Lithium secondary battery module

Abstract

To provide a lithium secondary battery module excellent in heat insulation effect, heat propagation prevention effect, and heat radiation effect.SOLUTION: The present disclosure relates to a lithium secondary battery module including two or more cell structures and a polymer-metal composite film located between the cell structures, wherein the polymer-metal composite film includes a polymer film; and metal coating layers located on both surfaces of the polymer film, and the polymer-metal composite film is exposed longer than the cell structures in a height direction or a width direction of the cell structures.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a lithium secondary battery module. [Background technology]

[0002] In recent years, the rapid spread of battery-powered electronic devices such as mobile phones, laptops, and electric vehicles has led to a rapid increase in demand for high-energy-density, high-capacity secondary batteries, which has led to active research and development efforts to improve the performance of lithium secondary batteries.

[0003] A lithium secondary battery is a battery that contains a cathode and an anode, which contain active materials that allow lithium ions to be intercalated and deintercalated, and an electrolyte. Electrical energy is produced through oxidation and reduction reactions that occur when lithium ions are intercalated and deintercalated at the cathode and anode.

[0004] The lithium secondary battery can be recharged and used continuously after discharge. However, since the performance of the lithium secondary battery varies depending on the charge / discharge state, efforts are being made to improve the performance of the lithium secondary battery by improving the charging method. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-117874 Summary of the Invention [Problem to be solved by the invention]

[0006] An embodiment provides a lithium secondary battery module with excellent heat insulation, heat propagation prevention, and heat dissipation effects. [Means for solving the problem]

[0007] One embodiment provides a lithium secondary battery module including two or more cell structures and a polymer-metal composite film positioned between the cell structures, wherein the polymer-metal composite film includes a polymer film; and metal coating layers positioned on both sides of the polymer film, and the polymer-metal composite film is exposed to a longer extent than the cell structures in the height or width direction of the cell structures.

[0008] The lithium secondary battery module according to an embodiment has advantages such as excellent heat insulation, heat propagation prevention, and heat dissipation. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view schematically illustrating a lithium secondary battery module according to an embodiment. [Figure 2] 1 is a cross-sectional view schematically illustrating a polymer-metal composite film according to one embodiment. [Figure 3] FIG. 1 is a schematic diagram illustrating a cell structure according to one embodiment. [Figure 4] FIG. 1 is a schematic diagram illustrating a cell structure according to one embodiment. [Figure 5] FIG. 1 is a schematic diagram illustrating a cell structure according to one embodiment. [Figure 6] FIG. 1 is a schematic diagram illustrating a cell structure according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the present invention is provided by way of example only and is not intended to limit the scope of the present invention, which is defined solely by the scope of the claims that follow.

[0011] The terms used herein are merely used to describe exemplary embodiments and are not intended to limit the present invention. The singular forms include the plural forms unless the context clearly indicates otherwise.

[0012] As used herein, "combinations thereof" refers to mixtures, laminates, composites, copolymers, alloys, blends, reaction products, and the like of compositions.

[0013] It should be understood that the terms "comprise," "comprise," or "have" are intended to specify the presence of embodied features, numbers, steps, components, or combinations thereof, but do not preclude the possible presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0014] In order to clearly show multiple layers and regions in the drawings, thicknesses have been exaggerated, and similar parts have been given the same reference numerals throughout the specification. When a layer, film, region, plate, or other part is referred to as being "on" or "above" another part, this includes not only being "directly on" that other part, but also the case where there is another part between them. Conversely, when a part is referred to as being "directly on" another part, it means that there is no other part in between. Furthermore, the term "layer" as used herein 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.

[0015] In this specification, unless otherwise specified, singular terms can also include plural terms. Also, unless otherwise specified, "A or B" can mean "including A, including B, or including A and B."

[0016] The term "metal" is understood to include general metals, transition metals, and semimetals (metalloids).

[0017] Unless otherwise defined in this specification, the particle size may be the average particle size. In addition, the particle size is the average particle size (D ) which means the diameter of particles with a cumulative volume of 50% in the particle size distribution. 50 ) can mean the average particle size (D 50The particle size can be measured by a method well known to those skilled in the art, for example, by using a particle size analyzer, or by using a transmission electron microscope or a scanning electron microscope. Another method is to use a measuring device that uses dynamic light-scattering, and then analyze the data to count the number of particles in each particle size range, and then calculate the average particle size (D 50 ) value can be obtained. Alternatively, it can be measured using the laser diffraction method. More specifically, when measuring by the laser diffraction method, particles to be measured are dispersed in a dispersion medium, and then introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT3000), and ultrasonic waves of about 28 kHz are irradiated at an output of 60 W, and the average particle size (D) at 50% of the particle size distribution in the measuring device is measured. 50 ) can be calculated.

[0018] FIG. 1 is a cross-sectional view schematically illustrating a lithium secondary battery module according to an embodiment, and FIG. 2 is a cross-sectional view schematically illustrating a polymer-metal composite film according to an embodiment.

[0019] In one embodiment, the height direction and width direction shown in Figures 1 and 2 are directions extending parallel to the surface (main surface) of the sheet-like component, and the height direction and width direction may be directions approximately perpendicular to each other.

[0020] In one embodiment, the length direction can be used in the same concept as the lamination direction in which the cell structure and the polymer-metal composite film are laminated, and the length direction may be a direction perpendicular to the surface (main surface) of the sheet-like component. In one embodiment, the length direction may be a direction approximately perpendicular to each of the height direction and the width direction.

[0021] The lithium secondary battery module will be described below with reference to FIGS.

[0022] A lithium secondary battery module according to one embodiment includes two or more cell structures and a polymer-metal composite film positioned between the cell structures, the polymer-metal composite film including a polymer film and metal coating layers positioned on both sides of the polymer film, and the polymer-metal composite film is exposed longer than the cell structures in a height or width direction of the cell structures.

[0023] In the past, polymer sheets were used between cell structures, but because these polymer sheets did not have a heat insulating function, they had the problem of being unable to effectively dissipate heat generated from the cell structures during battery charge and discharge.Furthermore, when a highly conductive sheet was used between cell structures, although it was possible to dissipate heat generated from the cell structures during battery charge and discharge, it was unable to prevent heat propagation to adjacent cell structures.

[0024] According to an embodiment, the lithium secondary battery module includes a polymer-metal composite film between cell structures that is exposed longer than the cell structures in the height or width direction. This provides excellent thermal insulation, heat propagation prevention, and heat dissipation effects to prevent the transfer of heat generated during battery operation, while also providing excellent elasticity.

[0025] The polymer-metal composite film can serve as an elastic sheet that maintains the separation between cell structures during charging and discharging of the lithium secondary battery and maintains the fastening pressure of the lithium secondary battery module structure.

[0026] In one embodiment, the thickness of the polymer-metal composite film may be 4 μm to 20 μm, for example, 5 μm to 20 μm, 5 μm to 15 μm, or 5 μm to 12 μm.

[0027] In one embodiment, the tensile strength (MD; Machine Direction) of the polymer-metal composite film is 200 N / mm 2 ~500N / mm 2 For example, 250 N / mm 2 ~500N / mm 2 , or 400N / mm 2 m~500N / mm 2 In one embodiment, the stretching ratio of the polymer-metal composite film may be 10% to 60%, for example, 20% to 60%, or 40% to 60%. In one embodiment, the tensile strength (MD) and stretching ratio of the polymer-metal composite film may be measured using an ASTM D882 testing machine or an ISO 527-3 testing machine.

[0028] In one embodiment, the polymer-metal composite film includes a polymer film; and metal coating layers located on both sides of the polymer film, and the polymer-metal composite film is exposed longer than the cell structure in the height or width direction of the cell structure.

[0029] In one embodiment, the length in the height direction or the length in the width direction of the polymer-metal composite film may be more than 100% and not more than 103% of the cell structure.

[0030] In one embodiment, the length in the height direction and the length in the width direction of the polymer-metal composite film may be more than 100% and not more than 103% of the cell structure.

[0031] In a specific embodiment, the height or width of the polymer-metal composite film may be 100.1% to 103%, 100.5% to 103%, 101% to 103%, 101.5% to 103%, or 101% to 102% of the cell structure.

[0032] When the numerical range is satisfied, a lithium secondary battery module having excellent heat insulation effect, heat propagation prevention effect, and heat dissipation effect can be realized.

[0033] If the height or width of the polymer-metal composite film is 100% or less of the cell structure, the insulating effect between the cell structures, the effect of preventing heat propagation, and the effect of heat dissipation may be insignificant, and if it exceeds 103%, it may be difficult to maintain the fastening pressure of the lithium secondary battery module structure.

[0034] polymer film The polymer film has low thermal conductivity and therefore can act as a heat insulator, preventing the transfer of heat generated from one cell structure to adjacent cell structures during battery charging and discharging. It can also prevent heat transfer to adjacent cell structures when the battery is in an abnormal state.

[0035] Furthermore, since the polymer film has excellent elasticity, it can function as an elastic sheet that maintains the separation between the cell structures even when the cell structures expand or contract during charging and discharging of the battery.

[0036] In one embodiment, the polymeric film may include polyethylene, polypropylene, polyamide, polyimide, polyethylene terephthalate, polyethylene naphthalate, polyacrylonitrile, poly(meth)acrylate, polymethyl(meth)acrylate, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl chloride, polyurethane, epoxy resin, nylon resin, acrylic resin, polystyrene, polyethylene oxide, polyvinyl alcohol, silicone resin, styrene-butadiene-rubber, acrylonitrile-butadiene-rubber, hydrogenated nitrile-butadiene-rubber, copolymers thereof, or mixtures thereof.

[0037] In one embodiment, the thickness of the polymer film may be 2 μm to 10 μm, for example, 4 μm to 10 μm, 2 μm to 8 μm, or 4 μm to 8 μm.

[0038] Metal coating layer The metal coating layer has high thermal conductivity and therefore can perform a heat dissipation function to release heat generated from the cell structure during charging and discharging of the battery.

[0039] In one embodiment, the metal coating layer may include Al, Cu, Fe, Ni, SUS (stainless steel), Ti, or a combination thereof.

[0040] In one embodiment, the thickness of the metal coating layer may be 0.5 μm to 5 μm, for example, 0.5 μm to 4 μm, 1 μm to 5 μm, or 1 μm to 4 μm.

[0041] In one embodiment, the ratio of the thickness of the polymer film to the thickness of the metal coating layer may be 1:1 to 10:1, for example, 2:1 to 10:1, 2.5:1 to 10:1, or 5:1 to 10:1.

[0042] When the thickness of the polymer film, the thickness of the metal coating layer, and the ratio of the thickness of the polymer film to the thickness of the metal coating layer satisfy the ranges, a lithium secondary battery module having excellent heat insulation effect between cell structures, heat propagation prevention effect, and heat dissipation effect can be realized.

[0043] Cell Structure The cell structure may hereinafter be referred to as a lithium secondary battery.

[0044] Depending on the shape, cell structures (lithium secondary batteries) can be classified into cylindrical, prismatic, pouch, coin, etc. Figures 3 to 6 are schematic diagrams showing cell structures according to an embodiment, with Figure 3 showing a cylindrical cell structure, Figure 4 showing a prismatic cell structure, and Figures 5 and 6 showing a pouch cell structure.

[0045] 3 to 6, the lithium secondary battery 100 may include an electrode assembly 40 having a separator 30 interposed between a positive electrode 10 and a negative electrode 20, and a case 50 containing the electrode assembly 40. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte (not shown). The lithium secondary battery 100 may include a sealing member 60 that seals the case 50, as shown in FIG.

[0046] In addition, in FIG. 4, the lithium secondary battery 100 can include a positive electrode lead tab 11 and a positive electrode terminal 12 , and a negative electrode lead tab 21 and a negative electrode terminal 22 .

[0047] As shown in FIGS. 5 and 6, the lithium secondary battery 100 may include electrode tabs 70, i.e., a positive electrode tab 71 and a negative electrode tab 72, which serve as electrical paths for conducting the current generated in the electrode assembly 40 to the outside.

[0048] In one embodiment, the cell structure 100 is a lithium secondary battery and may include a positive electrode 10 including a positive electrode active material, a negative electrode 20 including a negative electrode active material, a separator 30 positioned between the positive electrode and the negative electrode, and an electrolyte (not shown in the drawing).

[0049] In another embodiment, the cell structure is an all-solid-state secondary battery (not shown in the drawing), and the all-solid-state secondary battery may include a positive electrode, a negative electrode, and a solid electrolyte layer located between the positive electrode and the negative electrode.

[0050] The cell structure may be formed by stacking two or more unit cells each including a positive electrode, a negative electrode, and a separator, or two or more unit cells each including a positive electrode, a negative electrode, and a solid electrolyte layer, for example, 2 to 100, 3 to 50, or 4 to 20, of the unit cells.

[0051] positive electrode active material The positive electrode active material may be a compound capable of reversibly inserting and extracting lithium (lithiated insertion compound). Specifically, one or more of composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof may be used.

[0052] The composite oxide may be a lithium transition metal composite oxide, and specific examples thereof include lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate compound, cobalt-free lithium nickel-manganese oxide, or a combination thereof.

[0053] In one embodiment, a compound represented by any of the following formulas can be used: 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);Li a Mn 2-b X b O 4-c D c (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.05);Li a Ni 1-b-c Co b X c O 2-α D α (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.5, 0<α<2);Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≦a≦1.8, 0≦b≦0.5, 0≦c≦0.5, 0<α<2);Li a Ni b Co c L 1 d G e O2(0.90≦a≦1.8, 0≦b≦0.9, 0≦c≦0.5, 0≦d≦0.5, 0≦e≦0.1);Li a NiG bO2(0.90≦a≦1.8, 0.001≦b≦0.1);Li a CoG b O2(0.90≦a≦1.8, 0.001≦b≦0.1);Li a Mn 1-b G b O2(0.90≦a≦1.8, 0.001b≦0.1);Li a Mn2G b O4(0.90≦a≦1.8, 0.001≦b≦0.1);Li a Mn 1-g G g PO4(0.90≦a≦1.8, 0≦g≦0.5);Li (3-f) Fe2(PO4)3(0≦f≦2);Li a FePO4(0.90≦a≦1.8).

[0054] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; X is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; and L1 is Mn, Al, or a combination thereof.

[0055] In one embodiment, the positive electrode active material may be a high-nickel positive electrode active material in which the nickel content is 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more but 99 mol% or less relative to 100 mol% of metals excluding lithium from the lithium transition metal composite oxide. The high-nickel positive electrode active material can achieve high capacity and can be used in high-capacity, high-density lithium secondary batteries.

[0056] positive electrode A positive electrode for a lithium secondary battery can include a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer includes a positive electrode active material and can further include a binder and / or a conductive agent.

[0057] In one embodiment, the positive electrode may further include an additive that acts as a sacrificial positive electrode.

[0058] The content of the positive electrode active material may be 90% by weight to 99.5% by weight relative to 100% by weight of the positive electrode active material layer, and the contents of the binder and conductive agent may each be 0.5% by weight to 5% by weight relative to 100% by weight of the positive electrode active material layer.

[0059] The binder serves to firmly adhere the positive electrode active material particles to each other and to firmly adhere the positive electrode active material to the current collector. Representative examples of the binder 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, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylic resin, polyester resin, nylon, etc.

[0060] The conductive agent is used to impart conductivity to the electrode, and any material that does not undergo chemical changes and is electronically conductive in the battery that is constructed can be used. Examples of the conductive agent include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials containing copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fiber; conductive polymers such as polyphenylene derivatives; and mixtures thereof.

[0061] The current collector may be made of Al, but is not limited to this.

[0062] negative electrode active material The negative electrode active material includes a material capable of reversibly inserting / desorbing lithium ions, lithium metal, an alloy of lithium metal, a material capable of doping and undoping with lithium, or a transition metal oxide.

[0063] Examples of the material capable of reversibly inserting / desorbing lithium ions include carbon-based negative electrode active materials, which can include, for example, crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon can include graphite such as amorphous, plate-like, flaky, spherical, or fibrous natural graphite or artificial graphite, and examples of amorphous carbon can include soft carbon or hard carbon, mesophase pitch carbide, fired coke, and the like.

[0064] As the alloy of lithium metal, an alloy of lithium and a metal 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.

[0065] As the material capable of doping and undoping with lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material can be used. The Si-based negative electrode active material can be silicon, a silicon-carbon composite, SiOx (0 < x ≤ 2), a Si-Q alloy (Q is selected from alkali metals, alkaline earth metals, group 13 elements, group 14 elements (excluding Si), group 15 elements, group 16 elements, transition metals, rare earth elements, and combinations thereof), or a combination thereof. The Sn-based negative electrode active material can be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0066] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to one embodiment, the silicon-carbon composite may be in the form of silicon particles and the surfaces of the silicon particles coated with amorphous carbon. For example, it may include secondary particles (cores) formed by assembling primary silicon particles and an amorphous carbon coating layer (shell) located on the surfaces of the secondary particles. The amorphous carbon may also be located between the primary silicon particles, for example, the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0067] The silicon-carbon composite may further comprise crystalline carbon. For example, the silicon-carbon composite may comprise a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer disposed on the core.

[0068] The Si-based negative electrode active material or the Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material.

[0069] negative electrode The negative electrode for a lithium secondary battery includes a current collector and a negative electrode active material layer located on the current collector. The negative electrode active material layer includes a negative electrode active material and may further include a binder and / or a conductive agent.

[0070] For example, the negative electrode active material layer can contain 90% to 99% by weight of the negative electrode active material, 0.5% to 5% by weight of the binder, and 0% to 5% by weight of the conductive agent.

[0071] The binder serves to firmly adhere the negative electrode active material particles to each other and to the current collector. The binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0072] Non-aqueous binders may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyimide, or combinations thereof.

[0073] The aqueous binder is selected from styrene-butadiene rubber, (meth)acrylate styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polychlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenol resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0074] When an aqueous binder is used as the negative electrode binder, a cellulose-based compound that can impart viscosity can be further included. The cellulose-based compound can be a mixture of one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, or alkali metal salts thereof. The alkali metal can be sodium, potassium, or lithium.

[0075] The dry binder is a polymeric material that can be fiberized, and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0076] The conductive material is used to impart conductivity to the electrodes, and any material that does not undergo chemical change and is electronically conductive in the battery that is constructed can be used. Specific examples include carbon-based materials such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube; metal-based materials in the form of metal powder or metal fiber, including copper, nickel, aluminum, and silver; conductive polymers such as polyphenylene derivatives; and mixtures thereof.

[0077] 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 combinations thereof.

[0078] In another embodiment, when the cell stack is an all-solid-state secondary battery, the anode for the all-solid-state secondary battery may be a deposition-type anode. A deposition-type anode may refer to an anode that does not include a negative electrode active material when the battery is assembled, but in which lithium metal or the like is deposited or electrodeposited onto the anode during battery charging, and this serves as the negative electrode active material.

[0079] electrolyte The electrolyte for the lithium secondary battery contains a non-aqueous organic solvent and a lithium salt.

[0080] The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reactions of the battery can migrate.

[0081] The non-aqueous organic solvent may be a carbonate, ester, ether, ketone, or alcohol solvent, an aprotic solvent, or a combination thereof.

[0082] Examples of carbonate solvents that can be used include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC). Examples of ester solvents that can be used include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl acetate propionate, decanolide, mevalonolactone, valerolactone, and caprolactone. Examples of ether solvents that can be used include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, and tetrahydrofuran. Examples of ketone solvents that can be used include cyclohexanone. Examples of alcoholic solvents that can be used include ethyl alcohol and isopropyl alcohol, and examples of aprotic solvents that can be used include nitriles such as R-CN (R is a hydrocarbon group having 2 to 20 carbon atoms and having a linear, branched, or cyclic structure, which may contain a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane and 1,4-dioxolane; and sulfolanes.

[0083] The non-aqueous organic solvents can be used alone or in combination of two or more.

[0084] When a carbonate-based solvent is used, a cyclic carbonate and a chain carbonate can be mixed and used, and the cyclic carbonate and the chain carbonate can be mixed in a volume ratio of 1:1 to 1:9.

[0085] Lithium salts are substances that dissolve in organic solvents and act as a source of lithium ions within the battery, enabling basic lithium secondary battery operation and facilitating the movement of lithium ions between the positive and negative electrodes. Representative examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI), LiC4F9SO3, and LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (x and y are integers of 1m to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFOB), and lithium bis(oxalato)borate (LiBOB).

[0086] Separator Depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. Examples of such separators include polyethylene, polypropylene, polyvinylidene fluoride, and multilayer films of two or more of these. Of course, mixed multilayer films such as polyethylene / polypropylene two-layer separators, polyethylene / polypropylene / polyethylene three-layer separators, and polypropylene / polyethylene / polypropylene three-layer separators can also be used.

[0087] The separator can include a porous substrate and a coating layer comprising an organic material, an inorganic material, or a combination thereof located on one or both sides of the porous substrate.

[0088] The porous substrate may be a polymer film formed from any polymer selected from polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyacetal, polyamide, polyimide, polycarbonate, polyether ketone, polyaryl ether ketone, polyetherimide, polyamide imide, polybenzimidazole, polyethersulfone, polyphenylene oxide, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fiber, Teflon (registered trademark), and polytetrafluoroethylene, or a copolymer or mixture of two or more of these.

[0089] The organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0090] The inorganic material may include, but is not limited to, inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0091] The organic material and the inorganic material may be mixed in one coating layer, or a coating layer containing an organic material and a coating layer containing an inorganic material may be stacked.

[0092] solid electrolyte layer In the all-solid-state secondary battery according to an embodiment, the solid electrolyte layer may include an inorganic solid electrolyte such as a sulfide-based solid electrolyte or an oxide-based solid electrolyte.

[0093] In one embodiment, the solid electrolyte layer may include a sulfide-based solid electrolyte having excellent ionic conductivity. Examples of sulfide-based solid electrolyte particles include Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element, such as I or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, and Li2S-P2S5-Z. m S n (m and n are integers, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (wherein p and q are integers and M is P, Si, Ge, B, Al, Ga, or In), or a combination thereof.

[0094] In one embodiment, such a sulfide-based solid electrolyte can be obtained by mixing Li2S and P2S5 in a molar ratio of 50:50 to 90:10 or a molar ratio of 50:50 to 80:20, followed by selective heat treatment. Within this mixing ratio range, a sulfide-based solid electrolyte with excellent ionic conductivity can be produced. Other components, such as SiS2, GeS2, and B2S3, can also be added to further improve ionic conductivity.

[0095] Mechanical milling and solution milling can be used to mix sulfur-containing raw materials to produce a sulfide-based solid electrolyte. Mechanical milling involves placing the starting materials in a ball mill reactor and vigorously stirring them to finely mix them. When using the solution milling method, the starting materials are mixed in a solvent, and a solid electrolyte can be obtained as a precipitate. Furthermore, when heat treatment is performed after mixing, the crystals of the solid electrolyte become stronger, and ionic conductivity can be improved. In one embodiment, the sulfide-based solid electrolyte can be produced by mixing the sulfur-containing raw materials and heat treating them two or more times. In this case, a robust sulfide-based solid electrolyte with high ionic conductivity can be produced.

[0096] According to one embodiment, a sulfide-based solid electrolyte can be manufactured by a first heat treatment process in which sulfur-containing raw materials are mixed and fired at 120°C to 350°C, and a second heat treatment process in which the result of the first heat treatment is mixed and fired at 350°C to 800°C. The first and second heat treatment processes can be performed in an inert gas or nitrogen atmosphere, respectively. The first heat treatment process can be performed for 1 to 10 hours, and the second heat treatment process can be performed for 5 to 20 hours. The first heat treatment process can achieve the effect of milling small raw materials, and the second heat treatment process can synthesize the final solid electrolyte. By performing two or more heat treatments, a high-performance sulfide-based solid electrolyte with high ionic conductivity and robustness can be obtained, and such a solid electrolyte can be suitable for mass production. The temperature in the first heat treatment step can be, for example, 150°C to 330°C, or 200°C to 300°C, and the temperature in the second heat treatment step can be, for example, 380°C to 700°C, or 400°C to 600°C.

[0097] In one embodiment, the sulfide-based solid electrolyte can include an argyrodite-type sulfide. The argyrodite-type sulfide can be, for example, Li a M b P c S d A e(wherein a, b, c, d, and e are all 0 to 12, M is Ge, Sn, Si, or a combination thereof, and A is F, Cl, Br, or I). A specific example is Li 7-x PS 6-x A x (where x is 0.2 or more and 1.8 or less, and A is F, Cl, Br, or I). Argyrodite-type sulfides are 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 Examples include:

[0098] Sulfide-based solid electrolytes containing argyrodite-type sulfides have ionic conductivity of 10 -4 S / cm~10 -2 It has high ionic conductivity close to the S / cm range, does not induce a decrease in ionic conductivity, and can form a tight bond between the positive electrode active material and the solid electrolyte, and can also form a tight interface between the electrode layer and the solid electrolyte layer. All-solid-state secondary batteries containing this material can improve battery performance such as efficiency, coulombic efficiency, and life characteristics.

[0099] The argyrodite-type sulfide-based solid electrolyte can be prepared by mixing, for example, lithium sulfide and phosphorus sulfide, and optionally, lithium halide. After mixing, the mixture can be heat-treated. The heat-treatment process can include, for example, two or more heat-treatment steps. Here, in one embodiment, preparing the argyrodite-type sulfide-based solid electrolyte can include a first heat-treatment process in which raw materials are mixed and fired at 120°C to 350°C, and a second heat-treatment process in which the result of the first heat-treatment is mixed again and fired at 350°C to 800°C.

[0100] The solid electrolyte layer may also contain an oxide-based inorganic solid electrolyte. The oxide-based inorganic solid electrolyte may be, for example, Li1+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 - GeO2 - based ceramics, Garnet - based ceramics Li 3+x La3M2O 12 (M = Te, Nb, or Zr; x is an integer from 1m to 10), or mixtures thereof can be included.

[0101] Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are one example of the present invention, and the present invention is not limited to the following examples.

[0102] (Example) Example 1 A polymer-metal composite film was prepared by depositing aluminum on both sides of a polyethylene terephthalate polymer film with a thickness of approximately 5 μm, and then forming an aluminum metal coating layer with a thickness of approximately 2 μm on both sides. The polymer-metal composite film had a height of 63 mm.

[0103] Thereafter, a cell structure having a height of 62 mm was prepared, where the height of the polymer-metal composite film was 101.6% of the height of the cell structure.

[0104] As in FIG. 1, a polymer-metal composite film was interposed between four cell structures to produce a lithium secondary battery module according to Example 1.

[0105] Comparative Example 1 A lithium secondary battery module according to Comparative Example 1 was manufactured in the same manner as in Example 1, except that the height of the polymer-metal composite film and the height of the cell structure were the same, 62 mm. At this time, the height of the polymer-metal composite film was 100% of the height of the cell structure.

[0106] Comparative Example 2 A lithium secondary battery module according to Comparative Example 1 was manufactured in the same manner as in Example 1, except that the height of the polymer-metal composite film was 59 mm and the height of the cell structure was 62 mm. At this time, the height of the polymer-metal composite film was 95.2% of the height of the cell structure.

[0107] (Evaluation example) Evaluation example 1: Insulation evaluation The lithium secondary battery modules manufactured in Example 1, Comparative Example 1, and Comparative Example 2 were subjected to heat propagation evaluation (Propagation).

[0108] Each lithium secondary battery module is prepared by fastening three cell structures adjacent to each other in series, with two polymer-metal composite films positioned between each cell structure, and is placed in the chamber.

[0109] Then, heating pads were placed between the second cell structure located in the center of the lithium secondary battery module and the polymer-metal composite films located on both sides of the second cell structure, with the heating pads positioned between the first and second cell structures and between the second and third cell structures.

[0110] Thereafter, the temperature of the heating pad was increased at a rate of 6°C / min, and the time it took for the temperature of the adjacent first and third cell structures to reach 100°C was measured and shown in Table 1 below. The occurrence of thermal runaway in the lithium secondary battery module during the temperature increase process was also shown.

[0111] Evaluation example 2: Heat dissipation evaluation As in Evaluation Example 1, a lithium secondary battery module including a heating pad was prepared.

[0112] Then, the second cell was heated at 40°C for 10 minutes using a heating pad, and the time it took for the temperature of the second cell to return to room temperature (25°C) was measured.

[0113] If the measured time was 1 hour or less, it was marked with "◎", if it was more than 1 hour but less than 4 hours, it was marked with "○", and if it was 4 hours or more, it was marked with "△", as shown in Table 1 below.

[0114] [Table 1]

[0115] Referring to Table 1, it took 20 minutes for the temperature of the first and third cell structures adjacent to the second cell structure to reach 100°C in Example 1, while it took 10 minutes in Comparative Example 1, demonstrating the excellent heat insulating effect of Example 1. Furthermore, it was confirmed that in Comparative Example 2, where the cell structure was longer in height than the polymer-metal composite film, thermal runaway occurred, resulting in poor safety.

[0116] Furthermore, as a result of the heat dissipation evaluation, it can be confirmed that Example 1 has a much better heat dissipation effect than Comparative Examples 1 and 2.

[0117] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made within the scope of the claims, the detailed description of the invention, and the accompanying drawings, and it is natural that these also fall within the scope of the present invention. [Explanation of symbols]

[0118] 100 Lithium secondary battery 10 positive electrode 11 Positive electrode lead tab 12 Positive terminal 20 negative electrode 21 Negative electrode lead tab 22 Negative terminal 30 Separator 40 Electrode Assembly 50 cases 60 Sealing member 70 Electrode tab 71 Positive electrode tab 72 Negative electrode tab

Claims

1. A lithium secondary battery module including two or more cell structures and a polymer-metal composite film located between the cell structures, The polymer-metal composite film includes a polymer film; and a metal coating layer located on both sides of the polymer film. The polymer-metal composite film is exposed to a length longer than the cell structure in the height direction or width direction of the cell structure.

2. 2. The lithium secondary battery module according to claim 1, wherein the polymer-metal composite film has a height or width that is greater than 100% and less than or equal to 103% of the length of the cell structure.

3. 2. The lithium secondary battery module according to claim 1, wherein the polymer-metal composite film has a thickness of 4 μm to 20 μm.

4. The tensile strength (MD; Machine Direction) of the polymer-metal composite film is 200 N / mm 2 ~500N / mm 2 The lithium secondary battery module according to claim 1 ,

5. 2. The lithium secondary battery module according to claim 1, wherein the polymer-metal composite film has an elongation ratio of 10% to 60%.

6. 2. The lithium secondary battery module of claim 1, wherein the polymer film comprises polyethylene, polypropylene, polyamide, polyimide, polyethylene terephthalate, polyethylene naphthalate, polyacrylonitrile, poly(meth)acrylate, polymethyl(meth)acrylate, polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl chloride, polyurethane, epoxy resin, nylon resin, acrylic resin, polystyrene, polyethylene oxide, polyvinyl alcohol, silicone resin, styrene-butadiene-rubber, acrylonitrile-butadiene-rubber, hydrogenated nitrile-butadiene-rubber, a copolymer thereof, or a mixture thereof.

7. The lithium secondary battery module according to claim 1 , wherein the metal coating layer comprises Al, Cu, Fe, Ni, SUS, Ti, or a combination thereof.

8. The lithium secondary battery module according to claim 1, wherein the polymer film has a thickness of 2 μm to 10 μm.

9. 2. The lithium secondary battery module according to claim 1, wherein the metal coating layer has a thickness of 0.5 μm to 5 μm.

10. 2. The lithium secondary battery module of claim 1, wherein a ratio of the thickness of the polymer film to the thickness of the metal coating layer is 1:1 to 10:

1.

11. 2. The lithium secondary battery module according to claim 1, wherein the cell structure includes a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, a separator positioned between the positive electrode and the negative electrode, and an electrolyte.

12. 2. The lithium secondary battery module according to claim 1, wherein the cell structure includes a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and a solid electrolyte layer located between the positive electrode and the negative electrode.

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