such as in electronic devices, electrical appliances, and electric vehicles.

REFERENCE SIGNS LIST 10 Battery 11 Positive electrode layer 12 Negative electrode layer 13 First solid electrolyte layer 14 Second solid electrolyte layer 15 Positive electrode current collector layer 16 Negative electrode current collector layer 20 Solid electrolyte layer 30 Positive electrode side laminate 40 Negative electrode side laminate

Claims (3)

A positive electrode layer;
a negative electrode layer disposed opposite the positive electrode layer;
a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer,
the solid electrolyte layer includes a first solid electrolyte layer adjacent to the positive electrode layer and a second solid electrolyte layer adjacent to the negative electrode layer,
The porosity of the first solid electrolyte layer is 16% or more and 40% or less,
The porosity of the second solid electrolyte layer is 7% or less.
battery. The first solid electrolyte layer and the second solid electrolyte layer contain an argyrodite-type sulfide-based solid electrolyte as a solid electrolyte.
10. The battery of claim 1. A method for manufacturing a battery including a positive electrode layer, an anode layer disposed opposite the positive electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the anode layer, comprising the steps of:
the solid electrolyte layer includes a first solid electrolyte layer adjacent to the positive electrode layer and a second solid electrolyte layer adjacent to the negative electrode layer,
The manufacturing method includes:
forming the first solid electrolyte layer having a porosity of 16% or more and 40% or less;
forming the second solid electrolyte layer having a porosity of 7% or less;
How batteries are manufactured.

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