All-solid rechargeable battery

Abstract

An all-solid rechargeable battery is provided. According to one embodiment, the all-solid rechargeable battery comprises: a cell stack including a plurality of unit cells, elastic sheets disposed between the unit cells, and an outermost elastic sheet disposed at an outermost side of the unit cells, each unit cell including a negative electrode, a solid electrolyte layer, and a positive electrode; and a pouch accommodating the cell stack, wherein the outermost elastic sheet in the cell stack includes: a first region overlapping at least one among the negative electrodes, the solid electrolyte layers, and the positive electrodes; and second regions protruding from the first region so as to overlap at least portions of the tabs formed on either the negative electrodes or the positive electrodes.

Description

All-solid-state secondary battery

[0001] The present disclosure relates to an all-solid rechargeable battery.

[0002] Recently, driven by industrial demands, the development of batteries with high energy density and safety is actively underway. For example, lithium-ion batteries are being commercialized not only in the fields of information and communication devices but also in the automotive sector. In the automotive sector, safety is considered particularly important because it is directly related to human life.

[0003] Since commercially available lithium-ion batteries use electrolytes containing flammable organic solvents, there is a possibility of overheating and fire in the event of a short circuit. In response to this, all-solid-state secondary batteries using solid electrolytes instead of liquid electrolytes are being proposed.

[0004] All-solid-state secondary batteries can significantly reduce the likelihood of fire or explosion in the event of a short circuit by not using flammable organic solvents. Therefore, these all-solid-state batteries can offer significantly higher safety compared to lithium-ion batteries that use liquid electrolytes.

[0005] The information described above, disclosed in the background technology of this invention, is intended only to enhance understanding of the background of this disclosure and may therefore include information that does not constitute prior art.

[0006] The embodiments aim to provide an all-solid-state secondary battery that prevents an electrical short circuit between the tab and the pouch by insulating the tab connected to the electrode of the cell stack.

[0007] The embodiments aim to provide an all-solid-state secondary battery that insulates the tab without interfering with the welding of the tab and the lead tab.

[0008] A solid-state secondary battery of one embodiment comprises a cell stack comprising a plurality of unit cells including a negative electrode, a solid electrolyte layer, and a positive electrode, wherein the cell stack comprises an elastic sheet between the unit cells and an outermost elastic sheet provided at the outermost edge of the unit cells, and a pouch for housing the cell stack, wherein the outermost elastic sheet in the cell stack comprises a first region that overlaps with at least one of the negative electrode, the solid electrolyte layer, and the positive electrode, and a second region that protrudes from the first region so as to overlap with at least a portion of a tab formed on either the negative electrode or the positive electrode.

[0009] A solid-state secondary battery of one embodiment may further include a lead tab connected to the tabs and drawn out to the outside of the pouch.

[0010] The second region above may be folded at the outer edge of the first region and positioned at the outermost edge where the tabs are gathered.

[0011] The second area above may have a width greater than the width of the tab above.

[0012] The above tabs can be gathered at one location in the thickness direction of the cell stack and connected to a lead tab so that they can be drawn out to the outside of the pouch.

[0013] The above pouch includes a first case and a second case for accommodating the cell stack, and the first case and the second case may each have a first flange and a second flange facing each other at the outer edge of the cell stack.

[0014] The above pouch forms an inclined surface at the part where the tabs are gathered, and the second region can be in close contact between the part where the tabs are gathered and the inclined surface.

[0015] The second region can be folded again at the end of the inclined surface and be in close contact with the outermost surface of the stacked tabs in a gathered state.

[0016] The above pouch may include an aluminum sheet and a polypropylene (PP) layer covering the aluminum sheet.

[0017] The above pouch can be formed by heat-fusing a polypropylene (PP) layer covering the first flange and a polypropylene (PP) layer covering the second flange.

[0018] The length (Lr) of the second region above is formed to be longer than the length (Li) of the inclined surface (Li <Lr) 수 있다.

[0019] The length (Lr) of the second region above is formed to be shorter than the protrusion length (Lp) of the tabs (Lr <Lp) 수 있다.

[0020] The difference (Lp-Lr) between the protrusion length (Lp) of the above tabs and the length (Lr) of the second region may be formed to be longer than the required length (Ld) required for welding the lead tab and the tab (Lp-Lr > Ld).

[0021] The second region above may be positioned between the gathering portion of the tabs and the polypropylene (PP) layer.

[0022] The above tabs may include positive tabs connected to the positive electrode and negative tabs connected to the negative electrode.

[0023] The above positive tabs and the above negative tabs can be drawn out in opposite directions.

[0024] The above cell stack may further include a finishing tape that combines a plurality of unit cells together.

[0025] The cell stack may further include a first finishing tape provided in plurality on each side of a first direction in which the unit cells are drawn out in opposite directions, and a second finishing tape provided in plurality on each side of a second direction intersecting the first direction.

[0026] The embodiments further provide a second region in the outermost elastic sheet disposed at the outermost edge of the cell stack, and by placing the second region on the tabs connected to the electrodes to electrically insulate the tabs, electrical short circuit between the aluminum sheet of the pouch and the tabs can be prevented even when the insulating layer of the pouch melts.

[0027] The embodiments make the length of the second region smaller than the protruding length of the tab, so that the tab can be insulated to the maximum extent by the second region while simultaneously not interfering with the welding of the tab and the lead tab.

[0028] FIG. 1 is a cross-sectional view showing an all-solid-state secondary battery according to one embodiment.

[0029] FIG. 2 is a cross-sectional view showing the formation of a lithium metal layer of an all-solid-state secondary battery according to one embodiment.

[0030] FIG. 3 is an exploded perspective view of an all-solid-state secondary battery according to one embodiment of the present invention.

[0031] Figure 4 is a perspective view of a cell stack applied to Figure 3.

[0032] Figure 5 is a plan view of the outermost elastic sheet applied to the cell stack of Figure 4.

[0033] Figure 6 is a plan view of the tab portion in the unit cell applied to the cell stack of Figure 4.

[0034] Figure 7 is a plan view of the outermost elastic sheet applied to the tab portion of Figure 6.

[0035] Figure 8 is a plan view of a pouch in an all-solid-state secondary battery with the outermost elastic sheet of Figure 7 applied.

[0036] Figure 9 is a cross-sectional view along the line IX-IX of Figure 8.

[0037] Hereinafter, embodiments of the present invention are 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 embodied in various different forms and is not limited to the embodiments described herein.

[0038] Furthermore, throughout the specification, when a part is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0039] In the drawings, thicknesses have been enlarged to clearly represent various layers and regions, and the same reference numerals have been used for similar parts throughout the specification. When a part such as a layer, film, region, or plate is described as being "on" or "on" another part, this includes not only cases where it is "immediately on" another part, but also cases where there is another part in between. Conversely, when a part is described as being "immediately on" another part, it means that there is no other part in between.

[0040] In addition, the term "layer" here includes not only shapes formed on the entire surface when viewed in a plan view, but also shapes formed on some surfaces. Here, "or" is not interpreted in an exclusive sense, and for example, "A or B" is interpreted to include A, B, A+B, etc.

[0041] cathode for all-solid-state secondary batteries

[0042] In one embodiment, a positive electrode for an all-solid-state secondary battery is provided, comprising a current collector and a positive active material layer located on the current collector, wherein the positive active material layer comprises at least one of a positive active material, a sulfide-based solid electrolyte, a binder, and a conductive material. However, the positive electrode for an all-solid-state secondary battery is not limited thereto, and may include more or fewer components than the components described above.

[0043] In one embodiment, the positive electrode for the all-solid-state secondary battery is manufactured by applying a positive electrode composition comprising at least one of a positive electrode active material, a sulfide-based solid electrolyte, a binder, and a conductive material to a current collector, and then drying and rolling.

[0044] positive electrode active material

[0045] The above-mentioned positive active material may be applied without limitation as long as it is commonly used in all-solid-state secondary batteries. For example, the above-mentioned positive 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.

[0046] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5);

[0047] Li a A 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0048] Li a E 1-b X b O 2-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0049] Li a E 2-b Xb O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0050] 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);

[0051] 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);

[0052] 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);

[0053] 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);

[0054] 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);

[0055] Li a Ni 1-b-c Mr b X c O 2-αT2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 <α < 2);

[0056] The a Nor b E c G d O2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1);

[0057] The a Nor b Co c Mn 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);

[0058] The a NiG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0059] The a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0060] The a Mn 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0061] The a Mn2G b O4(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0062] The a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5);

[0063] QO2; QS2; LiQS2;

[0064] V2O5; LiV2O5;

[0065] LiZO2;

[0066] LiNiVO4;

[0067] Li (3-f) J2(PO4)3(0 ≤ f ≤ 2);

[0068] Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2);

[0069] Li a FePO4(0.90 ≤ a ≤ 1.8).

[0070] 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; and J is selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, and combinations thereof.

[0071] 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 oxide (LFP).

[0072] The above positive 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.

[0073] [Chemical Formula 1]

[0074] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2

[0075] 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 Each is independently 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.

[0076] [Chemical Formula 2]

[0077] Li a2 Co x2 M 3 1-x2 O2

[0078] In the above chemical formula 2, 0.9≤a2≤1.8, 0.6≤x2≤1, and M 3 It 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.

[0079] [Chemical Formula 3]

[0080] Li a3 Fe x3 M 4 (1-x3) PO4

[0081] 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.

[0082] Average particle size (D) of the above positive active material 50 The particle size can 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 size range can be harmoniously mixed with other components within the positive electrode active material layer and can achieve high capacity and high energy density.

[0083] The above positive active material may be in the form of secondary particles formed by the aggregation of a plurality of primary particles, or in the form of a single particle. In addition, the above positive active material may be spherical or have a shape close to spherical, or may be polyhedral or amorphous.

[0084] Sulfide-based solid electrolytes

[0085] Sulfide-based solid electrolytes include, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element, e.g., 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, and Li2S-P2S5-Z m S n (m and n are integers, and 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 may include a combination thereof.

[0086] 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. Within the above mixing ratio range, a sulfide-based solid electrolyte having excellent ionic conductivity can be manufactured. Additionally, ionic conductivity may be further improved by including other components such as SiS2, GeS2, B2S3, etc.

[0087] Mechanical milling or the solution method can be applied as mixing methods for sulfur-containing raw materials to manufacture sulfide-based solid electrolytes. Mechanical milling is a method in which starting materials are placed in a reactor and vigorously stirred with a ball mill or similar device to finely pulverize and mix the starting materials. When using the solution method, starting materials are mixed in a solvent to obtain a solid electrolyte as a precipitate. Furthermore, if heat treatment is performed after mixing, the crystals of the solid electrolyte can become more robust and the ionic conductivity can be improved. For example, a sulfide-based solid electrolyte can be manufactured by mixing sulfur-containing raw materials and heat-treating them two or more times; in this case, a robust sulfide-based solid electrolyte with high ionic conductivity can be produced.

[0088] For example, the sulfide-based solid electrolyte particles may include an argyrodite-type sulfide. The argyrodite-type sulfide is, for example, Li a M b P c S d A e It can be expressed by the chemical formula (where a, b, c, d, and e are all between 0 and 12, M is a metal excluding Li or a combination of multiple metals excluding Li, and A is F, Cl, Br, or I), and as a specific example, Li 7-x PS 6-x A xIt can be expressed by the chemical formula (where x is 0.2 or greater and 1.8 or less, and A is F, Cl, Br, or I). Specifically, the azirodite-type sulfide is 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.

[0089] Sulfide-based solid electrolyte particles containing such azirodite-type sulfides have an ionic conductivity of 10 at room temperature, which is the ionic conductivity of a typical liquid electrolyte. -4 to 10 -2 It has high ionic conductivity close to the S / cm range and can form a tight bond between the positive active material and the solid electrolyte without causing a decrease in ionic conductivity, and furthermore, can form a tight interface between the electrode layer and the solid electrolyte layer. An all-solid-state battery including this can improve battery performance such as rate characteristics, Coulomb efficiency, and lifespan characteristics.

[0090] An azirodite-type sulfide-based solid electrolyte can be prepared by mixing, for example, lithium sulfide and phosphorus sulfide, and optionally lithium halide. After mixing these, heat treatment may be performed. The heat treatment may include, for example, two or more heat treatment steps.

[0091] According to one embodiment, the average particle size (D50) of the sulfide-based solid electrolyte particles may be 5.0 μm or less, for example, 0.1 μm to 5.0 μm, 0.1 μm to 4.0 μm, 0.1 μm to 3.0 μm, 0.5 μm to 2.0 μm, or 0.1 μm to 1.5 μm. Alternatively, depending on the location or purpose of use, the sulfide-based solid electrolyte particles may be small particles having an average particle size (D50) of 0.1 μm to 1.0 μm, or large particles having an average particle size (D50) of 1.5 μm to 5.0 μm. Sulfide-based solid electrolyte particles within this particle size range can effectively penetrate between solid particles within the battery, and have excellent contact with the electrode active material and connectivity between solid electrolyte particles. The average particle size of the sulfide-based solid electrolyte particles may be measured using a microscopic image, for example, by measuring the size of about 20 particles in a scanning electron microscope image to obtain the particle size distribution and calculating D50 from it.

[0092] The content of the solid electrolyte in the anode 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 anode, and specifically, it can be said to be the content relative to the total weight of the anode active material layer.

[0093] In one embodiment, the positive active material layer may comprise, with respect to 100 weight% of the positive active material layer, 50 weight% to 99.35 weight% of a positive active material, 0.5 weight% to 35 weight% of a sulfide-based solid electrolyte, 0.1 weight% to 10 weight% of a fluorine-based resin binder, and 0.05 weight% to 5 weight% of vanadium oxide. When such content ranges are satisfied, the positive electrode for an all-solid-state secondary battery can achieve high capacity and high ionic conductivity while maintaining high adhesion, and the viscosity of the positive electrode composition can be maintained at an appropriate level, thereby improving processability.

[0094] bookbinder

[0095] The binder serves to adhere the positive active material particles well to each other and also to adhere the positive active material well to the current collector. Representative examples include polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc., but are not limited thereto.

[0096] Challenge

[0097] The above positive 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, carbon nanotubes; metal-based materials containing copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers such as polyphenylene derivatives; or a combination thereof.

[0098] The conductive material may be included in an amount of 0.1% to 5% by weight, or 0.1% to 3% by weight, relative to the total weight of each component of the anode for the all-solid-state battery, or relative to the total weight of the anode active material layer. Within the above content range, the conductive material can improve electrical conductivity without degrading battery performance.

[0099] When the above positive active material layer further comprises a conductive material, the above positive active material layer may comprise, with respect to 100 weight% of the above positive active material layer, 45 weight% to 99.25 weight% of a positive active material, 0.5 weight% to 35 weight% of a sulfide-based solid electrolyte, 0.1 weight% to 10 weight% of a fluorine-based resin binder, 0.05 weight% to 5 weight% of vanadium oxide, and 0.1 weight% to 5 weight% of a conductive material.

[0100] Meanwhile, the cathode for the lithium secondary battery described above may further include an oxide-based inorganic solid electrolyte in addition to the solid electrolyte described above. The oxide-based inorganic solid electrolyte is, 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 y TiO3, 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 may include a combination thereof.

[0101] All-solid-state secondary battery

[0102] In one embodiment, an all-solid-state secondary battery is provided, comprising the aforementioned positive and negative electrodes and a solid electrolyte layer located between the positive and negative electrodes. 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.

[0103] FIG. 1 is a cross-sectional view of an all-solid-state secondary battery according to one embodiment. Referring to FIG. 1, the all-solid-state secondary battery (100) may have a structure in which an electrode assembly is stacked, comprising a negative electrode (400) including a negative electrode current collector (401) and a negative electrode active material layer (403), a solid electrolyte layer (300), and a positive electrode (200) including a positive electrode active material layer (203) and a positive electrode current collector (201), and the assembly is housed in a case such as a pouch. The all-solid-state secondary battery (100) may further include an elastic layer (500) on the outer side of at least one of the positive electrode (200) and the negative electrode (400). FIG. 1 shows a single electrode assembly including a negative electrode (400), a solid electrolyte layer (300), and a positive electrode (200), but an all-solid-state battery may be manufactured by stacking two or more electrode assemblies.

[0104] cathode

[0105] A negative electrode for an all-solid-state battery may, for example, include a current collector and a negative electrode active material layer located on the current collector. The negative electrode active material layer may include a negative electrode active material and may further include a binder, a conductive material, and / or a solid electrolyte.

[0106] The above negative electrode 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.

[0107] A 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 amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0108] As the above lithium metal alloy, an alloy of lithium with 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 may be used.

[0109] As a material capable of doping and undoping the above lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used, and the Si-based negative electrode active material may include silicon, a silicon-carbon composite, or SiO₂. 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.

[0110] The silicon-carbon composite may be, for example, a silicon-carbon composite comprising a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer located 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-based pitch, mesophase pitch, petroleum-based pitch, coal-based oil, petroleum-based heavy oil, or polymer resins such as phenolic resin, furan resin, or polyimide resin may be used. In this case, the silicon content may be 10% to 50% by weight of the total weight of the silicon-carbon composite. Additionally, the content of the crystalline carbon may be 10% to 70% by weight of the total weight of the silicon-carbon composite, and the content of the amorphous carbon may be 20% to 40% by weight of the total weight of the silicon-carbon composite. Furthermore, the thickness of the amorphous carbon coating layer may be 5nm to 100nm.

[0111] The average particle size (D50) of the 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, wherein the atomic content ratio of Si:O within the silicon particles indicating the degree of oxidation may be 99:1 to 33:67. The silicon particles are SiO x It can be a particle, and in this case, SiO x In this case, the range of x may be greater than 0 and less than 2. Here, the average particle size (D50) is measured by a particle size analyzer using laser diffraction and refers to the diameter of a particle with a cumulative volume of 50% in the particle size distribution.

[0112] The above Si-based negative electrode active material or Sn-based negative electrode active material may 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 may be 1:99 to 90:10 by weight.

[0113] The content of the negative electrode active material in the above negative electrode active material layer may be 95% to 99% by weight with respect to the total weight of the negative electrode active material layer.

[0114] In one embodiment, the negative electrode active material layer further comprises a binder and optionally further comprises a conductive material. The content of the binder in the negative electrode active material layer may be 1% to 5% by weight based on the total weight of the negative electrode active material layer. Additionally, when further comprising a conductive material, the negative electrode active material layer may comprise 90% to 98% by weight of the negative electrode active material, 1% to 5% by weight of the binder, and 1% to 5% by weight of the conductive material.

[0115] The above binder serves to effectively bond the negative electrode active material particles to each other and also to effectively bond the negative electrode active material to the current collector. The above binder may include a water-insoluble binder, a water-soluble binder, or a combination thereof.

[0116] The above-mentioned water-insoluble 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.

[0117] Examples of the above water-soluble binders include rubber-based binders or polymer resin binders. 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, ethylenepropylenediene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0118] When a water-soluble binder is used as the above-mentioned cathode 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, alkali metal salts thereof, or combinations thereof. Na, K, or Li may be used as the alkali metal. The content of such a thickener may be 0.1 to 3 parts by weight per 100 parts by weight of the cathode active material.

[0119] The above conductive material is used to impart conductivity to an electrode and may include, for example, carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes; metal-based materials in the form of metal powder or metal fibers including copper, nickel, aluminum, silver, etc.; conductive polymers such as polyphenylene derivatives; or mixtures thereof.

[0120] As the above-mentioned cathode current collector, a material selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof may be used.

[0121] 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 contain a negative electrode active material when assembling the battery, but where lithium metal, etc., is precipitated during charging of the battery and acts as the negative electrode active material.

[0122] FIG. 2 is a schematic cross-sectional view of an all-solid-state secondary battery including a precipitation type negative electrode according to one embodiment. Referring to FIG. 2, the precipitation type negative electrode (400') may include a current collector (401) and a negative electrode coating layer (405) located on the current collector. An all-solid-state battery having such a precipitation type negative electrode (400') is initially charged in a state where no negative electrode active material is present, and during charging, a high-density lithium metal, etc. is precipitated between the current collector (401) and the negative electrode coating layer (405) to form a lithium metal layer (404), which can act as a negative electrode active material. Accordingly, in an all-solid-state battery that has undergone one or more charges, the precipitation type negative electrode (400') may include a current collector (401), a lithium metal layer (404) located on the current collector, and a negative electrode coating layer (405) located on the metal layer. The above lithium metal layer (404) refers to a layer in which lithium metal, etc. is precipitated during the charging process of the battery, and can be referred to as a metal layer or a negative electrode active material layer.

[0123] The above cathode coating layer (405) may include a metal, a carbon material, or a combination thereof that acts as a catalyst.

[0124] The above metal may include, for example, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, zinc, or a combination thereof, and may be composed of one of these or may be composed of several types of alloys. When the above metal exists in the form of particles, the average particle size (D50) may be about 4 μm or less, and for example, 10 nm to 4 μm.

[0125] 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 micro beads, 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.

[0126] When the above-mentioned cathode coating layer (405) 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-mentioned cathode coating layer (405) may include, for example, a carbon material supported with a catalyst metal, or may include a mixture of metal particles and carbon material particles.

[0127] The above cathode coating layer (405) may, for example, include the metal and amorphous carbon, and in this case, can effectively promote the precipitation of lithium metal.

[0128] The above cathode coating layer (405) may further include a binder, and the binder may be a conductive binder. Additionally, the above cathode coating layer (405) may further include general additives such as fillers, dispersants, ion conductive materials, etc.

[0129] The thickness of the above cathode coating layer (405) may be, for example, 100 nm to 20 μm, or 500 nm to 10 μm, or 1 μm to 5 μm.

[0130] The above-mentioned precipitation type cathode (400') may, for example, further include a thin film on the surface of the current collector, that is, between the current collector and the cathode 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 of these or composed of several types of alloys. The thin film can further flatten the precipitation shape of the lithium metal layer (404) and further improve the characteristics of the all-solid-state battery. The thin film may be formed by, for example, vacuum deposition, sputtering, plating, etc. The thickness of the thin film may be, for example, 1 nm to 500 nm.

[0131] solid electrolyte layer

[0132] The solid electrolyte layer (300) 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.

[0133] In one example, the solid electrolyte included in the anode (200) and the solid electrolyte included in the solid electrolyte layer (300) may include the same compound or different compounds. For example, if both the anode (200) and the solid electrolyte layer (300) include an azirodite-type sulfide-based solid electrolyte, the overall performance of the all-solid-state secondary battery may be improved. In addition, for example, if both the anode (200) and the solid electrolyte layer (300) include the aforementioned coated solid electrolyte, the all-solid-state secondary battery may achieve high capacity and high energy density while achieving excellent initial efficiency and lifespan characteristics.

[0134] Meanwhile, the average particle size (D) of the solid electrolyte included in the anode (200) 50 ) is the average particle size (D) of the solid electrolyte included in the solid electrolyte layer (300). 50It may be smaller than ). In this case, overall performance can be improved by increasing the mobility of lithium ions while maximizing the energy density of the all-solid-state battery. For example, the average particle size (D) of the solid electrolyte included in the cathode (200) 50 ) may be 0.1 μm to 1.0 μm, or 0.1 μm to 0.8 μm, and the average particle size (D) of the solid electrolyte included in the solid electrolyte layer (300) 50 The particle size ) can be 1.5 μm to 5.0 μm, or 2.0 μm to 4.0 μm, or 2.5 μm to 3.5 μm. When such a particle size range is satisfied, the energy density of the all-solid-state secondary battery is maximized, while lithium ion transport is facilitated to suppress resistance, thereby improving the overall performance of the all-solid-state secondary battery. Here, the average particle size (D) of the solid electrolyte 50 ) may be measured using a particle size analyzer utilizing laser diffraction. Alternatively, approximately 20 random particles may be selected from microscopic images such as those of a scanning electron microscope, their particle sizes measured, and their particle size distribution obtained, where D 50 You can also calculate the value.

[0135] The above solid electrolyte layer may further include a binder in addition to the solid electrolyte. In this case, styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, acrylate-based polymers, or combinations thereof may be used as the binder, but are not limited thereto, and any material used as a binder in the relevant technical field may be used. The above acrylate-based polymer may be, for example, butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0136] The above solid electrolyte layer can be formed by adding a solid electrolyte to a binder solution, coating it onto a substrate film, and drying it. The solvent of the binder solution may be isobutyryl isobutylate, xylene, toluene, benzene, hexane, or a combination thereof. Since the process for forming the above solid electrolyte layer is widely known in the field, a detailed description will be omitted.

[0137] The thickness of the solid electrolyte layer may be, for example, 10 μm to 150 μm.

[0138] The above solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0139] The above alkali metal salt may be, for example, a lithium salt. The content of the lithium salt in the above solid electrolyte layer may be 1 M or more, for example, 1 M to 4 M. In this case, the lithium salt can improve ion conductivity by improving the lithium ion mobility of the solid electrolyte layer.

[0140] The above lithium salts are, 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(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2), lithium bis(fluorosulfonyl)imide (LiFSI), It may include LiN(SO2F)2), LiCF3SO3, LiAsF6, LiSbF6, LiClO4, or a mixture thereof.

[0141] In addition, the lithium salt may be imide-based, for example, the imide-based lithium salt may include lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, LiN(SO2CF3)2) and lithium bis(fluorosulfonyl)imide (LiFSI, LiN(SO2F)2). The lithium salt can maintain or improve ionic conductivity by appropriately maintaining chemical reactivity with the ionic liquid.

[0142] The above ionic liquid refers to a salt or room temperature molten salt that has a melting point below room temperature, is in a liquid state at room temperature, and consists only of ions.

[0143] The above ionic liquid comprises 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) 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 - It may be a compound containing one or more anions selected from among.

[0144] The above ionic liquid may be one or more 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-methylimidazoliium bis(trifluoromethylsulfonyl)amide, and 1-ethyl-3-methylimidazoliium bis(trifluoromethylsulfonyl)amide.

[0145] The weight ratio of the solid electrolyte to the ionic liquid in the above solid electrolyte layer may be 0.1:99.9 to 90:10, and 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 increasing 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.

[0146] The above all-solid-state battery may be a unit cell having a structure of a positive electrode / solid electrolyte layer / negative electrode, a bicell having a structure of a negative electrode / solid electrolyte layer / positive electrode / solid electrolyte layer / negative electrode, or a stacked battery in which the structure of the unit cell is repeated.

[0147] The shape of the above-described solid-state battery is not particularly limited and may be, for example, coin-type, button-type, sheet-type, stacked-type, cylindrical-type, flat-type, etc. In addition, the above-described solid-state battery can be applied to large batteries used in electric vehicles, etc. For example, the above-described 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 a large amount of power storage, and for example, it can be used in electric bicycles or power tools.

[0148] FIG. 3 is an exploded perspective view of an all-solid-state secondary battery according to one embodiment of the present invention, and FIG. 4 is a perspective view of a cell stack applied to FIG. 3. Referring to FIG. 3 and FIG. 4, an all-solid-state secondary battery of one embodiment includes a cell stack (CS) and a pouch (P) that accommodates the cell stack (CS).

[0149] The cell stack (CS) comprises a plurality of unit cells (UC) including a stacked cathode (10), a solid electrolyte layer (20), and an anode (30), and has an elastic sheet (39) between the unit cells (UC), and further includes an outermost elastic sheet (40) provided at the outermost edge in the stacking direction (z-axis direction) in which the stacked unit cells (UC) are stacked.

[0150] For example, the pouch (P) includes a first case (C1) and a second case (C2) that accommodate a cell stack (CS). The first case (C1) and the second case (C2) are each provided on the outer edge of the cell stack (CS) and face each other.

[0151] The first case (C1) and the second case (C2) form a concave space that accommodates a cell stack (CS), and each is provided with a first flange (F1) and a second flange (F2) facing each other on the outer edge of the space. Since these first and second flanges (F1, F2) are heat-fused, a pouch (P) is formed by the first case (C1) and the second case (C2) that accommodate the cell stack (CS).

[0152] The first case (C1) and the second case (C2) are formed with the same structure and may include at least an aluminum sheet (S1) forming the outer surface and a polypropylene (PP) layer (S2) covering the aluminum sheet (S1) to form the inner surface.

[0153] The polypropylene (PP) layers (S2, S2) formed on the inner surfaces of the first case (C1) and the second case (C2) are heat-fused to each other at the first and second flanges (F1, F2) facing each other while accommodating the cell stack (CS), thereby forming a pouch (P). That is, the pouch (P) is completed by heat-fusion of the polypropylene (PP) layers (S2, S2) provided on the first and second flanges (F1, F2).

[0154] In addition, the first case (C1) and the second case (C2) may be formed as a multilayer sheet structure of two or more layers to surround the outside of the cell stack (CS). For example, the first case (C1) and the second case (C2) may be formed of a polymer sheet, a nylon sheet, and a metal sheet.

[0155] The polymer sheet forms the inner surface of the pouch and serves as an insulator and heat seal. A PET (polyethyleneterephthalate) sheet, a nylon sheet, or a PET-nylon composite sheet (referred to as "nylon sheet" for convenience), i.e., a nylon sheet, forms the outer surface of the pouch and protects the cell stack. A metal sheet provides mechanical strength to the pouch. The metal sheet is interposed between the polymer sheet and the nylon sheet and can be formed from an aluminum sheet, for example.

[0156] FIG. 5 is a plan view of the outermost elastic sheet applied to the cell stack of FIG. 4, and FIG. 6 is a plan view of the tab portion in the unit cell applied to the cell stack of FIG. 4. Referring to FIG. 3 through FIG. 6, in a cell stack (CS) in which unit cells (UC) are stacked, the outermost elastic sheet (40) includes a first region (41) and a second region (42).

[0157] In the outermost elastic sheet (40), the first region (41) overlaps with at least one of the cathode (10), the solid electrolyte layer (20), and the anode (20). The second region (42) protrudes from the first region (41) so as to overlap with at least a portion of the tab (T; T11, T31) formed on either the cathode (10) and the anode (20).

[0158] For example, the first region (41) is positioned in a charging and discharging area where the negative electrode (10) and the positive electrode (30) face each other with the solid electrolyte layer (20) in between, thereby buffering volume changes during charging of the unit cells (UC) under pressurized conditions and providing elasticity during discharge. In addition to the buffering and elastic action of the elastic sheet (39), the first region (41) makes the pressure of the unit cells (UC) more uniform.

[0159] The second region (42; 421, 422) is positioned to correspond to the tabs (T; T11, T31) that protrude from the first region (41) and are respectively connected to the negative electrode (10) and the positive electrode (30). Thus, the second region (42; 421, 422) electrically insulates the tabs (T; T11, T31) positioned at the outermost edge.

[0160] Specifically, the tabs (T; T11, T31) include negative tabs (T11) connected to the negative electrode (10) and positive tabs (T31) connected to the positive electrode (30). The negative tabs (T11) and positive tabs (T31) are drawn out in opposite directions from the cell stack (CS), that is, in the first direction (x-axis direction). The negative tabs (T11) are drawn out in the negative (-) first direction (x-axis direction), and the positive tabs (T31) are drawn out in the positive (+) first direction (x-axis direction). The area of ​​the unit cell (UC) that performs charging and discharging is set with the size of the first direction (x-axis direction) and the size of the second direction (y-axis direction) that intersects the first direction (x-axis direction).

[0161] In addition, lead tabs (43; 431, 432) are connected to the tabs (T; T11, T31). Thus, the lead tabs (43; 431, 432) bring the tabs (T; T11, T31) of the cell stack (CS) out to the outside of the pouch (P). To do this, the tabs (T; T11, T31) are gathered so as to be stacked on top of each other, and in the gathered state, are connected to the lead tabs (43; 431, 432) by welding.

[0162] For example, the tabs (T; T11, T31) are gathered at a location in the third direction (z-axis direction) that intersects the thickness direction of the cell stack (CS), i.e., the second direction (y-axis direction), and connected to the lead tabs (43; 431, 432) and drawn out to the outside of the pouch (P) (see FIG. 3, FIG. 4 and FIG. 9).

[0163] FIGS. 3, 4, and 9 illustrate a structure in which tabs (T; T11, T31) are gathered at the center of the thickness direction (z-axis direction) of the cell stack (CS) and connected to lead tabs (43; 431, 432). In this case, the path of the current formed during the charging and discharging of multiple unit cells (UC) can be made as uniform as possible.

[0164] Specifically, the lead tabs (43; 431, 432) include a negative lead tab (431) connected to the negative tabs (T11) and a positive lead tab (432) connected to the positive tabs (T31).

[0165] The negative lead tab (431) is welded to the upper surface (in FIG. 3) of the stacked and gathered negative tabs (T11). Additionally, the negative lead tab (431) may be further provided with an auxiliary tab (433) on the lower surface of the negative tabs (T11) to be more firmly connected to the upper and lower surfaces of the negative tabs (T11). The auxiliary tab (433) is placed only in the welding portion to prevent damage to the negative tabs (T11), such as tearing of the negative tabs (T11) being welded, and is located inside the pouch (P) without being drawn out to the outside.

[0166] Additionally, the positive lead tab (432) is welded to the upper surface (in FIG. 3) of the positive tabs (T31) that are stacked and gathered. Additionally, the positive lead tab (432) may be further provided with an auxiliary tab (434) on the lower surface of the positive tabs (T31) to be more securely connected to the upper and lower surfaces of the positive tabs (T31). The auxiliary tab (434) is positioned only in the welding area to prevent damage to the positive tabs (T31), such as tearing of the positive tabs (T31) being welded, and is located inside the pouch (P) without being drawn out to the outside.

[0167] Referring to FIGS. 3 and 4, the cell stack (CS) further includes a finishing tape (50) that combines a plurality of unit cells (UC) together. The finishing tape (50) includes a first finishing tape (51) and a second finishing tape (52).

[0168] The first finishing tape (51) is provided in multiple numbers on both the negative (-) and positive (+) sides of the first direction (x-axis direction) where the unit cells (UC) are drawn out in opposite directions. The first finishing tape (51) is provided on both sides of the negative tab (T11) and the second area (421), and is provided on both sides of the positive tab (T31) and the second area (422) to fix the unit cells (UC) to each other. The first finishing tape (51) is provided on the short sides of the four corners of the unit cells (UC) to fix the unit cells (UC).

[0169] The second finishing tape (52) is provided in multiple numbers on both the negative (-) and positive (+) sides of the second direction (y-axis direction) that intersects the first direction (x-axis direction). The second finishing tape (52) is provided in multiple numbers on both sides of the second direction (y-axis direction) where the negative and positive tabs (T11, T31) and the second area (421, 422) are not provided, thereby fixing the unit cells (UC) to each other. The second finishing tape (52) is provided in multiple numbers on the long side of the unit cells (UC) to fix the unit cells (UC).

[0170] FIG. 7 is a plan view of the outermost elastic sheet applied to the tab portion of FIG. 6, FIG. 8 is a plan view of the pouch in an all-solid-state secondary battery with the outermost elastic sheet of FIG. 7 applied, and FIG. 9 is a cross-sectional view along the line IX-IX of FIG. 8.

[0171] Referring to FIGS. 3 through 9, the second region (42; 421, 422) is folded at the outer edge of the first region (41) and placed at the outermost edge where the tabs (T; T11, T31) are stacked and gathered.

[0172] In this way, since the second region (42; 421, 422) is formed by extending from the first region (41) of the outermost elastic sheet (40), no separate component is required to electrically insulate the tabs (T; T11, T31). That is, handling of the outermost elastic sheet (40) leads directly to handling of the second region (42; 421, 422).

[0173] Referring to FIGS. 6 to 8, the second region (42; 421, 422) has a width (W42 > Wt) greater than the width (Wt) of the tap (T; T11, T31). That is, the second region (42; 421, 422) and the tap (T; T11, T31) have a width difference (ΔW) (W42 - Wt = ΔW). On both sides of the second direction (y-axis direction), there is a width difference (ΔW / 2) of half the size toward one side of the tap (T; T11, T31). Therefore, the second region (42; 421, 422) having a width difference (ΔW) can sufficiently cover the tap (T; T11, T31) and electrically insulate it.

[0174] Referring again to FIGS. 3, 8, and 9, the pouch (P) forms an inclined surface (P2) at the part (P1) where the tabs (T; T11, T31) are gathered, and a second region (42; 421, 422) is positioned between the tab (T) and the pouch (P), and is in close contact between the part (P1) where the tabs (T; T11, T31) are gathered and the inclined surface (P2). The second region (42; 421, 422) further includes a folded portion (44) that is folded again at the end of the inclined surface (P2), and the folded portion (44) is in close contact with the outermost surface of the tabs (T; T11, T31) stacked in a gathered state.

[0175] The second region (42; 421, 422) covers the tabs (T; T11, T31) on the inclined surface (P2) to provide electrical insulation. In addition, the bend portion (44) further covers the outermost surface of the stacked tabs (T; T11, T31) in a gathered state to provide further electrical insulation. The bend portion (44) can be formed within a range that does not interfere with the welding of the lead tabs (43; 431, 432) and the tabs (42; 421, 422).

[0176] The length (Lr) of the second region (42; 421, 422) is formed to be longer than the length (Li) of the inclined surface (P2) (Li <Lr). 즉 제2영역(42; 421, 422)이 경사면(P2)을 완전치 덮을 수 있다. 따라서 제2영역(42; 421, 422)은 경사면(P2)에서 폴리프로필렌(PP)층(S2)이 파괴되더라도 절연재로 작용하여, 파우치(P)의 알루미늄 시트(S1)가 제2영역(42; 421, 422)에 전기적으로 단락되는 것을 방지할 수 있다.

[0177] The length (Lr) of the second region (42; 421, 422) is formed to be shorter than the protrusion length (Lp) of the tabs (42; 421, 422) (Lr <Lp). 탭들(42; 421, 422)의 돌출 길이(Lp)와 제2영역(42; 421, 422)의 길이(Lr)의 차이(Lp-Lr)는 리드탭(43; 431, 432)과 탭들(42; 421, 422)의 용접시 요구되는 요구길이(Ld)보다 더 길게 형성된다((Lp-Lr)> Ld). Therefore, it enables welding of the lead tab (43; 431, 432) and the tabs (42; 421, 422) while preventing the inclined surface (P2) and the aluminum sheet (S1) from being electrically short-circuited in the second region (42; 421, 422).

[0178] The second region (42; 421, 422) is positioned between the portion (P1) where the tabs (42; 421, 422) are stacked and gathered, and the polypropylene (PP) layer (S2). Thus, even if the polypropylene (PP) layer (S2) of the pouch (P) is damaged, the second region (42; 421, 422), which acts as an insulating material, prevents an electrical short circuit between the tabs (42; 421, 422) and the aluminum sheet (S1).

[0179] The above description is merely one embodiment for implementing an all-solid-state secondary battery according to the present disclosure, and the present disclosure is not limited to the above-described embodiment. The technical spirit of the present disclosure extends to the scope in which various modifications can be made by anyone with ordinary knowledge in the field to which the invention belongs, without departing from the gist of the present disclosure as claimed in the following patent claims.

[0180] - Explanation of the symbols -

[0181] 10: Cathode 20: Solid electrolyte layer

[0182] 30: Anode 39: Elastic sheet

[0183] 40: Outermost elastic sheet 41: First region

[0184] 42, 421, 422: Area 2 43: Lead tab

[0185] 44: Bend section 50: Finishing tape

[0186] 51: 1st Closing Tape 52: 2nd Closing Tape

[0187] 431: Cathode lead tab 432: Positive lead tab

[0188] 433, 434: Auxiliary Tab C1: 1st Case

[0189] C2: Case 2 CS: Cell Stack

[0190] F1, F2: 1st and 2nd flanges Ld: Required length

[0191] Lp: Protrusion length Lr, Li: Length

[0192] P: Pouch P1: Gathering part

[0193] P2: Inclined surface S1: Aluminum sheet

[0194] S2: Polypropylene (PP) layer T: Tab

[0195] T11: Cathode tab T31: Positive tab

[0196] UC: Unit cell Wt, W42: Width

[0197] ΔW: Width difference

Claims

1. A cell stack comprising a plurality of unit cells including a cathode, a solid electrolyte layer, and an anode, and an outermost elastic sheet provided at the outermost edge of the unit cells; and It includes a pouch that accommodates the above cell stack, In the cell stack above, the outermost elastic sheet is A first region overlapping with at least one of the above-mentioned cathode, the above-mentioned solid electrolyte layer, and the above-mentioned anode, and A solid-state secondary battery comprising a second region protruding from the first region so as to overlap with at least a portion of a tab formed on either the cathode or the anode.

2. In Paragraph 1, A solid-state secondary battery further comprising a lead tab connected to the above tabs and drawn out to the outside of the pouch.

3. In Paragraph 1, The above second region is A solid-state secondary battery that is folded at the outer edge of the first region and positioned at the outermost edge where the tabs are gathered.

4. In Paragraph 3, The above second region is A solid-state secondary battery having a width greater than the width of the above tab.

5. In Paragraph 1, The above tabs A solid-state secondary battery that is gathered at one location in the thickness direction of the cell stack and connected to a lead tab and drawn out to the outside of the pouch.

6. In Paragraph 5, The above pouch is It includes a first case and a second case accommodating the above cell stack, and A solid-state secondary battery in which the first case and the second case each have a first flange and a second flange facing each other at the outer edge of the cell stack.

7. In Paragraph 6, The above pouch is A sloping surface is formed at the part where the above tabs are gathered, and The above second region is A solid-state secondary battery that is in close contact between the gathering portion of the above tabs and the above inclined surface.

8. In Paragraph 7, The above second region is A solid-state secondary battery that is in close contact with the outermost surface of the tabs stacked in a gathered state after being folded again at the end of the inclined surface.

9. In Paragraph 7, The above pouch is, Aluminum sheets, and All-solid-state secondary battery comprising a polypropylene (PP) layer covering the aluminum sheet.

10. In Paragraph 9, The above pouch is A solid-state secondary battery formed by heat-fusion of a polypropylene (PP) layer covering the first flange and a polypropylene (PP) layer covering the second flange.

11. In Paragraph 7, The length (Lr) of the second region above is It is formed to be longer than the length (Li) of the above inclined surface (Li <Lr)는, 전고체 이차 전지.

12. In Paragraph 11, The length (Lr) of the second region above is Formed shorter than the protrusion length (Lp) of the above tabs (Lr <Lp)는, 전고체 이차 전지.

13. In Paragraph 12, The difference (Lp-Lr) between the protrusion length (Lp) of the above tabs and the length (Lr) of the second region is All-solid-state secondary battery formed longer than the required length (Ld) for welding the lead tab and the tab ((Lp-Lr)> Ld).

14. In Paragraph 9, The above second region is A solid-state secondary battery disposed between the collecting portion of the above tabs and the above polypropylene (PP) layer.

15. In Paragraph 1, The above tabs A solid-state secondary battery comprising positive electrode tabs connected to the positive electrode and negative electrode tabs connected to the negative electrode.

16. In Paragraph 15, A solid-state secondary battery in which the positive electrode tabs and the negative electrode tabs are drawn out in opposite directions.

17. In Paragraph 1, The above cell stack is All-solid-state secondary battery further comprising a sealing tape that joins multiple unit cells together.

18. In Paragraph 1, The above cell stack is, A first finishing tape provided in plurality on each side of a first direction in which the above unit cells are drawn out in opposite directions, and A solid-state secondary battery further comprising a plurality of second finishing tapes provided on each side of a second direction intersecting the first direction.

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