All-solid rechargeable battery

Abstract

An all-solid rechargeable battery according to an embodiment includes: a stack cell including a plurality of battery cells which are stacked and include a plurality of negative electrodes, a plurality of solid electrolyte layers, and a plurality of positive electrodes; a plurality of positive electrode material tabs respectively extending from the plurality of positive electrodes of the stack cell; and a plurality of insulation members respectively surrounding and insulating the plurality of positive electrode material tabs.

Description

All-solid-state secondary battery

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

[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 composed entirely of solid materials and utilize solid electrolytes. These all-solid-state secondary batteries are safe, eliminating the risk of explosion due to electrolyte leakage. They also offer the advantages of being easy to manufacture in thin forms, offering high energy density and the ability to produce large capacities.

[0003] The embodiments are directed to providing an all-solid-state secondary battery capable of reducing a failure rate and improving performance by preventing short circuits between a positive electrode substrate tab and a negative electrode.

[0004] An all-solid-state secondary battery according to one embodiment includes a stack cell comprising a plurality of battery cells stacked together, each battery cell including a plurality of negative electrodes, a plurality of solid electrolyte layers, and a plurality of positive electrodes; a plurality of positive electrode substrate tabs each extending from the plurality of positive electrodes of the stack cell; and a plurality of insulating members surrounding and insulating each of the plurality of positive electrode substrate tabs.

[0005] The above-described positive electrode substrate tab has a tab bending portion that is bent, and the insulating member can be positioned at the tab bending portion.

[0006] The edge of the cathode protrudes more than the edge of the anode by a protrusion, and a portion of the insulating member may be positioned to overlap the protrusion.

[0007] A portion of the insulating member may be positioned in a recess surrounded by the edge of the positive electrode and the solid electrolyte layer adjacent to the edge of the positive electrode.

[0008] At least a portion of the insulating member may be in contact with the solid electrolyte layer forming the recessed portion.

[0009] The width of the above insulating member may be greater than the width of the recessed portion.

[0010] The above-described plurality of positive electrode substrate tabs further include a positive electrode lead tab connected together, wherein the positive electrode substrate tab includes one end of the positive electrode tab connected to an edge of the positive electrode, the other end of the positive electrode tab connected to the positive electrode lead tab, and a positive electrode tab connection portion connecting the one end of the positive electrode tab and the other end of the positive electrode tab, and the tab bending portion can be located at one end of the positive electrode tab.

[0011] The stack cell may further include a plurality of cathode substrate tabs extending from each of the plurality of cathodes; and a cathode lead tab connecting the plurality of cathode substrate tabs together.

[0012] The positive electrode includes a positive electrode current collecting layer, and a first positive electrode active material layer and a second positive electrode active material layer positioned on both sides of the positive electrode current collecting layer, and the positive electrode substrate tab can extend from the positive electrode current collecting layer.

[0013] The above positive electrode substrate tab may comprise the same material as the above positive electrode current collecting layer.

[0014] The above positive electrode substrate tab can be formed integrally with the positive electrode current collecting layer.

[0015] The above positive electrode includes a positive electrode current collecting layer and a positive electrode active material layer positioned on one surface of the positive electrode current collecting layer, and the positive electrode substrate tab extends from the positive electrode current collecting layer, and the thickness of the positive electrode substrate tab may be smaller than the thickness of the positive electrode current collecting layer.

[0016] The above positive electrode substrate tab may comprise the same material as the above positive electrode current collecting layer.

[0017] The stack cell may further include an elastic member positioned between adjacent battery cells.

[0018] The above insulating member may include an insulating layer coated on the positive electrode substrate tab or an insulating tape surrounding the positive electrode substrate tab.

[0019] According to embodiments, by installing an insulating member surrounding the positive electrode substrate tab, the stack cell can be pressurized to prevent the positive electrode substrate tab from contacting the negative electrode and causing a short circuit even when the thickness of the stack cell changes.

[0020] Therefore, the failure rate of all-solid-state secondary batteries can be reduced and their performance can be improved.

[0021] Figure 1 is a cross-sectional view of an all-solid-state battery.

[0022] Figure 2 is a cross-sectional view of an all-solid-state battery including a precipitated negative electrode.

[0023] Figure 3 is a cross-sectional view of an all-solid-state secondary battery according to one embodiment.

[0024] Figure 4 is an enlarged cross-sectional view of part A of Figure 3.

[0025] Figure 5 is a cross-sectional view of an all-solid-state secondary battery according to another embodiment.

[0026] Figure 6 is an enlarged cross-sectional view of part B of Figure 5.

[0027] 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.

[0028] 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.

[0029] 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 are other elements in between. Conversely, when an element is said to be "directly over" another element, it means that there are no other elements in between.

[0030] 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; for example, "A or B" is interpreted to include A, B, A+B, etc.

[0031] Cathode for all-solid-state secondary batteries

[0032] In one embodiment, a positive electrode for an all-solid-state secondary battery is provided, comprising a current collector and a positive electrode active material layer positioned on the current collector, wherein the positive electrode active material layer comprises at least one of a positive electrode active material, a sulfide-based solid electrolyte, a binder, and a conductive material. However, without limitation thereto, the positive electrode for an all-solid-state secondary battery may comprise more or less components than the components described above.

[0033] In one embodiment, the positive electrode for the all-solid-state secondary battery is manufactured by applying a positive electrode composition including at least one of a positive electrode active material, a sulfide-based solid electrolyte, a binder, and a conductive agent to a current collector, followed by drying and rolling.

[0034] positive electrode active material

[0035] 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.

[0036] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5);

[0037] 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);

[0038] 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);

[0039] Li a E 2-b X b O 4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0040] 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);

[0041] 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);

[0042] 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);

[0043] 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);

[0044] 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);

[0045] 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);

[0046] 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);

[0047] 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);

[0048] Li a NiG bO2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0049] Li a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0050] Li a Mn 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0051] Li a Mn2G b O4(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0052] Li a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5);

[0053] QO2; QS2; LiQS2;

[0054] V2O5; LiV2O5;

[0055] LiZO2;

[0056] LiNiVO4;

[0057] Li (3-f) J2(PO4)3(0 ≤ f ≤ 2);

[0058] Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2);

[0059] Li a FePO4(0.90 ≤ a ≤ 1.8).

[0060] 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.

[0061] 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).

[0062] 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.

[0063] [Chemical Formula 1]

[0064] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2

[0065] In the above chemical formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, and M 1 and M2 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.

[0066] [Chemical Formula 2]

[0067] Li a2 Co x2 M 3 1-x2 O2

[0068] 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.

[0069] [Chemical Formula 3]

[0070] Li a3 Fe x3 M 4 (1-x3) PO4

[0071] 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.

[0072] 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 within the positive electrode active material layer and can realize high capacity and high energy density.

[0073] 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.

[0074] Sulfide-based solid electrolyte

[0075] 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 S n (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.

[0076] 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.

[0077] 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.

[0078] 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 a metal other than Li or a combination of multiple metals other than Li, and A is F, Cl, Br, or I) 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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 components in the positive electrode, and specifically, it can be said to be the content relative to the total weight of the positive electrode active material layer.

[0083] In one embodiment, the 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 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.

[0084] bookbinder

[0085] The binder serves to adhere the positive electrode active material particles well to each other and also to adhere the positive electrode active material well to the current collector, and representative examples thereof include, but are not limited to, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, etc.

[0086] Challenge

[0087] The above-described 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.

[0088] 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 positive electrode active material layer. Within the above content range, the conductive material can improve electrical conductivity without degrading battery performance.

[0089] When the positive electrode active material layer further includes a conductive material, the 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 positive electrode active material layer.

[0090] 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 Zr1-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 a combination thereof.

[0091] All-solid-state secondary battery

[0092] 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.

[0093] 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 (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 secondary 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.

[0094] cathode

[0095] An anode for an all-solid-state battery may include, for example, a current collector and a layer of anode active material positioned on the current collector. The layer of anode active material includes a cathode active material and may further include a binder, a conductive material, and / or a solid electrolyte.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] As a material that can be doped and dedoped with lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used, and as a Si-based negative electrode active material, silicon, silicon-carbon composite, SiO x (0 <x<2), Si-Q 합금(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), Sn계 음극 활물질로는 Sn, SnO2, Sn-R 합금(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. 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.

[0100] 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.

[0101] The average particle diameter (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, and in this case, 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 are 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] The above binder serves to adhere the negative active material particles well to each other and also to adhere the negative active material well to the current collector. The binder may include an insoluble binder, a water-soluble binder, or a combination thereof.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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 (40') may include a current collector (41) and a negative electrode coating layer (45) positioned on the current collector. An all-solid-state battery including such a precipitation-type negative electrode (40') starts initial charging in a state in which no negative electrode active material is present, and upon charging, a 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 above lithium metal layer (44) refers to a layer in which lithium metal, etc. 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.

[0113] The above cathode coating layer (45) may include a metal, carbon material, or a combination thereof that acts as a catalyst.

[0114] 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.

[0115] 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.

[0116] 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 (405) may include, for example, a carbon material supported with a catalytic metal, or may include a mixture of metal particles and carbon material particles.

[0117] 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.

[0118] 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.

[0119] 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 ㎛.

[0120] 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.

[0121] solid electrolyte layer

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] The thickness of the solid electrolyte layer may be, for example, 10 ㎛ to 150 ㎛.

[0128] The above solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0129] 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.

[0130] 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.

[0131] Additionally, the lithium salt may be an imide type, for example, the imide type 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 the ionic liquid.

[0132] 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.

[0133] The ionic liquid may be a compound comprising a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, 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-.

[0134] 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.

[0135] 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.

[0136] The above-mentioned all-solid-state battery may be a unit battery having a structure of positive electrode / solid electrolyte layer / negative electrode, a bi-cell having a structure of positive electrode / solid electrolyte layer / negative electrode / solid electrolyte layer / positive electrode, or a laminated battery in which the structure of the unit battery is repeated.

[0137] 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.

[0138] Hereinafter, an all-solid-state secondary battery according to one embodiment will be described with reference to FIGS. 3 and 4.

[0139] FIG. 3 is a cross-sectional view of an all-solid-state secondary battery according to one embodiment, and FIG. 4 is an enlarged cross-sectional view of part A of FIG. 3.

[0140] As illustrated in FIGS. 3 and 4, an all-solid-state secondary battery according to one embodiment is a rechargeable and dischargeable secondary battery, and includes a stack cell (100), a plurality of positive electrode substrate tabs (200), a plurality of insulating members (300), a positive electrode lead tab (400), a plurality of negative electrode substrate tabs (500), and a negative electrode lead tab (600).

[0141] A stack cell (100) may include a plurality of battery cells (110) and a plurality of elastic members (120).

[0142] A plurality of battery cells (110) may be stacked. One battery cell (110) may include a positive electrode (111), a solid electrolyte layer (112), and a negative electrode (113). Here, the positive electrode (111) may include a cathode, and the negative electrode (113) may include an anode.

[0143] The positive electrode (111) may include a positive electrode current collecting layer (111a) and a positive electrode active material layer (111b) positioned on both sides of the positive electrode current collecting layer (111a). The positive electrode active material layer (111b) may include a first positive electrode active material layer (11) and a second positive electrode active material layer (12).

[0144] The positive electrode current collecting layer (111a) may have a plate shape or a foil shape. The positive electrode current collecting layer (111a) may include any one selected from aluminum (Al), indium (In), copper (Cu), magnesium (Mg), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), germanium (Ge), and lithium (Li).

[0145] The positive electrode active material layer (111b) may be formed by coating on both sides of the positive electrode current collecting layer (111a). However, it is not necessarily limited thereto and may be formed using various methods such as transfer. The positive electrode active material layer (111b) may include any one selected from lithium salts such as lithium nickel cobalt manganese oxide (NCM), lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium manganate, and lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfur, iron oxide, or vanadium oxide. The positive electrode (111) may be flexible.

[0146] The negative electrode (113) may include a negative electrode current collecting layer (113a) and a negative electrode coating layer (113b) positioned on one surface of the negative electrode current collecting layer (113a). The negative electrode current collecting layer (113a) may include a first negative electrode current collecting layer (13) and a second negative electrode current collecting layer (14) positioned on opposite sides of the positive electrode. The negative electrode coating layer (113b) may include a first negative electrode coating layer (15) and a second negative electrode coating layer (16) positioned on opposite sides of the positive electrode (111). The negative electrode coating layer (113b) may be positioned on one surface of the negative electrode current collecting layer (113a) facing the solid electrolyte layer (112). That is, the negative electrode coating layer (113b) may be positioned between the negative electrode current collecting layer (113a) and the solid electrolyte layer (112). Specifically, the first cathode coating layer (15) may be positioned between the solid electrolyte layer (112) and the first cathode current collecting layer (13), and the second cathode coating layer (16) may be positioned between the solid electrolyte layer (112) and the second cathode current collecting layer (14).

[0147] The negative electrode current collecting layer (113a) may have a plate shape or a foil shape. The negative electrode current collecting layer (113a) may include various known metals and compounds that do not react with lithium. The negative electrode current collecting layer (113a) may include any one selected from stainless steel (SUS), copper (Cu), titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni).

[0148] The cathode coating layer (113b) may include, but is not limited to, silver (Ag) and carbon (C). For example, the cathode coating layer (113b) may have a structure in which 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) are contained in a carbon layer including at least one of carbon black (CB), furnace black (FB), acetylene black (AB), ketjen black (KB), and graphene. When charging an all-solid-state secondary battery, lithium is precipitated between the negative electrode current collecting layer (113a) and the negative electrode coating layer (113b), and a lithium metal layer is formed between the negative electrode current collecting layer (113a) and the negative electrode coating layer (113b). After discharging the all-solid-state secondary battery, the lithium precipitated between the negative electrode current collecting layer (113a) and the negative electrode coating layer (113b) is removed, so that the negative electrode current collecting layer (113a) and the negative electrode coating layer (113b) can come into direct contact.

[0149] The maximum length (L1) of the positive electrode (111) may be shorter than the maximum length (L2) of the negative electrode (113) or the solid electrolyte layer (112). Therefore, the N / P ratio, which is the value obtained by dividing the capacity of the positive electrode by the capacity of the negative electrode, may be greater than 1. Here, the length is defined as the length set based on the X direction.

[0150] Accordingly, the edge of the cathode (113) can protrude by a protrusion (P) from the edge of the anode (111), and the anode (111) is recessed compared to the adjacent cathode (113), so that a recessed portion (R) can be formed on the outer side of the edge of the anode (111) along the X direction. The recessed portion (R) can be surrounded by the edge of the anode (111) and the solid electrolyte layer (112) adjacent to the edge of the anode (111).

[0151] The solid electrolyte layer (112) may be positioned between the positive electrode (111) and the negative electrode (113). That is, the solid electrolyte layer (112) may be positioned between the positive electrode active material layer (111b) and the negative electrode coating layer (113b). The solid electrolyte layer (112) may include a first solid electrolyte layer (17) positioned between the first positive electrode active material layer (11) and the first negative electrode coating layer (15), and a second solid electrolyte layer (18) positioned between the second positive electrode active material layer (12) and the second negative electrode coating layer (16).

[0152] The solid electrolyte layer (112) may include, but is not limited to, various known sulfide-based solid electrolyte materials. For example, the solid electrolyte layer (112) 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 P, Si, Ge, It may include one of B, Al, Ga, and In. The solid electrolyte layer (112) may include at least one of an amorphous and a crystalline layer.

[0153] In this embodiment, a battery cell (110) is illustrated in which a first positive electrode active material layer (11), a first solid electrolyte layer (17), a first negative electrode coating layer (15), and a first negative electrode current collecting layer (13) are sequentially laminated on the positive electrode current collecting layer (111a) based on the positive electrode current collecting layer (111a), and a second positive electrode active material layer (12), a second solid electrolyte layer (18), a second negative electrode coating layer (16), and a second negative electrode current collecting layer (14) are sequentially positioned below the positive electrode current collecting layer (111a). A battery cell (110) having such a laminated structure is referred to as a battery cell having a bi-cell structure. Here, the upper and lower positional relationship is set based on the Z direction.

[0154] Meanwhile, the elastic member (120) may be positioned between adjacent battery cells (110) or on the outside of the outermost battery cell (110).

[0155] A plurality of positive electrode substrate tabs (200) extending from a plurality of positive electrodes (111) of a stack cell (100) are bent and then electrically connected by welding to a positive electrode lead tab (400). In addition, in order to operate the stack cell (100) of an all-solid-state secondary battery and secure the performance of the stack cell (100), the stack cell (100) must be pressurized. When the stack cell (100) is pressurized, the thickness of the elastic member (120) decreases, and thus the overall thickness of the stack cell (100) also decreases.

[0156] In addition, when charging and discharging the stack cell (100), lithium is precipitated and restored from the negative electrode (113) and pressurized, so that the thickness of the stack cell (100) shrinks or expands. At this time, since the positive electrode (111) of the stack cell (100) is made of a flexible material, the shape of the positive electrode tab (200), such as by bending, also changes. In this way, the positive electrode tab (200) whose shape has changed, such as by bending or bending, may come into contact with the negative electrode (113), which may cause a short circuit.

[0157] However, in the present embodiment, by installing an insulating member (300) surrounding the positive electrode substrate tab (200), the stack cell (100) is pressed, so that even if the thickness of the stack cell (100) changes, the positive electrode substrate tab (200) can be prevented from coming into contact with the negative electrode (113) and causing a short circuit. This will be described in detail below.

[0158] A plurality of positive electrode substrate tabs (200) may each extend from the positive electrode current collecting layer (111a) of the plurality of positive electrodes (111). The positive electrode substrate tabs (200) may be formed of the same material as the positive electrode current collecting layer (111a) of the positive electrode (111) and may be formed integrally with the positive electrode current collecting layer (111a).

[0159] The positive electrode substrate tab (200) may include one end of the positive electrode tab (210) connected to the edge of the positive electrode (111), the other end of the positive electrode tab (220) connected to the positive electrode lead tab (400), and an positive electrode tab connection portion (230) connecting the one end of the positive electrode tab (210) and the other end of the positive electrode tab (220). The positive electrode tab end portion (210), the other end of the positive electrode tab (220), and the positive electrode tab connection portion (230) may be formed integrally as the same material.

[0160] The positive electrode substrate tab (200) may have a tab bending portion (TB) that is bent. This tab bending portion (TB) may be located at one end (210) of the positive electrode tab.

[0161] A plurality of insulating members (300) can surround and insulate each of the plurality of positive electrode substrate tabs (200). These insulating members (300) can be positioned at the tab bending portion (TB).

[0162] A portion of the insulating member (300) may be positioned to overlap with the protrusion (P) of the cathode (113). Accordingly, a portion of the insulating member (300) may be positioned in the recessed portion (R). And, at least a portion of the insulating member (300) may be in contact with the solid electrolyte layer (112) forming the recessed portion (R).

[0163] The insulating member (300) surrounds and insulates the positive electrode substrate tab (200), thereby preventing the tab bending portion (TB) of the bent positive electrode substrate tab (200) from contacting the negative electrode (113). Accordingly, a short circuit between the positive electrode substrate tab (200) and the negative electrode (113) can be prevented.

[0164] The insulating member (300) may be formed by coating an insulating layer surrounding the positive electrode substrate tab (200), or may be formed by using an insulating tape surrounding the positive electrode substrate tab (200). The insulating layer or the insulating tape may have a shape in which a polymer or a composite of a polymer and a ceramic is coated on a non-woven fabric (NWF). The non-woven fabric may include any one selected from polyester, polypropylene, and polyethylene, and the polymer may be any one selected from polyacrylate, PVdF-HFP (polyvinylidene fluoride-hexafluoropropylene), and H-NBR (hydrogenated nitrile butadiene rubber).

[0165] The width (W1) of the insulating member (300) may be greater than the width (W2) of the recessed portion (R). Accordingly, a portion of the positive electrode substrate tab (200) not covered by the insulating member (300) can be prevented from contacting the solid electrolyte layer (112) forming the recessed portion (R).

[0166] The positive electrode lead tab (400) can connect multiple positive electrode substrate tabs (200) together using the positive electrode connecting member (410).

[0167] In this way, by installing an insulating member (300) surrounding a portion of a positive electrode substrate tab (200) in a stack cell (100) including a battery cell (110) of a bi-cell structure, even if the thickness of the stack cell (100) changes and the positive electrode substrate tab (200) is severely bent during the process of pressing the stack cell (100), the positive electrode substrate tab (200) can be prevented from coming into contact with the negative electrode (113) and causing a short circuit. Accordingly, the failure rate of the all-solid-state secondary battery can be reduced and its performance can be improved.

[0168] Meanwhile, a plurality of negative electrode substrate tabs (500) may each extend from the negative electrode current collecting layer (113a) of the plurality of negative electrodes (113). The negative electrode substrate tabs (500) may be formed integrally with the negative electrode (113) as the same material as the negative electrode (113). In addition, the negative electrode lead tabs (600) may connect the plurality of negative electrode substrate tabs (600) together using a negative electrode connecting member (610).

[0169] Meanwhile, in the above embodiment, the battery cells forming the stack cell have a bi-cell structure, but other embodiments including battery cells having a mono-cell structure are also possible.

[0170] Hereinafter, with reference to FIGS. 5 and 6, an all-solid-state secondary battery according to another embodiment of the present invention will be described in detail.

[0171] FIG. 5 is a cross-sectional view of an all-solid-state secondary battery according to another embodiment, and FIG. 6 is an enlarged cross-sectional view of part B of FIG. 5.

[0172] The other embodiments illustrated in FIGS. 5 and 6 are substantially the same as the one embodiment illustrated in FIGS. 3 and 4 except for the structure of the battery cell, and thus a repeated description thereof will be omitted.

[0173] As illustrated in FIGS. 5 and 6, an all-solid-state secondary battery according to another embodiment of the present invention includes a stack cell (100), a plurality of positive electrode substrate tabs (200), a plurality of insulating members (300), a positive electrode lead tab (400), a plurality of negative electrode substrate tabs (500), and a negative electrode lead tab (600).

[0174] A stack cell (100) may include a plurality of battery cells (110) and a plurality of elastic members (120). One battery cell (110) may include a positive electrode (111), a solid electrolyte layer (112), and a negative electrode (113). The positive electrode (111) may include a positive electrode current collecting layer (111a), and a positive electrode active material layer (111b) positioned on one surface of the positive electrode current collecting layer (111a). The negative electrode (113) may include a negative electrode current collecting layer (113a), and a negative electrode coating layer (113b) positioned on one surface of the negative electrode current collecting layer (113a). The solid electrolyte layer (112) may be positioned between the positive electrode active material layer (111b) and the negative electrode coating layer (113b).

[0175] In this embodiment, a battery cell (110) is illustrated in which a positive electrode active material layer (111b), a solid electrolyte layer (112), a negative electrode coating layer (113b), and a negative electrode current collecting layer (113a) are sequentially laminated on a positive electrode current collecting layer (111a). A battery cell (110) having such a laminated structure is referred to as a battery cell having a mono-cell structure.

[0176] A plurality of positive electrode substrate tabs (200) may each extend from the positive electrode current collecting layer (111a) of the plurality of positive electrodes (111). At this time, the thickness (t2) of the positive electrode substrate tabs (200) may be smaller than the thickness (t1) of the positive electrode current collecting layer (111a).

[0177] The positive electrode substrate tab (200) may have a tab bending portion (TB) that is bent. This tab bending portion (TB) may be located at one end (210) of the positive electrode tab.

[0178] A plurality of insulating members (300) can surround and insulate each of the plurality of positive electrode substrate tabs (200). These insulating members (300) can be positioned at the tab bending portion (TB).

[0179] A part of the insulating member (300) may be positioned to overlap with the protrusion (P) of the cathode (113). Accordingly, a part of the insulating member (300) may be positioned in the recessed portion (R).

[0180] The insulating member (300) surrounds and insulates the positive electrode substrate tab (200), thereby preventing the tab bending portion (TB) of the bent positive electrode substrate tab (200) from contacting the negative electrode (113). Accordingly, a short circuit between the positive electrode substrate tab (200) and the negative electrode (113) can be prevented.

[0181] In this way, by installing an insulating member (300) surrounding a portion of a positive electrode substrate tab (200) in a stack cell (100) including a battery cell (110) of a mono-cell structure, even if the thickness of the stack cell (100) changes and the positive electrode substrate tab (200) is severely bent during the process of pressing the stack cell (100), the positive electrode substrate tab (200) can be prevented from coming into contact with the negative electrode (113) and causing a short circuit. Accordingly, the failure rate of the all-solid-state secondary battery can be reduced and its performance can be improved.

[0182] 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.

Claims

1. A stack cell comprising a plurality of battery cells stacked and including a plurality of cathodes, a plurality of solid electrolyte layers, and a plurality of anodes; a plurality of anode substrate tabs each extending from said plurality of anodes of said stack cell; and A plurality of insulating members surrounding and insulating each of the plurality of positive electrode substrate tabs An all-solid-state secondary battery comprising:

2. In paragraph 1, The above-mentioned positive electrode substrate tab has a tab bending portion that is bent, An all-solid-state secondary battery, wherein the insulating member is located at the tab bending portion.

3. In paragraph 2, The edge of the cathode protrudes by a protrusion greater than the edge of the anode, An all-solid-state secondary battery, wherein a portion of the insulating member is positioned to overlap the protrusion.

4. In paragraph 3, An all-solid-state secondary battery, wherein a portion of the insulating member is positioned in a recess surrounded by the edge of the positive electrode and the solid electrolyte layer adjacent to the edge of the positive electrode.

5. In paragraph 4, An all-solid-state secondary battery, wherein at least a portion of the insulating member is in contact with the solid electrolyte layer forming the recessed portion.

6. In paragraph 4, An all-solid-state secondary battery, wherein the width of the insulating member is greater than the width of the recessed portion.

7. In paragraph 3, Further comprising a positive lead tab connecting the plurality of positive electrode substrate tabs together, The above positive electrode substrate tab One end of the positive tab connected to the edge of the positive electrode, The other end of the positive tab connected to the positive lead tab, and An anode tab connection connecting one end of the anode tab and the other end of the anode tab Including, An all-solid-state secondary battery, wherein the above tab bending portion is located at one end of the positive tab.

8. In paragraph 7, a plurality of cathode substrate tabs each extending from said plurality of cathodes of said stack cell; and A cathode lead tab in which the above plurality of cathode substrate tabs are connected together. An all-solid-state secondary battery further comprising:

9. In paragraph 1, The above anode is anode current collecting layer, and It includes a first positive electrode active material layer and a second positive electrode active material layer located on both sides of the positive electrode current collecting layer, An all-solid-state secondary battery, wherein the positive electrode substrate tab extends from the positive electrode current collecting layer.

10. In paragraph 9, An all-solid-state secondary battery, wherein the positive electrode substrate tab comprises the same material as the positive electrode current collecting layer.

11. In paragraph 10, An all-solid-state secondary battery, wherein the positive electrode substrate tab is formed integrally with the positive electrode current collecting layer.

12. In paragraph 1, The above anode is anode current collecting layer, and A positive electrode active material layer located on one side of the positive electrode current collecting layer Including, An all-solid-state secondary battery, wherein the positive electrode substrate tab extends from the positive electrode current collecting layer, and the thickness of the positive electrode substrate tab is smaller than the thickness of the positive electrode current collecting layer.

13. In paragraph 12, An all-solid-state secondary battery, wherein the positive electrode substrate tab comprises the same material as the positive electrode current collecting layer.

14. In paragraph 1, An all-solid-state secondary battery, wherein the stack cell further comprises an elastic member positioned between adjacent battery cells.

15. In paragraph 1, An all-solid-state secondary battery, wherein the insulating member comprises an insulating layer coated on the positive electrode substrate tab or an insulating tape surrounding the positive electrode substrate tab.

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