Mold, power generation element and manufacturing method therefor, and all-solid-state battery and manufacturing method therefor

Abstract

The present invention provides an all-solid-state battery that makes it possible to suppress short-circuiting between a positive electrode layer and a negative electrode layer and a manufacturing method therefor, a power generation element that can constitute the all-solid-state battery and a manufacturing method therefor, and a mold for manufacturing the power generation element.　A mold according to the present invention comprises: a die that has a through hole for accommodating a powder material; and an upper punch and a lower punch that are inserted into the through hole for pressure-molding the powder material, wherein the die has an upper part that is for forming a positive electrode layer of a power generation element and a lower part that is for forming a solid electrolyte layer and a negative electrode layer of the power generation element, and the area of the through hole in the upper part in planar view is smaller than the area of the through hole in the lower part in planar view. A power generation element according to the present invention is a body obtained by integrally molding a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, and, in planar view, the area of the positive electrode layer is smaller than the area of the solid electrolyte layer and the negative electrode layer. An all-solid-state battery according to the present invention comprises a power generation element according to the present invention.

Description

Mold, power generating element and manufacturing method thereof, and all-solid-state battery and manufacturing method thereof

[0001] The present invention relates to an all-solid-state battery capable of suppressing short circuits between a positive electrode layer and a negative electrode layer, a manufacturing method thereof, a power generation element that can constitute the all-solid-state battery, a manufacturing method thereof, and a mold for manufacturing the power generation element.

[0002] In recent years, with the development of portable electronic devices such as mobile phones and laptop personal computers, and the practical application of electric vehicles, there has been a growing demand for small, lightweight batteries with high capacity and high energy density.

[0003] Currently, lithium batteries, especially lithium ion batteries, that can meet this requirement use lithium cobalt oxide (LiCoO ２ ), lithium nickel oxide (LiNiO ２ ), graphite or the like is used as the negative electrode active material, and an organic electrolyte solution containing an organic solvent and a lithium salt is used as the non-aqueous electrolyte.

[0004] Furthermore, with the further development of devices that use lithium-ion batteries, there is a demand for lithium-ion batteries with longer life, higher capacity, and higher energy density, as well as a high demand for the reliability of lithium-ion batteries with longer life, higher capacity, and higher energy density.

[0005] However, the organic electrolyte used in lithium-ion batteries contains flammable organic solvents, which can cause the organic electrolyte to generate excessive heat in the event of an abnormality such as a short circuit. Furthermore, with the recent trend toward higher energy density in lithium-ion batteries and an increasing amount of organic solvent in the organic electrolyte, there is a growing demand for greater reliability in lithium-ion batteries.

[0006] In light of the above, all-solid-state lithium secondary batteries (all-solid-state batteries) that do not use organic solvents have attracted attention. All-solid-state batteries use molded solid electrolytes that do not use organic solvents instead of conventional organic solvent-based electrolytes, and are batteries that are highly safe even in high-temperature environments.

[0007] Furthermore, because all-solid-state batteries are not only highly safe but also highly reliable, environmentally resistant, and have a long lifespan, they are expected to be maintenance-free batteries that can continue to contribute to social development while also contributing to safety and security. Providing all-solid-state batteries to society can contribute to the achievement of Goal 3 (Ensure healthy lives and promote well-being for all at all ages), Goal 7 (Ensure access to affordable, reliable, sustainable, and modern energy for all), Goal 11 (Make cities inclusive, safe, resilient, and sustainable cities and human settlements), and Goal 12 (Ensure sustainable consumption and production patterns) out of the 17 Sustainable Development Goals (SDGs) established by the United Nations.

[0008] Known all-solid-state batteries include, for example, a power generating element (e.g., a pellet-shaped power generating element) made of a three-layer molded body in which a solid electrolyte layer is interposed between a positive electrode layer formed by molding a positive electrode mixture and a negative electrode layer formed by molding a negative electrode mixture.

[0009] Such a power generation element is manufactured by pressure molding with a press machine using a powder molding die that includes a die having a through hole for holding powder (a composition for forming a solid electrolyte layer including a positive electrode mixture, a negative electrode mixture, and a solid electrolyte) and an upper punch and a lower punch for inserting into the through hole to pressurize the powder, as described in Patent Document 1, for example.

[0010] Patent Document 1 proposes a technology in which a power generation element, which is a powder compact, is molded using a die consisting of two separable parts, the die including an outer die having a molding hole and an upper die and a lower die that can enter and exit the molding hole, and then the outer die is separated into two halves and removed. Patent Document 1 also claims that molding the power generation element using the die can prevent burrs in the positive electrode layer and negative electrode layer from penetrating the solid electrolyte layer, thereby suppressing internal short circuits in the battery.

[0011] However, although the technology described in Patent Document 1 can suppress internal short circuits in all-solid-state batteries that may occur due to problems during the manufacturing of power generating elements, the edges of the above-mentioned integrally molded power generating elements (pellets, etc.) are prone to chipping, and there is a risk that, for example, during transportation from the manufacturing of the power generating elements to the assembly of the battery, part of the conductive component may fall off from the positive electrode layer or negative electrode layer of the power generating element, causing an internal short circuit in the all-solid-state battery.

[0012] Such an internal short circuit is likely to occur when the solid electrolyte layer is thinned to shorten the distance between the positive electrode layer and the negative electrode layer. Therefore, it is difficult to take measures such as thinning the solid electrolyte layer when attempting to improve the energy density of an all-solid-state battery, for example.

[0013] On the other hand, in conventional lithium-ion batteries using organic solvent-based electrolytes, the size of the negative electrode is usually larger than that of the positive electrode, which increases the distance between the edge of the positive electrode and the edge of the negative electrode. This makes it less likely that the above-mentioned problem of internal short circuiting due to the detachment of conductive components from the positive electrode or negative electrode will occur.

[0014] Also, in the case of all-solid-state batteries, a technology has been proposed in which one of the electrode layers (positive electrode layer and negative electrode layer) is made larger in area than the other, and these electrode layers are stacked together with an electrolyte layer interposed therebetween, the electrolyte layer having the same area as the larger electrode layer, and then the whole is pressed to obtain a power generating element (Patent Document 2). According to the manufacturing method described in Patent Document 2, even if the electrolyte layer is thin, the distance between the edge portion of the positive electrode layer and the edge portion of the negative electrode layer can be increased, which is expected to have the effect of suppressing internal short circuits in the battery.

[0015] JP 2004-356041 A JP 2015-125893 A

[0016] However, in the manufacturing method described in Patent Document 2, the area of ​​one of the electrode layers is different from the area of ​​the other electrode layer and the area of ​​the electrolyte layer. Therefore, the power generating element needs to be manufactured through many steps, such as first manufacturing each of the electrode layers separately, and then stacking and pressing the whole. This places a certain limit on improving the productivity of batteries, for example.

[0017] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an all-solid-state battery capable of suppressing short circuits between a positive electrode layer and a negative electrode layer, a manufacturing method thereof, a power generation element that can constitute the all-solid-state battery, a manufacturing method thereof, and a mold for manufacturing the power generation element.

[0018] The mold of the present invention is used to pressure-molde a powder material to manufacture a power generation element for an all-solid-state battery, and includes a die having a through hole for accommodating the powder material, and an upper punch and a lower punch for inserting into the through hole to pressure-molde the powder material, the die having an upper part for forming a positive electrode layer of the power generation element and a lower part for forming a solid electrolyte layer and a negative electrode layer of the power generation element, the area of ​​the through hole in the upper part of the die in a planar view being smaller than the area of ​​the through hole in the lower part of the die in a planar view, and the outline of the shape of the through hole in the upper part of the die does not intersect with the outline of the shape of the through hole in the lower part of the die in a planar view.

[0019] The power generating element of the present invention is for constituting an all-solid-state battery, and is characterized in that it has a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, and satisfies the following (1) or (2):

[0020] (1) The cathode layer, the solid electrolyte layer, and the anode layer are integrally molded, and in a plan view, the area of ​​the cathode layer is smaller than the areas of the solid electrolyte layer and the anode layer, and a contour line representing the shape of the cathode layer does not intersect with a contour line representing the shape of the anode layer or a contour line representing the shape of the solid electrolyte layer.

[0021] (2) In a process of integrally molding the positive electrode layer, the solid electrolyte layer, and the negative electrode layer using the mold of the present invention, the positive electrode layer is formed in the through-hole in the upper part of the die, and the solid electrolyte layer and the negative electrode layer are formed in the through-hole in the lower part of the die, and in a plan view, an area of ​​the positive electrode layer is smaller than areas of the solid electrolyte layer and the negative electrode layer, and a contour line representing the shape of the positive electrode layer does not intersect with a contour line representing the shape of the negative electrode layer and a contour line representing the shape of the solid electrolyte layer.

[0022] The power generation element of the present invention can be manufactured by a manufacturing method including a step of integrally molding the positive electrode layer, the solid electrolyte layer, and the negative electrode layer using the mold of the present invention, wherein in the step, the positive electrode layer is formed in the through hole in the upper part of the die, and the solid electrolyte layer and the negative electrode layer are formed in the through hole in the lower part of the die, such that, in a plan view, the area of ​​the positive electrode layer is smaller than the areas of the solid electrolyte layer and the negative electrode layer, and a contour line representing the shape of the positive electrode layer does not intersect with a contour line representing the shape of the negative electrode layer and a contour line representing the shape of the solid electrolyte layer.

[0023] The all-solid-state battery of the present invention is characterized in that the power generating element of the present invention is housed in an exterior body.

[0024] The all-solid-state battery of the present invention can be produced by a production method including the steps of producing a power generating element by the power generating element production method of the present invention, and housing the power generating element in an exterior body.

[0025] According to the present invention, it is possible to provide an all-solid-state battery capable of suppressing short circuits between a positive electrode layer and a negative electrode layer and a manufacturing method thereof, a power generation element that can constitute the all-solid-state battery and a manufacturing method thereof, and a mold for manufacturing the power generation element.

[0026] FIG. 1 is a cross-sectional view schematically showing an example of a mold of the present invention. FIG. 2 is a plan view schematically showing an example of a die in the mold of the present invention. FIG. 3 is a drawing for explaining the difference in size between the upper through-hole and the lower through-hole of the die in plan view. FIG. 4 is an explanatory diagram of a method for manufacturing a power generating element. FIG. 5 is an explanatory diagram of a method for manufacturing a power generating element. FIG. 6 is an explanatory diagram of a method for manufacturing a power generating element. FIG. 7 is an explanatory diagram of a method for manufacturing a power generating element. FIG. 8 is an explanatory diagram of a method for manufacturing a power generating element. FIG. 9 is an explanatory diagram of a method for manufacturing a power generating element. FIG. 10 is a cross-sectional view schematically showing an example of an all-solid-state battery of the present invention.

[0027] <Mold> The mold of the present invention is used to produce a power generating element for an all-solid-state battery by pressure molding a powder material.

[0028] Fig. 1 is a cross-sectional view schematically illustrating an example of a mold of the present invention. The mold 100 shown in Fig. 1 includes a die 200 having a through hole 230 for accommodating powder material for forming a power generation element, and an upper punch 300 and a lower punch 400 for inserting into the through hole 230 of the die 200 to pressure-mold the powder material. The through hole 230 penetrates from the top surface to the bottom surface of the die 200. The upper punch 300 is inserted from the upper opening of the through hole 230 of the die 200 and is slidable within the through hole 230, while the lower punch 400 is inserted from the lower opening of the through hole 230 of the die 200 and is slidable within the through hole 230.

[0029] As shown in Fig. 1(a), the die 200 has an upper part 210 and a lower part 220. Note that, as shown in Fig. 1(b), the die 200 is configured so that the upper part 210 and the upper part 220 can be separated.

[0030] 1A, in the through hole 230 of the die 200, the area of ​​the upper portion 210 is smaller than the area of ​​the lower portion 220 in a plan view. That is, as shown in FIG. 1B, the area of ​​the through hole 231 in the upper portion 210 is smaller than the area of ​​the through hole 232 in the lower portion 220 in a plan view. Note that FIG. 1 is a cross-sectional view, and therefore it is difficult to see the shapes of the through holes 230, 231, and 232 in a plan view. However, for example, if these shapes in a plan view are circular, as shown in FIG. 1, by making the inner diameter of the through hole 231 smaller than the inner diameter of the through hole 232, the area of ​​the through hole 231 in a plan view becomes smaller than the area of ​​the through hole 232 in a plan view. Furthermore, in a planar view, the contour line of the through hole 231 in the upper part 210 and the contour line of the through hole 232 in the lower part 220 do not intersect (i.e., as shown in Figure 3 below, in a die 200 combining the upper part 210 and the lower part 220, in a planar view, the entire through hole 231 in the upper part 210 is located inside the through hole 232 in the lower part 220).

[0031] As described above, in a power generation element in which the positive electrode layer, solid electrolyte layer, and negative electrode layer are all formed by pressure molding of powder materials, from the viewpoint of suppressing the occurrence of a short circuit due to the detachment of conductive components from the positive electrode layer or negative electrode layer, it is preferable to make the area of ​​the solid electrolyte layer and the negative electrode layer larger than the area of ​​the positive electrode layer in a plan view, and to make the distance between the edge portion of the positive electrode layer and the edge portion of the negative electrode layer as long as possible.

[0032] Therefore, in the mold of the present invention, a die having upper and lower portions with different areas of the through holes in a planar view (hereinafter, unless otherwise specified, the areas of the through holes, the positive electrode layer, the solid electrolyte layer, and the negative electrode all mean the areas in a planar view) is used.

[0033] That is, by forming the positive electrode layer in the upper part of the die with a smaller through-hole area and forming the solid electrolyte layer and the negative electrode layer in the lower part of the die with a larger through-hole area, it is possible to form a power generation element in which the areas of the solid electrolyte layer and the negative electrode layer are larger than those of the positive electrode layer as an integrally molded body. Therefore, the mold of the present invention can produce a highly reliable power generation element, which makes it possible to improve the reliability of an all-solid-state battery using this power generation element.

[0034] In this specification, the term "integrally molded body" in relation to a power generation element means a power generation element obtained by using a single mold to continuously form each layer without removing it from the mold (die) to form a power generation element having all the layers, and then removing it from the mold. A power generation element obtained by this procedure is presumed to have a different structure at the interface between the positive electrode layer and the solid electrolyte layer and at the interface between the negative electrode layer and the solid electrolyte layer from a power generation element obtained by separately molding the positive electrode layer, the solid electrolyte layer, and the negative electrode layer, laminating them, and applying pressure to the whole. For example, the power generation element is expected to have a higher adhesion between the positive electrode layer and the solid electrolyte layer and between the negative electrode layer and the solid electrolyte layer, and to ensure better characteristics.

[0035] The die of the metal mold may be configured as an integral body that cannot be separated or divided into multiple parts, but is preferably configured so that the upper and lower parts are separable, as shown in Fig. 1. When manufacturing an integrally molded power generation element by pressure molding the positive electrode layer, the solid electrolyte layer, and the negative electrode layer in a single mold, if a mold is used in which the area in a plan view of the portion of the die through-hole that accommodates the powder material where the positive electrode layer is to be formed is different from the area in a plan view of the portion where the solid electrolyte layer or the negative electrode layer is to be formed, it is difficult to remove the molded power generation element from the mold (its die), and there is a risk of burrs forming in the positive electrode layer and / or the negative electrode layer. If such burrs form and penetrate the solid electrolyte layer, they may cause a short circuit.

[0036] However, if the die of the mold is configured so that the upper and lower parts are separable, when removing the molded power generation element from the mold, the upper and lower parts can be separated, and the upper part, which has a smaller area of ​​the through hole, can be removed from the power generation element (its positive electrode layer), and then the power generation element can be easily removed from the through hole in the lower part by pushing up the power generation element from the negative electrode layer side with a lower punch.

[0037] Therefore, when the mold has a die configured so that the upper and lower parts can be separated, it is possible to form the power generation element as an integrally molded body while suppressing the occurrence of short circuits due to burrs or material falling off from the electrode layer, which may occur between the time of molding the power generation element and the subsequent assembly of the battery. This makes it possible to more efficiently produce highly reliable power generation elements, thereby improving the reliability of all-solid-state batteries that use this power generation element and also increasing their productivity.

[0038] Fig. 2 shows a plan view schematically illustrating an example of a die. Fig. 2(a) is a plan view of a die 200 as viewed from above. The die 200 shown in Fig. 2(a) is composed of two parts 201 and 202. As shown in Fig. 2(b), the parts 201 and 202 can be separated in the outward direction in plan view.

[0039] 2, when the die is composed of two or more parts and is separable, the power generation element can be formed as an integrally molded body using a mold, and when removing it from the die of the mold, the die can be separated to easily remove it from the power generation element. Therefore, when the die in the mold of the present invention is configured to be separable as described above, it is possible to more easily remove the power generation element after molding, and it is possible to further improve the productivity of the power generation element and the productivity of the all-solid-state battery using this power generation element.

[0040] Furthermore, in a mold, when the upper and lower parts of the die are separable, the upper part may be composed of two or more parts and may be separable in a direction toward the outside in a plan view. When a power generation element is manufactured using a mold in which the upper part of the die is separable, when removing the power generation element after molding, the upper and lower parts of the die are separated, the upper part is separated and removed from the power generation element, and then the power generation element can be pushed out from the negative electrode layer side using a lower punch, which makes it even easier to remove the power generation element from the die.

[0041] Furthermore, in a mold, when the upper and lower parts of the die are separable, the lower part may be composed of two or more parts and may be separable in a direction toward the outside in a plan view. When a power generation element is manufactured using a mold in which the lower part of the die is separable, when removing the power generation element after molding, the upper and lower parts of the die are separated, the lower part is divided and removed from the power generation element, and then the power generation element can be pushed out from the positive electrode layer side using an upper punch, which also makes it easier to remove the power generation element from the die.

[0042] Furthermore, in a mold, when the upper and lower parts of the die are separable, both the upper and lower parts may be made up of two or more parts and may be separable in a direction outward when viewed in a plane.

[0043] As described above, the die of the mold has through holes in the upper and lower parts that have different areas, with the area of ​​the through hole in the upper part being smaller than the area of ​​the through hole in the lower part. Therefore, the upper punch inserted into the through hole of the die from the upper side has a shape corresponding to the shape and size of the upper through hole, and the lower punch inserted into the through hole of the die from the lower side has a shape corresponding to the shape and size of the lower through hole.

[0044] It is preferable that the shape of the through-hole in the upper part of the die and the shape of the through-hole in the lower part of the die in plan view are the same (i.e., similar) except for the areas.

[0045] Furthermore, the distance between the closest points of the through holes in the upper and lower parts of the die is preferably 0.1 mm or more in plan view. In this case, since there is a difference of a certain amount or more between the areas of the through holes in the upper and lower parts of the die, the distance between the edge parts of the positive electrode layer and the negative electrode layer of the power generation element also becomes a certain amount or more, and the occurrence of a short circuit due to detachment of conductive material from the positive electrode layer or the negative electrode layer can be more effectively suppressed.

[0046] Fig. 3 is a diagram for explaining the difference in size between the through holes in the upper and lower parts of the die in plan view, in which the through holes in the lower part are indicated by dotted lines in a plan view that schematically shows the upper part of the die.

[0047] (a) of Figure 3 shows an example in which the shape (planar view shape) of the through hole 231 in the upper part 210 of the die and the through hole 232 in the lower part 220 of the die are circular. When the center position of the through hole 231 in the upper part 210 of the die and the center position of the through hole 232 in the lower part 220 of the die are the same in plan view, the above-mentioned "distance between the closest points in plan view" is the difference between the radius of the through hole 231 and the radius of the through hole 232 [length d1 in (a) of Figure 3].

[0048] Also, (b) of Figure 3 shows an example in which the shape (planar view shape) of the through hole 231 in the upper part 210 of the die and the through hole 232 in the lower part 220 of the die are square, and when, in plan view, the position of the center (intersection of the diagonals) of the through hole 231 in the upper part 210 of the die coincides with the position of the center (intersection of the diagonals) of the through hole 232 in the lower part 220 of the die, and the diagonals of the through hole 231 and the through hole 232 overlap, the above-mentioned "distance between the closest points in plan view" becomes the shortest distance between the side of the square forming the through hole 231 and the corresponding side of the square forming the through hole 232 [length d2 in (b) of Figure 3].

[0049] As mentioned above, in the die, in a plan view, the entire through hole 231 of the upper part 210 is located inside the through hole 232 of the lower part 220, and therefore the contour line representing the shape of the through hole 231 of the upper part 210 (the solid line representing the innermost circle in Figure 3(a) and the solid line representing the innermost square in Figure 3(b)) does not intersect with the contour line representing the shape of the through hole 232 of the lower part (the dotted line representing a circle in Figure 3(a) and the dotted line representing a square in Figure 3(b)).

[0050] There is no particular upper limit to the distance between the closest through holes in the upper part of the die and the closest through holes in the lower part of the die in a planar view, but if the distance is too large, it becomes difficult to adjust the balance between the capacity of the positive electrode layer and the capacity of the negative electrode layer in the power generation element to be formed, so it is preferable to set the distance to, for example, 1.0 mm or less.

[0051] The die, upper punch, and lower punch constituting the mold can be made of SKD (Steel Kougu Dies) material such as SKD11.

[0052] The planar shape (opening shape) of the through holes (upper and lower through holes) in the die is not particularly limited, and may be circular, elliptical, polygonal (quadrilateral such as square or rectangle, hexagonal such as regular hexagon, octagonal such as regular octagon, etc.), etc. In the case of a polygon, the corners may be curved.

[0053] Furthermore, when a lower punch is inserted into a lower through-hole of a larger die, it stops when it hits the lower surface of the upper die having a smaller through-hole. On the other hand, if an upper punch is inserted into a through-hole in the upper die and continues to be inserted, it can also penetrate into the lower through-hole in the larger die. Therefore, it is recommended that the upper punch be provided with a stopper that stops further insertion so that when the upper punch is inserted a distance equal to the length of the through-hole in the upper die, the bottom surface of the upper punch and the lower end of the upper die are flat without any steps. The stopper on the upper punch can be realized, for example, by providing a portion of the upper punch on the opposite side of the bottom surface that is initially inserted into the through-hole, that is larger than the area of ​​the upper through-hole in the die, or by providing a protrusion that can hook onto the upper through-hole in the die.

[0054] <Power Generation Element> The power generation element of the present invention is for constituting an all-solid-state battery and includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, and is an integrally molded body of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer. In plan view, the area of ​​the positive electrode layer is smaller than the areas of the solid electrolyte layer and the negative electrode layer. Therefore, even if a conductive component is detached from an edge portion of the positive electrode layer or the negative electrode layer, for example, between the manufacture of the power generation element and the assembly of the battery, the long distance between the edge portion of the positive electrode layer and the edge portion of the negative electrode layer effectively prevents a short circuit caused by the conductive component.

[0055] The positive electrode layer of the power generating element is formed from a positive electrode mixture containing a positive electrode active material and the like.

[0056] When the all-solid-state battery using the power generating element is a primary battery, the positive electrode active material can be the same as the positive electrode active material used in known non-aqueous electrolyte primary batteries. Specifically, for example, manganese dioxide, lithium-containing manganese oxide (e.g., LiMn ３ O ６ or a composite oxide having the same crystal structure as manganese dioxide (e.g., β-type, γ-type, or a mixed structure of β-type and γ-type) and containing 3.5% by mass or less, preferably 2% by mass or less, more preferably 1.5% by mass or less, particularly preferably 1% by mass or less of Li, ａ Ti ５／３ O ４ (4 / 3≦a<7 / 3) and other lithium-containing composite oxides; vanadium oxide; niobium oxide; titanium oxide; sulfides such as iron disulfide; graphite fluoride; Ag ２ Silver sulfides such as S; NiO ２ Nickel oxides such as:

[0057] When the all-solid-state battery in which the power generating element is used is a secondary battery, the positive electrode active material is not particularly limited as long as it is a positive electrode active material used in known non-aqueous electrolyte secondary batteries, that is, an active material capable of absorbing and releasing Li ions. Specific examples of the positive electrode active material include LiM ｒ Mn ２－ｒ O ４ (wherein M is at least one element selected from the group consisting of Li, Na, K, B, Mg, Ca, Sr, Ba, Ti, V, Cr, Zr, Fe, Co, Ni, Cu, Zn, Al, Sn, Sb, In, Nb, Ta, Mo, W, Y, Ru, and Rh, and 0≦r≦1), a spinel-type lithium manganese composite oxide represented by Li ｒ Mn （１－ｓ－ｒ） Ni ｓ M ｔ O （２－ｕ） F ｖ (wherein M is at least one element selected from the group consisting of Co, Mg, Al, B, Ti, V, Cr, Fe, Cu, Zn, Zr, Mo, Sn, Ca, Sr, and W, and 0.8≦r≦1.2, 0<s<0.5, 0≦t≦0.5, u+v<1, −0.1≦u≦0.2, 0≦v≦0.1), a layered compound represented by １－ｒ Mｒ O ２ (wherein M is at least one element selected from the group consisting of Al, Mg, Ti, V, Cr, Zr, Fe, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, and Ba, and 0≦r≦0.5), lithium cobalt composite oxide represented by LiNi １－ｒ M ｒ O ２ (wherein M is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Fe, Co, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, and Ba, and 0≦r≦0.5), a lithium nickel composite oxide represented by Li １＋ｓ M １－ｒ N ｒ P.O. ４ F ｓ (wherein M is at least one element selected from the group consisting of Fe, Mn, and Co, and N is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, V, and Ba, and 0≦r≦0.5, 0≦s≦1), Li ２ M １－ｒ N ｒ P ２ O ７ (wherein M is at least one element selected from the group consisting of Fe, Mn, and Co, and N is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, V, and Ba, and 0≦r≦0.5), and the like. Among these, only one type may be used, or two or more types may be used in combination.

[0058] When the all-solid-state battery in which the power generating element is used is a secondary battery, the average particle diameter of the positive electrode active material is preferably 0.1 μm or more, more preferably 0.5 μm or more, and preferably 25 μm or less, more preferably 10 μm or less, from the viewpoint of reducing side reactions that cause battery capacity degradation and increasing the density of the positive electrode. The positive electrode active material may be primary particles or secondary particles formed by aggregation of primary particles. When the positive electrode layer contains a solid electrolyte, using a positive electrode active material with an average particle diameter in the above range allows for a large interface with the solid electrolyte, thereby further improving the load characteristics of the battery.

[0059] The average particle diameter of the positive electrode active material and the average particle diameter of other particles (such as solid electrolytes) referred to in this specification are determined by a particle size distribution measuring device (such as a Microtrac particle size distribution measuring device "HRA9320" manufactured by Nikkiso Co., Ltd.) and are the 50% diameter value (D) in the volume-based integrated fraction when determining the integrated volume from particles with small particle sizes. ５０ ) means

[0060] When the positive electrode layer contains a solid electrolyte, the positive electrode active material preferably has a reaction suppression layer on its surface to suppress reaction with the solid electrolyte contained in the positive electrode layer.

[0061] If the positive electrode active material and the solid electrolyte come into direct contact in the positive electrode layer, the solid electrolyte may oxidize to form a resistance layer, which may reduce ionic conductivity in the layer. By providing a reaction suppression layer on the surface of the positive electrode active material that suppresses reaction with the solid electrolyte and preventing direct contact between the positive electrode active material and the solid electrolyte, it is possible to suppress the reduction in ionic conductivity in the positive electrode layer due to oxidation of the solid electrolyte.

[0062] The reaction suppression layer may be made of a material that has ion conductivity and can suppress the reaction between the positive electrode active material and the solid electrolyte. Examples of materials that can form the reaction suppression layer include oxides containing Li and at least one element selected from the group consisting of Nb, P, B, Si, Ge, Ti, Zr, Ta, and W, more specifically, LiNbO ３ Nb-containing oxides such as Li ３ P.O. ４ , Li ３ BO３ , Li ４ SiO ４ , Li ４ GeO ４ , LiTiO ３ , LiZrO ３ , Li ２ WO ４ The reaction suppression layer may contain only one of these oxides, or may contain two or more of them, or may contain a composite compound of two or more of these oxides. Among these oxides, it is preferable to use an Nb-containing oxide, such as LiNbO ３ It is more preferable to use

[0063] The reaction suppression layer is preferably present on the surface in an amount of 0.1 to 2.0 parts by mass per 100 parts by mass of the positive electrode active material, which allows for effective suppression of the reaction between the positive electrode active material and the solid electrolyte.

[0064] Examples of methods for forming a reaction suppression layer on the surface of a positive electrode active material include the sol-gel method, mechanofusion method, CVD method, PVD method, and ALD method.

[0065] The content of the positive electrode active material in the positive electrode layer is preferably 20 to 95 mass %.

[0066] Examples of conductive additives for the positive electrode include carbon materials such as carbon black (thermal black, furnace black, channel black, ketjen black, acetylene black, etc.), graphite (natural graphite, artificial graphite), graphene, vapor-grown carbon fiber, carbon nanofiber, and carbon nanotube; powders of Cu, Ni, Al, Au, and Pd alone or alloys thereof, or porous bodies thereof; and these may be used alone or in combination of two or more. The content of the conductive additive in the positive electrode layer is preferably 0.1 to 15% by mass.

[0067] The positive electrode layer may contain a solid electrolyte. The solid electrolyte used in the positive electrode layer is not particularly limited as long as it has Li ion conductivity, and examples thereof include sulfide-based solid electrolytes, hydride-based solid electrolytes, halide-based solid electrolytes, and oxide-based solid electrolytes.

[0068] The sulfide-based solid electrolyte is Li ２ S-P ２ S ５ , Li ２ S-SiS ２ , Li ２ S-P ２ S ５ -GeS ２ , Li ２ S-B ２ S ３ In addition to particles of glass, thio-LISICON type particles [Li １０ GeP ２ S １２ , Li ９．５４ Si １．７４ P １．４４ S １１．７ Cl ０．３ Li12-12a-b+c+6d-eM, etc. １ ３＋ａ－ｂ－ｃ－ｄ M ２ ｂ M ３ ｃ M ４ ｄ M ５ １２－ｅ X ｅ (However, M １ is Si, Ge or Sn, M ２ is P or V, M ３ is Al, Ga, Y or Sb, M ４ is Zn, Ca, or Ba, M ５ is either S or S and O, and X is F, Cl, Br or I, 0≦a<3, 0≦b+c+d≦3, 0≦e≦3], or argyrodite type [Li ６ P.S. ５ Li, such as Cl ７－ｋ P.S. ６－ｋ X ｋ (wherein X represents one or more halogen elements, and 0.2<k<2.0), Li ７－ｆ＋ｇ P.S. ６－ｆ Cl ｆ＋ｇ (wherein 0.05≦g≦0.9, −3.0f+1.8≦g≦−3.0f+5.7), Li ７－ｈ P.S.６－ｈ Cl ｉ Br ｊ (where h=i+j, 0<h≦1.8, 0.1≦i / j≦10.0) can also be used.

[0069] Examples of hydride-based solid electrolytes include LiBH ４ , LiBH ４ and a solid solution of the following alkali metal compound (e.g., LiBH ４ and the alkali metal compound in a molar ratio of 1:1 to 20:1. The alkali metal compound in the solid solution may be at least one selected from the group consisting of lithium halides (LiI, LiBr, LiF, LiCl, etc.), rubidium halides (RbI, RbBr, RbF, RbCl, etc.), cesium halides (CsI, CsBr, CsF, CsCl, etc.), lithium amide, rubidium amide, and cesium amide.

[0070] Examples of halide-based solid electrolytes include monoclinic LiAlCl ４ , defect spinel type or layer structure LiInBr ４ , monoclinic Li ６－３ｍ Y ｍ X ６ (wherein 0 < m < 2 and X = Cl or Br), and other known compounds described in, for example, WO 2020 / 070958 and WO 2020 / 070955 can also be used.

[0071] Examples of oxide-based solid electrolytes include Li ２ O-Al ２ O ３ -SiO ２ -P ２ O ５ -TiO ２ Li-based glass ceramics ２ O-Al ２ O ３ -SiO ２ -P ２ O ５ -GeO ２ Lithium-ion-based glass ceramics, garnet-type ７ La ３ Zr２ O １２ , NASICON type Li １＋Ｏ Al １＋Ｏ Ti ２－Ｏ (P.O. ４ ) ３ , Li １＋ｐ Al １＋ｐ Ge ２－ｐ (P.O. ４ ) ３ , perovskite-type Li ３ｑ La ２／３－ｑ TiO ３ Examples include:

[0072] Among these solid electrolytes, sulfide-based solid electrolytes are preferred because of their high Li ion conductivity, sulfide-based solid electrolytes containing Li and P are more preferred, and argyrodite-type sulfide-based solid electrolytes are even more preferred because of their particularly high Li ion conductivity and high chemical stability.

[0073] The content of the solid electrolyte in the positive electrode layer is preferably 4 to 80 mass %.

[0074] The positive electrode layer may contain a binder, but may not contain a binder if good moldability can be ensured without using a binder, such as in the case of containing a sulfide-based solid electrolyte.

[0075] Examples of the binder contained in the positive electrode layer include fluororesins such as PVDF.

[0076] When a binder is required in the positive electrode layer, the content thereof is preferably 15% by mass or less, and preferably 0.5% by mass or more. On the other hand, when a binder is not required in the positive electrode layer from the viewpoint of formability, the content thereof is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and even more preferably 0% by mass (i.e., no binder is contained).

[0077] The positive electrode layer may have a current collector. Examples of the current collector for the positive electrode layer include metal foils such as aluminum and stainless steel; sheet-like conductive porous substrates such as punched metal, mesh, expanded metal, and foamed metal; and carbon sheets. As the sheet-like conductive porous substrate, it is preferable to use a foamed metal porous body. A specific example of a foamed metal porous body is "Celmet (registered trademark)" from Sumitomo Electric Industries, Ltd.

[0078] When the positive electrode layer has a current collector, the current collector may be pressure-bonded to the surface of the positive electrode layer of the power generation element obtained by pressure molding, or the positive electrode layer and the current collector may be integrated at the same time as molding the positive electrode layer when forming the power generation element by pressure molding.

[0079] The thickness of the positive electrode layer is usually 50 μm or more, but from the viewpoint of increasing the capacity of the battery, it is preferably 200 μm or more, and is usually 2000 μm or less.

[0080] The thickness of the current collector for the positive electrode layer is preferably 0.01 to 0.1 mm.

[0081] The negative electrode layer of the power generating element is formed from a negative electrode mixture containing a negative electrode active material and the like.

[0082] When the all-solid-state battery using the power generating element is a primary battery, examples of the negative electrode active material include metallic lithium and lithium alloys (lithium-aluminum alloys, lithium-indium alloys, etc.).

[0083] When the all-solid-state battery using the power generation element is a secondary battery, the negative electrode active material can be, for example, one or a mixture of two or more carbonaceous materials capable of absorbing and releasing lithium, such as graphite, pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, mesocarbon microbeads (MCMB), and carbon fibers. Also usable as the negative electrode active material are simple substances, compounds, and alloys thereof containing elements such as Si, Sn, Ge, Bi, Sb, and In; compounds capable of charging and discharging at low voltages close to those of lithium metal, such as lithium-containing nitrides or lithium-containing oxides; lithium metal; and lithium / aluminum alloys. For example, Li ４Ti ５ O １２ and TiO ２ , NbO ２．５－δ (0≦δ≦0.5), MoO ３－δ (0≦δ≦1), WO ３－δ (0≦δ≦1), TiNb ２ O ７ Metal oxides such as WS ２ , MoS ２ or a mixture of two or more of these metal sulfides can also be used as the negative electrode active material.

[0084] The content of the negative electrode active material in the negative electrode layer is preferably 50 to 95 mass %.

[0085] The negative electrode layer can contain a solid electrolyte. The solid electrolyte contained in the negative electrode layer can be one or more of the sulfide-based solid electrolytes, hydride-based solid electrolytes, and oxide-based solid electrolytes previously exemplified as the solid electrolytes that can be contained in the positive electrode layer. Among the solid electrolytes exemplified above, sulfide-based solid electrolytes are more preferably used because they have high Li ion conductivity and also have the function of improving the formability of the negative electrode layer, and argyrodite-type sulfide-based solid electrolytes are even more preferably used.

[0086] The content of the solid electrolyte in the negative electrode layer is preferably 4 to 70 mass %.

[0087] The negative electrode layer may contain a conductive additive. Specific examples include carbon materials such as graphite (natural graphite, artificial graphite), graphene, carbon black, vapor-grown carbon fiber, carbon nanofiber, and carbon nanotube. The content of the conductive additive in the negative electrode layer is preferably 1 to 10 mass %.

[0088] The negative electrode layer may or may not contain a binder. Specific examples thereof include the same binders as those exemplified above as binders that can be contained in the positive electrode layer. For example, when the negative electrode layer contains a sulfide-based solid electrolyte, if good moldability can be ensured in forming the negative electrode layer without using a binder, the negative electrode layer may not contain a binder.

[0089] When a binder is required in the negative electrode layer, the content is preferably 15% by mass or less, and preferably 0.5% by mass or more. On the other hand, when good moldability can be obtained without the binder in the negative electrode layer, the content is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and even more preferably 0% by mass (i.e., no binder is contained).

[0090] The negative electrode layer may have a current collector. Examples of the current collector for the negative electrode layer include sheet-like conductive porous substrates such as copper or nickel foil, punched metal, mesh, expanded metal, and foamed metal; carbon sheets; and the like. As the sheet-like conductive porous substrate, it is preferable to use a foamed metal porous body. A specific example of a foamed metal porous body is "Celmet (registered trademark)" by Sumitomo Electric Industries, Ltd.

[0091] When the negative electrode layer has a current collector, the current collector may be pressure-bonded to the surface of the negative electrode layer of the power generation element obtained by pressure molding, or the negative electrode layer and the current collector may be integrated at the same time as molding the negative electrode layer when forming the power generation element by pressure molding.

[0092] The thickness of the negative electrode layer is usually 100 μm or more, but is preferably 200 μm or more from the viewpoint of increasing the capacity of the battery, and is usually 3000 μm or less.

[0093] The thickness of the current collector for the negative electrode layer is preferably 0.01 to 0.1 mm.

[0094] The solid electrolyte layer of the power generating element can use one or more of the sulfide-based solid electrolytes, hydride-based solid electrolytes, and oxide-based solid electrolytes listed above as examples of solid electrolytes that can be contained in the positive electrode layer. Among the above-listed solid electrolytes, it is more preferable to use a sulfide-based solid electrolyte, and it is even more preferable to use an argyrodite-type sulfide-based solid electrolyte, in order to improve battery characteristics.

[0095] The solid electrolyte layer may also have a porous body such as a resin nonwoven fabric as a support.

[0096] To form the solid electrolyte layer, a solid electrolyte layer-forming composition containing a solid electrolyte can be used, which can be pressure-molded to form the solid electrolyte layer. The solid electrolyte layer-forming composition may be composed of only the solid electrolyte as long as it can be molded into a layer using only the solid electrolyte, or may contain a binder (e.g., a fluororesin such as PVDF) together with the solid electrolyte, if necessary.

[0097] The thickness of the solid electrolyte layer is preferably 10 to 500 μm.

[0098] The power generation element can be manufactured by a process that includes integrally molding a positive electrode layer, a solid electrolyte layer, and a negative electrode layer using the mold of the present invention, and in this process, forming the positive electrode layer in a through-hole in the upper part of the die, and forming the solid electrolyte layer and the negative electrode layer in a through-hole in the lower part of the die, thereby making the area of ​​the positive electrode layer smaller than the areas of the solid electrolyte layer and the negative electrode layer in a planar view. Note that since the solid electrolyte layer and the negative electrode layer are formed in the same through-hole in the lower part of the die, their areas are approximately the same, but it is preferable that the solid electrolyte layer covers the opposing surface of the negative electrode layer.

[0099] Furthermore, the power generation element is formed using a mold having a die configured such that the entire upper through-hole is located inside the lower through-hole so that the outline representing the shape of the upper through-hole of the die does not intersect with the outline representing the shape of the lower through-hole in a planar view. As a result, the positive electrode layer, which has a smaller area, is positioned so that its entirety is located inside the negative electrode layer and solid electrolyte layer, which have larger areas, in a planar view (i.e., the outline representing the shape of the positive electrode layer does not intersect with the outline representing the shape of the negative electrode layer and the outline representing the shape of the solid electrolyte layer in a planar view).

[0100] An example of a manufacturing procedure for a power generation element will be described below with reference to Figures 4 to 11. The manufacturing procedure described below is an example using a mold having the cross-sectional structure shown in Figure 1, with an upper and lower section configured to be separable, and with a die having a separable upper section composed of two parts. However, the mold 100 shown in Figures 4 to 9 and 11 is provided with a stopper 301 for fixing the upper punch 300 in a position where there is no step between the bottom surface of the upper punch 300 and the end of the upper part 210 of the die on the lower part 220 side, so that the upper punch 300 does not enter the through-hole 232 of the lower part 220 of the die.

[0101] (i) First, as shown in FIG. 4 , upper punch 300 and lower punch 400 (hereinafter, these may be collectively referred to simply as “punches”), and upper portion 210 and lower portion 220 of die 200 are turned upside down and fixed so that the upper surface of upper punch 300 in the figure coincides with the upper surface of upper portion 210 of die 200 in the figure, and lower punch 400 is moved upward, and solid electrolyte layer-forming composition 600 is filled into through-holes 232.

[0102] (ii) Next, as shown in Fig. 5 , the solid electrolyte layer-forming composition 600 is pressurized (preliminary pressed) from above by the lower punch 400 to form a preliminarily molded body (preliminary solid electrolyte molded body) 610 for obtaining a solid electrolyte layer. Note that, in the mold 100 shown in Figs. 4 and 5 , as described above, the upper punch 300 is provided with the stopper 301, and the bottom surface (upper surface in Fig. 5 ) of the upper punch 300 and the end portion (upper end portion in Fig. 5 ) of the upper portion 210 of the die 200 are flush with each other without any steps, so that the bottom surface (lower surface in Fig. 5 ) of the preliminarily molded solid electrolyte body 610 can be flattened.

[0103] By first pressing the solid electrolyte layer-forming composition at a lower surface pressure to form a provisionally molded body, and then pressing it at a higher surface pressure to form the solid electrolyte layer, it is possible to form a solid electrolyte layer with a smaller porosity and higher ion conductivity while suppressing the occurrence of cracks, and to improve the adhesion between the solid electrolyte layer and the positive electrode layer and the negative electrode layer. Therefore, in the integral molding of the power generation element, it is preferable to form a provisionally molded body of the solid electrolyte.

[0104] The surface pressure of the pressure molding for forming the pre-molded body of the solid electrolyte varies slightly depending on the type of solid electrolyte, but is, for example, preferably 500 MPa or less, more preferably 400 MPa or less, and from the viewpoint of maintaining the shape of the pre-molded body well, is preferably 10 MPa or more, more preferably 30 MPa or more.

[0105] (iii) Next, as shown in FIG. 6 , while the die 200 and the punch are upside down and the upper punch 300 is fixed, the lower punch 400 is moved upward, and then the anode mixture 500 is filled into the through-holes 232, and the anode mixture 500 is placed on one main surface of the provisional molded body 610 of the solid electrolyte layer, i.e., on the upper surface of the provisional molded body 610 in the drawing.

[0106] (iv) Next, as shown in FIG. 7 , the anode mixture 500 placed on the upper surface of the provisionally molded body 610 of the solid electrolyte layer is pressed (preliminary pressed) from above by the lower punch 400 to form a provisionally molded body 510 (provisional molded body 510 of the anode mixture) for obtaining the anode layer.

[0107] For the anode layer, a temporary molded body of the anode mixture is formed in advance by applying pressure at a low surface pressure, and then the anode layer is formed by applying pressure at a higher surface pressure. This makes it possible to form an anode layer with a smaller porosity and higher ion conductivity while suppressing the occurrence of cracks, and to improve the adhesion between the anode layer and the solid electrolyte layer. Therefore, in the integral molding of the power generation element, it is preferable to form a temporary molded body of the anode mixture.

[0108] The surface pressure of the pressure molding for forming the provisionally molded body of the negative electrode mixture is, for example, preferably 1000 MPa or less, more preferably 700 MPa or less, and from the viewpoint of maintaining the shape of the provisionally molded body well, is preferably 30 MPa or more, more preferably 100 MPa or more.

[0109] (v) Next, with the upper punch 300 and the lower punch 400 still inserted in the upper portion 210 and the lower portion 220 of the die 200, respectively, the die 200 and the punches are inverted upside down, and as shown in FIG. 8 , the upper punch 300 is moved upward, and then the positive electrode mixture 700 is filled into the through-holes 231, and the positive electrode mixture 700 is placed on one main surface of the provisionally molded body 610 of the solid electrolyte, i.e., on the upper surface of the provisionally molded body 610 in the drawing.

[0110] 9 , the positive electrode mixture 700, the provisionally molded solid electrolyte body 610, and the provisionally molded negative electrode mixture body 510 are pressed from above (mainly pressed) by an upper punch 300. As a result, the positive electrode mixture, the provisionally molded solid electrolyte body, and the provisionally molded negative electrode mixture body are compressed, and a power generation element in which the positive electrode layer 70, the solid electrolyte layer 60, and the negative electrode layer 50 are stacked is formed.

[0111] The surface pressure during pressure molding to form the power generating element (surface pressure during main pressing) is preferably 600 MPa or more. The upper limit of the surface pressure during pressure molding to form the power generating element (surface pressure during main pressing) is usually about 2000 MPa.

[0112] Although the main pressing may be performed at a constant pressure, if the difference between the surface pressure during the main pressing and the surface pressure during the preliminary pressing of the solid electrolyte layer and / or the anode layer is large, cracks may be more likely to occur near the peripheral portions of the solid electrolyte layer and / or the anode layer that do not face the cathode layer. Therefore, a fixed-size pressing may be performed by preparing an upper punch (2) with a stroke different from that of the upper punch used to form the solid electrolyte layer and the anode layer. That is, as shown in FIG. 10 , a stopper 301 may be provided to stop the insertion of the upper punch (2) 310 into the through-hole in the upper portion 210 of the die 200 at a position where a cathode layer 70 of the desired thickness is obtained, thereby preventing excessive pressure from being applied to the power generation element. Furthermore, if the area of ​​the stopper is equal to or greater than the area of ​​the through-hole in the lower portion of the die in a plan view, pressure from the upper portion of the die is also applied to the peripheral portions of the solid electrolyte layer and / or the anode layer that do not face the cathode layer, thereby more effectively suppressing cracking.

[0113] Alternatively, prior to the main pressing, a cathode mixture placed on the upper surface of the provisionally molded body of the solid electrolyte may be pressed at a lower surface pressure to form a provisionally molded body of the cathode mixture, and then the provisionally molded body of the cathode mixture, the provisionally molded body of the solid electrolyte, and the provisionally molded body of the anode mixture may be pressed (mainly pressed) to form a power generating element.

[0114] By first pressing the positive electrode mixture at a lower surface pressure to form a preformed body of the positive electrode mixture and then pressing at a higher surface pressure to form the positive electrode layer, it is possible to form a positive electrode layer with a small porosity while suppressing the occurrence of cracks, and to improve the adhesion between the positive electrode layer and the solid electrolyte layer. Therefore, in the integral molding of the power generation element, it is preferable to form a preformed body of the positive electrode mixture.

[0115] The surface pressure of the pressure molding for forming the provisionally molded body of the positive electrode mixture is preferably 500 MPa or less, more preferably 450 MPa or less, and even more preferably 400 MPa or less. From the viewpoint of maintaining the shape of the provisionally molded body in a good condition, the surface pressure is preferably 30 MPa or more, more preferably 100 MPa or more, and even more preferably 150 MPa or more.

[0116] (vii) Next, the formed integrally molded power generating element is removed from the mold. In this case, first, as shown in FIG. 11, the upper punch 300 is moved upward, and then the upper part 210 of the die is separated from the lower part 220 while dividing it into two parts.

[0117] After removing the upper part 210 of the die, the negative electrode layer 50 of the power generating element can be pushed from below with the lower punch 400, thereby removing the power generating element from the through-hole 232 of the lower part 220 of the die.

[0118] Furthermore, when a die is used in which the upper and lower parts can be separated and the lower part can be divided into multiple parts (e.g., two), when removing the power generation element after integral molding, the lower punch is moved downward, and then the lower part of the die is separated into parts while being removed from the upper part, and then the upper punch is used to press the positive electrode layer of the power generation element, thereby allowing the power generation element to be removed from the through hole at the top of the die.

[0119] Furthermore, if a die is used in which the upper and lower parts cannot be separated but the entire die can be divided into multiple parts, when removing the power generation element after integral molding, the upper punch can be moved upward and the lower punch can be moved downward, and then the die can be divided into parts and removed from the power generation element, thereby allowing the power generation element to be removed from the die.

[0120] In addition, when using a die having an upper and lower part that can be separated but cannot be divided into multiple parts, when removing the power generation element after integral molding, a method can be used in which the upper and lower parts of the die are separated, and one of these is removed from the power generation element first, and then it is pushed out using an upper punch or a lower punch.

[0121] However, in order to better suppress the formation of burrs in the power generation element when it is removed from the die and to better suppress the detachment of conductive components from the positive electrode layer and the negative electrode layer, it is more preferable to use a die that allows the upper and lower parts to be separated and that allows the upper or lower part to be divided into multiple parts. Also, as described above, both the upper and lower parts of the die may be configured to be divided into multiple parts. In particular, if both the upper and lower parts of the die are divisible into multiple parts, the power generation element can be easily removed while placed on the upper surface of the lower punch without being pressed by the upper or lower punch, which is preferable in that the generation of burrs on the side surfaces of the power generation element can be further suppressed.

[0122] In the power generating element obtained in this manner, the area of ​​the positive electrode layer is smaller than the areas of the solid electrolyte layer and the negative electrode layer, but in this case, the distance between the nearest end of the positive electrode layer and the nearest end of the solid electrolyte layer and the nearest end of the negative electrode layer is preferably 0.1 mm or more in a plan view, which can more effectively suppress the occurrence of short circuits due to detachment of conductive material from the positive electrode layer and the negative electrode layer.

[0123] The distance between the closest points of the end of the positive electrode layer and the end of the solid electrolyte layer and the negative electrode layer in plan view is, for example, the difference between the radius of the positive electrode layer and the radius of the solid electrolyte layer and the negative electrode layer when the positive electrode layer, solid electrolyte layer, and negative electrode layer are circular in plan view and their centers are aligned. Also, when the positive electrode layer, solid electrolyte layer, and negative electrode layer are square in plan view and their centers (intersections of diagonals) are aligned and their respective diagonals overlap, the "distance between the closest points in plan view" is the shortest distance between the side of the square in the positive electrode layer and the corresponding side of the square in the solid electrolyte layer and the negative electrode layer.

[0124] There is no particular upper limit to the distance between the closest points of the end of the positive electrode layer and the end of the solid electrolyte layer and the negative electrode layer in a planar view. However, if the distance is too large, it becomes difficult to adjust the balance between the capacity of the positive electrode layer and the capacity of the negative electrode layer in the power generation element to be formed. Therefore, it is preferable to set the upper limit to, for example, 1.0 mm or less.

[0125] The distance between the closest points of the end of the positive electrode layer and the ends of the solid electrolyte layer and the negative electrode layer in a plan view is approximately the same as the distance between the closest points of the upper through-hole and the lower through-hole of the die used to integrally mold them. Therefore, the distance between the closest points of the end of the positive electrode layer and the ends of the solid electrolyte layer and the negative electrode layer in a plan view can be adjusted by adjusting the shape (size) of the upper through-hole and the shape (size) of the lower through-hole of the die in the die.

[0126] The planar shape of the power generating element can be circular, elliptical, or polygonal (e.g., quadrilateral such as a square or rectangle, hexagonal such as a regular hexagon, or octagonal such as a regular octagon) depending on the planar shape (opening shape) of the through-holes in the die (through-holes in the upper and lower parts of the die). In the case of a polygon, the corners can also be curved.

[0127] <All-Solid-State Battery> The all-solid-state battery of the present invention is formed by housing the power generating element of the present invention in an exterior body.

[0128] A longitudinal cross-sectional view schematically illustrating an example of an all-solid-state battery of the present invention is shown in Fig. 12. The all-solid-state battery 10 shown in Fig. 12 includes a power generating element 40 (power generating element of the present invention) having an anode layer 50, a cathode layer 70, and a solid electrolyte layer 60 interposed therebetween, and this power generating element 40 is enclosed in an exterior body formed by a recessed container (exterior container) 20 and a lid 21.

[0129] External terminals 80, 90 for electrically connecting to a device to which the all-solid-state battery 10 is applied are provided on the bottom surface of the recessed container 20 in the drawing. The external terminal 80 is electrically connected to the negative electrode layer 50 of the power generating element 40 through a conductive path 81. The external terminal 90 is electrically connected to the positive electrode layer 70 of the power generating element 40 through a lead 30 and a conductive path 91.

[0130] A porous body metal layer 31 is disposed on the surface of the anode layer 50 (the surface opposite the solid electrolyte layer 70), and the anode layer 50 is electrically connected to the porous body metal layer 31. The porous body metal layer 31 has pores and is made of metal, and therefore can be easily plastically deformed by applying a force in the thickness direction. Therefore, when forming the all-solid-state battery 10, the power generation element 40 is inserted into the recessed container 20 so as to be pressed against the porous body metal layer 32 (the metal porous body that constitutes it), thereby compressively deforming the porous body metal layer 31, thereby improving contact between the power generation element 40 and the anode layer 50. Furthermore, when a large number of all-solid-state batteries 10 are manufactured, the degree of electrical connection between the porous body metal layer 31 and the power generation element 40 in each of the all-solid-state batteries 10 can be made uniform. Therefore, the use of a porous body metal layer makes it possible to obtain an all-solid-state battery with lower internal resistance and reduced variation in individual internal resistance.

[0131] The porous metal layer may be formed from a porous body made of a metal that does not adversely affect the characteristics of the all-solid-state battery within the all-solid-state battery. However, it is preferable to use a foamed metal porous body (such as "Celmet (registered trademark)" manufactured by Sumitomo Electric Industries, Ltd.) because it is relatively easy to plastically deform it.

[0132] In addition, in the all-solid-state battery 10 shown in FIG. 12 , a pressing means 32 is provided between the lead 30 and the lid 21, and has the effect of pressing the power generating element 40 against the recessed container 20 side (the porous metal layer 31 side).

[0133] By providing this pressing means, in the case of an all-solid-state battery in which the power generating element and the conductive path (conductive path 81 in the figure) are in direct contact with each other, the contact between the power generating element and the conductive path can be improved, thereby reducing the internal resistance of the all-solid-state battery.

[0134] Furthermore, as shown in FIG. 12 , in the case of the all-solid-state battery 10 having a configuration in which the porous metal layer 31 is provided between the power generating element 40 and the conductive path 81, the power generating element 40 (the negative electrode layer 50 thereof) is pressed against the porous metal layer 31 by the pressing means 32, and therefore the power generating element 40 can be brought into better contact with the porous metal layer 31 while more satisfactorily plastically deforming the porous metal layer 31, thereby further improving the effects of lowering the internal resistance of the all-solid-state battery 10 and suppressing individual variations.

[0135] The pressing means may be a spacer made of an elastic material such as a rubber sheet or a spring (such as a leaf spring).

[0136] In addition, although FIG. 12 shows an embodiment in which the power generating element 40 is enclosed in the exterior body so that the negative electrode layer 50 is on the lower side in the figure and the positive electrode layer 70 is on the upper side in the figure, in the all-solid-state battery of the present invention, the power generating element can also be arranged upside down in comparison with the case of FIG. 12 .

[0137] In producing the all-solid-state battery of the present invention, the power generating element of the present invention may be housed in an exterior body in accordance with a conventional method.

[0138] As the exterior body of the all-solid-state battery, a battery container having a concave container (exterior container) and a lid as shown in FIG. 12; a flat (coin-shaped, button-shaped, etc.) or tubular (cylindrical, rectangular, etc.) battery container having a metal exterior can and a metal sealing body; a battery container made of a laminate film exterior body made of a metal laminate film such as an aluminum laminate film; and the like can be used.

[0139] 12, the battery container having a concave container and a lid can be made of ceramics or resin, and the lid can be made of ceramics, resin, or metal (such as an iron-nickel alloy or an iron-based alloy such as an iron-nickel-cobalt alloy).

[0140] In the concave container, the external terminal, the conductive path connecting the electrodes of the power generating element to the external terminal, and further the lead connecting the electrodes of the power generating element to the conductive path can be made of metals such as manganese, cobalt, nickel, copper, molybdenum, silver, palladium, tungsten, platinum, gold, etc., or alloys containing these.

[0141] The concave container and the lid can be sealed by bonding them together with an adhesive. In addition, when a metal sealing member is used, the lid side of the side wall of the concave container can be made of metal by placing a seal ring made of metal (such as an iron-nickel alloy or an iron-based alloy such as an iron-nickel-cobalt alloy) on the lid side of the side wall, and then the concave container and the lid can be welded together to seal the container.

[0142] The shape of the exterior body in a plan view may be circular or polygonal such as quadrilateral (square or rectangle). In the case of a polygonal shape, the corners may be curved.

[0143] The present invention can be implemented in other forms without departing from the spirit of the present invention. The embodiments disclosed in this application are merely examples, and the present invention is not limited to these embodiments. The scope of the present invention shall be interpreted in accordance with the appended claims rather than the description in the above specification, and all modifications within the scope of the claims are included in the scope of the claims.

[0144] The all-solid-state battery of the present invention can be used in the same applications as known primary batteries and secondary batteries, but since it has a solid electrolyte instead of an organic electrolyte solution, it has excellent heat resistance and can be preferably used in applications where it is exposed to high temperatures. Furthermore, the power generation element of the present invention can constitute the all-solid-state battery of the present invention. Furthermore, the mold of the present invention is useful for producing the power generation element of the present invention.

[0145] DESCRIPTION OF SYMBOLS 10 All-solid-state battery 20 Concave container 21 Lid 30 Lead 31 Porous metal layer 32 Pressing means 40 Power generating element 50 Negative electrode layer 60 Solid electrolyte layer 70 Positive electrode layer 80, 90 External terminal 81, 91 Conduction path 100 Mold 200 Die 210 Upper part of die 220 Lower part of die 230 Through hole 231 Upper through hole of die 232 Lower through hole of die 300, 310 Upper punch 301 Stopping portion 400 Lower punch 500 Negative electrode mixture 510 Preliminary molded body of negative electrode mixture 600 Composition for forming solid electrolyte layer 610 Preliminary molded body of solid electrolyte 700 Positive electrode mixture

Claims

1. A mold for manufacturing a power generation element for an all-solid-state battery by pressure-molding a powder material, comprising: a die having a through hole for accommodating the powder material; and an upper punch and a lower punch for inserting into the through hole to pressure-mold the powder material; the die having an upper part for forming a positive electrode layer of the power generation element and a lower part for forming a solid electrolyte layer and a negative electrode layer of the power generation element; the area of ​​the through hole in the upper part of the die in a planar view is smaller than the area of ​​the through hole in the lower part of the die in a planar view; and the outline of the shape of the through hole in the upper part of the die does not intersect with the outline of the shape of the through hole in the lower part of the die in a planar view.

2. The mold according to claim 1, wherein the die is separable outward in plan view.

3. The mold according to claim 1, wherein the die is configured so that the upper and lower parts are separable.

4. The mold according to claim 3, wherein the upper portion of the die is separable outward in plan view.

5. The mold according to claim 3, wherein the lower portion of the die is separable outward in plan view.

6. A mold according to claim 1, wherein the distance between the closest points of the through holes in the upper portion and the lower portion is 0.1 mm or more in a plan view.

7. A mold as described in claim 1, wherein the upper punch has a stop portion that stops the insertion of the upper punch into the through hole in the upper part and fixes its position at a position where there is no step between the bottom surface of the upper punch and the lower end of the upper part when the upper punch is inserted into the through hole in the upper part.

8. A power generation element for constituting an all-solid-state battery, comprising: a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer; the power generation element being an integrally molded body of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer; wherein, in a plan view, the area of ​​the positive electrode layer is smaller than the areas of the solid electrolyte layer and the negative electrode layer; and a contour line representing the shape of the positive electrode layer does not intersect with a contour line representing the shape of the negative electrode layer or a contour line representing the shape of the solid electrolyte layer.

9. A power generation element for constituting an all-solid-state battery, comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, wherein in a process of integrally molding the positive electrode layer, the solid electrolyte layer, and the negative electrode layer using the mold according to claim 1, the positive electrode layer is formed within the through-hole in the upper part of the die, and the solid electrolyte layer and the negative electrode layer are formed within the through-hole in the lower part of the die, wherein, in a plan view, the area of ​​the positive electrode layer is smaller than the areas of the solid electrolyte layer and the negative electrode layer, and a contour line representing the shape of the positive electrode layer does not intersect with a contour line representing the shape of the negative electrode layer or a contour line representing the shape of the solid electrolyte layer.

10. A method for manufacturing a power generation element for constituting an all-solid-state battery, the power generation element having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, the method comprising the step of integrally molding the positive electrode layer, the solid electrolyte layer, and the negative electrode layer using the mold according to claim 1, wherein in the step, the positive electrode layer is formed within the through-hole in the upper part of the die, and the solid electrolyte layer and the negative electrode layer are formed within the through-hole in the lower part of the die, and the area of ​​the positive electrode layer is smaller than the areas of the solid electrolyte layer and the negative electrode layer in a plan view, and the outline representing the shape of the positive electrode layer does not intersect with the outline representing the shape of the negative electrode layer and the outline representing the shape of the solid electrolyte layer.

11. An all-solid-state battery comprising the power generating element according to claim 8 or 9 housed within an exterior body.

12. A method for manufacturing an all-solid-state battery, comprising the steps of: manufacturing a power generating element by the method for manufacturing a power generating element according to claim 10; and housing the power generating element in an exterior body.

Images