All-solid-state batteries

Abstract

To provide an all-solid-state battery with excellent cycle characteristics that prevents capacity degradation due to deterioration of the negative electrode layer even after repeated charging and discharging. [Solution] The direction in which the negative electrode layer 10, the positive electrode layer 20, and the solid electrolyte layer 30 are stacked is defined as the T direction, one of the directions perpendicular to the T direction is defined as the X direction, and the direction perpendicular to both the T direction and the X direction is defined as the Y direction. The negative electrode current collector layer 11 has a negative electrode current collector layer main body portion 12 that overlaps with the negative electrode active material layer 15 in the T direction, and a negative electrode tab 14 that extends from the negative electrode current collector layer main body portion 12 in the X+ direction. The outer circumferential surface of the negative electrode layer 10 has a pair of side portions 13 and 16 that are opposite to each other in the Y direction. When viewed in the T direction, each side portion 13 and 16 has uneven portions 13a and 16a that repeat in the X direction.

Description

[Technical Field]

[0001] The present invention relates to an all-solid-state battery. [Background Art]

[0002] In recent years, research and development have been conducted on secondary batteries that contribute to energy efficiency, in order to enable more people to secure access to affordable, reliable, sustainable and advanced energy.

[0003] Among secondary batteries, all-solid-state batteries using a solid electrolyte as an electrolyte have attracted particular attention because they are excellent in terms of high safety due to the nonflammability of the solid electrolyte and higher energy density. As an all-solid-state battery, an all-solid-state battery having a stacked structure in which a plurality of positive electrode layers and negative electrode layers are alternately stacked with a solid electrolyte layer interposed therebetween has been studied (for example, Patent Document 1).

[0004] In Patent Document 1, the negative electrode layer is formed by stacking a current collector layer and an active material layer. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Laid-Open No. 2024-90260 [Summary of the Invention] [Problem to be Solved by the Invention]

[0006] During charging of a solid-state battery, metal (e.g., lithium) is deposited or incorporated into the active material layer of the negative electrode. During discharging, the metal deposited or incorporated into the active material layer of the negative electrode is released and moves towards the positive electrode layer. As a result, the active material layer expands or contracts with the charging and discharging of the solid-state battery. The active material layer at the edge of the negative electrode layer, or the metal deposited at the edge of the negative electrode layer, may detach due to the expansion or contraction of the active material layer. Therefore, the negative electrode layer may deteriorate with repeated charging and discharging of the solid-state battery.

[0007] The present invention aims to provide an all-solid-state battery with excellent cycle characteristics that are less susceptible to capacity degradation due to deterioration of the negative electrode layer even after repeated charging and discharging. [Means for solving the problem]

[0008] (1) The present invention relates to an all-solid-state battery in which a negative electrode layer having at least a negative electrode current collector layer and a positive electrode layer are stacked via a solid electrolyte layer, wherein the direction of stacking is defined as the stacking direction, one of the directions perpendicular to the stacking direction is defined as the first direction, and the direction perpendicular to the stacking direction and the first direction is defined as the second direction, the negative electrode current collector layer has a negative electrode tab extending to one side in the first direction, the outer circumferential surface of the negative electrode layer has a pair of side portions facing the second direction, and in view in the stacking direction, each of the side portions has an uneven surface.

[0009] According to the all-solid-state battery described in (1), the surface area of ​​the side surface of the negative electrode layer can be increased, making it easier to fix the metal deposited on the negative electrode layer to the side surface. This suppresses the metal deposited on the negative electrode layer from falling off, thereby suppressing the deterioration of the negative electrode layer. Therefore, it is possible to provide an all-solid-state battery with excellent cycle characteristics in which capacity reduction due to deterioration of the negative electrode layer is less likely to occur even after repeated charging and discharging.

[0010] (2) In the all-solid-state battery described in (1) above, if the distance in the second direction between the bottom of one of the recesses and protrusions that form the uneven portion and the vertex of the protrusion adjacent to the recess is defined as the amount of unevenness, then the amount of unevenness may be 0.10 mm or more and 0.40 mm or less.

[0011] (2) The all-solid-state battery described above suppresses the detachment of metal deposited on the negative electrode active material layer from the negative electrode active material layer, and also suppresses the occurrence of short circuits caused by the protrusions coming into contact with the surroundings.

[0012] (3) In the all-solid-state battery described in (1) above, if the distance in the second direction between the bottom of one of the recesses and protrusions that form the uneven portion and the vertex of the protrusion adjacent to the recess is defined as the amount of unevenness, then the amount of unevenness may be 0.40 mm or less.

[0013] (3) The all-solid-state battery described above can suppress the occurrence of short circuits caused by the protrusions coming into contact with the surroundings.

[0014] (4) In the all-solid-state battery described in (1) above, if the distance in the second direction between the bottom of one of the recesses and protrusions that form the uneven portion and the vertex of the protrusion adjacent to the recess is defined as the amount of unevenness, then the amount of unevenness may be 0.10 mm or more.

[0015] (4) The all-solid-state battery described above can suppress the shedding of metal deposited in the negative electrode active material layer from the negative electrode active material layer.

[0016] (5) In the all-solid-state battery described in (1) above, if the distance in the first direction between the vertex of one of the protrusions forming the uneven portion and the vertex of the protrusion adjacent to that protrusion is defined as the unevenness pitch, then the unevenness pitch may be 0.50 mm or more and 1.20 mm or less.

[0017] According to the all-solid-state battery described in (5), if the pitch of the bumps and dips is too small, it becomes difficult to secure space for metal to deposit between adjacent bumps, and there is a risk that the area of ​​the bumps and dips on which metal can be deposited cannot be sufficiently increased. On the other hand, as the pitch of the bumps and dips increases, the inclined surface of the bumps and dips becomes gentler, and the bumps and dips take on a shape that is close to a straight line. In that case, there is a risk that the surface area of ​​the bumps and dips cannot be sufficiently increased. However, with this configuration, these problems can be suppressed, and it is possible to prevent the metal deposited on the negative electrode active material layer from falling off the negative electrode active material layer.

[0018] (6) In the all-solid-state battery described in (1) above, if the distance in the first direction between the vertex of one of the protrusions forming the uneven portion and the vertex of the protrusion adjacent to that protrusion is defined as the unevenness pitch, then the unevenness pitch may be 0.50 mm or more.

[0019] According to the all-solid-state battery described in (6), a space for metal deposition can be secured between adjacent protrusions, thereby significantly increasing the area of ​​the uneven surface where metal can be deposited.

[0020] (7) In the all-solid-state battery described in (1) above, if the distance in the first direction between the vertex of one of the protrusions forming the uneven portion and the vertex of a protrusion adjacent to that protrusion is defined as the unevenness pitch, then the unevenness pitch may be 1.20 mm or less.

[0021] (7) With the all-solid-state battery described above, it is possible to suppress the unevenness from becoming nearly straight, thereby sufficiently increasing the surface area of ​​the unevenness. [Effects of the Invention]

[0022] According to the present invention, it is possible to provide an all-solid-state battery with excellent cycle characteristics in which capacity reduction due to deterioration of the negative electrode layer is less likely to occur even after repeated charging and discharging. [Brief explanation of the drawing]

[0023] [Figure 1] It is an external perspective view of the all-solid-state battery according to the embodiment. [Figure 2] It is a cross-sectional view of the all-solid-state battery taken along line II-II in FIG. 1. [Figure 3] It is a cross-sectional view of the all-solid-state battery taken along line III-III in FIG. 1. [Figure 4] It is an exploded perspective view of the all-solid-state battery. [Figure 5] It is a plan view of the negative electrode active material layer viewed in the lamination direction. [Figure 6] It is a plan view of the negative electrode layer viewed in the lamination direction. [Figure 7] It is an enlarged view of part VII in FIG. 5. DESCRIPTION OF EMBODIMENTS

[0024] Hereinafter, the all-solid-state battery 1 according to an embodiment of the present invention will be described. The type of the all-solid-state battery 1 is not particularly limited, and for example, it is an all-solid lithium battery using lithium ions as a charge transfer medium. As shown in FIGS. 1 to 4, the all-solid-state battery 1 has a structure in which a positive electrode layer 20 and a negative electrode layer 10 are laminated with a solid electrolyte layer 30 interposed therebetween.

[0025] In the present specification, the direction in which the positive electrode layer 20 and the negative electrode layer 10 are laminated with the solid electrolyte layer 30 interposed therebetween is defined as "T direction". The T direction corresponds to the lamination direction. One of the directions orthogonal to the T direction is defined as "X direction". The X direction corresponds to the first direction. The direction orthogonal to both the T direction and the X direction is defined as "Y direction". The Y direction corresponds to the second direction. One side in the X direction is defined as "X+ direction", and the opposite side to the X+ direction is defined as "X- direction".

[0026] (All-solid-state battery) The all-solid-state battery 1 comprises, for example, a plurality of negative electrode layers 10, a plurality of solid electrolyte layers 30, and a plurality of positive electrode layers 20. The negative electrode layers 10, solid electrolyte layers 30, positive electrode layers 20, and solid electrolyte layers 30 are stacked in this order. The total number of stacked negative electrode layers 10 and positive electrode layers 20 is not particularly limited, but is preferably 10 or more. Note that in Figures 2 to 4, the vicinity of each end in the T direction of the all-solid-state battery 1 is omitted from the illustration.

[0027] The all-solid-state battery 1 comprises an outer casing 5, a negative electrode tab lead 6, and a positive electrode tab lead 7. The outer casing 5 is provided on the surface of the all-solid-state battery 1. The outer casing 5 covers a laminate of a negative electrode layer 10, a solid electrolyte layer 30, and a positive electrode layer 20. The outer casing 5 is formed of, for example, resin. In Figure 1, the outer casing 5 is shown by a dashed line. The negative electrode tab lead 6 is connected to a bundled negative electrode tab 14 (described later). The negative electrode tab lead 6 is drawn out from the outer casing 5. The positive electrode tab lead 7 is connected to a bundled positive electrode tab 24 (described later). The positive electrode tab lead 7 is drawn out from the outer casing 5.

[0028] (Negative electrode layer) The negative electrode layer 10 has at least a negative electrode current collector layer 11, and more specifically, a negative electrode active material layer 15 and a negative electrode current collector layer 11. One negative electrode layer 10 has, for example, one negative electrode current collector layer 11 and two negative electrode active material layers 15 provided sandwiching the negative electrode current collector layer 11 in the T direction.

[0029] The negative electrode active material layer 15 contains a negative electrode active material. Examples of negative electrode active materials include lithium metal, lithium alloy, silicon (Si), silicon alloys and other silicon-based active materials, lithium titanate (Li4Ti5O 12 Examples include lithium transition metal oxides such as ), transition metal oxides such as TiO2, Nb2O3 and WO3, metal sulfides, metal nitrides, carbon materials such as graphite, soft carbon and hard carbon, and metallic indium. The negative electrode active material layer 15 is preferably composed of lithium metal. The negative electrode active material layer 15 may further contain a solid electrolyte, a conductive additive, a binder, etc.

[0030] The negative electrode active material layer 15 has a shape that is, for example, a flat plate with its surface extending in the X and Y directions. The shape of the negative electrode active material layer 15 when viewed in the T direction is, for example, a rectangle with its long side extending in the X direction. The thickness (one side) of the negative electrode active material layer 15 is preferably 0.005 mm or more and 0.100 mm or less.

[0031] The negative electrode current collector layer 11 is provided adjacent to the negative electrode active material layer 15. The negative electrode current collector layer 11 is not particularly limited, but is made of copper, for example. The shape of the negative electrode current collector layer 11 is, for example, foil-like. The thickness of the negative electrode current collector layer 11 is preferably 0.006 mm or more and 0.050 mm or less. The negative electrode current collector layer 11 has a negative electrode current collector layer body portion 12 and a negative electrode tab 14.

[0032] The negative electrode current collector layer main body 12 is the portion of the negative electrode current collector layer 11 that faces the positive electrode layer 20. The negative electrode current collector layer main body 12 is the portion that overlaps with the adjacent negative electrode active material layer 15 in the T direction. The shape of the negative electrode current collector layer main body 12 in view in the T direction is, for example, a roughly rectangular shape with its long side extending in the X direction. Alternatively, a metal (for example, lithium) may be deposited directly onto the negative electrode current collector layer main body 12 without providing the negative electrode active material layer 15.

[0033] The negative electrode tab 14 is a portion of the negative electrode current collector layer 11 that extends from the negative electrode current collector layer main body 12 in a predetermined direction. For example, the negative electrode tab 14 extends from the negative electrode current collector layer main body 12 to one side in the X direction (more specifically, the X- direction). The Y-direction dimension of the negative electrode tab 14 is smaller than the Y-direction dimension of the negative electrode current collector layer main body 12. The shape of the negative electrode tab 14 in a T-direction view is, for example, a roughly rectangular shape with its longer side extending in the X direction. The tips of multiple negative electrode tabs 14 are converged to one another.

[0034] (solid electrolyte layer) The solid electrolyte layer 30 is provided between the negative electrode layer 10 and the positive electrode layer 20. The solid electrolyte layer 30 contains a solid electrolyte material. Examples of solid electrolyte materials include sulfide solid electrolyte materials and oxide solid electrolyte materials.

[0035] (Positive electrode layer) The positive electrode layer 20 includes a positive electrode active material layer 25 and a positive electrode current collector layer 21. One positive electrode layer 20 includes, for example, one positive electrode current collector layer 21 and two positive electrode active material layers 25 provided sandwiching the positive electrode current collector layer 21 in the T direction.

[0036] The positive electrode active material layer 25 contains a positive electrode active material. Examples of positive electrode active materials include transition metal chalcogenides such as titanium disulfide, molybdenum disulfide, and niobium selenide, and transition metal oxides such as lithium nickelate (LiNiO2), lithium manganeseate (LiMnO2, LiMn2O4), and lithium cobaltate (LiCoO2). The positive electrode active material layer 25 may further contain a solid electrolyte, a conductive additive, a binder, and the like.

[0037] The positive electrode active material layer 25 has a shape that is, for example, a flat plate with its surface extending in the X and Y directions. The shape of the positive electrode active material layer 25 when viewed in the T direction is, for example, a rectangle with its longer side extending in the X direction.

[0038] An insulating frame 26, for example, is provided on the outer periphery of the positive electrode active material layer 25.

[0039] The insulating frame 26 contains an electronically insulating material. Examples of electronically insulating materials include insulating oxides such as alumina, resins such as polyvinylidene fluoride (PVDF), and rubbers such as styrene-butadiene rubber (SBR). The insulating frame 26 is preferably formed of alumina. The insulating frame 26 may also have ionic conductivity.

[0040] The insulating frame 26 has a substantially flat shape with its surface extending in the X and Y directions. The shape of the insulating frame 26 when viewed in the T direction is, for example, a substantially rectangular frame shape with its longer side extending in the X direction.

[0041] The insulating frame 26 can suppress short circuits in the all-solid-state battery 1 and improve the strength of the all-solid-state battery 1.

[0042] The positive electrode current collector layer 21 is provided adjacent to the positive electrode active material layer 25. The positive electrode current collector layer 21 is formed of a current collector. Examples of current collectors include aluminum, copper, nickel, vanadium, iron, titanium, stainless steel, gold, platinum, and carbon. The positive electrode current collector layer 21 is formed of aluminum, for example. The shape of the positive electrode current collector layer 21 is, for example, foil-like. The positive electrode current collector layer 21 has a positive electrode current collector layer body portion 22 and a positive electrode tab 24.

[0043] The positive electrode current collector layer body portion 22 is the portion of the positive electrode current collector layer 21 that overlaps with the positive electrode active material layer 25 adjacent to the positive electrode current collector layer 21 in the T direction, and more specifically, it is the portion that overlaps with at least one of the two positive electrode active material layers 25 adjacent to the positive electrode current collector layer 21 in the T direction. The shape of the positive electrode current collector layer body portion 22 in view in the T direction is, for example, a rectangle with its long side extending in the X direction.

[0044] Furthermore, if an insulating frame 26 is provided on the positive electrode active material layer 25, "the portion of the positive electrode current collector layer 21 that overlaps in the T direction with the positive electrode active material layer 25 adjacent to the positive electrode current collector layer 21" means the portion of the positive electrode current collector layer 21 that overlaps in the T direction with at least one of the following: the positive electrode active material layer 25 adjacent to the positive electrode current collector layer 21, and the insulating frame 26 provided on the outer periphery of the positive electrode active material layer 25.

[0045] The positive electrode tab 24 is a portion of the positive electrode current collector layer 21 that extends from the positive electrode current collector layer main body 22 in a predetermined direction. For example, the positive electrode tab 24 extends from the positive electrode current collector layer main body 22 to one side in the X direction (more specifically, the X+ direction). The Y-direction dimension of the positive electrode tab 24 is smaller than the Y-direction dimension of the positive electrode current collector layer main body 22. The shape of the positive electrode tab 24 in a T-direction view is, for example, a roughly rectangular shape with its longer side extending in the X direction. The tips of multiple positive electrode tabs 24 are converged to one another.

[0046] (Middle class) Furthermore, the all-solid-state battery 1 includes, for example, a plurality of intermediate layers 40 provided between adjacent negative electrode layers 10 and solid electrolyte layers 30.

[0047] The intermediate layer 40 includes, for example, a metal that can be alloyed with lithium and carbon. Examples of metals that can be alloyed with lithium include Mg, Zn, Al, In, Si, Ge, Sn, Ag, Au, Pt, Pd, Pb, Sb, and Bi. The shape of the intermediate layer 40 is, for example, a substantially rectangular plate with plate surfaces extending in the X and Y directions.

[0048] Since the intermediate layer 40 is formed to be more flexible than the negative electrode layer 10 and the solid electrolyte layer 30, it is easier for it to adhere to the negative electrode layer 10 and the solid electrolyte layer 30. The intermediate layer 40 helps to suppress delamination between the negative electrode layer 10 and the solid electrolyte layer 30.

[0049] (Shape of the negative electrode layer) Here, as shown in Figure 5, the outer surface of the negative electrode active material layer 15 has a pair of side portions 16 facing each other in the Y direction. Each side portion 16 extends along the X direction. In view in the T direction, each side portion 16 has an uneven portion 16a.

[0050] As shown in Figure 6, the outer circumferential surface of the negative electrode current collector layer body portion 12 has a pair of side portions 13 that are opposite each other in the Y direction. Each side portion 13 extends along the X direction. In view in the T direction, each side portion 13 has an uneven portion 13a that repeats in the X direction.

[0051] Side portion 13 and side portion 16 are collectively referred to as "side portions 13, 16". Uneven portion 13a and uneven portion 16a are collectively referred to as "uneven portion 13a, 16a". The outer circumferential surface of the negative electrode layer 10 has a pair of side portions 13, 16 that are opposite each other in the Y direction. In view in the T direction, each side portion 13, 16 has uneven portions 13a, 16a.

[0052] Furthermore, the uneven portion 13a of the negative electrode current collector layer main body 12 has the same shape as, for example, the uneven portion 16a of the negative electrode active material layer 15. For this reason, the following description of the uneven portions 13a and 16a will use the uneven portion 16a as a representative example.

[0053] The uneven portion 16a is concave or convex in the Y direction. The unevenness of the uneven portion 16a is repeated multiple times in the X direction, preferably 100 times or more. The uneven portion 16a is provided on at least one of the side portions 16, more specifically, on both. The uneven portion 16a may be pointed or rounded.

[0054] As shown in Figure 7, the uneven portion 16a has a plurality of recesses 16aa and a plurality of protrusions 16ab. The distance in the Y direction between the bottom 16aaa of one of the recesses 16aa and the vertex 16aba of the protrusion 16ab adjacent to the recess 16aa is defined as the "amount of unevenness L".

[0055] The amount of unevenness L is preferably 0.4 mm or less.

[0056] The amount of unevenness L is preferably 0.1 mm or more.

[0057] The amount of unevenness L is preferably 0.1 mm or more and 0.4 mm or less.

[0058] The distance in the X direction between the vertex 16aba of one of the protrusions 16ab that form the uneven portion 16a and the vertex 16aba of the adjacent protrusion 16ab is defined as the "unevenness pitch S".

[0059] The unevenness pitch S is preferably 1.2 mm or less.

[0060] The unevenness pitch S is preferably 0.5 mm or more.

[0061] The unevenness pitch S is preferably 0.5 mm or more and 1.2 mm or less.

[0062] The uneven portion 16a can be formed in the manufacturing process of the all-solid-state battery 1 by cutting the negative electrode layer 10 using a cutter with a wavy blade. The cutter with a wavy blade is, for example, a rotary cutter with a wavy blade. The amount of unevenness L and the pitch S of the uneven portion 16a can be adjusted by adjusting the shape of the wavy blade. The uneven portion 13a and the uneven portion 16a can be formed simultaneously, for example, by cutting the negative electrode current collector layer 11 and the negative electrode active material layer 15 in a stacked state.

[0063] <Effects according to the embodiment> According to the above embodiment, the following effects can be obtained.

[0064] According to the above embodiment, the negative electrode current collector layer 11 has a negative electrode current collector layer main body portion 12 that overlaps with the negative electrode active material layer 15 in the T direction, and a negative electrode tab 14 that extends from the negative electrode current collector layer main body portion 12 in the X+ direction. The outer circumferential surface of the negative electrode layer 10 has a pair of side portions 13 and 16 that are opposite to each other in the Y direction. In view in the T direction, each side portion 13 and 16 has an uneven portion 13a and 16a.

[0065] With this configuration, the surface area of ​​the side portions 13 and 16 of the negative electrode layer 10 can be increased, making it easier to fix the metal deposited on the negative electrode layer 10 to the side portions 13 and 16. This suppresses the metal deposited on the negative electrode layer 10 from falling off, thereby suppressing the deterioration of the negative electrode layer 10. Therefore, it is possible to provide an all-solid-state battery 1 with excellent cycle characteristics in which capacity reduction due to deterioration of the negative electrode layer is less likely to occur even after repeated charging and discharging.

[0066] According to the above embodiment, the negative electrode layer 10 has a negative electrode active material layer 15. The outer circumferential surface of the negative electrode active material layer 15 has a pair of side portions 16 that are opposite to each other in the Y direction. In view in the T direction, each side portion 16 has an uneven portion 16a.

[0067] When the negative electrode layer 10 has a negative electrode active material layer 15, metal is deposited on the side surface 16 of the negative electrode active material layer 15 during charging of the all-solid-state battery 1. With this configuration, the metal deposited on the negative electrode active material layer 15 can be easily fixed to the side surface 16 of the negative electrode active material layer 15. This makes it possible to suppress the metal deposited on the negative electrode active material layer 15 from falling off the negative electrode active material layer 15.

[0068] According to the above embodiment, the outer circumferential surface of the negative electrode active material layer 15 has a pair of side portions 16 that are opposite to each other in the Y direction. In view in the T direction, each side portion 16 has an uneven portion 16a.

[0069] When the negative electrode layer 10 has a negative electrode active material layer 15, metal is deposited on the side surface 16 of the negative electrode active material layer 15 during charging of the all-solid-state battery 1. With this configuration, the metal deposited on the negative electrode active material layer 15 can be easily fixed to the side surface 16 of the negative electrode active material layer 15. This makes it possible to suppress the metal deposited on the negative electrode active material layer 15 from falling off the negative electrode active material layer 15.

[0070] Among the multiple recesses 16aa and multiple protrusions 16ab that form the uneven portion 16a of the negative electrode active material layer 15, the distance in the Y direction between the bottom 16aaa of one recess 16aaa and the vertex 16aba of the protrusion 16ab adjacent to the recess 16aa is defined as the "amount of unevenness L". It is preferable that the amount of unevenness L is 0.4 mm or less.

[0071] With this configuration, it is possible to suppress the Y-direction dimension of the protrusion 16ab from becoming too large, and thus it is possible to suppress the occurrence of short circuits caused by the tip of the protrusion 16ab coming into contact with the surroundings.

[0072] The amount of unevenness L is preferably 0.10 mm or more.

[0073] With this configuration, the surface area of ​​the uneven portion 16a can be sufficiently increased, so that the metal deposited on the uneven portion 16a can be sufficiently fixed to the uneven portion 16a. This makes it possible to suppress the metal deposited on the negative electrode active material layer 15 from falling off the negative electrode active material layer 15.

[0074] The amount of unevenness L is preferably 0.10 mm or more and 0.40 mm or less.

[0075] With this configuration, it is possible to suppress the metal deposited on the negative electrode active material layer 15 from falling off the negative electrode active material layer 15, and to suppress the occurrence of short circuits caused by the protrusions 16ab coming into contact with the surroundings.

[0076] Among the multiple protrusions 16ab that form the uneven surface 16a of the negative electrode active material layer 15, the distance in the X direction between the vertex 16aba of one protrusion 16ab and the vertex 16aba of the adjacent protrusion 16ab is defined as the "unevenness pitch S". The unevenness pitch S is preferably 1.2 mm or less.

[0077] With this configuration, the surface area of ​​the uneven portion 16a can be sufficiently increased by increasing the number of irregularities forming the uneven portion 16a. As a result, the metal deposited on the uneven portion 16a can be sufficiently fixed to the uneven portion 16a, thereby suppressing the metal deposited on the negative electrode active material layer 15 from falling off the negative electrode active material layer 15.

[0078] The unevenness pitch S is preferably 0.50 mm or more.

[0079] With this configuration, it is easier to secure space for metal to precipitate between adjacent protrusions, making it easier to fix the metal precipitated on the uneven portion 16a to the uneven portion 16a. This prevents the metal precipitated on the negative electrode active material layer 15 from falling off the negative electrode active material layer 15.

[0080] The unevenness pitch S is preferably 0.50 mm or more and 1.20 mm or less.

[0081] If the unevenness pitch S is too small, it becomes difficult to secure space for metal to precipitate between adjacent protrusions, which may prevent a sufficient increase in the area of ​​the uneven surface 16a where metal can precipitate. On the other hand, as the unevenness pitch S increases, the inclined surface of the uneven surface 16a becomes gentler, and the uneven surface 16a takes on a shape close to a straight line. In that case, it may not be possible to sufficiently increase the surface area of ​​the uneven surface 16a. However, with this configuration, these problems can be suppressed, and the metal precipitated on the negative electrode active material layer 15 can be prevented from falling off the negative electrode active material layer 15.

[0082] In the above embodiment, the negative electrode layer 10 had a negative electrode current collector layer 11 and a negative electrode active material layer 15. However, the negative electrode layer does not need to have a negative electrode active material layer as long as it has at least a negative electrode current collector layer. In that case, it is conceivable that metal (lithium) will be deposited on the side surface of the negative electrode current collector layer during charging of the all-solid-state battery. The metal deposited on the negative electrode current collector layer may detach from the negative electrode current collector layer as the all-solid-state battery expands or contracts.

[0083] However, by forming an uneven surface on the side surface of the negative electrode current collector layer, and by making the configuration of the uneven surface of the negative electrode current collector layer the same as the uneven surface 16a of the negative electrode active material layer 15 in the above embodiment, the same effects as in the above embodiment can be obtained.

[0084] The present invention is not limited to the configuration of the above embodiments, and can be modified and applied as appropriate without altering the essence of the invention. Furthermore, a combination of two or more of the desirable configurations described in the above embodiments also constitutes the present invention. [Examples]

[0085] 1. Manufacturing of all-solid-state batteries (Negative electrode current collector) As a negative electrode current collector, a copper foil was prepared having a main body with a surface surface that has a surface surface with a surface has been prepared, having a main body with a surface surface with a surface surface that has a surface surface with a surface surface that has a surface surface with a surface surface that has a surface surface with a surface surface that has a surface surface with a surface surface that has a surface surface with a surface surface that has a surface surface with a surface surface that has a surface surface with a surface surface that has a surface surface with a surface surface that has a surface

[0086] (Fabrication of the negative electrode layer) As the negative electrode active material layer, lithium foil (thickness: 40 μm) was prepared, having uneven surfaces on its sides with an unevenness L of 0.05 mm, 0.10 mm, 0.20 mm, 0.40 mm, or 0.50 mm and an unevenness pitch S of 0.30 mm, 0.50 mm, 0.70 mm, 1.20 mm, or 1.50 mm. The lithium foil was laminated onto the surface of each of the prepared copper foils to create the negative electrode layer. The unevenness L and unevenness pitch S of the copper foil and the unevenness L and unevenness pitch S of the lithium foil were adjusted by using different wavy blades.

[0087] (Fabrication of the positive electrode layer) As the positive electrode current collector, an aluminum foil (thickness: 5.0 μm) having a 15.0 μm tab portion, which had a main body portion and a tab portion extending from the main body portion, was prepared. 80 parts by mass of lithium nickel cobalt manganese composite oxide (NCM622) was mixed as the positive electrode active material, 17 parts by mass of argyrodite-type sulfide solid electrolyte as the solid electrolyte, 2 parts by mass of carbon black as a conductive additive, and 1 part by mass of SBR (styrene-butadiene rubber) binder as a binder. The resulting mixture was dispersed in 43 parts by mass of butyl butyrate to prepare a positive electrode active material layer slurry. The obtained positive electrode active material layer slurry was applied to one surface of the positive electrode current collector using a bar coater to a basis weight of 27 mg / cm2 after drying, and dried to form a positive electrode active material layer with a thickness of 80.0 μm, thereby creating the positive electrode layer.

[0088] (Preparation of solid electrolyte layer transfer sheet) A dispersion of argyrodite-type sulfide solid electrolyte (median diameter: 3.0 μm) was applied to a support sheet and dried to form an argyrodite-type sulfide solid electrolyte layer, thereby preparing a solid electrolyte layer transfer sheet.

[0089] (Preparation of the intermediate layer transfer sheet) A total of 95 parts by mass of Sn particles (median diameter: 0.07 μm) as metal nanoparticles and acetylene black (median diameter: 0.05 μm) as amorphous carbon were mixed with 5 parts by mass of a PVDF-based binder. The resulting mixture was dispersed in 1000 parts by mass of NMP (N-methyl-2-pyrrolidone) to prepare an intermediate layer slurry. The resulting intermediate layer slurry was applied to a support sheet and dried to prepare an intermediate layer transfer sheet with a final thickness of 3.0 μm.

[0090] (Fabrication of all-solid-state batteries) An intermediate layer of an intermediate layer transfer sheet was transferred onto the metallic lithium foil of the negative electrode layer, and then the negative electrode layer and the intermediate layer were press-bonded to create an intermediate layer-negative electrode layer laminate. Next, the solid electrolyte layer of a solid electrolyte layer transfer sheet was placed on the intermediate layer of the intermediate layer-negative electrode layer laminate, and after press-bonding, the support sheet of the solid electrolyte layer transfer sheet was peeled off to create a solid electrolyte layer-intermediate layer-negative electrode layer laminate. Next, the positive electrode active material layer of the positive electrode layer was placed on the solid electrolyte layer of the solid electrolyte layer-intermediate layer-negative electrode layer laminate, and press-bonded to create a positive electrode layer-solid electrolyte layer-intermediate layer-negative electrode layer laminate. The obtained laminate was housed in an outer casing, the tab portion of the positive electrode layer was connected to the positive electrode tab lead, and the tab portion of the negative electrode layer was connected to the positive electrode tab lead, and then the outer casing was sealed to obtain an all-solid-state battery.

[0091] The dimensions of the stacked portion of the all-solid-state battery (in other words, the portion of the all-solid-state battery excluding the positive and negative electrode tabs) were set to X × Y × T = 530 mm × 102 mm × 0.245 mm. The X-direction dimension of the negative electrode active material layer 15 was set to 0.010 mm.

[0092] 2. Evaluation Charge-discharge tests were conducted using the obtained all-solid-state batteries. For the fabricated batteries, charge-discharge tests were repeated four times at a rate of 0.1C with a lower voltage limit of 2.5V and an upper voltage limit of 4.2V, and the discharge capacity of the fourth cycle was taken as the initial capacity. The capacity at this time was set to 100%, and the percentage relative to this was calculated. For each example and comparative example, 10 all-solid-state batteries were used for the tests. In the charge-discharge tests, charge-discharge cycles were repeated 500 times at a rate of 0.5C in an environment of 55°C with a lower voltage limit of 2.5V and an upper voltage limit of 4.2V.

[0093] The presence or absence of short circuits was checked in all-solid-state batteries after charge-discharge testing. For each example and comparative example, the discharge capacity retention rate (%) (sometimes simply referred to as "capacity retention rate") after charge-discharge testing was measured. For each example and comparative example, if the capacity retention rate was less than 90%, it was evaluated as having a short circuit (defective), and if the capacity retention rate was 90% or higher, it was evaluated as not having a short circuit (good). In addition, for comparative examples evaluated as defective, the cause of the short circuit was also investigated.

[0094] 3.Measurement results Tables 1 to 5 show the amount of unevenness L (mm), the unevenness pitch S (mm), the capacity retention rate (%) after the charge / discharge test, the evaluation results regarding the presence or absence of short circuits, and the cause of the short circuits for each comparative example and each example. Although not shown in each table, in the case of the comparative example where the amount of unevenness L was 0 mm and the unevenness pitch S was 0 mm, the capacity retention rate was 35%, which was evaluated as poor.

[0095] Table 1 shows the results for Comparative Examples 1-1 to 1-5, where the amount of unevenness L was 0.05 mm and the unevenness pitch S was one of 0.30 mm, 0.50 mm, 0.70 mm, 1.20 mm, or 1.50 mm.

[0096] [Table 1]

[0097] Table 2 shows the results for Comparative Examples 1-1 to 1-5, where the amount of unevenness L was 0.10 mm and the unevenness pitch S was one of 0.30 mm, 0.50 mm, 0.70 mm, 1.20 mm, or 1.50 mm.

[0098] [Table 2]

[0099] Table 3 shows the results for Comparative Examples 3-1, 3-2 and Examples 3-1 to 3-3, where the amount of unevenness L was 0.20 mm and the unevenness pitch S was one of 0.30 mm, 0.50 mm, 0.70 mm, 1.20 mm, or 1.50 mm.

[0100] [Table 3]

[0101] Table 4 shows the results for Comparative Examples 4-1, 4-2 and Examples 4-1 to 4-3, where the amount of unevenness L was 0.40 mm and the unevenness pitch S was one of 0.30 mm, 0.50 mm, 0.70 mm, 1.20 mm, or 1.50 mm.

[0102] [Table 4]

[0103] Table 5 shows the results for Comparative Examples 5-1 to 5-5, where the amount of unevenness L was 0.50 mm and the unevenness pitch S was one of 0.30 mm, 0.50 mm, 0.70 mm, 1.20 mm, or 1.50 mm.

[0104] [Table 5]

[0105] First, let's consider the amount of unevenness L.

[0106] Examples 2-1 to 2-3, 3-1 to 3-3, and 4-1 to 4-3 showed that good results were obtained when the amount of surface irregularities L was between 0.20 mm and 0.40 mm. This suggests that sufficient cycle characteristics can be imparted to all-solid-state batteries when the amount of surface irregularities L is between 0.20 mm and 0.40 mm.

[0107] According to Comparative Examples 1-1 to 1-5, when the amount of unevenness L was 0.05 mm, short circuits occurred at all unevenness pitches S. In Comparative Examples 1-1 to 1-5, detachment of the negative electrode layer was observed. When the amount of unevenness L is too small, the shape of the uneven parts becomes relatively linear, resulting in insufficient surface area of ​​the uneven parts, which is thought to have prevented sufficient suppression of metal detachment in the negative electrode active material layer.

[0108] On the other hand, in each example and comparative examples 3-1, 3-2, 4-1, 4-2, 5-1 to 5-5, when the amount of unevenness L was 0.10 mm or more, detachment of the negative electrode layer was not necessarily observed. This suggests that detachment of the negative electrode can be suppressed by having an unevenness amount L of 0.10 mm or more.

[0109] According to Comparative Examples 5-1 to 5-5, when the amount of unevenness L was 0.5 mm, a short circuit occurred at all unevenness pitches S. In Comparative Examples 1-1 to 1-5, the tip of the protrusion on the side surface of the negative electrode layer was in contact with the surrounding structure of the negative electrode layer. When the amount of unevenness L is too large, the Y-direction dimension of the protrusion becomes relatively large, making it easier for the tip of the protrusion to come into contact with the surrounding structure, and thus making a short circuit more likely to occur.

[0110] On the other hand, according to each example and comparative examples 1-1 to 1-5, 2-1, 2-1, and 3-2, when the amount of unevenness L was 0.40 mm or less, the occurrence of a short circuit due to contact between the negative electrode layer (protrusions) and the surroundings was not necessarily observed. This suggests that the occurrence of a short circuit caused by contact between the negative electrode layer and the surroundings can be suppressed by having an amount of unevenness L of 0.40 mm or less.

[0111] Next, we will consider the unevenness pitch S.

[0112] Examples 1-1, 2-1, 3-1, 4-1, and 5-1 showed that good results were obtained when the surface irregularity pitch S was between 0.50 mm and 1.20 mm. This suggests that a surface irregularity pitch S of 0.50 mm to 1.2 mm can impart sufficient cycle characteristics to all-solid-state batteries.

[0113] According to Comparative Examples 1-1, 2-1, 3-1, 4-1, and 5-1, when the unevenness pitch S was 0.30 mm, short circuits occurred at all levels of unevenness L. When the level of unevenness L was relatively small (Comparative Examples 1-1 and 2-1), short circuits occurred due to the detachment of the negative electrode layer. It is thought that if the unevenness pitch S is too small, it becomes difficult to secure space for metal deposition between adjacent protrusions, and therefore the area of ​​the uneven surface where metal can be deposited could not be sufficiently increased. Also, when the level of unevenness L was relatively large (Comparative Examples 3-1, 4-1, and 5-1), short circuits occurred due to contact with the surrounding area of ​​the protrusions. When the unevenness pitch S is too large, there are a relatively large number of protrusions with relatively large dimensions in the Y direction on the side surface, so it is thought that a short circuit occurs when any of the protrusions come into contact with the surrounding area. However, when the level of unevenness L was relatively large (Comparative Examples 3-1, 4-1, and 5-1), the occurrence of short circuits due to the detachment of the negative electrode layer was suppressed.

[0114] According to Comparative Examples 1-5, 2-5, 3-5, 4-5, and 5-5, when the unevenness pitch S was 1.50 mm, short circuits occurred at all levels of unevenness L. When the level of unevenness L was relatively small (Comparative Examples 1-5, 2-5, and 3-5), short circuits occurred due to the detachment of the negative electrode layer. When the unevenness pitch S was too large, the inclined surface of the uneven part became gentler, and the uneven part became relatively linear. In that case, it is thought that the surface area of ​​the uneven part could not be sufficiently increased. Also, when the level of unevenness L was relatively large (Comparative Examples 3-1, 4-1, and 5-1), short circuits occurred due to contact with the surrounding area of ​​the protrusions. Furthermore, when the level of unevenness L was relatively large (Comparative Examples 3-1, 4-1, and 5-1), the occurrence of short circuits due to the detachment of the negative electrode layer was suppressed. [Explanation of Symbols]

[0115] 1: All-solid-state battery, 10: Negative electrode layer, 11: Negative electrode current collector layer, 13, 16: Side parts, 13a, 16a: Uneven parts, 14: Negative electrode tab, Negative electrode active material layer 15, 16aa: Recess, 16aaa: Bottom of recess, 16ab: Convex part, 16aba: Top of convex part, 20: Positive electrode layer, 30: Solid electrolyte layer, L: Amount of unevenness, S: Pitch of unevenness.

Claims

1. An all-solid-state battery comprising a negative electrode layer having at least a negative electrode current collector layer and a positive electrode layer, stacked via a solid electrolyte layer, If the direction of stacking is defined as the stacking direction, one of the directions perpendicular to the stacking direction is defined as the first direction, and the direction perpendicular to both the stacking direction and the first direction is defined as the second direction, The negative electrode current collector layer has a negative electrode tab extending to one side in the first direction, The outer circumferential surface of the negative electrode layer has a pair of side portions that are opposite to each other in the second direction, In the stacking direction view, each of the side surfaces has an uneven surface, thus an all-solid-state battery.

2. If the distance in the second direction between the bottom of one of the recesses and protrusions that form the aforementioned uneven portion and the vertex of the protrusion adjacent to the recess is defined as the amount of unevenness, The all-solid-state battery according to claim 1, wherein the amount of unevenness is 0.10 mm or more and 0.40 mm or less.

3. If the distance in the second direction between the bottom of one of the recesses and protrusions that form the aforementioned uneven portion and the vertex of the protrusion adjacent to the recess is defined as the amount of unevenness, The all-solid-state battery according to claim 1, wherein the amount of unevenness is 0.40 mm or less.

4. If the distance in the second direction between the bottom of one of the recesses and protrusions that form the aforementioned uneven portion and the vertex of the protrusion adjacent to the recess is defined as the amount of unevenness, The all-solid-state battery according to claim 1, wherein the amount of unevenness is 0.10 mm or more.

5. If the distance in the first direction between the vertex of one of the protrusions forming the aforementioned uneven portion and the vertex of an adjacent protrusion is defined as the unevenness pitch, The all-solid-state battery according to claim 1, wherein the aforementioned unevenness pitch is 0.50 mm or more and 1.20 mm or less.

6. If the distance in the first direction between the vertex of one of the protrusions forming the aforementioned uneven portion and the vertex of an adjacent protrusion is defined as the unevenness pitch, The all-solid-state battery according to claim 1, wherein the aforementioned unevenness pitch is 0.50 mm or more.

7. If the distance in the first direction between the vertex of one of the protrusions forming the aforementioned uneven portion and the vertex of an adjacent protrusion is defined as the unevenness pitch, The all-solid-state battery according to claim 1, wherein the aforementioned unevenness pitch is 1.20 mm or less.

Images