Composite Substrate for Lithium Secondary Battery, Electrode Including the Same, and Lithium Secondary Battery Including the Same

Abstract

The present invention relates to a composite substrate for a lithium secondary battery; and an electrode and a lithium secondary battery including the same. More specifically, the composite substrate of the present invention comprises a first metal layer; a second metal layer; and a composite layer disposed between the first metal layer and the second metal layer. The composite layer comprises a coil configured to receive an alternating magnetic field and generate an induced current, and the first metal layer, the second metal layer, and the coil are electrically connected to each other.

Description

Technology Field

[0001] The present invention relates to a wirelessly rechargeable electrode and a lithium secondary battery including the same. Background Technology

[0003] Recently, driven by industrial demands, the development of batteries with high energy density and safety is actively underway. For example, lithium-ion batteries are being commercialized not only in the fields of information and communication devices but also in the automotive sector. In the automotive sector, safety is considered particularly important because it is directly related to human life.

[0004] Recently, all-solid-state batteries have been proposed in which the liquid electrolyte of lithium-ion batteries is replaced with a solid electrolyte. By not using flammable organic dispersion media, all-solid-state batteries can significantly reduce the likelihood of fire or explosion in the event of a short circuit. Therefore, such all-solid-state batteries can possess excellent safety. The problem to be solved

[0006] The problem that the present invention aims to solve is to provide a composite substrate for a lithium secondary battery capable of wireless charging.

[0007] Another problem that the present invention aims to solve is to provide an electrode for a lithium secondary battery capable of wireless charging.

[0008] Another problem that the present invention aims to solve is to provide a lithium secondary battery with excellent charging characteristics. means of solving the problem

[0010] A composite substrate for a lithium secondary battery according to the concept of the present invention may include a first metal layer; a second metal layer; and a composite layer disposed between the first metal layer and the second metal layer. The composite layer may include a coil configured to receive an alternating magnetic field and generate an induced current. The first metal layer, the second metal layer, and the coil may be electrically connected to each other.

[0011] An electrode for a lithium secondary battery according to another concept of the present invention may comprise a composite substrate; and an electrode layer on the composite substrate. The composite substrate may comprise a first metal layer, a second metal layer, and a composite layer disposed between the first metal layer and the second metal layer. The composite layer may comprise a coil configured to receive an alternating magnetic field and generate an induced current. The first metal layer, the second metal layer, and the coil may be electrically connected to each other.

[0012] A lithium secondary battery according to another concept of the present invention comprises a first bipolar electrode, wherein the first bipolar electrode may comprise a composite substrate, an anode layer on one side of the composite substrate, and a cathode layer on the other side of the composite substrate. The composite substrate may comprise a first metal layer, a second metal layer, and a composite layer disposed between the first metal layer and the second metal layer. The composite layer may comprise a receiving coil for wireless charging. Effects of the invention

[0014] A composite substrate according to one embodiment of the present invention can improve the wireless charging efficiency of a lithium secondary battery by including a receiving coil inside. Generally, a bipolar stack cell formed by series connection has reduced charging efficiency due to current dispersion, but a lithium secondary battery according to the embodiments of the present invention can improve charging efficiency by including the composite substrate. In addition, space efficiency can be improved compared to using a wireless charging device that applies a coil by adding it externally. Brief explanation of the drawing

[0016] FIG. 1 is a conceptual diagram briefly illustrating a lithium secondary battery according to embodiments of the present invention. FIG. 2 is a cross-sectional view of an electrode for a lithium secondary battery according to one embodiment of the present invention. FIG. 3 is an exploded perspective view of a composite substrate according to one embodiment. FIG. 4 is a cross-sectional view of a composite substrate according to one embodiment. FIG. 5 is a cross-sectional view of a lithium secondary battery according to one embodiment of the present invention. FIG. 6 is a cross-sectional view of a lithium secondary battery according to one embodiment of the present invention. FIG. 7 is a cross-sectional view of an electrode (bipolar electrode) for a lithium secondary battery according to one embodiment. FIG. 8 is a cross-sectional view of a lithium secondary battery according to one embodiment. FIGS. 9 to 11 are cross-sectional views for explaining a method of manufacturing a composite substrate according to one embodiment. Specific details for implementing the invention

[0017] In order to fully understand the structure and effects of the present invention, preferred embodiments of the present invention are described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and various modifications can be made. The description of these embodiments is provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention.

[0018] In order to fully understand the structure and effects of the present invention, preferred embodiments of the present invention are described with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and various modifications can be made. The description of these embodiments is provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention.

[0019] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Additionally, in the drawings, the thicknesses of the components are exaggerated for the effective description of the technical content. Throughout the specification, parts indicated by the same reference numeral represent the same components.

[0020] The embodiments described herein will be described with reference to cross-sectional and / or plan views, which are exemplary illustrations of the invention. In the drawings, the thicknesses of films and regions are exaggerated for effective description of the technical content. Accordingly, the regions illustrated in the drawings are schematic in nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific forms of regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, third, etc., have been used to describe various components in the various embodiments of this specification, these components should not be limited by such terms. These terms are used merely to distinguish one component from another. The embodiments described and illustrated herein also include their complementary embodiments.

[0021] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, 'comprises' and / or 'comprising' do not exclude the presence or addition of one or more other components to the mentioned components.

[0022] In this specification, each of the phrases such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0024] FIG. 1 is a cross-sectional view of an all-solid-state battery (10) according to one embodiment of the present invention.

[0025] Referring to FIG. 1, an all-solid-state battery (10) according to one embodiment includes a positive electrode layer (100), a negative electrode layer (200) facing the positive electrode layer (100), and a solid electrolyte layer (300) disposed between the positive electrode layer (100) and the negative electrode layer (200). However, the all-solid-state battery (10) may further include an additional functional layer, such as an adhesion-enhancing layer, disposed between the positive electrode layer (100) and the solid electrolyte layer (300) or between the negative electrode layer (200) and the solid electrolyte layer (300).

[0026] An anode layer (100) of one embodiment includes an anode current collector (110) and an anode active material layer (120) disposed on the anode current collector (110). The anode active material layer (120) may include an anode active material, a solid electrolyte, a conductive material, and a binder.

[0027] The positive current collector (110) can provide a reference surface on which the positive active material layer (120) is placed. The positive current collector (110) may include, for example, a plate or foil comprising indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0028] Meanwhile, unlike as illustrated in FIG. 1, the positive current collector (110) may be omitted in one embodiment of the present invention. Although not illustrated, a carbon layer with a thickness of 0.1 μm to 4 μm may be further disposed between the positive current collector (110) and the positive active material layer (120) to increase the bonding strength between the positive current collector (110) and the positive active material layer (120).

[0029] The cathode active material is a material capable of reversibly absorbing and desorbing lithium ions. The cathode active material may include, for example, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, and lithium iron phosphate, as well as nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but is not necessarily limited to these. Each cathode active material may be a single material or a mixture of two or more materials.

[0030] Lithium transition metal oxides are, for example, Li a A 1-b B b D2(0.90≤a≤1, 0≤b≤0.5), Li a E 1-b B b O 2-c D c (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05), LiE 2-b B b O 4-c D c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1-b-c Co b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Lia Nor 1-b-c Co b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Nor 1-b-c Mn b B c D α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α≤2), Li a Nor 1-b-c Mn b B c O 2-α F α (0.90≤a≤1, 0≤b≤0.5, 0≤c≤0.05, 0<α<2), Li a Nor b E c G d O2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1), Li a Nor b Co c Mn d GeO2(0.90≤a≤1, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1), Li a NiG b O2(0.9≤a≤1, 0.001≤b≤0.1), Li a CoG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a MnG b O2(0.90≤a≤1, 0.001≤b≤0.1), Li a Mn2GbO4(0.90≤a≤1, 0.001≤b≤0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiIO2, LiNiVO4, Li 3-f J2(PO4)3(0≤f≤2), Li 3-fIt is a compound represented by any one of Fe2(PO4)3 (0≤f≤2) or LiFePO4. In such compounds, the uppercase “A” is Ni, Co, Mn, or a combination thereof; the uppercase “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; the uppercase “D” is O, F, S, P, or a combination thereof; the uppercase “E” is Co, Mn, or a combination thereof; the uppercase “F” is F, S, P, or a combination thereof; the uppercase “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; the uppercase “Q” is Ti, Mo, Mn, or a combination thereof; the uppercase “I” is Cr, V, Fe, Sc, Y, or a combination thereof; and the uppercase “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0031] The cathode active material may include, for example, a lithium salt of a transition metal oxide having a layered rock salt type structure among the lithium transition metal oxides described above. The "layered rock salt type structure" is, for example, a cubic rock salt type structure. <111> It is a structure in which oxygen and metal atomic layers are alternately and regularly arranged in a specific direction, thereby forming a two-dimensional plane for each atomic layer. The "cubic rock salt type structure" represents a sodium chloride (NaCl) type structure, which is a type of crystal structure; specifically, it exhibits a structure in which face-centered cubic lattices (fcc) formed by cations and anions, respectively, are offset from each other by half the ridge of the unit lattice. Lithium transition metal oxides having such a layered rock salt type structure are, for example, LiNi x Co y Al z O2(NCA) or LiNi x Co y Mn zO2(NCM) (0 <x<1,0<y<1, 0<z<1, x+y+z=1) 등의 삼원계 리튬전이금속산화물일 수 있다. 양극활물질이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 전고체 전지(10)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0032] The aforementioned compound contained in the cathode active material may be covered by a coating layer (not shown). The cathode active material may also be a mixture of the aforementioned compound and the compound to which the coating layer is added. Meanwhile, the coating layer added to the surface of the cathode active material may include, for example, oxides, hydroxides, oxyhydroxides, oxycarbonates, or hydroxycarbonates of the following coating elements. The compounds forming this coating layer are amorphous or crystalline. The coating elements included in the coating layer may include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The coating layer may include, for example, Li2O-ZrO2 (LZO). The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the cathode active material. The method for forming the coating layer is, for example, spray coating or immersion.

[0033] When the positive electrode active material is a ternary lithium transition metal oxide such as NCA or NCM and contains nickel (Ni), the capacity density of the all-solid-state battery (10) is increased, and the metal leaching of the positive electrode active material in the charged state can be reduced. As a result, the cycle characteristics of the all-solid-state battery (10) in the charged state are improved. Meanwhile, “cycle characteristics” is a characteristic that indicates the degree of deterioration of the all-solid-state battery (10) due to charging and discharging of the all-solid-state battery (10). An all-solid-state battery (10) with high cycle characteristics has a small degree of deterioration due to charging and discharging, while an all-solid-state battery (10) with low cycle characteristics may have a large degree of deterioration due to charging and discharging.

[0034] The shape of the cathode active material may include particle shapes such as spheres or ellipsoids. The particle size and content of the cathode active material are not particularly limited.

[0035] The solid electrolyte may include a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. Sulfide-based solid electrolytes include, for example, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), 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, n are positive numbers, uppercase “Z” is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, uppercase “M” is one of P, Si, Ge, B, Al, Ga, In), Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may include at least one selected from (0≤x≤2).

[0036] Sulfide-based solid electrolytes are, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I xIt may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0037] Alternatively, sulfide-based solid electrolytes are Li 7-a-c M a PS 6-c X c It may be an argyrodite-type compound containing (0≤a≤2, (0≤c≤2)). Here, X may be F, Br, Cl, or a combination thereof. M may be candium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof.

[0038] The density of the azyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. By having a density of 1.5 g / cc or higher for the azyrodite-type solid electrolyte, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0039] The solid electrolyte included in the positive electrode active material layer (120) may have a smaller average particle size (D50) compared to the solid electrolyte included in the solid electrolyte layer (300). For example, the average particle size (D50) of the solid electrolyte included in the positive electrode active material layer (120) may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the average particle size (D50) of the solid electrolyte included in the solid electrolyte layer (300). Meanwhile, the average particle size (D50) may be a median diameter measured using a laser particle size distribution meter.

[0040] The positive active material layer (120) may include a conductive material. The conductive material may have conductivity without causing chemical changes in the all-solid-state battery (10), thereby increasing the conductivity of the positive active material and the solid electrolyte. The conductive material may include a carbon-based material. The conductive material may include, for example, one or more selected from graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0041] The positive active material layer (120) may further include a binder. The binder may include a material for bonding the positive active material, solid electrolyte, and conductive material included in the positive active material layer (120), and for improving the bonding strength with the positive current collector (110). The binder may include, for example, polyvinylidene fluoride, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0042] Based on 100 parts by weight of the total positive active material, solid electrolyte, conductive material, and binder, the positive active material layer (120) may contain 70 parts by weight or more and 92 parts by weight or less of the positive active material. Based on 100 parts by weight of the total positive active material, solid electrolyte, conductive material, and binder, the positive active material layer (120) may contain 0.5 parts by weight or more and 1.5 parts by weight or less of the binder.

[0043] Based on 100 parts by weight of solid electrolyte, the positive active material layer (120) may contain 1 part by weight or more and 50 parts by weight or less of a conductive material. If the conductive material is included in the positive active material layer (120) in an amount less than 1 part by weight based on 100 parts by weight of solid electrolyte, the proportion of the conductive material decreases, and the electrical conductivity of the positive active material layer (120) may decrease. If the conductive material is included in the positive active material layer (120) in an amount exceeding 50 parts by weight based on 100 parts by weight of solid electrolyte, the proportion of the conductive material is excessively high, and a coating layer covering the surface of the solid electrolyte may not be properly formed.

[0044] The positive active material layer (120) may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids in addition to the positive active material, solid electrolyte, conductive material, and binder described above.

[0045] The solid electrolyte layer (300) is disposed between the positive electrode layer (100) and the negative electrode layer (200) and includes a sulfide-based solid electrolyte with excellent lithium ion conductivity characteristics. The solid electrolyte included in the solid electrolyte layer (300) may be the same as or different from any one of the materials that can be included in the solid electrolyte included in the aforementioned positive electrode active material layer (120).

[0046] The solid electrolyte layer (300) of one embodiment may include a sulfide-based solid electrolyte. The sulfide-based solid electrolyte may be manufactured by processing starting materials, such as Li2S or P2S5, by a melt quenching method or a mechanical milling method. Additionally, heat treatment may be performed after such processing. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. Furthermore, the solid electrolyte may include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the sulfide-based solid electrolyte materials described above, for example. For example, the solid electrolyte may be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material containing Li2S-P2S5 to form the solid electrolyte, the molar ratio of Li2S and P2S5 is, for example, in the range of Li2S : P2S5 = 50 : 50 to 90 : 10.

[0047] Sulfide-based solid electrolytes are, for example, Li 7-x PS 6-x Cl x (0≤x≤2), Li 7-x PS 6-x Br x (0≤x≤2), and Li 7-x PS 6-x I x It may be an argyrodite-type compound comprising one or more selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound comprising one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0048] Alternatively, sulfide-based solid electrolytes are Li 7-a-c M a PS 6-c X cIt may be an argyrodite-type compound containing (0≤a≤2, (0≤c≤2)). Here, X may be F, Br, Cl, or a combination thereof. M may be candium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo), tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh), iridium (Ir), nickel (Ni), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), mercury (Hg), aluminum (Al), gallium (Ga), indium (In), thallium (Tl), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), arsenic (As), antimony (Sb), bismuth (Bi), or a combination thereof.

[0049] The density of the azyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the azyrodite-type solid electrolyte has a density of 1.5 g / cc or higher, the internal resistance of the all-solid-state battery is reduced, and defects such as penetration and short circuit of the solid electrolyte film due to lithium dendrite formation can be prevented. The elastic modulus of the solid electrolyte is, for example, 15 GPa to 35 GPa.

[0050] The solid electrolyte layer (300) may further include a binder. The binder included in the solid electrolyte layer (300) is, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these. The binder of the solid electrolyte layer (300) may be the same as or different from the binder included in the positive electrode active material layer (120) or the binder included in the negative electrode coating layer (220).

[0051] The negative electrode layer (200) may include a negative electrode current collector (210) and a negative electrode coating layer (220) on the negative electrode current collector (210). The negative electrode current collector (210) may provide a reference surface on which the negative electrode coating layer (220) is placed. The negative electrode current collector (210) may include, for example, a material that does not react with lithium, that is, does not form any alloys or compounds with lithium. For example, the negative electrode current collector (210) may include at least one metal selected from the group consisting of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative electrode current collector (210) may be 1 μm to 20 μm, more specifically 5 μm to 15 μm, and more specifically 7 μm to 10 μm.

[0052] The negative current collector (210) may be composed of one of the metals described above, or may include an alloy of two or more metals or a coating material. The negative current collector (210) may, for example, have a plate-like or foil-like shape. Meanwhile, in one embodiment, the negative current collector (210) may be omitted.

[0053] The negative electrode coating layer (220) can allow lithium metal to grow between the all-solid-state battery (10) and the negative electrode current collector (210) during charging. The negative electrode coating layer (220) can serve as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0054] The cathode coating layer (220) may include metal and carbon materials. For example, the cathode coating layer (220) may include at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The cathode coating layer (220) may include at least one carbon material selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In one embodiment, the cathode coating layer (220) may include a mixture of carbon black and silver (Ag).

[0055] The cathode coating layer (220) may further include other additives in addition to metal and carbon. The cathode coating layer (220) may further include at least one additive selected from the group consisting of, for example, binders, fillers, coating agents, dispersants, and ion-conducting aids.

[0056] The negative electrode coating layer (220) may have a smaller thickness compared to the positive electrode active material layer (120). The thickness of the negative electrode coating layer (220) may be, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer (120). The thickness of the negative electrode coating layer (220) may be, for example, 1 µm to 20 µm, 2 µm to 10 µm, or 3 µm to 7 µm. If the thickness of the negative electrode coating layer (220) is excessively thin, lithium dendrites formed between the negative electrode coating layer (220) and the negative electrode current collector (210) may cause the negative electrode coating layer (220) to collapse, thereby degrading the cycle characteristics of the all-solid-state battery (10). If the thickness of the negative electrode coating layer (220) increases excessively, the energy density of the all-solid-state battery (10) decreases, and the internal resistance of the all-solid-state battery (10) due to the negative electrode coating layer (220) increases, which may degrade the cycle characteristics of the all-solid-state battery (10).

[0057] Meanwhile, although not illustrated, a carbon layer may be further included to improve adhesion between the cathode coating layer (220) and the solid electrolyte layer (300).

[0058] In one embodiment, the solid electrolyte layer (300) may include an anode solid electrolyte layer (310) and a cathode solid electrolyte layer (320). The anode solid electrolyte layer (310) may be adjacent to the anode layer (100), and the cathode solid electrolyte layer (320) may be adjacent to the cathode layer (200). Each of the anode solid electrolyte layer (310) and the cathode solid electrolyte layer (320) may include the solid electrolyte described above.

[0060] An electrode for a lithium secondary battery according to embodiments of the present invention comprises a composite substrate including a wireless charging receiving coil. The receiving coil receives a magnetic field generated from a separate transmitting coil and can generate an induced current according to the principle of electric induction. A lithium secondary battery including the electrode can be wirelessly charged without a separate receiving device and can improve the charging characteristics of the lithium secondary battery. Hereinafter, an electrode for a lithium secondary battery according to embodiments of the present invention will be described.

[0062] FIG. 2 is a cross-sectional view of an electrode for a lithium secondary battery according to one embodiment of the present invention.

[0063] Referring to FIG. 2, the electrode (ELT) for a lithium secondary battery may include a composite substrate (CPS); and an electrode layer (ETL) on the composite substrate (CPS).

[0064] The composite substrate (CPS) may include a first metal layer (MEL1); a second metal layer (MEL2); and a composite layer (CML) disposed between the first metal layer (MEL1) and the second metal layer (MEL2). The first metal layer (MEL1) and the second metal layer (MEL2) may be electrically connected to each other through the composite layer (CML).

[0065] FIG. 3 is an exploded perspective view of a composite substrate according to one embodiment. FIG. 4 is a cross-sectional view of a composite substrate according to one embodiment.

[0066] Referring to FIGS. 3 and 4, the composite layer (CML) of the composite substrate (CPS) may include a wireless charging receiving coil (COL).

[0067] A wireless charging receiving coil (COL) is a structure in which a conductor is wound around a central axis and contains an empty space within the wound conductor. The structure may be a spiral wound in a planar shape, or a helix structure wound three-dimensionally along the axis center. The wireless charging receiving coil (COL) can generate an induced current by an alternating magnetic field generated by a separate transmitting coil.

[0068] In one embodiment, the composite substrate (COS) may include a plurality of wireless charging receiving coils (COL). This allows for improved charging efficiency.

[0069] A wireless charging receiver coil (COL) can generate an induced current through magnetic induction or magnetic resonance.

[0070] Referring to FIGS. 3 and 4, the composite layer (CML) of the composite substrate (CPS) may further include a polymer (POL). Specifically, the composite layer (CML) may include a polymer (POL) and a receiving coil (COL) embedded in the polymer (POL). At least a portion of the receiving coil (COL) may be embedded in the polymer (POL). The internal central axis space of the receiving coil (COL) may be filled with the polymer (POL).

[0071] In one embodiment, the first metal layer (MEL1) and the second metal layer (MEL2) can be electrically connected to each other through a receiving coil (COL). For example, one end of the receiving coil (COL) is in contact with the first metal layer (MEL1), and the other end of the receiving coil (COL) is in contact with the second metal layer (MEL2), so that the first metal layer (MEL1) and the second metal layer (MEL2) can be electrically connected to each other.

[0072] In one embodiment, the composite layer (CPS) may further include a rectifier. Specifically, the rectifier may include a diode. The rectifier can convert the alternating current generated in the receiving coil (COL) into direct current. This can improve charging efficiency.

[0073] In one embodiment, the rectifier may be embedded within the polymer (POL) described above.

[0074] The rectifier is electrically connected to the receiving coil (COL). The rectifier may also electrically connect the first metal layer (MEL1) and the second metal layer (MEL2) to each other.

[0075] In one embodiment, the polymer (POL) may include at least one of epoxy resin, polyurethane, acrylic resin, polyimide (PI), and polyvinyl alcohol (PVA).

[0076] The composite layer (CML) can reduce the weight of the substrate compared to a substrate made solely of metal by including a polymer. This allows for the improvement of the energy density of lithium secondary batteries using a composite substrate (CPS).

[0077] The efficiency and direction of wireless charging can be determined by the arrangement direction of the wireless charging receiving coil (COL) within the composite layer (CPS).

[0078] In one embodiment, the wireless charging receiving coil (COL) may be positioned such that the central axis of the wireless charging receiving coil (COL) is aligned parallel to the thickness direction (third direction, D3) of the composite substrate (CPS). By positioning the wireless charging receiving coil (COL) parallel to the thickness direction (third direction, D3) of the composite substrate (CPS), changes in thickness due to charging and discharging of the lithium secondary battery can be mitigated. That is, the receiving coil (COL) can not only improve the charging characteristics of the cell but also enhance the structural stability of the cell.

[0079] + The direction symbols (D1, D2, D3) are missing from the drawing; please add them.

[0080] In one embodiment, the material of the wireless charging receiving coil (COL) may be a metal with excellent electrical conductivity. As an example, the wireless charging receiving coil (COL) may include copper, a copper alloy, silver, a silver alloy, aluminum, or an aluminum alloy.

[0081] The electrode layer (ETL) may be either the positive electrode composite layer (CML) or the negative electrode composite layer (NML).

[0082] In one embodiment, the positive composite layer (CML) may include the positive active material layer (120) described above with reference to FIG. 1. As an example, the positive composite layer (CML) may be the positive active material layer (120).

[0083] In one embodiment, the anode composite layer (CML) may include a lithium transition metal oxide. As an example, the anode composite layer may include at least one of lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganese oxide (lithium manganate), and lithium iron phosphate. The anode composite layer (CML) may further include the binder and conductive material described above with reference to FIG. 1.

[0084] In one embodiment, the anode composite layer (CML) may further include a solid electrolyte. The solid electrolyte may be selected from the solid electrolyte of the anode layer (100) described above with reference to FIG. 1. As an example, the anode composite layer (CML) may include a sulfide-based solid electrolyte, and specifically, may include an argyrodite-type sulfide-based solid electrolyte.

[0085] In another embodiment, the anode composite layer (CML) may not include the solid electrolyte described above with reference to FIG. 1.

[0086] In one embodiment, the cathode composite layer (AML) may include the cathode coating layer (220) described above with reference to FIG. 1. As an example, the cathode composite layer (AML) may be the cathode coating layer (220).

[0087] Referring again to FIG. 2, in one embodiment, each of the first and second metal layers (MEL1, MEL2) may comprise at least one of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), aluminum (Al), or an alloy thereof.

[0089] FIG. 5 is a cross-sectional view of a lithium secondary battery according to an embodiment of the present invention. Referring to FIG. 5, the lithium secondary battery (CEL) may include a composite substrate (CPS); a first electrode layer (ETL1) on the composite substrate (CPS); a first electrolyte layer (SEL1) on the first electrode layer (ETL1); a second electrode layer (ETL2) on the first electrolyte layer (SEL1); and a current collector (COE) on the second electrode layer. That is, the lithium secondary battery (CEL) may include the electrode (ELT) described above with reference to FIG. 2 to FIG. 4.

[0090] In one embodiment, the composite substrate (CPS) is the same as described with reference to FIGS. 2 to 4. The first electrode layer (ETL1) is either the positive composite layer or the negative composite layer, and the second electrode layer (ETL2) may be the other of the positive composite layer and the negative composite layer. Each of the positive composite layer and the negative composite layer is the same as described with reference to FIGS. 2 to 4.

[0091] In one embodiment, the current collector (COE) may be either the positive current collector (110) and the negative current collector (210) described above with reference to FIG. 1. For example, when the second electrode layer (ETL2) is a positive composite layer, the current collector (COE) may be the positive current collector (110) of FIG. 1, and when the second electrode layer (ETL2) is a negative composite layer, the current collector (COE) may be the negative current collector (210) of FIG. 1.

[0092] In one embodiment, the first electrolyte layer (SEL1) may be the solid electrolyte layer (300) described above with reference to FIG. 1. That is, the lithium secondary battery (CEL) may be an all-solid-state battery containing a solid electrolyte.

[0093] In another embodiment, the first electrolyte layer (SEL1) may include a separator and an electrolyte. That is, the lithium secondary battery (CEL) may be a lithium-ion battery containing an electrolyte. In this case, the positive electrode composite layer described above with reference to FIG. 2 may not include a solid electrolyte, and the negative electrode composite layer may include a negative electrode active material.

[0094] As a separator, polyethylene, polypropylene, polyvinylidene fluoride, or multilayer films of two or more layers thereof may be used, and of course, mixed multilayer films such as polyethylene / polypropylene two-layer separator, polyethylene / polypropylene / polyethylene three-layer separator, polypropylene / polyethylene / polypropylene three-layer separator may be used.

[0095] The separator may 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.

[0096] The porous substrate may be a polymer membrane formed from any one of the following: polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyacetal; polyamide; polyimide; polycarbonate; polyetherketone; polyaryletherketone; polyetherimide; polyamideimide; polybenzimidazole; polyethersulfone; polyphenylene oxide; cyclic olefin copolymer; polyphenylene sulfide; polyethylene naphthalate; glass fiber; Teflon; and polytetrafluoroethylene, or a copolymer or mixture of two or more of these.

[0097] The above organic material may include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0098] The above inorganic materials are Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, It may include, but is not limited to, inorganic particles selected from SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof.

[0099] The above organic and inorganic materials may exist mixed in a single coating layer, or may exist in a stacked form with a coating layer containing organic materials and a coating layer containing inorganic materials.

[0100] The electrolyte (ELL) for lithium secondary batteries contains a non-aqueous organic solvent and a lithium salt.

[0101] The above-mentioned non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.

[0102] The above-mentioned non-aqueous organic solvent may be a carbonate-based, ester-based, ether-based, ketone-based, or alcohol-based solvent, an aprotic solvent, or a combination thereof.

[0103] The above carbonate-based solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc.

[0104] Ester-based solvents such as methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methylpropionate, ethylpropionate, decanolide, mevalonolactone, valerolactone, and caprolactone may be used.

[0105] As ether-based solvents, dibutyl ether, tetraglame, diglame, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. may be used. Additionally, as ketone-based solvents, cyclohexanone, etc. may be used. As alcohol-based solvents, ethyl alcohol, isopropyl alcohol, etc. may be used, and as aprotic solvents, nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond, an aromatic ring, or an ether group); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane, 1,4-dioxolane; sulfolanes, etc. may be used.

[0106] The above-mentioned non-aqueous organic solvent can be used alone or in a mixture of two or more types.

[0107] In addition, when using a carbonate-based solvent, a mixture of cyclic carbonates and chain carbonates can be used, and the cyclic carbonates and chain carbonates can be mixed in a volume ratio of 1:1 to 1:9.

[0108] The above lithium salt is a substance that dissolves in an organic solvent and acts as a source of lithium ions within the battery, enabling the basic operation of a lithium secondary battery and facilitating the movement of lithium ions between the anode and cathode. 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, LiN(C x F 2x+1 SO2)(C y F 2y+1 It may include one or more selected from SO2)(x and y are integers from 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0109] A material capable of reversibly intercalating / deintercalating the above lithium ions may be a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, and examples of the amorphous carbon include soft carbon or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0110] As the above lithium metal alloy, 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 may be used.

[0111] As a material capable of doping and undoping the above lithium, a Si-based negative electrode active material or a Sn-based negative electrode active material may be used. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiOx (0 < x < 2), a Si-Q alloy (wherein 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 may be Sn, SnO2, a Sn-based alloy, or a combination thereof.

[0112] 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 amorphous carbon coated on the surface of the silicon particles. For example, it may include a secondary particle (core) assembled from silicon primary particles and an amorphous carbon coating layer (shell) located on the surface of the secondary particle. The amorphous carbon may also be located between the silicon primary particles, so that, for example, the silicon primary particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0113] The silicon-carbon composite may further include crystalline carbon. For example, the silicon-carbon composite may include a core comprising crystalline carbon and silicon particles and an amorphous carbon coating layer located on the surface of the core.

[0114] The above Si-based or Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material.

[0116] FIG. 6 is a cross-sectional view of a lithium secondary battery according to one embodiment of the present invention.

[0117] A lithium secondary battery (CEL) may include a first composite substrate (CPS1); a first electrode layer (ETL1) on the first composite substrate (CPS1); a first electrolyte layer (SEL1) on the first electrode layer (ETL1); a second electrode layer (ETL2) on the first electrolyte layer (SEL1); and a second composite substrate (CPS2) on the second electrode layer.

[0118] Each of the first and second composite materials (CPS1, CPS2) is identical to that described with reference to FIGS. 2 to 4.

[0119] In one embodiment, the first electrode layer (ETL1) may be either the positive composite layer or the negative composite layer, and the second electrode layer (ETL2) may be the other of the positive composite layer and the negative composite layer. Each of the positive composite layer and the negative composite layer is the same as described with reference to FIGS. 2 to 4.

[0120] In one embodiment, the current collector (COE) may be either the positive current collector (110) and the negative current collector (210) described above with reference to FIG. 1. For example, when the second electrode layer (ETL2) is a positive composite layer, the current collector (COE) may be the positive current collector (110) of FIG. 1, and when the second electrode layer (ETL2) is a negative composite layer, the current collector (COE) may be the negative current collector (210) of FIG. 1.

[0121] In one embodiment, the first electrolyte layer (SEL1) may be the solid electrolyte layer (300) described above with reference to FIG. 1. That is, the lithium secondary battery (CEL) may be an all-solid-state battery containing a solid electrolyte.

[0122] In another embodiment, the first electrolyte layer (SEL1) may include a separator and an electrolyte. That is, the lithium secondary battery (CEL) may be a lithium-ion battery containing an electrolyte. In this case, the positive electrode composite layer described above with reference to FIG. 2 may not include a solid electrolyte, and the negative electrode composite layer may include a negative electrode active material.

[0123] The negative electrode active material, separator, and electrolyte are each the same as those described above with reference to FIG. 5.

[0125] FIG. 7 is a cross-sectional view illustrating a bipolar electrode for a lithium secondary battery according to one embodiment. Referring to FIG. 7, the bipolar electrode (UEL) may include a composite substrate (CPS); a first electrode layer (ETL1) on one side of the composite substrate (CPS); and a second electrode layer (ETL2) on the other side of the composite substrate (CPS).

[0126] The composite substrate (CPS) is the same as described with reference to FIGS. 2 to 4.

[0127] The first electrode layer (ETL1) may be either the positive composite layer or the negative composite layer, and the second electrode layer (ETL2) may be the other one of the positive composite layer and the negative composite layer. Each of the positive composite layer and the negative composite layer is the same as described with reference to FIGS. 2 to 4. That is, the electrode (UEL) according to one embodiment may be a bipolar electrode in which electrode layers of different polarities are formed on both sides of a composite substrate (CPS).

[0129] FIG. 8 is a cross-sectional view for illustrating a lithium secondary battery according to one embodiment. Referring to FIG. 8, the lithium secondary battery (CEL) may include a first bipolar electrode (UEL1); a first electrolyte layer (SEL1) on one side of the first electrode (UEL1); a second bipolar electrode (UEL2) on the first electrolyte layer (SEL1); a second electrolyte layer (SEL2) on the other side of the first electrode (UEL1); and a third bipolar electrode (UEL3) on the second electrolyte layer (SEL2). That is, the lithium secondary battery (CEL) may include a plurality of bipolar electrodes (ELT) as described above with reference to FIG. 6.

[0130] Each of the first to third bipolar electrodes (UEL1, UEL2, UEL3) is identical to the bipolar electrode (UEL) described above with reference to FIG. 7. Specifically, the first bipolar electrode (UEL1) may include a first composite substrate (CPS1); a first positive composite layer (CAL1) on one side of the composite substrate (CPS1); and a first negative composite layer (NAL1) on the other side of the composite substrate (CPS1). The second bipolar electrode (UEL2) may include a second composite substrate (CPS2); a second positive composite layer (CAL2) on one side of the composite substrate (CPS2); and a second negative composite layer (NAL2) on the other side of the composite substrate (CPS2). The third bipolar electrode (UEL3) includes a third composite substrate (CPS3); It may include a third positive electrode composite layer (CAL3) on one side of the composite substrate (CPS3) and a third negative electrode composite layer (NAL3) on the other side of the composite substrate (CPS3).

[0131] Each of the first to third composite materials (CPS1, CPS2, CPS3) is identical to the composite material (CPS) described above with reference to FIGS. 2 to 4.

[0132] Referring again to FIGS. 2 and FIGS. 4, for example, the first composite substrate (CPS1) may include a first metal layer (MEL1), a second metal layer (MEL2), and a composite layer (CML) disposed between the first metal layer (MEL1) and the second metal layer (MEL2). The composite layer (CML) may include a wireless charging receiving coil (COL).

[0133] In one embodiment, the first to third bipolar electrodes (UEL1, UEL2, UEL3) can be connected in series with each other.

[0134] The aforementioned lithium secondary battery (CEL) can be wirelessly charged without a separate receiving device by including a wireless charging receiving coil (COL). Furthermore, since wireless charging can be performed on all of the composite materials, charging efficiency can be improved. In particular, the charging efficiency of internal electrodes, which suffer from reduced charging efficiency in a series structure, can be improved.

[0135] In addition, since wireless and wired charging can be performed simultaneously, the charging efficiency of lithium secondary batteries can be further improved.

[0136] Hereinafter, a method for manufacturing the composite material described above is explained.

[0137] FIGS. 9 to 11 are cross-sectional views for explaining a method of manufacturing a composite substrate according to one embodiment.

[0138] Referring to FIG. 9, a polymer solution (POS) can be prepared. The polymer solution (POS) may include a polymer or a polymer precursor. As an example, the polymer precursor may include at least one of a polymer monomer (MNO) and a prepolymer.

[0139] In one embodiment, the polymer may comprise at least one of polyethylene terephthalate, polyolefin, polyester, polyacetal, polyamide, polyimide, polycarbonate, polyetherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene oxide, cyclic olefin copolymer, polyphenylene sulfide, polyethylene naphthalate, and polytetrafluoroethylene. The polymer monomer (MNO) and the prepolymer may each be a monomer or prepolymer constituting the polymer.

[0140] In one embodiment, the polymer solution (POS) may further comprise a polymerization initiator. In one example, the polymerization initiator may comprise at least one of a thermal polymerization initiator or a photopolymerization initiator.

[0141] Referring to FIG. 10, a wireless charging receiving coil (COL) can be placed and fixed within a polymer solution (POS). The receiving coil (COL) can be placed and fixed along a predetermined interval within the polymer solution (POS).

[0142] The fixing means is not particularly limited, and as an example, one end of the receiving coil (COL) can be fixed with a fixing member.

[0143] In one embodiment, a rectifier may be further placed in the polymer solution (POS). The rectifier may be electrically connected to a burner coil (COL).

[0144] Referring to FIGS. 10 and 11, a composite layer (CML) can be formed by curing a polymer solution (POS) in which a wireless charging receiving coil (COL) is placed.

[0145] Referring to FIG. 11, one end and the other end of the wireless charging receiving coil (COL) of the composite layer (CML) can be exposed. For example, by partially cutting the top and bottom of the polymer, one end and the other end of the wireless charging receiving coil (COL) can be exposed. Through this, the receiving coil (COL) can be brought into contact with the first metal layer (MEL1) and the second metal layer (MEL2) that are subsequently formed. As a result, the first metal layer (MEL1) and the second metal layer (MEL2) can be electrically connected to each other.

[0146] If the composite layer (CML) includes a rectifier, the first conductor connected to the rectifier may be exposed at the top of the composite layer (CML), and the second conductor connected to the rectifier may be exposed at the bottom of the composite layer (CML). Through this, the first metal layer (MEL1) and the second metal layer (MEL2) formed thereafter can be electrically connected to the rectifier. Consequently, the first metal layer (MEL1) and the second metal layer (MEL2) can be electrically connected to each other.

[0147] Referring to FIG. 12, metal layers can be formed on both sides of the composite layer (CML). Specifically, a first metal layer (MEL1) can be formed on one side of the composite layer (CML), and a second metal layer (MEL2) can be formed on the other side of the composite layer (CML).

[0148] In one embodiment, first and second metal layers (MEL1, MEL2) can be formed by depositing metal on both sides of a composite layer (CML). As an example, layers of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), aluminum (Al), or alloys thereof can be formed on both sides of the composite layer (CML).

[0150] Hereinafter, embodiments and comparative examples of the present invention are described. However, the following embodiments are merely examples of the present invention, and the present invention is not limited to the following embodiments.

[0151] Example 1

[0152] (Composite entry)

[0153] One copper coil with a diameter of 20 mm and a length of 20 mm was placed in a polyimide solution and heat-treated to form a composite layer with a thickness of 10 µm. Then, copper was deposited on both sides of the composite layer to produce a composite substrate in which metal layers with a thickness of 1 µm were formed on each side of the composite layer.

[0154] (Cathode active material slurry)

[0155] LiNi as a positive electrode active material 0.90 Co 0.05 Al 0.05O2 (NCA), Li6PS5Cl (D50 = 0.5 μm, crystalline), which is an argyrodite-type crystal, as a solid electrolyte, carbon nanotubes (CNT) as a conductive material, and polyvinylidene fluoride (PVDF) as a binder were prepared. The positive active material, solid electrolyte, conductive material, and binder were mixed in order in an N-methyl-2-pyrrolidone (NMP) solvent in a weight ratio of 85:10.5:3:1.5 to prepare a positive active material slurry.

[0156] (Cathode coating layer slurry)

[0157] A cathode coating layer slurry was prepared by mixing carbon black (CB) with a primary particle size of about 30 nm and silver (Ag) particles with an average particle size (D50) of about 60 nm in water at a weight ratio of 3:1.

[0158] (Solid electrolyte membrane)

[0159] A mixture was prepared by mixing polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) with an argyrodite-type crystal Li6PS5Cl sulfide-based solid electrolyte (D50 = 3 μm, crystalline). The mixture was stirred to prepare a dough, and then the prepared dough was passed through a roller to form a sheet.

[0160] (Lithium secondary battery)

[0161] A cathode layer was manufactured by applying and drying a cathode coating layer slurry on one side of a composite substrate manufactured by the above method to form a cathode coating layer.

[0162] An anode layer was manufactured by applying and drying the above anode active material slurry onto an aluminum current collector to form an anode active material layer.

[0163] A unit cell was manufactured by placing a solid electrolyte film between the anode layer and the cathode layer and applying pressure. Three of the unit cells were stacked and connected in series to manufacture a lithium secondary battery.

[0165] Example 2

[0166] A lithium secondary battery was manufactured in the same manner as in Example 1, except that when manufacturing the composite substrate, four coils with a diameter of 5 mm and a length of 5 mm were placed in a polyimide solution and heat-treated to form a composite layer.

[0168] Example 3

[0169] A lithium secondary battery was manufactured in the same manner as in Example 1, except that a rectifier was additionally connected to the coil when manufacturing the composite material.

[0171] Example 4

[0172] A composite substrate, a positive electrode active material slurry, a negative electrode coating layer slurry, and a solid electrolyte membrane were prepared in the same manner as in Example 1.

[0173] (Lithium secondary battery)

[0174] A cathode coating layer was formed by applying and drying a cathode coating layer slurry on one side of a composite substrate manufactured by the above method. A bipolar electrode was prepared by applying a positive active material slurry on the other side of the composite substrate to form a positive active material layer.

[0175] Three bipolar electrodes manufactured as described above were prepared, and a solid electrolyte membrane was placed between the bipolar electrodes and then pressurized to manufacture a lithium secondary battery. That is, a lithium secondary battery in which three bipolar electrodes are connected in series was manufactured.

[0177] Comparative Example 1

[0178] A positive electrode active material slurry, a negative electrode coating layer slurry, and a solid electrolyte membrane were prepared in the same manner as in Example 1.

[0179] The above positive active material slurry was applied and dried on an aluminum current collector to form a positive active material layer. That is, a positive layer comprising a positive current collector and a positive active material layer was manufactured.

[0180] A cathode coating layer was formed by applying and drying a cathode coating layer slurry onto a copper current collector. That is, a cathode layer comprising a cathode current collector and a cathode coating layer was manufactured. A unit cell was manufactured by placing a solid electrolyte film between the anode layer and the cathode layer and applying pressure. Three of the unit cells were stacked and connected in series to manufacture a lithium secondary battery.

[0182] Evaluation Example 1: Charging Rate and DC-iR Measurement

[0183] A current was applied to the upper and lower surfaces of a lithium secondary battery (unit cell stack) according to Comparative Example 1, and charging was performed at a constant current of 0.33C at 25°C (wired charging). Afterwards, the time until the battery reached 4.25V was measured.

[0184] A lithium secondary battery according to Examples 1 to 4 was placed on a wireless charging pad to perform wireless charging. At the same time, current was applied to the upper and lower surfaces of the lithium secondary battery (unit cell stack) according to Examples 1 to 4 to perform charging at a constant current of 0.33C at 25°C (wired charging). The 0.33C value excludes the current applied during wireless charging. Afterward, the time until the battery reached 4.25V was measured.

[0185] In addition, the voltage drop (V) generated by applying an additional current of 0.1C for 1 second at SOC80 (a state where the battery is charged to 80% capacity when the total charge capacity is set to 100%, which means a state where the battery is discharged to 80%) during charging of the lithium secondary batteries of Examples 1 to 4 and Comparative Example 1 was measured. From these results, the DC internal resistance (DC-iR) was calculated and is shown in Table 1.

[0186] division Time to reach 4.25V during constant current charging (min) DC-iR(Ω) Example 1 184.6 9.8 Example 2 182.9 9.12 Example 3 184.5 9.7 Example 4 178.8 8.4 Comparative Example 1 189.2 11.6

[0187] Referring to Table 1, it can be seen that the charging characteristics (charging speed, internal resistance) of the lithium secondary battery according to the embodiments of the present invention, which can perform wired and wireless charging simultaneously, are excellent.

Claims

Claim 1 A composite substrate for a lithium secondary battery comprising: a first metal layer; a second metal layer; and a composite layer disposed between the first metal layer and the second metal layer, wherein the composite layer comprises a coil configured to receive an alternating magnetic field and generate an induced current, and wherein the first metal layer, the second metal layer, and the coil are electrically connected to each other. Claim 2 A composite substrate for a lithium secondary battery according to claim 1, wherein the composite layer further comprises a polymer, and at least a portion of the coil is embedded within the polymer. Claim 3 A composite substrate for a lithium secondary battery according to claim 1, wherein the polymer comprises at least one of epoxy resin, polyurethane, acrylic resin, polyimide (PI), and polyvinyl alcohol (PVA). Claim 4 In claim 1, the coil is a composite substrate for a lithium secondary battery in which the central axis of the coil is arranged parallel to the thickness direction of the composite substrate. Claim 5 A composite substrate for a lithium secondary battery according to claim 1, wherein one end of the coil is in contact with the first metal layer and the other end of the coil is in contact with the second metal layer, and the first metal layer and the second metal layer are electrically connected to each other through the coil. Claim 6 A composite substrate for a lithium secondary battery according to claim 1, wherein the composite layer further comprises a rectifier electrically connected to the coil, the first metal layer and the second metal layer are electrically connected to each other through the rectifier, and the rectifier converts the induced current generated in the coil into a direct current. Claim 7 A composite substrate for a lithium secondary battery according to claim 1, wherein the electrode layer is either a positive electrode composite layer or a negative electrode composite layer. Claim 8 In claim 7, the anode layer comprises a lithium transition metal oxide, a composite substrate for a lithium secondary battery. Claim 9 In claim 8, the anode composite layer further comprises a sulfide-based solid electrolyte, a composite substrate for a lithium secondary battery. Claim 10 A composite substrate for a lithium secondary battery according to claim 8, wherein the cathode composite layer comprises: at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn); and at least one carbon material selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. Claim 11 An electrode for a lithium secondary battery comprising: a composite substrate; and an electrode layer on the composite substrate, wherein the composite substrate comprises a first metal layer, a second metal layer, and a composite layer disposed between the first metal layer and the second metal layer, and the composite layer comprises a coil configured to receive an alternating magnetic field and generate an induced current, and the first metal layer, the second metal layer, and the coil are electrically connected to each other. Claim 12 An electrode for a lithium secondary battery according to claim 11, wherein the composite layer further comprises a polymer, and at least a portion of the coil is embedded within the polymer. Claim 13 An electrode for a lithium secondary battery according to claim 11, wherein the polymer comprises at least one of epoxy resin, polyurethane, acrylic resin, polyimide (PI), and polyvinyl alcohol (PVA). Claim 14 In claim 11, the coil is an electrode for a lithium secondary battery, wherein the central axis of the coil is arranged parallel to the thickness direction of the composite substrate. Claim 15 An electrode for a lithium secondary battery according to claim 11, wherein one end of the coil is in contact with the first metal layer and the other end of the coil is in contact with the second metal layer, and the first metal layer and the second metal layer are electrically connected to each other through the coil. Claim 16 An electrode for a lithium secondary battery according to claim 11, wherein the composite layer further comprises a rectifier electrically connected to the coil, the first metal layer and the second metal layer are electrically connected to each other through the rectifier, and the rectifier converts the induced current generated in the coil into a direct current. Claim 17 A lithium secondary battery comprising a first bipolar electrode, wherein the first bipolar electrode comprises a composite substrate, an anode layer on one side of the composite substrate, and a cathode layer on the other side of the composite substrate, wherein the composite substrate comprises a first metal layer, a second metal layer, and a composite layer disposed between the first metal layer and the second metal layer, and wherein the composite layer comprises a receiving coil for wireless charging. Claim 18 A lithium secondary battery according to claim 17, further comprising: a first electrolyte layer on one side of the first bipolar electrode; a second bipolar electrode on the first electrolyte layer; a second electrolyte layer on the other side of the first bipolar electrode; and a third bipolar electrode on the second electrolyte layer. Claim 19 A lithium secondary battery according to claim 17, wherein one end of the coil is in contact with the first metal layer and the other end of the coil is in contact with the second metal layer, and the first metal layer and the second metal layer are electrically connected to each other through the coil. Claim 20 A lithium secondary battery according to claim 17, wherein the composite layer further comprises a rectifier electrically connected to the coil, the first metal layer and the second metal layer are electrically connected to each other through the rectifier, and the rectifier converts an alternating current generated in the coil into a direct current.

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