All-solid rechargeable battery

Abstract

This all-solid rechargeable battery includes: a first unit cell including a first lower current collecting layer, a first solid electrolyte layer, and a first upper current collecting layer that are stacked in a first direction; and a second unit cell disposed on the first upper current collecting layer of the first unit cell and including a second lower current collecting layer, a second solid electrolyte layer, and a second upper current collecting layer that are stacked in the first direction, wherein the first upper current collecting layer includes a first upper extension portion extending in a second direction crossing the first direction, and the second lower current collecting layer includes a second lower extension portion extending in the second direction and welded to the first upper extension portion.

Description

All-solid-state secondary battery

[0001] It is about all-solid-state secondary batteries.

[0002] Recent reports of explosion risks in batteries using liquid electrolytes have led to the development of all-solid-state secondary batteries. All-solid-state secondary batteries are batteries composed entirely of solid materials and utilize solid electrolytes.

[0003] These all-solid-state secondary batteries are safe because there is no risk of explosion due to electrolyte leakage, and they have the advantage of being easy to manufacture thin batteries.

[0004] When the alignment between each layer is incorrect during the manufacture of an all-solid-state secondary battery, there is a problem in which a lithium metal layer is formed unevenly on the surface of the negative electrode current collector layer when the battery is charged.

[0005] If a lithium metal layer is formed unevenly on the surface of the current collecting layer of an all-solid-state secondary battery, the capacity of the battery may decrease, or cracks may occur in the solid electrolyte layer located between the negative electrode current collecting layer and the positive electrode active material layer, causing a short circuit between the positive electrode and the negative electrode.

[0006] One embodiment is to provide an all-solid-state secondary battery in which alignment between a positive electrode active material layer and a negative electrode current collecting layer is improved, while a migration path of lithium ions moving from a positive electrode active material layer to a negative electrode current collecting layer during charging is expanded, thereby uniformly forming a lithium metal layer on the surface of the negative electrode current collecting layer during charging, thereby improving the capacity of the battery while suppressing short circuits between the positive electrode and the negative electrode.

[0007] In addition, it is intended to provide an all-solid-state secondary battery in which a plurality of unit cells form a bi-cell structure or a bipolar cell structure, even though the plurality of unit cells include an inclined surface that improves the capacity of the battery while suppressing short circuits between the positive and negative electrodes.

[0008] One side provides an all-solid-state secondary battery, comprising a first unit cell including a first lower current collecting layer, a first solid electrolyte layer, and a first upper current collecting layer stacked in a first direction, and a second unit cell positioned on the first upper current collecting layer of the first unit cell and including a second lower current collecting layer, a second solid electrolyte layer, and a second upper current collecting layer stacked in the first direction, wherein the first upper current collecting layer includes a first upper extension portion extending in a second direction intersecting the first direction, and the second lower current collecting layer includes a second lower extension portion extending in the second direction and welded to the first upper extension portion.

[0009] The first upper extension portion may not overlap with the first solid electrolyte layer and the second solid electrolyte layer in the first direction, and the second lower extension portion may not overlap with the first solid electrolyte layer and the second solid electrolyte layer in the first direction.

[0010] The first upper current collecting layer may further include a first upper overlapping portion extending from the first upper extension portion between the first solid electrolyte layer and the second solid electrolyte layer, and the second lower current collecting layer may further include a second lower overlapping portion extending from the second lower extension portion between the first solid electrolyte layer and the second solid electrolyte layer and overlapping the first upper overlapping portion in the first direction.

[0011] The first upper overlapping portion of the first upper current collecting layer can be in contact with the second lower overlapping portion of the second lower current collecting layer.

[0012] The first upper overlapping portion of the first upper current collecting layer and the second lower overlapping portion of the second lower current collecting layer can be non-welded to each other.

[0013] The first upper current collecting layer may further include an elastic sheet positioned between the first upper overlapping portion and the second lower overlapping portion of the second lower current collecting layer.

[0014] The elastic sheet can be in contact with the first upper overlapping portion of the first upper current collecting layer and the second lower overlapping portion of the second lower current collecting layer.

[0015] The third unit cell further includes a third lower current collecting layer, a third solid electrolyte layer, and a third upper current collecting layer, which are positioned on the second upper current collecting layer of the second unit cell and are stacked in the first direction, wherein the second upper current collecting layer includes a second upper extension portion extending in the second direction, and the third lower current collecting layer may include a third lower extension portion extending in the second direction and welded to the second upper extension portion.

[0016] The second upper extension portion and the third lower extension portion may extend in opposite directions from the first upper extension portion and the second lower extension portion in the second direction.

[0017] The first lower current collecting layer, the second upper current collecting layer, and the third lower current collecting layer may have the same first polarity, and the first upper current collecting layer, the second lower current collecting layer, and the third upper current collecting layer may have the same second polarity.

[0018] The first unit cell, the second unit cell, and the third unit cell can form a bi-cell structure.

[0019] The first lower current collecting layer, the second lower current collecting layer, and the third lower current collecting layer may have the same first polarity, and the first upper current collecting layer, the second upper current collecting layer, and the third upper current collecting layer may have the same second polarity.

[0020] The first unit cell, the second unit cell, and the third unit cell can form a bipolar cell structure.

[0021] The second unit cell may further include a positive electrode active material layer positioned between the second lower current collecting layer and the second solid electrolyte layer, a negative electrode coating layer positioned between the second solid electrolyte layer and the second upper current collecting layer, a first inclined surface extending from one end of the second lower current collecting layer to one end of the second solid electrolyte layer, a second inclined surface extending from the other end of the second lower current collecting layer to the other end of the second solid electrolyte layer, a third inclined surface extending from one end of the second upper current collecting layer to the one end of the second solid electrolyte layer, and a fourth inclined surface extending from the other end of the second upper current collecting layer to the other end of the second solid electrolyte layer.

[0022] The area of ​​the interface between the second upper current collecting layer and the negative electrode coating layer may be wider than the area of ​​the positive electrode active material layer.

[0023] The area of ​​the interface between the second upper current collecting layer and the cathode coating layer may be wider than the area of ​​the second lower current collecting layer.

[0024] When charging, a lithium metal layer may be formed between the second upper current collecting layer and the negative electrode coating layer.

[0025] The area of ​​the lithium metal layer may be wider than the area of ​​the positive electrode active material layer.

[0026] The area of ​​the above lithium metal layer may be wider than the area of ​​the second lower current collecting layer.

[0027] One end of the lithium metal layer can separate the third inclined surface, and the other end of the lithium metal layer can separate the fourth inclined surface.

[0028] According to one embodiment, an all-solid-state secondary battery is provided in which alignment between a positive electrode active material layer and a negative electrode current collecting layer is improved, while a migration path of lithium ions moving from a positive electrode active material layer to a negative electrode current collecting layer during charging is expanded, thereby uniformly forming a lithium metal layer on the surface of the negative electrode current collecting layer during charging, thereby improving the capacity of the battery while suppressing short circuits between the positive electrode and the negative electrode.

[0029] In addition, an all-solid-state secondary battery is provided in which a plurality of unit cells form a bi-cell structure or a bipolar cell structure, even though the plurality of unit cells include an inclined surface that improves the capacity of the battery while suppressing short circuits between the positive and negative electrodes.

[0030] Figure 1 is a cross-sectional view of an all-solid-state battery.

[0031] Figure 2 is a cross-sectional view of an all-solid-state battery including a precipitated negative electrode.

[0032] Figure 3 is a cross-sectional view showing the front of an all-solid-state secondary battery according to one embodiment.

[0033] Figure 4 is a cross-sectional view showing a side surface of an all-solid-state secondary battery according to one embodiment.

[0034] Fig. 5 is a cross-sectional view showing a second unit cell of an all-solid-state secondary battery according to one embodiment.

[0035] FIG. 6 is a cross-sectional view showing a lithium metal layer formed in a second unit cell of an all-solid-state secondary battery according to one embodiment.

[0036] Fig. 7 is a cross-sectional view showing an example of a second unit cell of an all-solid-state secondary battery according to one embodiment.

[0037] Fig. 8 is a cross-sectional view showing another example of a second unit cell of an all-solid-state secondary battery according to one embodiment.

[0038] FIG. 9 is a cross-sectional view showing another example of a second unit cell of an all-solid-state secondary battery according to one embodiment.

[0039] Fig. 10 is a cross-sectional view showing a side surface of an all-solid-state secondary battery according to another embodiment.

[0040] Fig. 11 is a cross-sectional view showing a side surface of an all-solid-state secondary battery according to another embodiment.

[0041] Figure 12 is a cross-sectional view showing a side surface of an all-solid-state secondary battery according to another embodiment.

[0042] Figure 13 is a cross-sectional view showing a side surface of an all-solid-state secondary battery according to another embodiment.

[0043] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0044] Additionally, throughout the specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0045] To clearly illustrate various layers and regions in the drawings, their thicknesses are enlarged, and similar parts are designated by the same drawing reference numerals throughout the specification. When an element such as a layer, film, region, or plate is said to be "over" or "on" another element, this includes not only the case where it is "directly over" the other element, but also the case where there is another element in between. Conversely, when an element is said to be "directly over" another element, it means that there is no other element in between.

[0046] Furthermore, the term "layer" here includes not only shapes formed on the entire surface when observed in a plan view, but also shapes formed on a portion of the surface. Here, "or" is not interpreted in an exclusive sense, and for example, "A or B" is interpreted to include A, B, A+B, etc.

[0047] Cathode for all-solid-state secondary batteries

[0048] In one embodiment, a positive electrode for an all-solid-state secondary battery is provided, comprising a current collector and a first positive electrode active material layer positioned on the current collector, wherein the first positive electrode active material layer includes a positive electrode active material, a sulfide-based solid electrolyte, a fluorine-based resin binder, and vanadium oxide.

[0049] The above-mentioned positive electrode for an all-solid-state secondary battery is manufactured by applying a positive electrode composition including a positive electrode active material, a sulfide-based solid electrolyte, a fluorine-based resin binder, and vanadium oxide to a current collector, and then drying and rolling.

[0050] The above-described positive electrode composition generally exhibits strong alkalinity due to residual lithium such as LiOH and other components, which may result in gelation or aggregation of the fluorine-based resin binder. However, according to one embodiment, the addition of vanadium oxide suppresses gelation of the fluorine-based resin binder, thereby maintaining the viscosity of the positive electrode composition and ensuring processability. Furthermore, since there is no need for a neutralizing agent, deterioration of the sulfide-based solid electrolyte caused by the neutralizing agent can be prevented, thereby improving the performance of the all-solid-state secondary battery.

[0051] vanadium oxide

[0052] The above vanadium oxide is a component that does not dissolve in the solvent of the positive electrode composition, and can control the strong basicity of the positive electrode composition to prevent gelation of the fluorine-based resin binder, while simultaneously suppressing deterioration of the sulfide-based solid electrolyte, thereby improving the ionic conductivity of the positive electrode. It is understood that vanadium oxide controls the pH through physical and / or chemical reactions with the -OH group in the positive electrode composition in a strongly basic state, thereby suppressing gelation of the fluorine-based resin binder. The vanadium oxide has a more excellent ability to suppress gelation of the fluorine-based resin binder by controlling basicity than other transition metal oxides such as titanium oxide or tungsten oxide, has low reactivity with the sulfide-based solid electrolyte, and suppresses deterioration of the sulfide-based solid electrolyte, thereby improving the ionic conductivity of the all-solid-state secondary battery and enhancing the overall performance.

[0053] The above vanadium oxides include, for example, V2O3, VO2, V2O4, V2O 5, Or a combination thereof may be included. In addition, the vanadium oxide may be included in an amount of 0.01 wt% to 5 wt% based on 100 wt% of the first positive electrode active material layer, for example, 0.05 wt% to 5 wt%, 0.1 wt% to 5 wt%, 0.5 wt% to 5 wt%, or 0.5 wt% to 3 wt%. When the vanadium oxide is included in such an amount, the viscosity of the positive electrode composition can be appropriately maintained without a decrease in capacity, thereby improving processability and enhancing the ionic conductivity of the positive electrode.

[0054] According to one embodiment, since vanadium oxide is added to the positive electrode composition and dispersed therein, the positive electrode composition is coated on the current collector, so the vanadium oxide may be dispersed within the manufactured first positive electrode active material layer. This is distinct from a form in which vanadium oxide is coated on the surface of the positive electrode active material or the sulfide-based solid electrolyte.

[0055] In one example, the vanadium oxide may be pentavalent vanadium oxide (vanadium(V) oxide), in which case the melting point of the vanadium oxide may be 1000°C or lower, for example, 600°C to 800°C, or 650°C to 690°C. The pentavalent vanadium oxide is excellent in suppressing gelation of a fluorine-based resin binder in the positive electrode and is advantageous in improving the overall performance of the battery.

[0056] In addition, the vanadium oxide may be in the form of particles, and the average particle diameter (D50) may be 10 nm to 10 ㎛, for example, 10 nm to 5 ㎛, 10 nm to 3 ㎛, 50 nm to 1 ㎛, 50 nm to 500 nm, or 500 nm to 1 ㎛. Vanadium oxide having such properties is suitable for incorporation into a positive electrode composition, and can effectively suppress gelation of the positive electrode composition without adversely affecting the positive electrode. If the particle diameter of the vanadium oxide is too small, it may not be properly dispersed within the positive electrode, thereby blocking the movement path of electrons and ions, thereby deteriorating battery performance, or may not sufficiently perform its role of suppressing gelation of the binder. On the contrary, if the particle diameter of the vanadium oxide is too large, it may itself block the movement path of electrons and ions, thereby deteriorating battery performance.

[0057] Fluorine resin binder

[0058] The above fluorine-based resin binder may be a general resin binder containing fluorine, and may include, for example, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-trichloroethylene copolymer, polyvinylidene fluoride-chlorotrifluoroethylene copolymer, polytetrafluoroethylene, or a combination thereof.

[0059] The weight average molecular weight of the fluorinated resin binder may be approximately 50 kDa to 5,000 kDa, or 100 kDa to 2,000 kDa. In addition, the glass transition temperature of the fluorinated resin binder may be -10°C or lower, and the melting point may be 100°C or higher. The melting viscosity of the fluorinated resin binder may be approximately 10 kP to 50 kP. In addition, the fluorinated resin binder may be in the form of particles, and the average particle diameter thereof may be approximately 50 nm to 200 μm. The fluorinated resin binder having such properties can implement excellent adhesive strength even when added in a small amount to the positive electrode composition, and can increase the durability of the battery without adversely affecting the battery performance.

[0060] The fluorine-based resin binder may be included in an amount of 0.1 wt% to 10 wt% based on 100 wt% of the first positive electrode active material layer, for example, 0.1 wt% to 8 wt%, 0.1 wt% to 6 wt%, 0.1 wt% to 5 wt%, 0.5 wt% to 4 wt%, or 1 wt% to 3 wt%. When the fluorine-based resin binder is included in the above content range, it can exhibit excellent adhesive strength without adversely affecting the positive electrode.

[0061] positive electrode active material

[0062] The above-mentioned positive electrode active material can be applied without limitation as long as it is generally used in all-solid-state secondary batteries. For example, the above-mentioned positive electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium, and may include a compound represented by any one of the following chemical formulas.

[0063] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5);

[0064] Li a A 1-b Xb O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0065] Li a HAVE BEEN 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0066] Li a HAVE BEEN 2-b X b O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0067] Li a Ni 1-b-c Co b X c D α (0.90 ≤ a ≤1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.5, 0 <α ≤ 2);

[0068] Li a Ni 1-b-c Co b X c O 2-α T α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0069] Li a Ni 1-b-c Co b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0070] Li a Ni 1-b-c Mr b X c D α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2);

[0071] Li a Ni 1-b-c Mr b X c O 2-α T α (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0072] Li a Ni 1-b-c Mr b X c O 2-α T2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2);

[0073] Li a Ni b HAVE BEEN c G d O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1);

[0074] Li a Ni b Co c Mr d G e O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤0.5, 0.001 ≤ e ≤ 0.1);

[0075] Li a NiG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0076] Li a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0077] Li a Mr 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0078] Li a Mn2G bO4(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0079] Li a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5);

[0080] QO2; QS2; LiQS2;

[0081] V2O5; LiV2O5;

[0082] LiZO2;

[0083] LiNiVO4;

[0084] Li (3-f) J2(PO4)3(0 ≤ f ≤ 2);

[0085] Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2);

[0086] Li a FePO4(0.90 ≤ a ≤ 1.8).

[0087] In the above chemical formulas, A is selected from the group consisting of Ni, Co, Mn, and combinations thereof; X is selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is selected from the group consisting of O, F, S, P, and combinations thereof; E is selected from the group consisting of Co, Mn, and combinations thereof; T is selected from the group consisting of F, S, P, and combinations thereof; G is selected from the group consisting of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; Q is selected from the group consisting of Ti, Mo, Mn, and combinations thereof; Z is selected from the group consisting of Cr, V, Fe, Sc, Y, and combinations thereof; J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof.

[0088] The above-mentioned positive electrode active material may be, for example, lithium cobalt oxide (LCO), lithium nickel oxide (LNO), lithium nickel cobalt oxide (NC), lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium nickel manganese oxide (NM), lithium manganese oxide (LMO), or lithium iron phosphate (LFP).

[0089] The above positive electrode active material may include a lithium nickel-based oxide represented by the following chemical formula 1, a lithium cobalt-based oxide represented by the following chemical formula 2, a lithium iron phosphate-based compound represented by the following chemical formula 3, or a combination thereof.

[0090] [Chemical Formula 1]

[0091] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2

[0092] In the above chemical formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, and M 1 and M 2 is one or more elements independently selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0093] [Chemical Formula 2]

[0094] Li a2 Co x2 M 3 1-x2 O2

[0095] In the above chemical formula 2, 0.9≤a2≤1.8, 0.6≤x2≤1, and M 3 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0096] [Chemical Formula 3]

[0097] Li a3 Fe x3 M 4 (1-x3) PO4

[0098] In the above chemical formula 3, 0.9≤a3≤1.8, 0.6≤x3≤1, and M 4 is one or more elements selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0099] The average particle diameter (D50) of the positive electrode active material may be 1 μm to 25 μm, for example, 3 μm to 25 μm, 5 μm to 25 μm, 5 μm to 20 μm, 8 μm to 20 μm, or 10 μm to 18 μm. A positive electrode active material having such a particle diameter range can be harmoniously mixed with other components in the first positive electrode active material layer and can realize high capacity and high energy density.

[0100] The above-mentioned positive electrode active material may be in the form of a secondary particle formed by agglomeration of a plurality of primary particles, or may be in the form of a single particle. In addition, the above-mentioned positive electrode active material may be spherical or nearly spherical in shape, or may be polyhedral or irregular in shape.

[0101] Sulfide-based solid electrolyte

[0102] Sulfide-based solid electrolytes include, for example, Li2S-P2S5, Li2S-P2S5--LiX (where X is a halogen element, for example, I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z. m Sn (m, n are integers, Z is Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are integers, and M is P, Si, Ge, B, Al, Ga or In), or a combination thereof.

[0103] Such sulfide-based solid electrolytes can be obtained, for example, by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10, or 50:50 to 80:20, and optionally heat-treating them. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be produced. Here, the ionic conductivity can be further improved by further including other components such as SiS2, GeS2, and B2S3.

[0104] Methods for mixing sulfur-containing raw materials for producing sulfide-based solid electrolytes include mechanical milling or the solution method. Mechanical milling involves placing the starting raw materials in a reactor and vigorously stirring them with a ball mill or similar device to finely atomize and mix them. Using the solution method, the starting raw materials are mixed in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, heat treatment after mixing can solidify the crystals of the solid electrolyte and improve ionic conductivity. For example, a sulfide-based solid electrolyte can be produced by mixing sulfur-containing raw materials and heat-treating them twice or more, resulting in a sulfide-based solid electrolyte with high ionic conductivity and robustness.

[0105] For example, the sulfide-based solid electrolyte particles may include argyrodite-type sulfides. The argyrodite-type sulfides may include, for example, Li a M b P c S d A e(wherein a, b, c, d, and e are all 0 or more and 12 or less, M is Ge, Sn, Si, or a combination thereof, and A is F, Cl, Br, or I) and can be expressed by the chemical formula, and a specific example is Li 7-x PS 6-x A x (x is 0.2 or more and 1.8 or less, and A is F, Cl, Br, or I) can be expressed by the chemical formula. The above argyrodite-type sulfide is specifically Li3PS4, Li7P3S 11 , Li7PS6, Li6PS5Cl, Li6PS5Br, Li 5.8 PS 4.8 Cl 1.2 , Li 6.2 PS 5.2 Br 0.8 It could be the back.

[0106] Sulfide-based solid electrolyte particles containing these argyrodite-type sulfides have an ionic conductivity of 10, which is the ionic conductivity of a typical liquid electrolyte at room temperature. -4 10 inland -2 It has a high ionic conductivity approaching the S / cm range, can form a close bond between a positive electrode active material and a solid electrolyte without causing a decrease in ionic conductivity, and can further form a close interface between an electrode layer and a solid electrolyte layer. An all-solid-state battery including this can have improved battery performance, such as rate characteristics, Coulombic efficiency, and cycle life characteristics.

[0107] An argyrodite-type sulfide-based solid electrolyte can be prepared, for example, by mixing lithium sulfide, phosphorus sulfide, and optionally, a lithium halide. After mixing, a heat treatment may be performed. The heat treatment may include, for example, two or more heat treatment steps.

[0108] According to one embodiment, the average particle diameter (D50) of the sulfide-based solid electrolyte particles may be 5.0 ㎛ or less, for example, 0.1 ㎛ to 5.0 ㎛, 0.1 ㎛ to 4.0 ㎛, 0.1 ㎛ to 3.0 ㎛, 0.5 ㎛ to 2.0 ㎛, or 0.1 ㎛ to 1.5 ㎛. Alternatively, the sulfide-based solid electrolyte particles may be small particles having an average particle diameter (D50) of 0.1 ㎛ to 1.0 ㎛, or may be large particles having an average particle diameter (D50) of 1.5 ㎛ to 5.0 ㎛, depending on the location or purpose of use. The sulfide-based solid electrolyte particles having such a particle diameter range can effectively penetrate between solid particles in a battery, and have excellent contact with an electrode active material and connectivity between solid electrolyte particles. The average particle size of the sulfide-based solid electrolyte particles may be measured from a microscope image, for example, by measuring the sizes of about 20 particles in a scanning electron microscope image to obtain a particle size distribution and calculating D50 from this.

[0109] The content of the solid electrolyte in the positive electrode for the all-solid-state battery may be 0.5 wt% to 35 wt%, for example, 1 wt% to 35 wt%, 5 wt% to 30 wt%, 8 wt% to 25 wt%, or 10 wt% to 20 wt%. This is the content relative to the total weight of the components in the positive electrode, and specifically, it can be said to be the content relative to the total weight of the first positive electrode active material layer.

[0110] In one embodiment, the first positive electrode active material layer may include 50 wt% to 99.35 wt% of the positive electrode active material, 0.5 wt% to 35 wt% of the sulfide-based solid electrolyte, 0.1 wt% to 10 wt% of the fluorine-based resin binder, and 0.05 wt% to 5 wt% of the vanadium oxide, based on 100 wt% of the first positive electrode active material layer. When this content range is satisfied, the positive electrode for an all-solid-state secondary battery can implement high capacity and high ionic conductivity while maintaining high adhesiveness, and the viscosity of the positive electrode composition can be maintained at an appropriate level, thereby improving processability.

[0111] Challenge

[0112] The first positive electrode active material layer may further include a conductive material. The conductive material is used to impart conductivity to the electrode, and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, and carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, and the like in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or combinations thereof.

[0113] The conductive material may be included in an amount of 0.1 wt% to 5 wt%, or 0.1 wt% to 3 wt%, based on the total weight of each component of the positive electrode for the all-solid-state battery, or based on the total weight of the first positive electrode active material layer. Within the above content range, the conductive material may improve electrical conductivity without degrading battery performance.

[0114] When the first positive electrode active material layer further includes a conductive material, the first positive electrode active material layer may include 45 wt% to 99.25 wt% of the positive electrode active material, 0.5 wt% to 35 wt% of the sulfide-based solid electrolyte, 0.1 wt% to 10 wt% of the fluorine-based resin binder, 0.05 wt% to 5 wt% of the vanadium oxide, and 0.1 wt% to 5 wt% of the conductive material, based on 100 wt% of the first positive electrode active material layer.

[0115] Meanwhile, the positive electrode for the lithium secondary battery may further include an oxide-based inorganic solid electrolyte in addition to the above-described solid electrolyte. The oxide-based inorganic solid electrolyte may be, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate (Li x La yTiO3, 0 <x<2, 0<y<3), Li2O, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2계 세라믹스, 가넷(Garnet)계 세라믹스 Li 3+x La3M2O 12 (M= Te, Nb, or Zr; x is an integer from 1 to 10), or a combination thereof.

[0116] All-solid-state secondary battery

[0117] In one embodiment, an all-solid-state secondary battery is provided, including the aforementioned positive electrode and negative electrode and a solid electrolyte layer positioned between the positive electrode and negative electrode. The all-solid-state secondary battery may also be referred to as an all-solid-state battery or an all-solid-state lithium secondary battery.

[0118] Figure 1 is a cross-sectional view of an all-solid-state battery.

[0119] Referring to FIG. 1, the all-solid-state battery (1000) may have a structure in which an electrode assembly in which a negative electrode (40) including a negative electrode collector (41) and a negative electrode active material layer (43), a solid electrolyte layer (30), and a positive electrode (20) including a positive electrode active material layer (23) and a positive electrode collector (21) are laminated is housed in a case such as a pouch. The all-solid-state battery (1000) may further include an elastic layer (50) on the outer side of at least one of the positive electrode (20) and the negative electrode (40). Although FIG. 1 illustrates one electrode assembly including a negative electrode (40), a solid electrolyte layer (30), and a positive electrode (20), an all-solid-state battery may be manufactured by laminating two or more electrode assemblies.

[0120] cathode

[0121] An anode for an all-solid-state battery may include, for example, a current collector and a negative electrode active material layer positioned on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder, a conductive material, and / or a solid electrolyte.

[0122] The above negative active material may include a material capable of reversibly intercalating / deintercalating lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

[0123] The material capable of reversibly intercalating / deintercalating the lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, and the like.

[0124] As the above lithium metal alloy, an alloy of lithium and one or more metals selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0125] As the material capable of doping and dedoping the lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used, and the Si-based negative electrode active material may be silicon, a silicon-carbon composite, or SiO. x(0<x<2), Si-Q 합금(상기 Q는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Si은 아님), 상기 Sn계 음극 활물질로는 Sn, SnO2, Sn-R 합금(상기 R은 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 15족 원소, 16족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 상기 원소 Q 및 R로는 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, 및 이들의 조합으로 이루어진 군에서 선택되는 것을 사용할 수 있다.

[0126] The silicon-carbon composite may be, for example, a silicon-carbon composite including a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer positioned on the surface of the core. The crystalline carbon may be artificial graphite, natural graphite, or a combination thereof. As the amorphous carbon precursor, coal pitch, mesophase pitch, petroleum pitch, coal oil, petroleum heavy oil, or a polymer resin such as a phenol resin, a furan resin, or a polyimide resin may be used. At this time, the content of silicon may be 10 wt% to 50 wt% with respect to the total weight of the silicon-carbon composite. In addition, the content of the crystalline carbon may be 10 wt% to 70 wt% with respect to the total weight of the silicon-carbon composite, and the content of the amorphous carbon may be 20 wt% to 40 wt% with respect to the total weight of the silicon-carbon composite. In addition, the thickness of the amorphous carbon coating layer may be 5 nm to 100 nm.

[0127] The average particle diameter (D50) of the above silicon particles may be 10 nm to 20 μm, for example, 10 nm to 500 nm. The silicon particles may exist in an oxidized form, and at this time, the atomic content ratio of Si:O in the silicon particles, which indicates the degree of oxidation, may be 99:1 to 33:67. The silicon particles may be SiO x It can be a particle, in which case SiO x In the range of x, it can be greater than 0 and less than 2. Here, the average particle diameter (D50) is measured by a particle size analyzer using laser diffraction and means the diameter of particles having a cumulative volume of 50% by volume in the particle size distribution.

[0128] The above Si-based negative electrode active material or Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material. The mixing ratio of the Si-based negative electrode active material or Sn-based negative electrode active material and the carbon-based negative electrode active material can be 1:99 to 90:10 by weight.

[0129] The content of the negative active material in the above negative active material layer may be 95 wt% to 99 wt% with respect to the total weight of the negative active material layer.

[0130] In one embodiment, the negative electrode active material layer further includes a binder and may optionally further include a conductive material. The content of the binder in the negative electrode active material layer may be 1 wt% to 5 wt% based on the total weight of the negative electrode active material layer. In addition, when the negative electrode active material layer further includes a conductive material, the negative electrode active material layer may include 90 wt% to 98 wt% of the negative electrode active material, 1 wt% to 5 wt% of the binder, and 1 wt% to 5 wt% of the conductive material.

[0131] The above binder serves to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the current collector. The binder may include an insoluble binder, a water-soluble binder, or a combination thereof.

[0132] The above-described non-aqueous binder may include, for example, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, a polymer comprising ethylene oxide, an ethylene propylene copolymer, polystyrene, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or a combination thereof.

[0133] The water-soluble binder may be a rubber-based binder or a polymer resin binder. The rubber-based binder may be selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile-butadiene rubber, acrylic rubber, butyl rubber, fluororubber, and combinations thereof. The polymer resin binder may be selected from polyethylene oxide, polyvinylpyrrolidone, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0134] When a water-soluble binder is used as the negative electrode binder, a thickener capable of imparting viscosity may be used together, and the thickener may include, for example, a cellulose-based compound. The cellulose-based compound may include carboxymethyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, an alkali metal salt thereof, or a combination thereof. Na, K, or Li may be used as the alkali metal. The amount of the thickener used may be 0.1 to 3 parts by weight based on 100 parts by weight of the negative electrode active material.

[0135] The conductive material is used to provide conductivity to the electrode, and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, and carbon nanotubes; metal-based materials in the form of metal powder or metal fibers, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0136] The negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof.

[0137] As another example, the negative electrode for the all-solid-state battery may be a precipitation-type negative electrode. The precipitation-type negative electrode refers to a negative electrode that does not include a negative electrode active material when the battery is assembled, but in which lithium metal or the like is precipitated when the battery is charged, and this acts as a negative electrode active material.

[0138] Figure 2 is a cross-sectional view of an all-solid-state battery including a precipitated negative electrode.

[0139] Referring to FIG. 2, the precipitation-type negative electrode (40') may include a current collector (41) and a negative electrode coating layer (45) positioned on the current collector. An all-solid-state battery having such a precipitation-type negative electrode (40') starts initial charging in a state in which no negative electrode active material is present, and during charging, high-density lithium metal or the like is precipitated between the current collector (41) and the negative electrode coating layer (45) to form a lithium metal layer (44), which may function as a negative electrode active material. Accordingly, in an all-solid-state battery that has been charged at least once, the precipitation-type negative electrode (40') may include a current collector (41), a lithium metal layer (44) positioned on the current collector, and a negative electrode coating layer (45) positioned on the metal layer. The lithium metal layer (44) refers to a layer in which lithium metal or the like is precipitated during the charging process of the battery, and may be referred to as a metal layer or a negative electrode active material layer.

[0140] The above cathode coating layer (45) may include a metal, carbon material, or a combination thereof that acts as a catalyst.

[0141] The metal may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or a combination thereof, and may be composed of one type of these or may be composed of an alloy of several types. When the metal is present in the form of particles, the average particle diameter (D50) thereof may be about 4 μm or less, for example, 10 nm to 4 μm.

[0142] The carbon material may be, for example, crystalline carbon, amorphous carbon, or a combination thereof. The crystalline carbon may be, for example, natural graphite, artificial graphite, mesophase carbon microbeads, or a combination thereof. The amorphous carbon may be, for example, carbon black, activated carbon, acetylene black, Denka black, Ketjen black, or a combination thereof.

[0143] When the above-described negative electrode coating layer (45) includes both the metal and the carbon material, the mixing ratio of the metal and the carbon material may be, for example, a weight ratio of 1:10 to 2:1. In this case, the precipitation of lithium metal can be effectively promoted and the characteristics of the all-solid-state battery can be improved. The above-described negative electrode coating layer (45) may include, for example, a carbon material supported with a catalytic metal, or may include a mixture of metal particles and carbon material particles.

[0144] The above cathode coating layer (45) may include, for example, the metal and amorphous carbon, in which case it can effectively promote the precipitation of lithium metal.

[0145] The above cathode coating layer (45) may further include a binder, and the binder may be a conductive binder. In addition, the above cathode coating layer (45) may further include general additives such as fillers, dispersants, and ionic conductive agents.

[0146] The thickness of the cathode coating layer (45) may be, for example, 100 nm to 20 ㎛, or 500 nm to 10 ㎛, or 1 ㎛ to 5 ㎛.

[0147] The above-described precipitated negative electrode (40') may further include, for example, a thin film on the surface of the current collector, i.e., between the current collector and the negative electrode coating layer. The thin film may include an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium may be, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., and may be composed of one type thereof or may be composed of multiple types of alloys. The thin film may further flatten the precipitated form of the lithium metal layer (44) and further improve the characteristics of the all-solid-state battery. The thin film may be formed by, for example, a vacuum deposition method, a sputtering method, a plating method, etc. The thickness of the thin film may be, for example, 1 nm to 500 nm.

[0148] solid electrolyte layer

[0149] The solid electrolyte layer (30) may include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, etc. The specific details of the sulfide-based solid electrolyte and the oxide-based solid electrolyte are as described above.

[0150] In one example, the solid electrolyte included in the positive electrode (20) and the solid electrolyte included in the solid electrolyte layer (30) may include the same compound or different compounds. For example, when both the positive electrode (20) and the solid electrolyte layer (30) include an argyrodite-type sulfide-based solid electrolyte, the overall performance of the all-solid-state secondary battery may be improved. In addition, for example, when both the positive electrode (20) and the solid electrolyte layer (30) include the above-described coated solid electrolyte, the all-solid-state secondary battery may implement high capacity and high energy density while implementing excellent initial efficiency and lifespan characteristics.

[0151] Meanwhile, the average particle diameter (D50) of the solid electrolyte included in the positive electrode (20) may be smaller than the average particle diameter (D50) of the solid electrolyte included in the solid electrolyte layer (30). In this case, the energy density of the all-solid-state battery can be maximized while increasing the mobility of lithium ions, thereby improving the overall performance. For example, the average particle diameter (D50) of the solid electrolyte included in the positive electrode (20) may be 0.1 ㎛ to 1.0 ㎛, or 0.1 ㎛ to 0.8 ㎛, and the average particle diameter (D50) of the solid electrolyte included in the solid electrolyte layer (30) may be 1.5 ㎛ to 5.0 ㎛, or 2.0 ㎛ to 4.0 ㎛, or 2.5 ㎛ to 3.5 ㎛. When this particle size range is satisfied, the energy density of the all-solid-state secondary battery can be maximized while lithium ion transport is facilitated, resistance is suppressed, and the overall performance of the all-solid-state secondary battery can be improved. Here, the average particle diameter (D50) of the solid electrolyte can be measured using a particle size analyzer using laser diffraction. Alternatively, the particle size can be measured by selecting 20 or so random particles from a microscope image such as a scanning electron microscope, obtaining a particle size distribution, and calculating the D50 value from this.

[0152] The above solid electrolyte layer may further include a binder in addition to the solid electrolyte. At this time, the binder may be styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, an acrylate polymer, or a combination thereof, but is not limited thereto, and any binder used in the relevant technical field may be used. The acrylate polymer may be, for example, butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0153] The above solid electrolyte layer can be formed by adding a solid electrolyte to a binder solution, coating the same on a base film, and drying the same. The solvent of the binder solution may be isobutyryl isobutyrate, xylene, toluene, benzene, hexane, or a combination thereof. Since the solid electrolyte layer formation process is widely known in the art, a detailed description thereof will be omitted.

[0154] The thickness of the solid electrolyte layer may be, for example, 10 μm to 150 μm.

[0155] The solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0156] The above alkali metal salt may be, for example, a lithium salt. The content of the lithium salt in the solid electrolyte layer may be 1 M or more, for example, 1 M to 4 M. In this case, the lithium salt may improve ion conductivity by enhancing the lithium ion mobility of the solid electrolyte layer.

[0157] The above lithium salts include, for example, LiSCN, LiN(CN)2, Li(CF3SO2)3C, LiC4F9SO3, LiN(SO2CF2CF3)2, LiCl, LiF, LiBr, LiI, LiB(C2O4)2, LiBF4, LiBF3(C2F5), lithium bis(oxalato)borate (LiBOB), lithium oxalyldifluoroborate (LIODFB), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, It may include LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4 or mixtures thereof.

[0158] In addition, the lithium salt may be an imide-based one, and for example, the imide-based lithium salt may include lithium bis(trifluoro methanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). The lithium salt may maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with an ionic liquid.

[0159] The above ionic liquid has a melting point below room temperature and is a salt or room-temperature molten salt that is liquid at room temperature and consists only of ions.

[0160] The above ionic liquid may be a compound including a) one or more cations selected from ammonium-based, pyrrolidinium-based, pyridinium-based, pyrimidinium-based, imidazolium-based, piperidinium-based, pyrazolium-based, oxazolium-based, pyridazinium-based, phosphonium-based, sulfonium-based, triazolium-based, and mixtures thereof, and b) one or more anions selected from BF4-, PF6-, AsF6-, SbF6-, AlCl4-, HSO4-, ClO4-, CH3SO3-, CF3CO2-, Cl-, Br-, I-, BF4-, SO4-, CF3SO3-, (FSO2)2N-, (C2F5SO2)2N-, (C2F5SO2)(CF3SO2)N-, and (CF3SO2)2N-.

[0161] The ionic liquid may be at least one selected from the group consisting of, for example, N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, N-butyl-N-methylpyrrolidinium bis(3-trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide.

[0162] In the above solid electrolyte layer, the weight ratio of the solid electrolyte and the ionic liquid may be 0.1:99.9 to 90:10, for example, 10:90 to 90:10, 20:80 to 90:10, 30:70 to 90:10, 40:60 to 90:10, or 50:50 to 90:10. A solid electrolyte layer satisfying the above range can maintain or improve ionic conductivity by improving the electrochemical contact area with the electrode. Accordingly, the energy density, discharge capacity, rate characteristics, etc. of the all-solid-state battery can be improved.

[0163] The above-mentioned all-solid-state battery may include a unit cell having a structure of positive electrode / solid electrolyte layer / negative electrode, a bi-cell structure having a structure of positive electrode / solid electrolyte layer / negative electrode / solid electrolyte layer / positive electrode, or a bipolar cell structure in which unit cells are repeatedly stacked.

[0164] The shape of the above-mentioned all-solid-state battery is not particularly limited, and may be, for example, coin-shaped, button-shaped, sheet-shaped, stacked, cylindrical, flat, etc. In addition, the above-mentioned all-solid-state battery can be applied to large-scale batteries used in electric vehicles, etc. For example, the above-mentioned all-solid-state battery can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, it can be used in fields requiring large amounts of power storage, and for example, it can be used in electric bicycles or power tools.

[0165] Hereinafter, an all-solid-state secondary battery according to an embodiment will be described with reference to FIGS. 3 to 9. The all-solid-state secondary battery (1000) according to an embodiment is a secondary battery capable of being charged and discharged. Hereinafter, the positive electrode includes a cathode, and the negative electrode includes an anode.

[0166] Fig. 3 is a longitudinal cross-sectional view showing the front of an all-solid-state secondary battery according to one embodiment. Fig. 2 is a longitudinal cross-sectional view showing an all-solid-state secondary battery in a second direction (Y) intersecting the first direction (X) illustrated in Fig. 2. Fig. 4 is a longitudinal cross-sectional view showing a side of an all-solid-state secondary battery according to one embodiment. Fig. 4 is a longitudinal cross-sectional view showing an all-solid-state secondary battery in a third direction (Z) intersecting the first direction (X) and the second direction (Y) illustrated in Fig. 4.

[0167] Referring to FIGS. 3 and 4, an all-solid-state secondary battery (1000) according to one embodiment includes a first unit cell (CE1) and a second unit cell (CE2) that are stacked in a first direction (X) to form a bi-cell structure.

[0168] The first unit cell (CE1) includes a first lower current collecting layer (LC1), a first negative electrode coating layer (AC1), a first solid electrolyte layer (SE1), a first positive electrode active material layer (CA1), and a first upper current collecting layer (UC1) sequentially stacked in a first direction (X).

[0169] The first lower current collecting layer (LC1) is a negative electrode current collecting layer. The first lower current collecting layer (LC1) faces the first solid electrolyte layer (SE1) with the first negative electrode coating layer (AC1) therebetween. The first lower current collecting layer (LC1) may include various known metals and compounds that do not react with lithium. The first lower current collecting layer (LC1) may include stainless steel (SUS), etc., and may have a plate shape or a foil shape. For example, the first lower current collecting layer (LC1) may include at least one of copper (Cu), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The area of ​​the first lower current collecting layer (LC1) may be greater than the area of ​​the first positive electrode active material layer (CA1) and the area of ​​the first upper current collecting layer (UC1). The first lower current collecting layer (LC1) includes a first lower extension portion (LE1) extending in a second direction (Y) intersecting the first direction (X), and the first lower extension portion (LE1) can be connected to the second upper extension portion (UE2) of the second upper current collecting layer (UC2) of the second unit cell (CE2) via various known connecting members, but is not limited thereto.

[0170] The first cathode coating layer (AC1) is positioned between the first lower current collecting layer (LC1) and the first solid electrolyte layer (SE1). The first cathode coating layer (AC1) is in contact with the first lower current collecting layer (LC1) and the first solid electrolyte layer (SE1). The first cathode coating layer (AC1) may include, but is not limited to, silver (Ag) and carbon (C). For example, the first cathode coating layer (AC1) may include particles formed of a metal or semiconductor including at least one of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn) on a carbon layer including at least one of carbon black, furnace black (FB), acetylene black (AB), ketjen black (KB), and graphene. During charging, lithium is precipitated between the first lower current collecting layer (LC1) and the first negative electrode coating layer (AC1), forming a lithium metal layer between the first lower current collecting layer (LC1) and the first negative electrode coating layer (AC1). After discharging, lithium is deprecipitated between the first lower current collecting layer (LC1) and the first negative electrode coating layer (AC1), allowing the first lower current collecting layer (LC1) and the first negative electrode coating layer (AC1) to come into direct contact. The area of ​​the interface between the first negative electrode coating layer (AC1) and the first lower current collecting layer (LC1) is wider than the area of ​​the first upper current collecting layer (UC1).

[0171] The first solid electrolyte layer (SE1) is positioned between the first positive electrode active material layer (CA1) and the first negative electrode coating layer (AC1). The first solid electrolyte layer (SE1) is in direct contact with the first positive electrode active material layer (CA1) and the first negative electrode coating layer (AC1). The first solid electrolyte layer (SE1) may include, but is not limited to, various known sulfide-based solid electrolyte materials. For example, the first solid electrolyte layer (SE1) may be Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element, for example, I, Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-ZmSn (m, n are positive numbers, Z is one of Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-LipMOq (p, q are positive numbers, M is one of P, Si, It may include one of Ge, B, Al, Ga, and In. The first solid electrolyte layer (SE1) may include at least one of an amorphous and a crystalline material.

[0172] The first positive electrode active material layer (CA1) is positioned between the first solid electrolyte layer (SE1) and the first upper current collecting layer (UC1). The first positive electrode active material layer (CA1) may be coated on the first upper current collecting layer (UC1), but is not limited thereto. The first positive electrode active material layer (CA1) includes lithium nickel cobalt manganese oxide (NCM). For example, the first positive electrode active material layer (CA1) may include at least one of lithium salts such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfur, iron oxide, or vanadium oxide. The area of ​​the first positive electrode active material layer (CA1) is wider than the area of ​​the first upper current collecting layer (UC1), and narrower than the area of ​​the interface between the first lower current collecting layer (LC1) and the first negative electrode coating layer (AC1). Here, the area of ​​the first positive electrode active material layer (CA1) refers to the area of ​​the lower surface of the first positive electrode active material layer (CA1), but is not limited thereto. The first positive electrode active material layer (CA1) forms a positive electrode (cathode) together with the first upper current collecting layer (UC1), but is not limited thereto.

[0173] The first upper current collecting layer (UC1) is a positive electrode current collecting layer. The first upper current collecting layer (UC1) includes aluminum (Al) and may have a plate shape or a foil shape. For example, the first upper current collecting layer (UC1) may include at least one of indium (In), copper (Cu), magnesium (Mg), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), and lithium (Li). The area of ​​the first upper current collecting layer (UC1) may be narrower than the area of ​​the first positive electrode active material layer (CA1) and the area of ​​the interface between the first lower current collecting layer (LC1) and the first negative electrode coating layer (AC1).

[0174] The first upper current collecting layer (UC1) includes a first upper extension portion (UE1) and a first upper overlapping portion (UO1).

[0175] The first upper extension (UE1) extends in a second direction (Y) intersecting the first direction (X). The first upper extension (UE1) is welded to the second lower extension (LE2) of the second lower current collecting layer (LC2) of the second unit cell (CE2). The first upper extension (UE1) is welded to the second lower extension (LE2) of the second lower current collecting layer (LC2) by a weld (WP). The first upper extension (UE1) does not overlap the first solid electrolyte layer (SE1) and the second solid electrolyte layer (SE2) of the second unit cell (CE2) in the first direction (X). The first upper extension (UE1) extends in an opposite direction to the first lower extension (LE1) in the second direction (Y).

[0176] The first upper overlapping portion (UO1) extends from the first upper extension portion (UE1) between the first solid electrolyte layer (SE1) and the second solid electrolyte layer (SE2) of the second unit cell (CE2). The first upper overlapping portion (UO1) is located between the first solid electrolyte layer (SE1) and the second solid electrolyte layer (SE2). The first upper overlapping portion (UO1) is located between the first positive electrode active material layer (CA1) and the second lower current collecting layer (LC2) of the second unit cell (CE2) in the first direction (X), and overlaps the second lower overlapping portion (LO2) of the second lower current collecting layer (LC2) in the first direction (X). The first upper overlapping portion (UO1) is in contact with the second lower overlapping portion (LO2) of the second lower current collecting layer (LC2). The first upper overlapping portion (UO1) is non-welded with the second lower overlapping portion (LO2), and the first upper extension portion (UE1) is welded with the second lower extension portion (LE2) by a welding portion (WP). Welding between the first upper extension portion (UE1) and the second lower extension portion (LE2) can be performed using a welding means such as a laser beam irradiated in a non-overlapping direction with the first solid electrolyte layer (SE1) and the second solid electrolyte layer (SE2) in the first direction (X).

[0177] The front surface of the first unit cell (CE1) described above may have a substantially diamond shape due to the inclined surfaces, but is not limited thereto. A second unit cell (CE2) is laminated on the first unit cell (CE1), and the second unit cell (CE2) may have a shape rotated 180 degrees around the second direction (Y) with respect to the first unit cell (CE1).

[0178] Fig. 5 is a cross-sectional view showing a second unit cell of an all-solid-state secondary battery according to one embodiment.

[0179] Referring to FIGS. 3 to 5, the second unit cell (CE2) is positioned on the first upper current collecting layer (UC1) of the first unit cell (CE1). The second unit cell (CE2) includes a second lower current collecting layer (LC2), a second positive electrode active material layer (CA2), a second solid electrolyte layer (SE2), a second negative electrode coating layer (AC2), a second upper current collecting layer (UC2), a first inclined surface (IS1), a second inclined surface (IS2), a third inclined surface (IS3), and a fourth inclined surface (IS4) sequentially stacked in the first direction (X). The first unit cell (CE1) also includes inclined surfaces that are the same as the first inclined surface (IS1), the second inclined surface (IS2), the third inclined surface (IS3), and the fourth inclined surface (IS4) of the second unit cell (CE2).

[0180] The second lower current collecting layer (LC2) is a positive electrode current collecting layer. The second lower current collecting layer (LC2) includes aluminum (Al) and may have a plate shape or a foil shape. For example, the second lower current collecting layer (LC2) may include at least one of indium (In), copper (Cu), magnesium (Mg), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), and lithium (Li). The area of ​​the second lower current collecting layer (LC2) may be narrower than the second area (D2) of the second positive electrode active material layer (CA2) and the first area (D1) of the interface between the second upper current collecting layer (UC2) and the second negative electrode coating layer (AC2).

[0181] The second lower collector layer (LC2) includes a second lower extension portion (LE2) and a second lower overlapping portion (LO2).

[0182] The second lower extension portion (LE2) extends in a second direction (Y) intersecting the first direction (X). The second lower extension portion (LE2) is welded to the first upper extension portion (UE1) of the first upper current collecting layer (UC1) of the first unit cell (CE1). The second lower extension portion (LE2) is welded to the first upper extension portion (UE1) of the first upper current collecting layer (UC1) by a weld portion (WP). The second lower extension portion (LE2) does not overlap the second solid electrolyte layer (SE2) and the first solid electrolyte layer (SE1) of the first unit cell (CE1) in the first direction (X). The second lower extension portion (LE2) extends in the same direction as the first upper extension portion (UE1) in the second direction (Y), and the second lower extension portion (LE2) extends in an opposite direction to the second upper extension portion (UE2) in the second direction (Y).

[0183] The second lower overlapping portion (LO2) extends from the second lower extension portion (LE2) between the second solid electrolyte layer (SE2) and the first solid electrolyte layer (SE1) of the first unit cell (CE1). The second lower overlapping portion (LO2) is located between the second solid electrolyte layer (SE2) and the first solid electrolyte layer (SE1). The second lower overlapping portion (LO2) is located between the second positive electrode active material layer (CA2) and the first upper current collecting layer (UC1) of the first unit cell (CE1) in the first direction (X), and overlaps the first upper overlapping portion (UO1) of the first upper current collecting layer (UC1) in the first direction (X). The second lower overlapping portion (LO2) is in contact with the first upper overlapping portion (UO1) of the first upper current collecting layer (UC1). The second lower overlap (LO2) is non-welded with the first upper overlap (UO1), and the second lower extension (LE2) is welded with the first upper extension (UE1) by a weld (WP).

[0184] The second positive electrode active material layer (CA2) is positioned between the second solid electrolyte layer (SE2) and the second lower current collecting layer (LC2). The second positive electrode active material layer (CA2) may be coated on the second lower current collecting layer (LC2), but is not limited thereto. The second positive electrode active material layer (CA2) includes lithium nickel cobalt manganese oxide (NCM). For example, the second positive electrode active material layer (CA2) may include at least one of lithium salts such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfur, iron oxide, or vanadium oxide. The second area (D2) of the second positive electrode active material layer (CA2) is wider than the area of ​​the second lower current collecting layer (LC2), and is narrower than the first area (D1) of the interface between the second upper current collecting layer (UC2) and the second negative electrode coating layer (AC2). Here, the area of ​​the second positive electrode active material layer (CA2) refers to the area of ​​the upper surface of the second positive electrode active material layer (CA2), but is not limited thereto. The second positive electrode active material layer (CA2) forms a positive electrode (cathode) together with the second lower current collecting layer (LC2), but is not limited thereto.

[0185] The second solid electrolyte layer (SE2) is positioned between the second positive electrode active material layer (CA2) and the second negative electrode coating layer (AC2). The second solid electrolyte layer (SE2) is in direct contact with the second positive electrode active material layer (CA2) and the second negative electrode coating layer (AC2). The second solid electrolyte layer (SE2) may include, but is not limited to, various known sulfide-based solid electrolyte materials. For example, the second solid electrolyte layer (SE2) may be Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element, for example, I, Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-ZmSn (m, n are positive numbers, Z is one of Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-LipMOq (p, q are positive numbers, M is one of P, Si, It may include one of Ge, B, Al, Ga, and In. The second solid electrolyte layer (SE2) may include at least one of an amorphous and a crystalline layer.

[0186] The second cathode coating layer (AC2) is positioned between the second upper current collecting layer (UC2) and the second solid electrolyte layer (SE2). The second cathode coating layer (AC2) is in contact with the second upper current collecting layer (UC2) and the second solid electrolyte layer (SE2). The second cathode coating layer (AC2) may include, but is not limited to, silver (Ag) and carbon (C). For example, the second cathode coating layer (AC2) may include particles formed of a metal or semiconductor including at least one of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn) on a carbon layer including at least one of carbon black, furnace black (FB), acetylene black (AB), ketjen black (KB), and graphene. During charging, lithium is deposited between the second upper current collecting layer (UC2) and the second negative electrode coating layer (AC2), so that a lithium metal layer is formed between the second upper current collecting layer (UC2) and the second negative electrode coating layer (AC2). After discharging, lithium is de-deposited between the second upper current collecting layer (UC2) and the second negative electrode coating layer (AC2), so that the second upper current collecting layer (UC2) and the second negative electrode coating layer (AC2) can be in direct contact. The first area (D1) of the interface between the second negative electrode coating layer (AC2) and the second upper current collecting layer (UC2) is wider than the area of ​​the second lower current collecting layer (LC2). The first area (D1) of the interface between the second negative electrode coating layer (AC2) and the second upper current collecting layer (UC2) is wider than the second area (D2) of the second positive electrode active material layer (200) by the first inclined surface (IS1), the second inclined surface (IS2), the third inclined surface (IS3), and the fourth inclined surface (IS4).

[0187] The second upper current collecting layer (UC2) is a negative electrode current collecting layer. The second upper current collecting layer (UC2) faces the second solid electrolyte layer (SE2) with the second negative electrode coating layer (AC2) therebetween. The second upper current collecting layer (UC2) may include various known metals and compounds that do not react with lithium. The second upper current collecting layer (UC2) may include stainless steel (SUS), etc., and may have a plate shape or a foil shape. For example, the second upper current collecting layer (UC2) may include at least one of copper (Cu), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The area of ​​the second upper current collecting layer (UC2) may be wider than the second area (D2) of the second positive electrode active material layer (CA2) and the area of ​​the second lower current collecting layer (LC2). The second upper current collecting layer (UC2) includes a second upper extension portion (UE2) extending in a second direction (Y) intersecting the first direction (X), and the second upper extension portion (UE2) can be connected to the first lower extension portion (LE1) of the first lower current collecting layer (LC1) of the first unit cell (CE1) via various known connecting members, but is not limited thereto. The second upper extension portion (UE2) extends in the same direction as the first lower extension portion (LE1) in the second direction (Y), and the second upper extension portion (UE2) extends in opposite directions in the second direction (Y) to the second lower extension portion (LE2) and the first upper extension portion (UE1).

[0188] The second upper current collecting layer (UC2) and the first lower current collecting layer (LC1) have a negative electrode having the same first polarity, and the second lower current collecting layer (LC2) and the first upper current collecting layer (UC1) connected to each other have a positive electrode having the same second polarity. For example, the first unit cell (CE1) and the second unit cell (CE2) form a bi-cell structure.

[0189] The first inclined plane (IS1) extends from one end (101) of the second lower current collecting layer (LC2) in the third direction (Z) through one end (201) of the second positive electrode active material layer (CA2) in the third direction (Z) to one end (301) of the second solid electrolyte layer (SE2) in the third direction (Z). The first inclined plane (IS1) is wider than the third inclined plane (IS3) and longer than the third inclined plane (IS3). The first inclined plane (IS1) contacts the third inclined plane (IS3) at one end (301) of the second solid electrolyte layer (SE2).

[0190] The second inclined plane (IS2) extends from the other end (102) in the third direction (Z) of the second lower current collecting layer (LC2) through the other end (202) in the third direction (Z) of the second positive electrode active material layer (CA2) to the other end (302) in the third direction (Z) of the second solid electrolyte layer (SE2). The second inclined plane (IS2) is wider than the fourth inclined plane (IS4) and longer than the fourth inclined plane (IS4). The second inclined plane (IS2) is in contact with the fourth inclined plane (IS4) at the other end (302) of the second solid electrolyte layer (SE2).

[0191] The third inclined plane (IS3) extends from one end (401) in the third direction (Z) of the second upper current collecting layer (UC2) through one end (501) in the third direction (Z) of the second cathode coating layer (AC2) to one end (301) in the third direction (Z) of the second solid electrolyte layer (SE2). The third inclined plane (IS3) is narrower than the first inclined plane (IS1) and shorter than the first inclined plane (IS1).

[0192] The fourth inclined plane (IS4) extends from the other end (402) in the third direction (Z) of the second upper current collecting layer (UC2) through the other end (502) of the second cathode coating layer (AC2) to the other end (302) in the third direction (Z) of the second solid electrolyte layer (SE2). The fourth inclined plane (IS4) is narrower than the second inclined plane (IS2) and shorter than the second inclined plane (IS2).

[0193] The first inclined plane (IS1), the second inclined plane (IS2), the third inclined plane (IS3), and the fourth inclined plane (IS4) can be formed by cutting the upper and lower ends of the second unit cell (CE2) in a tapered manner using various known cutting means such as a laser beam, but are not limited thereto.

[0194] The second unit cell (CE2) may be formed substantially in a diamond shape by the first inclined plane (IS1), the second inclined plane (IS2), the third inclined plane (IS3), and the fourth inclined plane (IS4), but is not limited thereto.

[0195] Since the second unit cell (CE2) is defined in a diamond shape by the first inclined plane (IS1), the second inclined plane (IS2), the third inclined plane (IS3), and the fourth inclined plane (IS4), the first area (D1) of the interface between the second negative electrode coating layer (AC2) and the second upper current collecting layer (UC2), where lithium is precipitated during charging to form a lithium metal layer, is wider than the second area (D2) of the second positive electrode active material layer (CA2).

[0196] Figures 6 are cross-sectional views illustrating the formation of a lithium metal layer in a second unit cell of an all-solid-state secondary battery according to one embodiment. Figure 6 (A) is a cross-sectional view illustrating the second unit cell after discharge, and Figure 6 (B) is a cross-sectional view illustrating the second unit cell after charge.

[0197] Referring to (A) and (B) of FIG. 6, when charging, lithium ions (LI) move from the second positive electrode active material layer (CA2) through the second solid electrolyte layer (SE2) to the interface between the second negative electrode coating layer (AC2) and the second upper current collecting layer (UC2) and are precipitated at the interface between the second negative electrode coating layer (AC2) and the second upper current collecting layer (UC2). As a result, a lithium metal layer (LM) is formed at the interface between the second negative electrode coating layer (AC2) and the second upper current collecting layer (UC2) when charging. The area of ​​the lithium metal layer (LM) may be wider than the area of ​​the second positive electrode active material layer (CA2) and the area of ​​the second lower current collecting layer (LC2), but is not limited thereto. One end (601) of the lithium metal layer (LM) separates the third inclined surface (IS3), and the other end (602) of the lithium metal layer (LM) separates the fourth inclined surface (IS4). The lithium metal layer (LM) forms an anode together with the second upper current collecting layer (UC2) and the second negative electrode coating layer (AC2), but is not limited thereto.

[0198] Referring to FIGS. 6 and 5, the second unit cell (CE2) is defined in a diamond shape by the first inclined plane (IS1), the second inclined plane (IS2), the third inclined plane (IS3), and the fourth inclined plane (IS4), so that the first area (D1) of the interface between the second negative electrode coating layer (AC2) where lithium is precipitated during charging and the second upper current collecting layer (UC2) is wider than the second area (D2) of the second positive electrode active material layer (CA2), thereby improving the alignment between the second positive electrode active material layer (CA2) and the second upper current collecting layer (UC2), and at the same time, expanding the width of the movement path of lithium ions (LI) moving from the second positive electrode active material layer (CA2) to the second upper current collecting layer (UC2) during charging, thereby uniformly forming a lithium metal layer (LM) between the second upper current collecting layer (UC2) and the second negative electrode coating layer (AC2) during charging, thereby improving the capacity of the battery and suppressing short circuiting between the positive and negative electrodes.

[0199] That is, the alignment between the second positive electrode active material layer (CA2) and the second upper current collecting layer (UC2) is improved, and at the same time, the movement path of lithium ions (LI) moving from the second positive electrode active material layer (CA2) to the second upper current collecting layer (UC2) during charging is expanded, so that a lithium metal layer (LM) is uniformly formed on the surface of the second upper current collecting layer (UC2) during charging, thereby improving the capacity of the battery and providing a second unit cell (CE2) in which short circuits between the positive electrode and the negative electrode are suppressed.

[0200] Fig. 7 is a cross-sectional view showing an example of a second unit cell of an all-solid-state secondary battery according to one embodiment.

[0201] Referring to FIG. 7, a second unit cell (CE2) according to an example includes a second lower current collecting layer (LC2), a second positive electrode active material layer (CA2), a second solid electrolyte layer (SE2), a second upper current collecting layer (UC2), a second negative electrode coating layer (AC2), a first inclined surface (IS1), a second inclined surface (IS2), a third inclined surface (IS3), and a fourth inclined surface (IS4).

[0202] The first slope (IS1) may have substantially the same width and length as the third slope (IS3).

[0203] The second slope (IS2) may have substantially the same width and length as the fourth slope (IS4).

[0204] The area from one end of the second solid electrolyte layer (SE2) where the first inclined surface (IS1) and the third inclined surface (IS3) come into contact to the other end of the second solid electrolyte layer (SE2) where the second inclined surface (IS2) and the fourth inclined surface (IS4) come into contact is wider than the area of ​​the second positive electrode active material layer (CA2).

[0205] The width of the second solid electrolyte layer (SE2) of the second unit cell (CE2) from one end to the other end is made wider than the width of the second positive electrode active material layer (CA2) by the first inclined plane (IS1), the second inclined plane (IS2), the third inclined plane (IS3), and the fourth inclined plane (IS4), thereby improving the alignment between the second positive electrode active material layer (CA2) and the second upper current collecting layer (UC2), and at the same time, expanding the width of the movement path of lithium ions moving from the second positive electrode active material layer (CA2) to the second upper current collecting layer (UC2) during charging. Therefore, a lithium metal layer is uniformly formed between the second upper current collecting layer (UC2) and the second negative electrode coating layer (AC2) during charging, thereby improving the capacity of the battery and suppressing short circuiting between the positive electrode and the negative electrode.

[0206] That is, the alignment between the second positive electrode active material layer (CA2) and the second upper current collecting layer (UC2) is improved, and at the same time, the movement path of lithium ions moving from the second positive electrode active material layer (CA2) to the second upper current collecting layer (UC2) during charging is expanded, so that a lithium metal layer is uniformly formed on the surface of the second upper current collecting layer (UC2) during charging, thereby improving the capacity of the battery and providing a second unit cell (CE2) in which short circuiting between the positive electrode and the negative electrode is suppressed.

[0207] Fig. 8 is a cross-sectional view showing another example of a second unit cell of an all-solid-state secondary battery according to one embodiment.

[0208] Referring to FIG. 8, a second unit cell (CE2) according to another example includes a second lower current collecting layer (LC2), a second positive electrode active material layer (CA2), a second solid electrolyte layer (SE2), a second upper current collecting layer (UC2), a second negative electrode coating layer (AC2), a first inclined surface (IS1), a second inclined surface (IS2), a third inclined surface (IS3), and a fourth inclined surface (IS4).

[0209] The first slope (IS1) may have substantially the same width and length as the third slope (IS3).

[0210] The second slope (IS2) may have substantially the same width and length as the fourth slope (IS4).

[0211] The area from one end of the second solid electrolyte layer (SE2) where the first inclined surface (IS1) and the third inclined surface (IS3) come into contact to the other end of the second solid electrolyte layer (SE2) where the second inclined surface (IS2) and the fourth inclined surface (IS4) come into contact is wider than the area of ​​the second positive electrode active material layer (CA2).

[0212] The second solid electrolyte layer (SE2) includes a first sub-electrolyte layer (310) in contact with the second positive electrode active material layer (CA2) and a second sub-electrolyte layer (320) in contact with the second negative electrode coating layer (AC2).

[0213] The first sub-electrolyte layer (310) is formed on the surface of the second positive electrode active material layer (CA2), the second sub-electrolyte layer (320) is formed on the surface of the second negative electrode coating layer (AC2), and the first sub-electrolyte layer (310) and the second sub-electrolyte layer (320) are bonded to form a second unit cell (CE2).

[0214] Even if the first sub-electrolyte layer (310) and the second sub-electrolyte layer (320) are joined to form the second unit cell (CE2), the width from one end of the second solid electrolyte layer (SE2) of the second unit cell (CE2) to the other end is made wider than the width of the second positive electrode active material layer (CA2) by the first inclined plane (IS1), the second inclined plane (IS2), the third inclined plane (IS3), and the fourth inclined plane (IS4) formed by the cutting process, and the alignment between the second positive electrode active material layer (CA2) and the second upper current collecting layer (UC2) is improved, so that the width of the movement path of lithium ions moving from the second positive electrode active material layer (CA2) to the second upper current collecting layer (UC2) during charging is expanded, and thus a lithium metal layer is uniformly formed between the second upper current collecting layer (UC2) and the second negative electrode coating layer (AC2) during charging, thereby improving the capacity of the battery and suppressing short circuiting between the positive electrode and the negative electrode.

[0215] That is, the alignment between the second positive electrode active material layer (CA2) and the second upper current collecting layer (UC2) is improved, and at the same time, the movement path of lithium ions moving from the second positive electrode active material layer (CA2) to the second upper current collecting layer (UC2) during charging is expanded, so that a lithium metal layer is uniformly formed on the surface of the second upper current collecting layer (UC2) during charging, thereby improving the capacity of the battery and providing a second unit cell (CE2) in which short circuiting between the positive electrode and the negative electrode is suppressed.

[0216] FIG. 9 is a cross-sectional view showing another example of a second unit cell of an all-solid-state secondary battery according to one embodiment.

[0217] Referring to FIG. 9, a second unit cell (CE2) according to another example includes a second lower current collecting layer (LC2), a second positive electrode active material layer (CA2), a second solid electrolyte layer (SE2), a second upper current collecting layer (UC2), a second negative electrode coating layer (AC2), a first inclined surface (IS1), a second inclined surface (IS2), a third inclined surface (IS3), and a fourth inclined surface (IS4).

[0218] The first slope (IS1) may have substantially the same width and length as the third slope (IS3).

[0219] The second slope (IS2) may have substantially the same width and length as the fourth slope (IS4).

[0220] At least one of the first inclined plane (IS1) and the third inclined plane (IS3) includes a first vertical plane (VS1) located at one end of the second solid electrolyte layer (SE2), and at least one of the second inclined plane (IS2) and the fourth inclined plane (IS4) includes a second vertical plane (VS2) located at the other end of the second solid electrolyte layer (SE2). The first vertical plane (VS1) and the second vertical plane (VS2) can be formed by various known cutting processes.

[0221] Since the alignment between the second positive electrode active material layer (CA2) and the second upper current collecting layer (UC2) is improved by the first inclined plane (IS1), the second inclined plane (IS2), the third inclined plane (IS3), the fourth inclined plane (IS4), the first vertical plane (VS1), and the second vertical plane (VS2) formed by the cutting process, the movement path of lithium ions moving from the second positive electrode active material layer (CA2) to the second upper current collecting layer (UC2) during charging is suppressed from becoming uneven, and thus a lithium metal layer is uniformly formed between the second upper current collecting layer (UC2) and the second negative electrode coating layer (AC2) during charging, thereby improving the capacity of the battery and suppressing short circuiting between the positive electrode and the negative electrode.

[0222] That is, the alignment between the second positive electrode active material layer (CA2) and the second upper current collecting layer (UC2) is improved, so that the movement path of lithium ions moving from the second positive electrode active material layer (CA2) to the second upper current collecting layer (UC2) during charging becomes uniform, thereby providing a second unit cell (CE2) in which a lithium metal layer is uniformly formed on the surface of the second upper current collecting layer (UC2) during charging, thereby improving the capacity of the battery and suppressing short circuits between the positive electrode and the negative electrode.

[0223] For example, an all-solid-state secondary battery (1000) including a first unit cell (CE1) and a second unit cell (CE2) is provided, in which alignment between a positive electrode active material layer and a negative electrode current collecting layer is improved, and a migration path of lithium ions moving from a positive electrode active material layer to a negative electrode current collecting layer during charging is expanded, thereby uniformly forming a lithium metal layer on the surface of the negative electrode current collecting layer during charging, thereby improving the capacity of the battery and suppressing short circuits between the positive electrode and the negative electrode.

[0224] In addition, an all-solid-state secondary battery (1000) is provided in which a plurality of unit cells, namely a first unit cell (CE1) and a second unit cell (CE2), form a bi-cell structure, even though the first unit cell (CE1) and the second unit cell (CE2) include an inclined surface that improves the capacity of the battery while suppressing short circuits between the positive and negative electrodes.

[0225] Hereinafter, an all-solid-state secondary battery according to another embodiment will be described with reference to FIG. 10. Below, differences from the all-solid-state secondary battery according to the above-described embodiment will be described.

[0226] Fig. 10 is a cross-sectional view showing a side surface of an all-solid-state secondary battery according to another embodiment.

[0227] Referring to FIG. 10, an all-solid-state secondary battery (1002) according to another embodiment includes a first unit cell (CE1), a second unit cell (CE2), and an elastic sheet (ES) that are stacked in a first direction (X) to form a bi-cell structure.

[0228] The first unit cell (CE1) includes a first lower current collecting layer (LC1), a first negative electrode coating layer (AC1), a first solid electrolyte layer (SE1), a first positive electrode active material layer (CA1), and a first upper current collecting layer (UC1) sequentially stacked in a first direction (X).

[0229] The second unit cell (CE2) is positioned on the first upper current collecting layer (UC1) of the first unit cell (CE1) with an elastic sheet (ES) therebetween. The second unit cell (CE2) includes a second lower current collecting layer (LC2), a second positive electrode active material layer (CA2), a second solid electrolyte layer (SE2), a second negative electrode coating layer (AC2), and a second upper current collecting layer (UC2) sequentially stacked in the first direction (X).

[0230] An elastic sheet (ES) is positioned between a first unit cell (CE1) and a second unit cell (CE2). The elastic sheet (ES) is positioned between a first upper overlapping portion (UO1) of a first upper current collecting layer (UC1) of the first unit cell (CE1) and a second lower overlapping portion (LO2) of a second lower current collecting layer (LC2) of the second unit cell (CE2). The elastic sheet (ES) contacts the first upper overlapping portion (UO1) of the first upper current collecting layer (UC1) and the second lower overlapping portion (LO2) of the second lower current collecting layer (LC2). The elastic sheet (ES) may include various known conductive elastic materials, such as a conductive polymer.

[0231] The first unit cell (CE1) and the second unit cell (CE2) can be pressed toward each other, and since an elastic sheet (ES) is positioned between the first unit cell (CE1) and the second unit cell (CE2), the first unit cell (CE1) and the second unit cell (CE2) are prevented from being damaged by the pressure, and at the same time, the contact area between the first unit cell (CE1) and the second unit cell (CE2) is increased by the elastic restoring force of the elastic sheet (ES), so that the battery reliability and battery performance of the all-solid-state secondary battery (1002) are improved.

[0232] For example, an all-solid-state secondary battery (1002) including a first unit cell (CE1) and a second unit cell (CE2) is provided, in which alignment between a positive electrode active material layer and a negative electrode current collecting layer is improved, and a migration path of lithium ions moving from a positive electrode active material layer to a negative electrode current collecting layer during charging is expanded, thereby uniformly forming a lithium metal layer on the surface of the negative electrode current collecting layer during charging, thereby improving the capacity of the battery and suppressing short circuits between the positive electrode and the negative electrode.

[0233] In addition, an all-solid-state secondary battery (1002) is provided in which a plurality of unit cells, namely a first unit cell (CE1) and a second unit cell (CE2), form a bi-cell structure, even though the first unit cell (CE1) and the second unit cell (CE2) include an inclined surface that improves the capacity of the battery while suppressing short circuits between the positive and negative electrodes.

[0234] In addition, since the elastic sheet (ES) is positioned between the first unit cell (CE1) and the second unit cell (CE2), the first unit cell (CE1) and the second unit cell (CE2) are prevented from being damaged by pressure, and at the same time, the contact area between the first unit cell (CE1) and the second unit cell (CE2) is increased by the elastic restoring force of the elastic sheet (ES), thereby providing an all-solid-state secondary battery (1002) with improved battery reliability and battery performance.

[0235] Hereinafter, an all-solid-state secondary battery according to another embodiment will be described with reference to FIG. 11. Below, differences from the all-solid-state secondary battery according to the above-described embodiment will be described.

[0236] Fig. 11 is a cross-sectional view showing a side surface of an all-solid-state secondary battery according to another embodiment.

[0237] Referring to FIG. 11, an all-solid-state secondary battery (1003) according to another embodiment includes a first unit cell (CE1), a second unit cell (CE2), a third unit cell (CE3), a fourth unit cell (CE4), a fifth unit cell (CE5), and a sixth unit cell (CE6) that are stacked in a first direction (X) to form a bi-cell structure.

[0238] The first unit cell (CE1) includes a first lower current collecting layer (LC1), a first negative electrode coating layer (AC1), a first solid electrolyte layer (SE1), a first positive electrode active material layer (CA1), and a first upper current collecting layer (UC1) sequentially stacked in a first direction (X).

[0239] The second unit cell (CE2) is positioned on the first upper current collecting layer (UC1) of the first unit cell (CE1). The second unit cell (CE2) includes a second lower current collecting layer (LC2), a second positive electrode active material layer (CA2), a second solid electrolyte layer (SE2), a second negative electrode coating layer (AC2), and a second upper current collecting layer (UC2) sequentially stacked in the first direction (X).

[0240] The third unit cell (CE3) has the same laminated structure as the first unit cell (CE1), and includes a third lower current collecting layer (LC3), a third negative electrode coating layer (AC3), a third solid electrolyte layer (SE3), a third positive electrode active material layer (CA3), and a third upper current collecting layer (UC3) sequentially laminated in the first direction (X).

[0241] The third lower current collecting layer (LC3) is a negative current collecting layer. The third lower current collecting layer (LC3) includes a third lower extension portion (LE3) extending in the second direction (Y). The third lower extension portion (LE3) is welded to the second upper extension portion (UE2) of the second upper current collecting layer (UC2) of the second unit cell (CE2) by a weld portion (WP). The third lower extension portion (LE3) and the second upper extension portion (UE2) extend in opposite directions in the second direction (Y) relative to the first upper extension portion (UE1) and the second lower extension portion (LE2).

[0242] The third upper current collecting layer (UC3) is a positive current collecting layer. The third upper current collecting layer (UC3) includes a third upper extension portion (UE3) extending in the second direction (Y), and the third upper extension portion (UE3) is welded to the lower extension portion of the lower current collecting layer of the fourth unit cell (CE4) by a weld portion (WP).

[0243] The first lower current collecting layer (LC1), the second upper current collecting layer (UC2), and the third lower current collecting layer (LC3) have negative electrodes having the same first polarity, and the first upper current collecting layer (UC1), the second lower current collecting layer (LC2), and the third upper current collecting layer (UC3) have positive electrodes having the same second polarity.

[0244] For example, the first unit cell (CE1), the second unit cell (CE2), and the third unit cell (CE3) form a bi-cell structure.

[0245] The fourth unit cell (CE4) and the sixth unit cell (CE6) have the same laminated structure as the second unit cell (CE2), and the fifth unit cell (CE5) has the same laminated structure as the first unit cell (CE1) and the third unit cell (CE3).

[0246] For example, the first unit cell (CE1), the second unit cell (CE2), the third unit cell (CE3), the fourth unit cell (CE4), the fifth unit cell (CE5), and the sixth unit cell (CE6) form a bi-cell structure.

[0247] For example, an all-solid-state secondary battery (1003) is provided, which includes a plurality of unit cells including a first unit cell (CE1) and a second unit cell (CE2), in which alignment between a positive electrode active material layer and a negative electrode current collecting layer is improved, and a migration path of lithium ions moving from a positive electrode active material layer to a negative electrode current collecting layer during charging is expanded, thereby uniformly forming a lithium metal layer on the surface of the negative electrode current collecting layer during charging, thereby improving the capacity of the battery and suppressing short circuits between the positive electrode and the negative electrode.

[0248] In addition, an all-solid-state secondary battery (1003) is provided in which a plurality of unit cells, including a first unit cell (CE1) and a second unit cell (CE2), which are a plurality of unit cells, form a bi-cell structure, even though the plurality of unit cells include an inclined surface that improves the capacity of the battery while suppressing short circuits between the positive and negative electrodes.

[0249] Hereinafter, an all-solid-state secondary battery according to another embodiment will be described with reference to FIG. 12. Below, differences from the all-solid-state secondary battery according to the above-described embodiment will be described.

[0250] Figure 12 is a cross-sectional view showing a side surface of an all-solid-state secondary battery according to another embodiment.

[0251] Referring to FIG. 12, an all-solid-state secondary battery (1004) according to another embodiment includes a first unit cell (CE1) and a second unit cell (CE2) that are stacked in a first direction (X) to form a bipolar cell structure.

[0252] The first unit cell (CE1) includes a first lower current collecting layer (LC1), a first positive electrode active material layer (CA1), a first solid electrolyte layer (SE1), a first negative electrode coating layer (AC1), and a first upper current collecting layer (UC1) sequentially laminated in a first direction (X). The first unit cell (CE1) has the same laminated structure as the second unit cell (CE2).

[0253] The first lower current collecting layer (LC1) is a positive current collecting layer.

[0254] The first upper current collecting layer (UC1) is a cathode current collecting layer. The first lower extension portion (LE1) of the first upper current collecting layer (UC1) is welded to the second lower extension portion (LE2) of the second lower current collecting layer (LC2), which is a cathode current collecting layer, by a welding portion (WP).

[0255] The first lower current collecting layer (LC1) of the first unit cell (CE1) and the second lower current collecting layer (LC2) of the second unit cell (CE2) have positive electrodes of the same first polarity, and the first upper current collecting layer (UC1) and the second upper current collecting layer (UC2) have negative electrodes of the same second polarity.

[0256] For example, the first unit cell (CE1) and the second unit cell (CE2) form a bipolar cell structure.

[0257] For example, an all-solid-state secondary battery (1004) including a first unit cell (CE1) and a second unit cell (CE2) is provided, in which alignment between a positive electrode active material layer and a negative electrode current collecting layer is improved, and a migration path of lithium ions moving from a positive electrode active material layer to a negative electrode current collecting layer during charging is expanded, thereby uniformly forming a lithium metal layer on the surface of the negative electrode current collecting layer during charging, thereby improving the capacity of the battery and suppressing short circuits between the positive electrode and the negative electrode.

[0258] In addition, an all-solid-state secondary battery (1004) is provided in which a plurality of unit cells, namely a first unit cell (CE1) and a second unit cell (CE2), form a bipolar cell structure, even though the first unit cell (CE1) and the second unit cell (CE2) include an inclined surface that improves the capacity of the battery while suppressing short circuits between the positive and negative electrodes.

[0259] Hereinafter, an all-solid-state secondary battery according to another embodiment will be described with reference to FIG. 13. Hereinafter, differences from the all-solid-state secondary battery according to the above-described embodiment will be described.

[0260] Figure 13 is a cross-sectional view showing a side surface of an all-solid-state secondary battery according to another embodiment.

[0261] Referring to FIG. 13, an all-solid-state secondary battery (1005) according to another embodiment includes a first unit cell (CE1), a second unit cell (CE2), a third unit cell (CE3), a fourth unit cell (CE4), a fifth unit cell (CE5), and a sixth unit cell (CE6) that are stacked in a first direction (X) to form a bipolar cell structure.

[0262] The first unit cell (CE1) includes a first lower current collecting layer (LC1), a first positive electrode active material layer (CA1), a first solid electrolyte layer (SE1), a first negative electrode coating layer (AC1), and a first upper current collecting layer (UC1) sequentially laminated in a first direction (X). The first unit cell (CE1) has the same laminated structure as the second unit cell (CE2).

[0263] The first lower current collecting layer (LC1) is a positive current collecting layer.

[0264] The first upper current collecting layer (UC1) is a cathode current collecting layer. The first lower extension portion (LE1) of the first upper current collecting layer (UC1) is welded to the second lower extension portion (LE2) of the second lower current collecting layer (LC2), which is a cathode current collecting layer, by a welding portion (WP).

[0265] The third unit cell (CE3) includes a third lower current collecting layer (LC3), a third positive electrode active material layer (CA3), a third solid electrolyte layer (SE3), a third negative electrode coating layer (AC3), and a third upper current collecting layer (UC3) sequentially stacked in the first direction (X). The third unit cell (CE3) has the same stacked structure as the second unit cell (CE2).

[0266] The third lower current collecting layer (LC3) is a positive current collecting layer. The third lower current collecting layer (LC3) includes a third lower extension portion (LE3) extending in the second direction (Y). The third lower extension portion (LE3) is welded to the second upper extension portion (UE2) of the second upper current collecting layer (UC2) of the second unit cell (CE2) by a weld portion (WP). The third lower extension portion (LE3) and the second upper extension portion (UE2) extend in opposite directions in the second direction (Y) from the first upper extension portion (UE1) and the second lower extension portion (LE2).

[0267] The third upper current collecting layer (UC3) is a negative current collecting layer. The third upper current collecting layer (UC3) includes a third upper extension portion (UE3) extending in the second direction (Y), and the third upper extension portion (UE3) is welded to the lower extension portion of the lower current collecting layer of the fourth unit cell (CE4) by a weld portion (WP).

[0268] The first lower current collecting layer (LC1), the second lower current collecting layer (LC2), and the third lower current collecting layer (LC3) have positive electrodes of the same first polarity, and the first upper current collecting layer (UC1), the second upper current collecting layer (UC2), and the third upper current collecting layer (UC3) have negative electrodes of the same second polarity.

[0269] For example, the first unit cell (CE1), the second unit cell (CE2), and the third unit cell (CE3) form a bipolar cell structure.

[0270] The fourth unit cell (CE4), the fifth unit cell (CE5), and the sixth unit cell (CE6) have the same laminated structure as the second unit cell (CE2).

[0271] For example, the first unit cell (CE1), the second unit cell (CE2), the third unit cell (CE3), the fourth unit cell (CE4), the fifth unit cell (CE5), and the sixth unit cell (CE6) form a bipolar cell structure.

[0272] For example, an all-solid-state secondary battery (1005) is provided, which includes a plurality of unit cells including a first unit cell (CE1) and a second unit cell (CE2), in which alignment between a positive electrode active material layer and a negative electrode current collecting layer is improved, and a migration path of lithium ions moving from a positive electrode active material layer to a negative electrode current collecting layer during charging is expanded, thereby uniformly forming a lithium metal layer on the surface of the negative electrode current collecting layer during charging, thereby improving the capacity of the battery and suppressing short circuits between the positive electrode and the negative electrode.

[0273] In addition, an all-solid-state secondary battery (1005) is provided in which a plurality of unit cells, including a first unit cell (CE1) and a second unit cell (CE2), which are a plurality of unit cells, form a bipolar cell structure, even though the plurality of unit cells include an inclined surface that improves the capacity of the battery while suppressing short circuits between the positive and negative electrodes.

[0274] Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

[0275] [Explanation of symbols]

[0276] A first unit cell (CE1), a first lower current collecting layer (LC1), a first solid electrolyte layer (SE1), a first upper current collecting layer (UC1), a first upper extension (UE1), a second unit cell (CE2), a second lower current collecting layer (LC2), a second lower extension (LE2), a second solid electrolyte layer (SE2), a second upper current collecting layer (UC2)

Claims

1. A first unit cell including a first lower current collecting layer, a first solid electrolyte layer, and a first upper current collecting layer stacked in a first direction; and A second unit cell positioned on the first upper current collecting layer of the first unit cell, and including a second lower current collecting layer, a second solid electrolyte layer, and a second upper current collecting layer stacked in the first direction. Includes, The first upper current collecting layer includes a first upper extension portion extending in a second direction intersecting the first direction, An all-solid-state secondary battery wherein the second lower current collecting layer includes a second lower extension portion extending in the second direction and welded to the first upper extension portion.

2. In paragraph 1, The first upper extension portion does not overlap with the first solid electrolyte layer and the second solid electrolyte layer in the first direction, An all-solid-state secondary battery in which the second lower extension portion does not overlap the first solid electrolyte layer and the second solid electrolyte layer in the first direction.

3. In paragraph 1, The first upper current collecting layer further includes a first upper overlapping portion extending from the first upper extension portion between the first solid electrolyte layer and the second solid electrolyte layer, An all-solid-state secondary battery, wherein the second lower current collecting layer further includes a second lower overlapping portion extending from the second lower extension portion between the first solid electrolyte layer and the second solid electrolyte layer and overlapping the first upper overlapping portion in the first direction.

4. In paragraph 3, An all-solid-state secondary battery in which the first upper overlapping portion of the first upper current collecting layer is in contact with the second lower overlapping portion of the second lower current collecting layer.

5. In paragraph 4, An all-solid-state secondary battery in which the first upper overlapping portion of the first upper current collecting layer and the second lower overlapping portion of the second lower current collecting layer are non-welded to each other.

6. In paragraph 3, An all-solid-state secondary battery further comprising an elastic sheet positioned between the first upper overlapping portion of the first upper current collecting layer and the second lower overlapping portion of the second lower current collecting layer.

7. In paragraph 6, An all-solid-state secondary battery in which the elastic sheet is in contact with the first upper overlapping portion of the first upper current collecting layer and the second lower overlapping portion of the second lower current collecting layer.

8. In paragraph 1, A third unit cell is further included, which is positioned on the second upper current collecting layer of the second unit cell and includes a third lower current collecting layer, a third solid electrolyte layer, and a third upper current collecting layer stacked in the first direction, The second upper current collecting layer includes a second upper extension portion extending in the second direction, An all-solid-state secondary battery wherein the third lower current collecting layer includes a third lower extension portion extending in the second direction and welded to the second upper extension portion.

9. In paragraph 8, An all-solid-state secondary battery in which the second upper extension portion and the third lower extension portion extend in opposite directions from the first upper extension portion and the second lower extension portion in the second direction.

10. In paragraph 8, The first lower current collecting layer, the second upper current collecting layer, and the third lower current collecting layer have the same first polarity, An all-solid-state secondary battery wherein the first upper current collecting layer, the second lower current collecting layer, and the third upper current collecting layer have the same second polarity.

11. In paragraph 10, An all-solid-state secondary battery in which the first unit cell, the second unit cell, and the third unit cell form a bi-cell structure.

12. In paragraph 8, The first lower current collecting layer, the second lower current collecting layer, and the third lower current collecting layer have the same first polarity, An all-solid-state secondary battery wherein the first upper current collecting layer, the second upper current collecting layer, and the third upper current collecting layer have the same second polarity.

13. In paragraph 12, An all-solid-state secondary battery wherein the first unit cell, the second unit cell, and the third unit cell form a bipolar cell structure.

14. In paragraph 1, The above second unit cell is, A positive electrode active material layer positioned between the second lower current collecting layer and the second solid electrolyte layer; A cathode coating layer positioned between the second solid electrolyte layer and the second upper current collecting layer; A first inclined surface extending from one end of the second lower current collecting layer to one end of the second solid electrolyte layer; A second inclined surface extending from the other end of the second lower current collecting layer to the other end of the second solid electrolyte layer; A third inclined surface extending from one end of the second upper current collecting layer to one end of the second solid electrolyte layer; and A fourth inclined surface extending from the other end of the second upper current collecting layer to the other end of the second solid electrolyte layer An all-solid-state secondary battery further comprising:

15. In paragraph 14, An all-solid-state secondary battery in which the area of ​​the interface between the second upper current collecting layer and the negative electrode coating layer is wider than the area of ​​the positive electrode active material layer.

16. In paragraph 15, An all-solid-state secondary battery in which the area of ​​the interface between the second upper current collecting layer and the negative electrode coating layer is wider than the area of ​​the second lower current collecting layer.

17. In paragraph 15, An all-solid-state secondary battery in which a lithium metal layer is formed between the second upper current collecting layer and the negative electrode coating layer during charging.

18. In paragraph 17, An all-solid-state secondary battery in which the area of ​​the lithium metal layer is wider than the area of ​​the positive electrode active material layer.

19. In paragraph 18, An all-solid-state secondary battery in which the area of ​​the lithium metal layer is wider than the area of ​​the second lower current collecting layer.

20. In paragraph 17, One end of the lithium metal layer separates the third inclined surface, An all-solid-state secondary battery in which the other end of the lithium metal layer separates the fourth inclined surface.

Images