All-solid secondary battery

Abstract

An all-solid secondary battery according to an embodiment comprises: an all-solid cell comprising a positive electrode, a negative electrode, and a solid electrolyte layer; support plates supporting the respective surfaces of the all-solid cell; and uniform pressure applying members positioned between the all-solid cell and the support plates and applying uniform pressure to the all-solid cell, wherein the uniform pressure applying members comprise: piezoelectric element layers facing the respective surfaces of the all-solid cell and generating a piezoelectric current due to uneven pressure resulting from the surface unevenness of the all-solid cell; and pressure compensation layers positioned on one surface of the piezoelectric element layers and compensating for the uneven pressure by using the piezoelectric current.

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

[0004] The embodiments are intended to provide an all-solid-state secondary battery capable of improving the performance of the all-solid-state secondary battery by uniformly pressurizing the all-solid-state cell.

[0005] However, the technical problems to be solved by the present invention are not limited to the problems described above, and other problems not mentioned can be clearly understood by those skilled in the art from the description of the invention described below.

[0006] According to one embodiment of the present invention for solving the above technical problem, an all-solid-state secondary battery comprises: an all-solid-state cell including a positive electrode, a negative electrode, and a solid electrolyte layer; a support plate supporting both surfaces of the all-solid-state cell; and a uniform pressure applying member positioned between the all-solid-state cell and the support plate to apply uniform pressure to the all-solid-state cell, wherein the uniform pressure applying member comprises: a piezoelectric element layer facing both surfaces of the all-solid-state cell and generating a piezoelectric current by an uneven pressure due to surface unevenness of the all-solid-state cell; and a pressure compensation layer positioned on one surface of the piezoelectric element layer and compensating for the uneven pressure using the piezoelectric current.

[0007] The pressure compensation layer includes a heat shrinkable layer that is in contact with one surface of the piezoelectric element layer and includes a heat shrinkable material, and a resistance element that is located within the heat shrinkable layer and is electrically connected to the piezoelectric element to generate resistance heat by the piezoelectric current, and a part of the heat shrinkable layer is contracted by the resistance heat to compensate for the uneven pressure.

[0008] The above heat shrinkable layer may include any one heat shrinkable material selected from polyolefin, fluoropolymer, BiNi1-xFexO3 (bismuth-nickel-iron oxide), and Bi0.95La0.05NiO3 (bismuth-lanthanum nickel oxide).

[0009] The piezoelectric element layer may be positioned between the heat shrinkable layer and the all-solid-state cell.

[0010] The piezoelectric element layer may include an inelastic layer including an inelastic material, and a plurality of piezoelectric elements positioned inside the inelastic layer.

[0011] The above inelastic layer can be in contact with both sides of the above all-solid-state cell.

[0012] The above inelastic layer can surround the plurality of piezoelectric elements.

[0013] The above inelastic layer may include any one inelastic material selected from inelastic rubber, inelastic clay, plastic, and ceramic.

[0014] The above inelastic layer may further include any one insulating material selected from glass, ceramic, plastic, urea foam, foam rubber insulation, and rigid urethane.

[0015] According to embodiments, by installing a uniform pressure applying member including a piezoelectric element layer and a pressure compensation layer, it is possible to finely control even local pressure increases due to surface irregularities of an all-solid-state cell, thereby applying uniform pressure to the all-solid-state cell. Accordingly, the performance of an all-solid-state secondary battery can be improved.

[0016] In addition, since uniform pressure can be applied to areas where it is difficult to apply uniform pressure, such as areas adjacent to electrode tabs of an all-solid-state secondary battery, the performance of the all-solid-state secondary battery can be improved.

[0017] In addition, since it is installed inside an all-solid-state secondary battery, it is possible to continuously apply uniform pressure to the all-solid-state cell within the life of the all-solid-state secondary battery, thereby improving the life of the all-solid-state secondary battery.

[0018] The following drawings attached to this specification illustrate preferred embodiments of the present invention, and together with the detailed description of the invention described below, serve to further understand the technical idea of ​​the present invention, and therefore, the present invention should not be interpreted as being limited to matters described in such drawings.

[0019] Figure 1 is a cross-sectional view of an all-solid-state secondary battery.

[0020] Figure 2 is a cross-sectional view of an all-solid-state secondary battery including a precipitated negative electrode.

[0021] Figure 3 is a cross-sectional view of an all-solid-state secondary battery according to one embodiment.

[0022] Figure 4 is an enlarged view of a portion of Figure 3.

[0023] FIGS. 5 to 7 are drawings sequentially explaining the principle of applying uniform pressure to an all-solid-state cell of an all-solid-state secondary battery according to one embodiment.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] Cathode for all-solid-state secondary batteries

[0029] In one embodiment, a positive electrode for an all-solid-state secondary battery is provided, which includes a current collecting layer and a positive electrode active material layer positioned on the current collecting layer, wherein the positive electrode active material layer includes at least one of a positive electrode 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 less components than the components described above.

[0030] In one embodiment, a positive electrode for an 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 material to a current collecting layer, followed by drying and rolling.

[0031] positive electrode active material

[0032] The cathode active material can be applied without limitation as long as it is one commonly used in all-solid-state secondary batteries. For example, the cathode active material may be a compound capable of reversible lithium intercalation and deintercalation, and may include a compound represented by any of the following chemical formulas.

[0033] Li a A 1-b X b D2(0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5);

[0034] 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);

[0035] 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);

[0036] Li a E 2-b X b O4-c D c (0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05);

[0037] 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);

[0038] 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);

[0039] 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);

[0040] 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);

[0041] 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);

[0042] 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);

[0043] 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);

[0044] 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);

[0045] The a NiG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0046] The a CoG b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0047] The a Mn 1-b G b O2(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0048] The a Mn2G b O4(0.90 ≤ a ≤ 1.8, 0.001 ≤ b ≤ 0.1);

[0049] The a Mn 1-g G g PO4(0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5);

[0050] QO2; QS2; LiQS2;

[0051] V2O5; LiV2O5;

[0052] LiZO2;

[0053] LiNiVO4;

[0054] Li (3-f) J2(PO4)3(0 ≤ f ≤ 2);

[0055] Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2);

[0056] Li a FePO4(0.90 ≤ a ≤ 1.8).

[0057] 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.

[0058] The cathode 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).

[0059] The 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.

[0060] [Chemical Formula 1]

[0061] Li a1 Ni x1 M 1 y1 M 2 1-x1-y1 O2

[0062] In the above chemical formula 1, 0.9≤a1≤1.8, 0.3≤x1≤1, 0≤y1≤0.7, and M 1 and M 2 is one or more elements independently selected from the group consisting of Al, B, Ba, Ca, Ce, Co, Cr, Cu, F, Fe, Mg, Mn, Mo, Nb, P, S, Si, Sr, Ti, V, W, and Zr.

[0063] [Chemical Formula 2]

[0064] Li a2 Co x2 M 3 1-x2 O2

[0065] 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.

[0066] [Chemical Formula 3]

[0067] Li a3 Fe x3 M 4 (1-x3) PO4

[0068] 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.

[0069] 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.

[0070] 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.

[0071] Sulfide-based solid electrolyte

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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 the electrode layer and the 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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 the above content ranges are satisfied, the positive electrode for an all-solid-state secondary battery can maintain high adhesiveness while implementing high capacity and high ionic conductivity, and the viscosity of the positive electrode composition can be maintained at an appropriate level, thereby improving processability.

[0081] bookbinder

[0082] 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.

[0083] Challenge

[0084] 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.

[0085] 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.

[0086] 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.

[0087] Meanwhile, the positive electrode for the lithium secondary battery may further include an oxide-based inorganic solid electrolyte in addition to the above-described solid electrolyte. The oxide-based inorganic solid electrolyte may be, for example, Li 1+x Ti 2-x Al(PO4)3(LTAP)(0≤x≤4), Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 0≤y<1), PB(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y(PO4)3, 0 <x<2, 0<y<3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1, 0≤y≤1), lithium lanthanum titanate (Li x La 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.

[0088] All-solid-state secondary battery

[0089] In one embodiment, an all-solid-state secondary battery is provided, which includes the aforementioned positive electrode, 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.

[0090] Figure 1 is a cross-sectional view of an all-solid-state battery.

[0091] Referring to FIG. 1, the all-solid-state battery (1000) may have a structure in which an electrode assembly in which a negative electrode (40) including a negative electrode current collecting layer (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 current collecting layer (21) are laminated is housed in a case such as a pouch. The all-solid-state battery (1000) may further include an elastic layer (50) on the outer side of at least one of the positive electrode (20) and the negative electrode (40). Although FIG. 1 illustrates one electrode assembly including a negative electrode (40), a solid electrolyte layer (30), and a positive electrode (20), an all-solid-state battery may be manufactured by laminating two or more electrode assemblies.

[0092] cathode

[0093] An anode for an all-solid-state battery may include, for example, a current collecting layer and a negative electrode active material layer positioned on the current collecting layer. The negative electrode active material layer includes a negative electrode active material and may further include a binder, a conductive material, and / or a solid electrolyte.

[0094] The 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.

[0095] Materials capable of reversibly intercalating / deintercalating lithium ions include carbon-based negative electrode active materials, such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of 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 amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, and calcined coke.

[0096] As an alloy of lithium metal, 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 can be used.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] The 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.

[0101] The content of the negative active material in the negative active material layer may be 95 wt% to 99 wt% with respect to the total weight of the negative active material layer.

[0102] 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.

[0103] The above binder serves to adhere the negative electrode active material particles well to each other and also to adhere the negative electrode active material well to the current collecting layer. The binder may include an insoluble binder, a water-soluble binder, or a combination thereof.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] The cathode current collecting layer 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.

[0109] 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.

[0110] Figure 2 is a cross-sectional view of an all-solid-state battery including a precipitated negative electrode.

[0111] Referring to FIG. 2, the precipitation-type negative electrode (40') may include a current collecting layer (41) and a negative electrode coating layer (45) positioned on the current collecting layer (41). An all-solid-state battery having such a precipitation-type negative electrode (40') starts initial charging in a state in which no negative electrode active material exists, and during charging, high-density lithium metal or the like is precipitated between the current collecting layer (41) and the negative electrode coating layer (45) to form a lithium metal layer (44), which may function as the negative electrode active material. Accordingly, in an all-solid-state battery that has been charged more than once, the precipitation-type negative electrode (40') may include a current collecting layer (41), a lithium metal layer (44) positioned on the current collecting layer (41), and a negative electrode coating layer (45) positioned on the metal layer. The lithium metal layer (44) refers to a layer in which lithium metal or the like is precipitated during the charging process of the battery, and may be referred to as a metal layer or a negative electrode active material layer.

[0112] The cathode coating layer (45) may include a metal, carbon material, or a combination thereof that acts as a catalyst.

[0113] 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 of these or an alloy of several types. When the metal is present in the form of particles, the average particle diameter (D50) may be about 4 μm or less, for example, 10 nm to 4 μm.

[0114] 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.

[0115] When the cathode coating layer (45) includes both metal and carbon material, the mixing ratio of the metal and 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 cathode coating layer (45) may include, for example, a carbon material supported with a catalytic metal, or may include a mixture of metal particles and carbon material particles.

[0116] The cathode coating layer (45) may include, for example, a metal and amorphous carbon, in which case the precipitation of lithium metal can be effectively promoted.

[0117] The cathode coating layer (45) may further include a binder, and the binder may be a conductive binder. In addition, the cathode coating layer (45) may further include general additives such as fillers, dispersants, and ionic conductive agents.

[0118] 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 ㎛.

[0119] The precipitation-type negative electrode (40') may further include, for example, a thin film on the surface of the current collecting layer (41), that is, between the current collecting layer (41) and the negative electrode coating layer (45). 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 precipitation 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.

[0120] solid electrolyte layer

[0121] 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.

[0122] 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.

[0123] 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.

[0124] The solid electrolyte layer may further include a binder in addition to the solid electrolyte. The binder may include, but is not limited to, styrene butadiene rubber, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, an acrylate polymer, or a combination thereof, and any binder used in the art may be used. The acrylate polymer may be, for example, butyl acrylate, polyacrylate, polymethacrylate, or a combination thereof.

[0125] A solid electrolyte layer can be formed by adding a solid electrolyte to a binder solution, coating the solution on a substrate film, and drying the solution. The solvent for the binder solution may be isobutyryl isobutyrate, xylene, toluene, benzene, hexane, or a combination thereof. The solid electrolyte layer formation process is widely known in the art, so a detailed description will be omitted.

[0126] The thickness of the solid electrolyte layer may be, for example, 10 μm to 150 μm.

[0127] The solid electrolyte layer may further include an alkali metal salt, and / or an ionic liquid, and / or a conductive polymer.

[0128] The 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 ionic conductivity by enhancing the mobility of lithium ions in the solid electrolyte layer.

[0129] 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.

[0130] 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.

[0131] Ionic liquids are salts or molten salts that are composed only of ions and are liquid at room temperature, with a melting point below room temperature.

[0132] 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-.

[0133] The ionic liquid may be, for example, one or more selected from the group consisting of 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.

[0134] In the 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.

[0135] The all-solid-state battery may be a unit cell having a structure of anode / solid electrolyte layer / cathode, a bi-cell having a structure of cathode / solid electrolyte layer / cathode / solid electrolyte layer / cathode, or a laminated battery in which the structure of the unit cell is repeated.

[0136] The shape of the all-solid-state battery is not particularly limited, and may be, for example, coin-shaped, button-shaped, sheet-shaped, stacked, cylindrical, or flat. Furthermore, all-solid-state batteries can be applied to large-scale batteries used in electric vehicles, for example. For example, all-solid-state batteries can be used in hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). Furthermore, they can be used in fields requiring large amounts of power storage, such as electric bicycles or power tools.

[0137] Hereinafter, an all-solid-state secondary battery according to one embodiment will be described with reference to FIGS. 3 and 4.

[0138] FIG. 3 is a cross-sectional view of an all-solid-state secondary battery according to one embodiment, and FIG. 4 is an enlarged view of a portion of FIG. 3.

[0139] As illustrated in FIGS. 3 and 4, an all-solid-state secondary battery according to one embodiment includes an all-solid-state cell (100), a support plate (200), and a uniform pressure applying member (300).

[0140] The all-solid-state cell (100) may have a stack cell structure in which a plurality of unit cells (UC) and elastic members (EM) are stacked.

[0141] One unit cell (UC) may include a positive electrode (11), a negative electrode (13), and a solid electrolyte layer (12). Here, the positive electrode (11) may include a cathode, and the negative electrode (13) may include an anode. The positive electrode (11) may include a positive electrode current collecting layer (11a), and a positive electrode active material layer (11b) positioned on one surface of the positive electrode current collecting layer (11a). The positive electrode current collecting layer (11a) 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). The cathode active material layer (11b) may include any one selected from lithium salts such as 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.

[0142] The negative electrode (13) may include a negative electrode current collecting layer (13a) and a negative electrode coating layer (13b) positioned on one surface of the negative electrode current collecting layer (13a). The negative electrode current collecting layer (13a) may have a plate shape or a foil shape. The negative electrode current collecting layer (13a) may include various known metals and compounds that do not react with lithium. The negative electrode current collecting layer (13a) may include any one selected from stainless steel (SUS), copper (Cu), titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The negative electrode coating layer (13b) may include silver (Ag) and carbon (C), but is not limited thereto. For example, the cathode coating layer (13b) 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 (Li) is deposited between the negative electrode current collecting layer (13a) and the negative electrode coating layer (13b), and a lithium metal layer is formed between the negative electrode current collecting layer (13a) and the negative electrode coating layer (13b). After discharging the all-solid-state secondary battery, the lithium deposited between the negative electrode current collecting layer (13a) and the negative electrode coating layer (13b) is removed, so that the negative electrode current collecting layer (13a) and the negative electrode coating layer (13b) can come into direct contact.

[0143] The solid electrolyte layer (12) may be positioned between the positive electrode active material layer (11b) and the negative electrode coating layer (13b). The solid electrolyte layer (12) may include, but is not limited to, various known sulfide-based solid electrolyte materials. For example, the solid electrolyte layer (12) 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 (12) may include at least one of an amorphous and a crystalline layer.

[0144] The elastic member (EM) may include an elastic material such as rubber, elastomer, or foam.

[0145] In order for lithium (Li) to grow and be reduced uniformly during charging and discharging of an all-solid-state secondary battery, a uniform pressure must be applied to the entire surface area of ​​the all-solid-state secondary battery. To this end, an elastic member (EM) is installed between adjacent unit cells (UC) to provide elasticity to the unit cells (UC), thereby allowing a constant pressure to be applied to the unit cells (UC).

[0146] The support plate (200) can support and pressurize both sides of the all-solid-state cell (100).

[0147] The support plate (200) may include an upper support plate (210) and a lower support plate (220) that are positioned spaced apart from each other. The upper support plate (210) and the lower support plate (220) may have the same size and may face each other spaced apart from each other by a predetermined distance. The upper support plate (100) and the lower support plate (200) may each face both sides of the all-solid-state cell (100) and press both sides of the all-solid-state cell (100).

[0148] The uniform pressure applying member (300) is located between the all-solid cell (100) and the support plate (200) and can apply uniform pressure to the all-solid cell (100).

[0149] The uniform pressure application member (300) may include a piezoelectric element layer (310) and a pressure compensation layer (320).

[0150] The piezoelectric element layer (310) may be positioned facing both sides of the all-solid-state cell (100). When charging and discharging the all-solid-state secondary battery, local surface irregularities (SE, see FIG. 5) may occur in the all-solid-state cell (100) due to a side reaction. This local surface irregularities (SE) locally increase the volume, generating irregular pressure. This irregular pressure may cause uneven pressure to be applied to the all-solid-state cell.

[0151] However, in this embodiment, the piezoelectric element layer (310) can generate a piezoelectric current (I) by utilizing this uneven pressure.

[0152] The piezoelectric element layer (310) may include an inelastic layer (311) and a plurality of piezoelectric elements (312).

[0153] The inelastic layer (311) may include an inelastic material that does not return to its original shape after deformation. Inelastic materials do not have a standard elastic modulus and do not follow Hooke's law, which is the basis for defining the elastic modulus (Young's modulus). The inelastic layer (311) may include an inelastic material such as inelastic rubber, inelastic clay, plastic, or ceramic.

[0154] The inelastic layer (311) can be in direct contact with both sides of the all-solid cell (100).

[0155] A plurality of piezoelectric elements (312) may be positioned within the inelastic layer (311). The piezoelectric elements may be surrounded by the inelastic layer (311).

[0156] When the piezoelectric element (312) is located inside the elastic layer, a piezoelectric current (I) is continuously generated in the piezoelectric element (312) due to the force of the elastic layer pulling the deformed piezoelectric element (312) to both sides. Therefore, resistance heat is continuously generated in the pressure compensation layer (320) connected to the piezoelectric element (312), which becomes a problem. However, as in the present embodiment, when the piezoelectric element (312) is located inside the inelastic layer (311), the inelastic layer (311) does not apply pressure to the deformed piezoelectric element (312), so unnecessary resistance heat can be prevented from being generated in the pressure compensation layer (320) connected to the piezoelectric element (312).

[0157] The pressure compensation layer (320) may be positioned on one surface of the piezoelectric element layer (310). That is, the pressure compensation layer (320) may be positioned on the piezoelectric element layer (310) positioned on the conductor cell (100) and may be positioned below the piezoelectric element layer (310) positioned below the conductor cell (100). The pressure compensation layer (320) may compensate for the uneven pressure by using the piezoelectric current (I) generated in the piezoelectric element layer (310).

[0158] The pressure compensation layer (320) may include a heat shrinkage layer (321) and a resistance element (322).

[0159] The heat shrink layer (321) is in contact with one surface of the piezoelectric element layer (310) and may include a heat shrink material. The heat shrink material is a material that has the property of shrinking due to heat.

[0160] The heat shrinkable layer (321) may include a heat shrinkable material such as polyolefin, fluoropolymer, BiNi1-xFexO3 (bismuth-nickel-iron oxide), or Bi0.95La0.05NiO3 (bismuth-lanthanum nickel oxide).

[0161] The resistance element (322) is located within the heat shrink layer (321) and is electrically connected to the piezoelectric element (312) so as to generate resistance heat by the piezoelectric current (I) generated in the piezoelectric element (312).

[0162] A portion of the heat shrinkable layer (321) may be contracted by this resistance heat to compensate for the uneven pressure.

[0163] Hereinafter, the principle of applying uniform pressure to the all-solid-state cell of the all-solid-state secondary battery according to the present embodiment will be described in detail with reference to the drawings.

[0164] FIGS. 5 to 7 are drawings sequentially explaining the principle of applying uniform pressure to an all-solid-state cell of an all-solid-state secondary battery according to one embodiment.

[0165] First, as illustrated in FIG. 5, when surface irregularities (SE) are locally generated in the all-solid-state cell (100), the volume locally increases due to the local surface irregularities (SE) caused by the local side reaction of the all-solid-state cell (100), thereby generating an irregular pressure in the adjacent piezoelectric element layer (310). Accordingly, the thickness of the inelastic layer (311) at the position corresponding to the surface irregularities (SE) decreases from t1 to t2, and the thickness of the piezoelectric element (312a) at the position corresponding to the surface irregularities (SE) also decreases from h1 to h2. Accordingly, the piezoelectric element (312a) contracts, thereby generating a piezoelectric current (I). In addition, the piezoelectric current (I) generates resistance heat in the resistance element (322a).

[0166] Next, as illustrated in FIG. 6, the thickness of the heat shrinkage layer (321) decreases from d1 to d2 due to the resistive heat generated in the resistance element (322). At this time, the thickness of the inelastic layer (311) increases as much as the thickness of the heat shrinkage layer (321) decreases, so that the boundary surface (TE) of the inelastic layer (311) and the heat shrinkage layer (321) can be convexly deformed into the same shape as the surface asperities (SE). Accordingly, the uneven pressure exerted on the piezoelectric element layer (310) at the position corresponding to the surface asperities (SE) decreases. Accordingly, the thickness of the piezoelectric element (312a) increases from h2 to h3. In addition, as the thickness of the piezoelectric element (312a) is restored, the amount of piezoelectric current (I) generated decreases, and the resistive heat generated in the resistance element (322a) also decreases, so that the shrinkage ratio of the heat shrinkage layer (321) also decreases.

[0167] Next, as illustrated in Fig. 7, as the thickness of the piezoelectric element (312a) is restored to its original thickness h1, the piezoelectric current (I) is not generated, and resistance heat is not generated in the resistance element (322a). In addition, as the thickness of the inelastic layer (311) at a position corresponding to the surface irregularities (SE) is also almost restored from t2 to t1, the irregularity pressure due to the surface irregularities (SE) is reduced.

[0168] In this way, in the present embodiment, by installing a uniform pressure applying member (300) including a piezoelectric element layer (310) and a pressure compensation layer (320), it is possible to finely control even the local pressure increase due to the surface unevenness (SE) of the all-solid-state cell (100), thereby applying uniform pressure to the all-solid-state cell (100). Accordingly, the performance of the all-solid-state secondary battery can be improved.

[0169] In addition, since uniform pressure can be applied to areas where it is difficult to apply uniform pressure, such as areas adjacent to electrode tabs of an all-solid-state secondary battery, the performance of the all-solid-state secondary battery can be improved.

[0170] In addition, since it is installed inside an all-solid-state secondary battery, it is possible to continuously apply uniform pressure to the all-solid-state cell within the life of the all-solid-state secondary battery, thereby improving the life of the all-solid-state secondary battery.

[0171] Meanwhile, the inelastic layer (311) may further include an insulating material. The insulating material may include glass, ceramic, plastic, urea foam, foam rubber insulation, rigid urethane, etc. Such an insulating material may be flame retardant at temperatures below 100 degrees Celsius and have a thermal conductivity of approximately 0.02 W / mk.

[0172] If the heat shrinkage layer (321) is unintentionally contracted due to heat generated in the all-solid-state cell and remains in a permanently contracted state, the overall pressure applied to the all-solid-state cell may be reduced, thereby reducing the performance of the all-solid-state secondary battery.

[0173] Accordingly, by positioning the piezoelectric element layer (310) between the heat shrinkage layer (321) and the all-solid-state cell (100), it is possible to prevent the heat shrinkage layer (321) from being unintentionally contracted due to heat generated in the all-solid-state cell (100).

[0174] In addition, since the non-elastic layer (311) in contact with the all-solid cell (100) further includes an insulating material, heat generated in the all-solid cell (100) is prevented from being transferred to the heat shrinkage layer (321), thereby preventing the heat shrinkage layer (321) from being unintentionally contracted due to heat generated in the all-solid cell (100).

[0175] 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. An all-solid-state cell comprising an anode, a cathode, and a solid electrolyte layer; A support plate supporting both sides of the above all-solid-state cell; and A uniform pressure applying member positioned between the above-mentioned all-solid-state cell and the above-mentioned support plate, which applies uniform pressure to the above-mentioned all-solid-state cell. Including, The above uniform pressure application absence A piezoelectric element layer facing both sides of the above-mentioned all-solid-state cell and generating a piezoelectric current by the uneven pressure due to the uneven surface of the above-mentioned all-solid-state cell, and A pressure compensation layer located on one side of the piezoelectric element layer and compensating for the uneven pressure using the piezoelectric current. An all-solid-state secondary battery comprising:

2. In paragraph 1, The above pressure compensation layer A heat shrinkable layer in contact with one surface of the piezoelectric element layer and including a heat shrinkable material, and A resistive element located within the heat shrinkage layer and electrically connected to the piezoelectric element to generate resistive heat by the piezoelectric current. Including, An all-solid-state secondary battery, wherein a portion of the heat shrinkable layer is contracted by the resistance heat to compensate for the uneven pressure.

3. In paragraph 2, An all-solid-state secondary battery, wherein the heat shrinkable layer comprises one heat shrinkable material selected from polyolefin, fluoropolymer, BiNi1-xFexO3 (bismuth-nickel-iron oxide), and Bi0.95La0.05NiO3 (bismuth-lanthanum nickel oxide).

4. In paragraph 2, An all-solid-state secondary battery, wherein the piezoelectric element layer is positioned between the heat shrinkable layer and the all-solid-state cell.

5. In paragraph 1, The above piezoelectric element layer An inelastic layer comprising an inelastic material, and A plurality of piezoelectric elements located within the above inelastic layer An all-solid-state secondary battery comprising:

6. In paragraph 5, An all-solid-state secondary battery, wherein the above-mentioned inelastic layer is in contact with both surfaces of the all-solid-state cell.

7. In paragraph 5, An all-solid-state secondary battery, wherein the above-mentioned inelastic layer surrounds the plurality of piezoelectric elements.

8. In paragraph 5, An all-solid-state secondary battery, wherein the inelastic layer comprises any one inelastic material selected from inelastic rubber, inelastic clay, plastic, and ceramic.

9. In paragraph 5, An all-solid-state secondary battery, wherein the above-mentioned inelastic layer further comprises one insulating material selected from glass, ceramic, plastic, urea foam, foam rubber insulation, and rigid urethane.

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