JP7748276B2 - All solid state battery - Google Patents

Description

The present invention relates to an all-solid-state battery, and more specifically, to an all-solid-state battery that can prevent molten metallic lithium (Li) from leaking from the laminated exterior even when the power generating element reaches a predetermined temperature or higher and the metallic Li melts.

Conventionally, a laminated all-solid-state battery has been proposed in which the connection parts are not likely to be deformed or damaged even when an external force is applied to the laminate exterior (see Patent Document 1).

Japanese Patent Application Laid-Open No. 2018-129153

The present inventors have conducted extensive research into the application of external pressure to all-solid-state batteries such as those described in Patent Document 1 in order to reduce contact resistance between the positive electrode or negative electrode and the solid electrolyte, or between two unit cells. As a result, the present inventors have discovered a new technical problem: when the power generating element reaches a predetermined temperature or higher and the metallic Li melts, there is a risk of the molten metallic Li leaking from the sealing portion of the laminate film that makes up the laminate exterior body.

The present invention was made based on this new technical challenge, and aims to provide an all-solid-state battery that can prevent molten metallic Li from leaking from the laminated exterior even when the power-generating element reaches a predetermined temperature or higher and the metallic Li melts.

As a result of extensive research into achieving this objective, the inventors discovered that this could be achieved by providing a specified Li leakage prevention member in contact with the end of the sealing portion between the laminate films on the power generating element side, leading to the completion of the present invention.

That is, the all-solid-state battery of the present invention comprises a power generating element having a laminated structure in which a negative electrode active material layer containing metallic lithium (Li), a solid electrolyte layer, and a positive electrode active material layer are stacked, and a laminated exterior body that houses the power generating element and is made of a laminated film. This laminated exterior body is located outside the power generating element in a direction perpendicular to the stacking direction of the power generating element, and has a sealing section in which the laminated films are overlapped and bonded together. This all-solid-state battery further comprises a Li leakage prevention member provided in contact with the end of the sealing section on the power generating element side. This Li leakage prevention member contains a metal that alloys with metallic Li to form an alloy with a higher melting point than metallic Li.

According to the present invention, a specified Li leakage prevention member is provided in contact with the end of the sealing portion between the laminate films on the power generation element side. This makes it possible to provide an all-solid-state battery that can prevent molten metallic Li from leaking from the laminate exterior even when the power generation element reaches a specified temperature or higher and the metallic Li melts.

FIG. 2 is a partial cross-sectional view schematically illustrating the vicinity of a sealing portion of an example of the all-solid-state battery of the present invention. FIG. 2 is a partial cross-sectional view schematically illustrating a modified example of the all-solid-state battery illustrated in FIG. 1 . FIG. 2 is a partial cross-sectional view schematically illustrating a modified example of the all-solid-state battery illustrated in FIG. 1 . FIG. 2 is a partial cross-sectional view schematically illustrating a modified example of the all-solid-state battery illustrated in FIG. 1 . FIG. 2 is a partial cross-sectional view schematically illustrating a modified example of the all-solid-state battery illustrated in FIG. 1 . FIG. 2 is a plan view schematically illustrating a state in which a laminate film portion is cut away in a modified example of the all-solid-state battery illustrated in FIG. 1 . FIG. 2 is a partial cross-sectional view schematically illustrating a modified example of the all-solid-state battery illustrated in FIG. 1 . FIG. 2 is a partial cross-sectional view schematically illustrating a modified example of the all-solid-state battery illustrated in FIG. 1 . FIG. 2 is a partial cross-sectional view schematically illustrating a modified example of the all-solid-state battery illustrated in FIG. 1 .

The all-solid-state battery of the present invention will be described in detail below with reference to the drawings. Note that the dimensional proportions of the drawings cited below have been exaggerated for the sake of explanation and may differ from the actual proportions.

(First Example)
1 , the all-solid-state battery 1 of this example includes a power generating element 10 and a laminated exterior body 20 that houses the power generating element 10. The power generating element 10 has a structure in which a negative electrode active material layer 11 containing metallic Li, a solid electrolyte layer 13, and a positive electrode active material layer 15 are laminated together. In this example, the laminated exterior body 20 has a structure in which so-called bathtub-shaped laminate films 21, 21 are bonded together so as to face each other. The laminated exterior body 20 is located outside the power generating element 10 in a direction perpendicular to the lamination direction of the power generating element 10 (the left-right direction on the paper), and has a sealing portion 23 in which the laminated films 21, 21 are overlapped and bonded together.

Furthermore, the all-solid-state battery 1 of this example is equipped with a Li leakage prevention member 30 provided in contact with the end of the sealing portion 23 on the power generating element 10 side. This Li leakage prevention member 30 contains a metal that alloys with metallic Li to form an alloy with a higher melting point than metallic Li.

Note that the arrow Z in the figure indicates the flow direction of the molten Li metal. Although not shown, in this example, external pressure is applied in the stacking direction of the power generating elements. This also applies to the following examples. Also, in this example, multiple unit cells are stacked and electrically connected in parallel by negative electrode current collectors 17 and positive electrode current collectors 19 (not shown). Note that the number of unit cells can be selected as appropriate. Furthermore, in this example, a portion of the Li leakage prevention member 30 is sandwiched between laminate films 21, 21 at the sealing portion 23. Also, the laminate film 21 has a structure in which an inner resin layer 211, a metal layer 213, and an outer resin layer 215 are stacked.

Next, the advantages of this example will be described.
According to this example, the aforementioned Li leakage prevention member 30 is provided in contact with the end of the sealing portion 23 on the side of the power generating element 10, and therefore, the metallic Li melted at a melting point of 180°C is alloyed with the metal of the Li leakage prevention member 30 and solidified, thereby preventing the molten metallic Li from leaking from the laminated outer casing 20. Furthermore, according to this example, the volume of the metal expands slightly due to the alloying, filling the gap between the laminate film 21 and the Li leakage prevention member 30 and blocking the flow of the molten metallic Li, thereby also preventing the molten metallic Li from leaking from the laminated outer casing 20. Furthermore, according to this example, a portion of the Li leakage prevention member 30 is sandwiched between the laminate films, which not only prevents the molten metallic Li from leaking from the laminated outer casing 20 but also makes it easy to arrange the Li leakage prevention member 30 within the laminated outer casing 20.

(Second Example)
As shown in FIG. 2 , the all-solid-state battery 2 of this example has the same configuration as the all-solid-state battery 1 of the first example, except that the Li leakage prevention member 30 has an insulating coating 31 with a melting point of 120° C. or higher and 180° C. or lower, and the melting point of the insulating coating 31 is lower than the melting point of the inner resin layer 211 of the laminate film 21.

Next, the advantages of this example will be described.
According to this example, since the Li leakage prevention member 30 is covered with the insulating coating 31, in addition to the advantages of the first example, it is possible to prevent short circuits during operation at the normal operating temperature of an all-solid-state battery, which is approximately 100° C. Furthermore, according to this example, since the Li leakage prevention member 30 is covered with the insulating coating 31 having the aforementioned melting point, it is possible to fix the Li leakage prevention member 30 when forming the sealing portion 23. This eliminates the need to prepare a separate adhesive, for example, and therefore the size of the Li leakage prevention member 30 can be reduced.

(Third Example)
As shown in FIG. 3 , the all-solid-state battery 3 of this example has the same configuration as the all-solid-state battery of the first example, except that the Li leakage prevention member 30 has a flexible foil shape protruding from the sealing portion 23, and further, a tip 30A of the Li leakage prevention member 30 is positioned outside the negative electrode active material layer 11 that is located outermost in the power-generating element 10 in the stacking direction of the power-generating element 10.

Next, the advantages of this example will be described.
According to this example, since the Li leakage prevention member 30 has the foil shape described above, in addition to the advantages of the first example, the Li leakage prevention member 30 can be disposed in an area where molten metal Li is likely to collect. As a result, the force with which the flow of molten metal Li collides with the Li leakage prevention member 30 and the weight of the molten metal Li can reduce the gap between the laminate film 21 and the Li leakage prevention member 30 as shown by arrow Y. This allows the size of the Li leakage prevention member 30 to be reduced, and the time required to block the flow of molten metal Li can be shortened. Furthermore, according to this example, the tip 30A of the Li leakage prevention member 30 is disposed outside the outermost negative electrode active material layer 11 in the stacking direction of the power-generating element 10, so that leakage of molten metal Li originating from the outermost negative electrode active material layer 11 can be reliably prevented.

(Fourth Example)
As shown in FIG. 4 , the all-solid-state battery 4 of this example has the same configuration as the all-solid-state battery of the first example, except that the Li leakage prevention member 30 has a thin plate shape along the laminate films 21, 21 that are bonded to the sealing portion 23 and protrude in two directions from the sealing portion 23.

Next, the advantages of this example will be described.
According to this example, since Li leakage prevention member 30 has the aforementioned thin plate shape, in addition to the advantages of the first example, the force with which the flow of molten metal Li collides with Li leakage prevention member 30 and the weight of the molten metal Li collected in Li leakage prevention member 30 can reduce the gap between laminate films 21, 21 and Li leakage prevention member 30 on both sides of sealing portion 23 as shown by arrow Y. Therefore, the size of Li leakage prevention member 30 can be reduced and the time required to block the flow of molten metal Li can be further shortened.

(Fifth Example)
As shown in FIG. 5 , the all-solid-state battery 5 of this example has the same configuration as the all-solid-state battery of the fourth example, except that the tip 30A of the Li leakage prevention member 30 is positioned outside the negative electrode active material layer 11 that is located outermost in the power-generating element 10 in the stacking direction of the power-generating element 10.

Next, the advantages of this example will be described.
According to this example, in the stacking direction of the power generating element 10, the tip 30A of the Li leakage prevention member 30 is positioned outside the negative electrode active material layer 11 that is located outermost in the power generating element 10. Therefore, in addition to the advantages of the fourth example, leakage of molten metallic Li originating from the negative electrode active material layer 11 located outermost can also be reliably prevented.

(Sixth Example)
6 is a plan view schematically illustrating the all-solid-state battery 6 of this example, with the upper laminate film cut away in the direction perpendicular to the paper surface. The sealing portion 23 is indicated by a two-dot chain line in the drawing. As shown in FIG. 6, the all-solid-state battery 6 of this example has the same configuration as the all-solid-state battery of the first example, except that the laminated exterior body 20 has a rectangular shape in a plan view, and the Li leakage prevention member 30 is provided along an edge of the laminated exterior body 20 other than the edge along which the current collecting tabs 40, 40 protruding from the laminated exterior body 20 are disposed.

Next, the advantages of this example will be described.
According to this example, the laminated outer casing 20 has a rectangular shape when viewed in a plane, and the Li leakage prevention member 30 is provided along an edge other than the edge on which the current collecting tabs 40, 40 are arranged, so that in addition to the advantages of the first example, short circuits can be prevented.

(Seventh Example)
7 , the all-solid-state battery 7 of this example is arranged so that the stacking direction of the power generating element 10 is horizontal, and the Li leakage prevention member 30 having the insulating coating 31 described above is provided only vertically below the power generating element 10 (downward in the plane of the drawing) and in a position that does not contact the current collecting tab (not shown), except that it has the same configuration as the all-solid-state battery of Example 5. For example, when the laminate exterior body has a rectangular shape in a plan view, the current collecting tab is provided on an edge other than the vertically downward edge, although this is not shown.

Next, the advantages of this example will be described.
According to this example, the Li leakage prevention member 30 is disposed only vertically below the power generating element 10 where molten metal Li is likely to collect, and therefore, in addition to the advantages of the fifth example, it is possible to reduce the amount of Li leakage prevention member 30 used. Furthermore, according to this example, the Li leakage prevention member 30 has the insulating coating 31 and is disposed at a position where it does not come into contact with the current collecting tab, thereby preventing short circuits.

(Eighth and Ninth Examples)
As shown in Fig. 8, the all-solid-state battery 8 of this example has the same configuration as the all-solid-state battery of Example 4, except that the Li leakage prevention member 30 having the insulating coating 31 described above has an uneven surface. Also, as shown in Fig. 9, the all-solid-state battery 9 of this example has the same configuration as the all-solid-state battery of Example 4, except that the Li leakage prevention member 30 having the insulating coating 31 described above contains a plurality of metal particles 33.

Next, the advantages of this example will be described.
According to the above example, the Li leakage prevention member 30 having the insulating coating 31 has an uneven surface 30B with a surface roughness Ra of about 3.2 to 100 or includes an aggregate of a plurality of metal particles 33, so that in addition to the advantages of the fourth embodiment, the number of contact areas with the molten Li metal can be increased, thereby making it possible to reduce the size of the Li leakage prevention member 30 while preventing short circuits.

Next, we will provide a detailed explanation of the specifications, materials, etc. of the components in each of the above-mentioned embodiments.

Current collecting tabs used for positive and negative electrodes are made of metal materials such as aluminum, copper, titanium, nickel, alloys of these, and stainless steel. However, they are not limited to these materials, and any conventionally known material used as current collecting tabs for lithium-ion secondary batteries can be used.

The laminate exterior can be expressed as a laminated structure of an inner resin layer as a thermocompression bonded layer, a metal layer, and an outer resin layer as an outer protective layer (however, the thermocompression bonded layer and the outer protective layer may be composed of multiple layers). The metal layer need only function as a moisture-resistant barrier film, and can be made of not only aluminum foil, but also stainless steel foil, nickel foil, plated iron foil, etc., although aluminum foil is preferred as it is thin, lightweight, and easy to process.

Usable configurations for laminate exteriors can be listed in the format of (inner resin layer/metal layer/outer resin layer): unstretched polypropylene/aluminum/nylon, unstretched polypropylene/aluminum/polyethylene terephthalate, unstretched polypropylene/polyethylene terephthalate/aluminum/polyethylene terephthalate, unstretched polypropylene/aluminum/nylon/polyethylene terephthalate, unstretched polypropylene/nylon/aluminum/nylon/polyethylene terephthalate, polyethylene/nylon/aluminum/nylon/polyethylene terephthalate, linear low-density polyethylene/aluminum/polyethylene/nylon, low-density polyethylene/polyethylene terephthalate/aluminum/polyethylene/polyethylene terephthalate, unstretched polypropylene/low-density polyethylene/aluminum/nylon/polyethylene terephthalate, etc.

Examples of metals contained in the Li leakage prevention member include magnesium, aluminum, zinc, and tin. The material constituting the insulating coating of the Li leakage prevention member can be appropriately selected from the materials constituting the inner resin layer described above. It is preferable that the foil-shaped or thin plate-shaped portion of the Li leakage prevention member is large enough and thick enough to be sufficiently alloyed with the metallic Li of the power generation element.

The positive electrode current collector is a conductive member that functions as a flow path for electrons that are released from the positive electrode toward an external load as the battery reaction (charge/discharge reaction) progresses, or that flow from the power source toward the positive electrode. There are no particular restrictions on the material that makes up the positive electrode current collector. Examples of materials that can be used to make the positive electrode current collector include metals and conductive resins.

Specifically, examples of metals include aluminum, nickel, iron, stainless steel, titanium, and copper. In addition, a clad material of nickel and aluminum, a clad material of copper and aluminum, and the like may also be used. Furthermore, a foil in which a metal surface is coated with aluminum may also be used. Among these, aluminum, stainless steel, copper, and nickel are preferred from the viewpoints of electronic conductivity, battery operating potential, and the like.
Furthermore, examples of the resin having electrical conductivity include resins in which a conductive filler is added to a non-conductive polymer material.

The current collector may have a single layer structure made of a single material, or a laminate structure made of an appropriate combination of layers made of these materials. From the viewpoint of reducing the weight of the current collector, it is preferable that the current collector includes at least a conductive resin layer made of a resin having electrical conductivity. Furthermore, from the viewpoint of blocking the movement of lithium ions between the cell layers, a metal layer may be provided on a part of the current collector.
There is no particular limitation on the thickness of the positive electrode current collector, but it is, for example, 10 to 100 μm.

The positive electrode active material layer contains a positive electrode active material capable of absorbing and releasing lithium ions. The positive electrode active material layer is disposed on the surface of the positive electrode current collector (see Figure 1, etc.).

The positive electrode active material is not particularly limited as long as it is a material that can release lithium ions during the charging process of the secondary battery and absorb lithium ions during the discharging process. An example of such a positive electrode active material includes a material containing an M1 element and an O element, where the M1 element contains at least one element selected from the group consisting of Li, Mn, Ni, Co, Cr, Fe, and P. Examples of such a positive electrode active material include layered rock salt active materials such as LiCoO ₂ , LiMnO ₂ , LiNiO ₂ , and Li(Ni-Mn-Co)O ₂ , spinel active materials such as LiMn ₂ O ₄ and LiNi _0.5 Mn _1.5 O ₄ , olivine active materials such as LiFePO ₄ and LiMnPO ₄ , and Si-containing active materials such as Li ₂ FeSiO ₄ and Li ₂ MnSiO ₄ . Examples of oxide active materials other than those mentioned above include Li ₄ Ti ₅ O ₁₂ and LiVO ₂ .

Furthermore, the positive electrode active material may contain elemental sulfur. Examples of positive electrode active materials containing elemental sulfur include, but are not limited to, elemental sulfur (S), as well as particles or thin films of organic sulfur compounds or inorganic sulfur compounds. Any material may be used as long as it utilizes the oxidation-reduction reaction of sulfur to release lithium ions during charging and absorb lithium ions during discharging. Examples of organic sulfur compounds include disulfide compounds, sulfur-modified polyacrylonitriles, sulfur-modified polyisoprenes, rubeanic acid (dithiooxamide), polycarbon sulfides, and the like, as exemplified by the compounds described in International Publication No. 2010/044437. Among these, disulfide compounds, sulfur-modified polyacrylonitriles, and rubeanic acid are preferred, with sulfur-modified polyacrylonitrile being particularly preferred. As disulfide compounds, dithiobiurea derivatives, those having a thiourea group, a thioisocyanate, or a thioamide group are more preferred. Here, sulfur-modified polyacrylonitrile is a modified polyacrylonitrile containing sulfur atoms, obtained by mixing sulfur powder and polyacrylonitrile and heating the mixture under an inert gas or reduced pressure. Its estimated structure is, for example, as shown in Chem. Mater. 2011, 23, 5024-5028, in which polyacrylonitrile is ring-closed to form a polycyclic ring, and at least a portion of S is bonded to C. The compound described in this document has strong peak signals near 1330 cm ^-1 and 1560 cm ^-1 in its Raman spectrum, and further has peaks near 307 cm ^-1 , 379 cm ^-1 , 472 cm ^-1 , and 929 cm ^-1 . On the other hand, inorganic sulfur compounds are preferred because of their excellent stability, and specific examples include elemental sulfur (S), Li ₂ S, TiS ₂ , TiS ₃ , TiS ₄ , NiS, NiS ₂ , CuS, FeS _{2 ,} MoS ₂ , and MoS _3. Among these, S, Li ₂ S, S-carbon composite, TiS ₂ , TiS ₃ , TiS ₄ , FeS ₂ , and MoS ₂ are preferred, with elemental sulfur (S), Li ₂ S, TiS ₂ , and FeS ₂ being more preferred, and elemental sulfur (S) or Li ₂ S being particularly preferred from the viewpoint of high capacity. Note that, as elemental sulfur (S), α-sulfur, β-sulfur, and γ-sulfur having an S ₈ structure can be used. During discharge, these sulfur elements (S) absorb lithium ions and exist in the positive electrode active material layer in the form of lithium (poly)sulfides.
In some cases, two or more positive electrode active materials may be used in combination. Of course, positive electrode active materials other than those mentioned above may also be used.

From the viewpoint of output characteristics, the positive electrode active material layer preferably contains a layered rock salt type active material containing lithium and cobalt (for example, Li(Ni—Mn—Co)O ₂ ) or a positive electrode active material containing sulfur as the positive electrode active material.

The shape of the positive electrode active material can be, for example, particulate (spherical, fibrous), thin film, etc. When the positive electrode active material is particulate, its average particle size (D50) is preferably, for example, in the range of 1 nm to 100 μm, more preferably in the range of 10 nm to 50 μm, even more preferably in the range of 100 nm to 20 μm, and particularly preferably in the range of 1 to 20 μm. In this specification, the average particle size (D50) of the positive electrode active material can be measured by laser diffraction scattering.

The content of the positive electrode active material in the positive electrode active material layer is not particularly limited, but is preferably in the range of 30 to 99% by mass, more preferably in the range of 40 to 90% by mass, and even more preferably in the range of 45 to 80% by mass.

The positive electrode active material layer preferably further contains a solid electrolyte. Examples of solid electrolytes include sulfide solid electrolytes and oxide solid electrolytes.

From the viewpoint of exhibiting excellent lithium ion conductivity and being able to better adapt to volume changes in the electrode active material that occur during charging and discharging, the solid electrolyte is preferably a sulfide solid electrolyte containing the element S, more preferably a sulfide solid electrolyte containing the element Li, the element M, and the element S, where the element M contains at least one element selected from the group consisting of P, Si, Ge, Sn, Ti, Zr, Nb, Al, Sb, Br, Cl, and I, and even more preferably a sulfide solid electrolyte containing the elements S, Li, and P.

The sulfide solid electrolyte may have a Li ₃ PS ₄ skeleton, a Li ₄ P ₂ S ₇ skeleton, or a Li ₄ P ₂ S ₆ skeleton. Examples of sulfide solid electrolytes having a Li ₃ PS ₄ skeleton include LiI-Li ₃ PS ₄ , LiI-LiBr-Li ₃ PS ₄ , and Li ₃ PS ₄ . Examples of sulfide solid electrolytes having a Li ₄ P ₂ S ₇ skeleton include Li-P-S solid electrolytes known as LPS. Examples of sulfide solid electrolytes that may be used include LGPS, which is represented by Li _(4-x) Ge _(1-x) P _x S ₄ (where x satisfies 0<x<1). More specifically, examples include LPS (Li ₂ S—P ₂ S ₅ ), Li ₇ P ₃ S ₁₁ , Li _3.2 P _0.96 S, Li _3.25 Ge _0.25 P _0.75 S ₄ , Li ₁₀ GeP ₂ S ₁₂ , and Li ₆ PS ₅ X (wherein X is Cl, Br, or I). The term “Li ₂ S—P ₂ S ₅ ” refers to a sulfide solid electrolyte obtained using a raw material composition containing Li ₂ S and P ₂ S ₅ , and the same applies to other descriptions. Among these, sulfide solid electrolytes are preferably selected from the group consisting of LPS (Li ₂ S—P 2 S ₅ ), Li ₆ PS ₅ X (wherein X is Cl, Br, or I), Li 7 P ₃ S ₁₁ , Li _3.2 P _0.96 S, and Li ₃ PS _4, from the viewpoint that they have high ionic conductivity and a _low bulk modulus and can therefore follow the volume change of the electrode active material _that accompanies charge and discharge.

The content of solid electrolyte in the positive electrode active material layer is not particularly limited, but is preferably in the range of 1 to 70 mass%, more preferably in the range of 10 to 60 mass%, and even more preferably in the range of 20 to 55 mass%. In addition to the positive electrode active material and solid electrolyte, the positive electrode active material layer may further contain at least one of a conductive additive and a binder.

The thickness of the positive electrode active material layer varies depending on the configuration of the desired lithium-ion secondary battery, but is preferably within the range of 0.1 to 1000 μm, and more preferably 40 to 100 μm.

The solid electrolyte layer is typically a layer interposed between the positive electrode active material layer and the negative electrode current collector during full discharge, and contains a solid electrolyte (typically as the main component). The specific form of the solid electrolyte contained in the solid electrolyte layer is the same as that described above, so a detailed description will be omitted here.

The content of the solid electrolyte in the solid electrolyte layer is, for example, preferably in the range of 10 to 100 mass %, more preferably in the range of 50 to 100 mass %, and even more preferably in the range of 90 to 100 mass %, relative to the total mass of the solid electrolyte layer.
The solid electrolyte layer may further contain a binder in addition to the above-mentioned solid electrolyte.

The thickness of the solid electrolyte layer varies depending on the configuration of the desired lithium-ion secondary battery, but is preferably within the range of 0.1 to 1000 μm, and more preferably 10 to 40 μm.

The negative electrode current collector is a conductive member that functions as a flow path for electrons that are released from the negative electrode toward the power source as the battery reaction (charge/discharge reaction) progresses, or that flow from an external load toward the negative electrode. The negative electrode current collector essentially contains copper. The negative electrode current collector may be composed of copper alone, or an alloy of copper and another metal. Furthermore, the negative electrode current collector may be composed of a conductive resin made by adding a conductive filler containing copper to a non-conductive polymer material. There are no particular restrictions on the thickness of the negative electrode current collector, but an example is 10 to 100 μm.

The negative electrode active material layer is of the so-called lithium deposition type, in which metallic Li is deposited on the negative electrode current collector during the charging process. Therefore, the thickness of the negative electrode active material layer increases as the charging process progresses, and decreases as the discharging process progresses. The negative electrode active material layer does not need to be present during full discharge, but in some cases, a negative electrode active material layer consisting of a certain amount of metallic Li may be present during full discharge. Furthermore, the thickness of the negative electrode active material layer (metallic lithium layer) during full charge is not particularly limited, but is typically 0.1 to 1000 μm.

The negative electrode active material layer may contain graphite and Si alloy in addition to metallic Li.

While the present invention has been described above using a few examples, it is not limited to these and various modifications are possible within the scope of the present invention. For example, the components described above are not limited to the configurations shown in each example, and it is possible to change the details of the specifications of the Li leakage prevention member, or to apply the components of each example to other examples. Furthermore, each example has been described using a conventional power generating element in which multiple unit cells are stacked and electrically connected in parallel, but it is also possible to create a bipolar power generating element in which multiple unit cells are stacked and electrically connected in series. Furthermore, while each example has been described using a so-called stacked power generating element, the all-solid-state battery of the present invention can also be applied to a so-called wound-type power generating element that includes a stacked structure.

1, 2, 3, 4, 5, 6, 7, 8, 9 All-solid-state battery 10 Power generating element 11 Negative electrode active material layer 13 Solid electrolyte layer 15 Positive electrode active material layer 17 Negative electrode current collector 19 Positive electrode current collector 20 Laminated outer casing 21 Laminated film 211 Inner resin layer 213 Metal layer 215 Outer resin layer 23 Sealing portion 30 Li leakage prevention member 30A Tip 30B Uneven surface 31 Insulating coating 33 Metal particles 40 Current collecting tab

Claims (10)

The battery includes a power generating element having a structure in which a negative electrode active material layer containing metallic lithium (Li), a solid electrolyte layer, and a positive electrode active material layer are laminated, and a laminate exterior body that houses the power generating element and is made of a laminate film,
an all-solid-state battery, wherein the laminate exterior body is located outside the power-generating element in a direction perpendicular to the stacking direction of the power-generating element, and the laminate films have a sealing portion that is overlapped and bonded to each other,
a Li leakage prevention member provided in contact with an end of the sealing portion on the power generating element side;
10. An all-solid-state battery, wherein the Li leakage prevention member contains a metal that alloys with the metallic Li to form an alloy having a melting point higher than that of the metallic Li. The all-solid-state battery described in claim 1, characterized in that the Li leakage prevention member has an insulating coating having a melting point of 120°C or higher and 180°C or lower. The all-solid-state battery described in claim 2, characterized in that the melting point of the insulating coating is lower than the melting point of the inner resin layer of the laminate film. The all-solid-state battery described in claim 1, characterized in that the Li leakage prevention member has a flexible foil shape protruding from the sealing portion. The all-solid-state battery described in claim 1, characterized in that the Li leakage prevention member has a thin plate shape that protrudes in two directions from the sealing portion and follows the shape of each of the bonded laminate films. 6. The all-solid-state battery according to claim 4, wherein a tip of the Li leakage prevention member is disposed outside a negative electrode active material layer that is positioned outermost in the power-generating element in a stacking direction of the power-generating element. The laminate exterior body has a rectangular shape in a plan view,
2. The all-solid-state battery according to claim 1, wherein the Li leakage prevention member is provided on a side other than a side on which a current collecting tab protruding from the laminate exterior body is disposed. The power generating elements are arranged so that the stacking direction is horizontal,
2. The all-solid-state battery according to claim 1, wherein the Li leakage prevention member is provided only vertically below the power generating element. The all-solid-state battery described in claim 8, characterized in that the Li leakage prevention member is located in a position that does not contact the current collecting tab protruding from the laminate outer casing. The all-solid-state battery described in claim 1, characterized in that the Li leakage prevention member has an uneven surface or contains a plurality of metal particles.