Composite substrate, deposition-type negative electrode containing the same, and lithium secondary battery containing the same

Abstract

The present invention provides a composite substrate that exhibits excellent electrical conductivity and can mitigate volume changes in the deposition-type anode. [Solution] The present invention relates to a composite substrate for a deposition-type negative electrode, a negative electrode containing the same, and a lithium secondary battery containing the same. More specifically, the composite substrate of the present invention includes an elastic layer and a metal layer on the elastic layer, the elastic layer comprising a polymer foam and a carbon-based conductive material. The deposition-type negative electrode of the present invention comprises a composite substrate and a coating layer on the composite substrate, the composite substrate comprising an elastic layer and a metal layer on the elastic layer, the elastic layer comprising a polymer foam and a carbon-based conductive material.

Description

[Technical Field]

[0001] The present invention relates to a composite substrate, a deposition-type negative electrode containing the same, and a lithium secondary battery containing the deposition-type negative electrode containing the composite substrate. [Background technology]

[0002] Recently, there has been active development of batteries with high energy density and safety due to industrial demands. For example, lithium-ion batteries are being put into practical use not only in the fields of information-related equipment and communication equipment, but also in the automotive sector. In the automotive sector, safety is particularly important because it is related to human safety.

[0003] All-solid-state batteries have been proposed in which the electrolyte of lithium-ion batteries is replaced with a solid electrolyte. Because all-solid-state batteries do not use flammable organic solvents, the possibility of fire or explosion in the event of a short circuit can be greatly reduced. Therefore, such all-solid-state batteries can offer superior safety. [Overview of the project] [Problems that the invention aims to solve]

[0004] The problem that the present invention aims to solve is to provide a composite substrate that has desired or improved electrical conductivity and can mitigate volume changes in a deposited anode.

[0005] Another problem that the present invention aims to solve is to provide a deposition-type anode that has desired or improved electrical conductivity and can mitigate volume changes due to lithium deposition.

[0006] Another problem that the present invention aims to solve is to provide a lithium secondary battery having desired or improved lifespan characteristics by mitigating volume changes through lithium deposition. [Means for solving the problem]

[0007] A composite substrate for a deposition-type anode according to one embodiment of the present invention includes an elastic layer and a metal layer on the elastic layer, wherein the elastic layer may include a polymer foam and a carbon-based conductive material.

[0008] A deposition-type anode according to another embodiment of the present invention comprises a composite substrate and a coating layer on the composite substrate, wherein the composite substrate comprises an elastic layer and a metal layer on the elastic layer, and the elastic layer may include a polymer foam and a carbon-based conductive material.

[0009] A lithium secondary battery according to another embodiment of the present invention includes a positive electrode layer, a deposited negative electrode layer, and an electrolyte layer interposed between the positive electrode layer and the negative electrode layer, wherein the negative electrode layer includes a composite substrate, and the composite substrate may include an elastic layer and a metal layer on the elastic layer. The elastic layer may include a polymer foam and a carbon-based conductive material. [Effects of the Invention]

[0010] Lithium secondary batteries containing a deposition-type negative electrode undergo volume changes during charging and discharging. The composite substrate according to the present invention can reduce the volume change of a lithium secondary battery containing it by including an elastic layer. Furthermore, unlike general descriptions which consist only of metal, the composite substrate can have a lower density by including an elastic layer, and as a result, the energy density of the battery containing it can be improved. In addition, the composite substrate can prevent a decrease in electrical conductivity due to the introduction of the elastic layer by further including a conductive material.

[0011] The lithium secondary battery according to the present invention has excellent electrical conductivity and lifespan characteristics due to the inclusion of the composite substrate. [Brief explanation of the drawing]

[0012] [Figure 1] This is a cross-sectional view of a lithium secondary battery including a deposition-type anode according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention. [Figure 3]This is a plan view of an all-solid-state battery according to one embodiment of the present invention. [Figure 4] This is a cross-sectional view of an all-solid-state battery according to another embodiment of the present invention. [Figure 5] This is a cross-sectional view of a deposition-type anode according to one embodiment. [Figure 6] This is a cross-sectional view of a composite substrate according to one embodiment. [Figure 7] This is an enlarged view of region M in Figure 6, used to illustrate the elastic layer. [Figure 8] This is a perspective view of a composite substrate according to one embodiment. [Figure 9A] This is an exploded perspective view of a composite substrate according to another embodiment. [Figure 9B] Figure 9A is a cross-sectional view of the composite substrate. [Figure 10A] This is a cross-sectional view of a unit cell of a lithium secondary battery according to one embodiment. [Figure 10B] This is a cross-sectional view of a stacked-cell lithium secondary battery according to one embodiment. [Figure 11] This is a cross-sectional view illustrating a method for manufacturing a composite substrate according to one embodiment. [Figure 12] This is a cross-sectional view illustrating a method for manufacturing a composite substrate according to one embodiment. [Figure 13] This is a cross-sectional view illustrating a method for manufacturing a composite substrate according to one embodiment. [Figure 14] This is a cross-sectional view illustrating a method for manufacturing a composite substrate according to one embodiment. [Modes for carrying out the invention]

[0013] To fully understand the structure and effects of the present invention, preferred embodiments will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and can be embodied in various forms and modified in many ways. These embodiments are provided solely to ensure that the disclosure of the present invention is complete and to fully inform those with ordinary skill in the art of which the invention pertains.

[0014] In this specification, when a given component is referred to as being on another component, it means that it can be formed directly on the other component or that a third component may be interposed between them. Furthermore, in the drawings, the thickness of components is exaggerated for the sake of efficient illustration of the technical content. Parts indicated by the same reference number throughout the specification refer to the same component.

[0015] The embodiments described herein are explained with reference to cross-sectional and / or plan views, which are ideal illustrative representations of the present invention. In the drawings, the thicknesses of films and regions are exaggerated for the efficient explanation of the technical content. Therefore, the regions illustrated in the drawings have schematic attributes, and the shapes of the regions illustrated in the drawings are for illustrative purposes only of the specific shape of the region of the element and are not intended to limit the scope of the invention. In the various embodiments herein, terms such as first, second, third, etc., have been used to describe various components, but these components should not be limited by such terms. These terms are used merely to distinguish certain components from others. The embodiments described and illustrated herein also include complementary embodiments.

[0016] The terms used herein are for illustrative purposes only and are not intended to limit the invention. In this specification, singular forms include plural forms unless specifically mentioned in the text. The terms “comprises” and / or “comprising” as used in this specification do not preclude the presence or addition of one or more other components of the configuration of the secondary battery mentioned.

[0017] In this specification, each of the terms 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 or all possible combinations of the items listed together with the applicable term.

[0018] Where the terms “approximately” or “substantially” are used in relation to numerical values ​​in this specification, the numerical values ​​are intended to include a tolerance of ±10% of the stated value. If a range is specified, that range includes all values ​​within that range, such as in increments of 0.1%.

[0019] In lithium secondary batteries containing a deposition-type negative electrode, lithium-containing metal may be deposited and dissolved on the negative electrode during the charge-discharge process. This allows a lithium layer to form on the negative electrode substrate after charging. The lithium layer may contain lithium or a lithium alloy.

[0020] Figure 1 is a cross-sectional view illustrating a lithium secondary battery including a deposition-type anode according to one embodiment of the present invention. Referring to Figure 1, the lithium secondary battery including a deposition-type anode may include a positive electrode layer PAL, a negative electrode layer NAL, and an electrolyte layer EEL interposed between the positive electrode layer PAL and the negative electrode layer NAL. The electrolyte layer EEL may include a liquid electrolyte, a solid electrolyte, a semi-solid electrolyte, or a combination thereof.

[0021] The positive electrode layer PAL may include a positive electrode current collector COL and a positive electrode active material layer AML on the positive electrode current collector COL.

[0022] The liquid electrolyte may be an organic electrolyte. The organic electrolyte may contain an organic solvent and a lithium salt. The semi-solid electrolyte may include a polymer and a liquid electrolyte impregnated within the polymer as a gel-type electrolyte. The solid electrolyte is the same as the solid electrolyte described later.

[0023] In one embodiment, the electrolyte layer EEL may correspond to the solid electrolyte layer 300 described later with reference to Figure 3.

[0024] The negative electrode layer NAL may include a negative electrode current collector and a coating layer CTL on the negative electrode current collector. In one embodiment, the negative electrode current collector may be a composite substrate CPS, which will be described later.

[0025] After charging a lithium secondary battery, a lithium layer can be formed on the negative electrode current collector. The lithium layer can be formed between the coating layer CTL and the negative electrode current collector. The coating layer CTL can promote the uniform formation of the lithium layer.

[0026] Below, we will describe an all-solid-state battery using a solid electrolyte as one embodiment of a lithium secondary battery including a deposition-type negative electrode.

[0027] Figure 2 is a cross-sectional view of an all-solid-state battery according to one embodiment of the present invention. Figure 3 is a plan view of an all-solid-state battery according to one embodiment of the present invention.

[0028] Referring to Figure 2, an all-solid-state battery 10 according to one embodiment may include 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, it is not limited thereto, and the all-solid-state battery 10 may further include additional functional layers, such as adhesion-enhancing layers, 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.

[0029] In one embodiment, the positive electrode layer 100 may include a positive electrode current collector 110 and a positive electrode active material layer 120 disposed on the positive electrode current collector 110. Although not shown, the positive electrode active material layer 120 may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0030] The positive electrode current collector 110 can provide a reference surface on which the positive electrode active material layer 120 is placed. The positive electrode current collector 110 may include a plate or foil containing, for example, 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 alloys thereof.

[0031] On the other hand, unlike what is illustrated in FIG. 2, in one embodiment of the present invention, the positive electrode current collector 110 may be omitted. Although not shown, a carbon layer having a thickness ranging from 0.1 μm to 4 μm may be further disposed between the positive electrode current collector 110 and the positive electrode active material layer 120 to enhance the bonding strength between the positive electrode current collector 110 and the positive electrode active material layer 120.

[0032] The positive electrode active material may include a material capable of reversibly absorbing and desorbing lithium ions. The positive electrode active material may include a plurality of particles. The positive electrode active material may be, 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; nickel sulfide, copper sulfide, lithium sulfide, iron oxide, vanadium oxide, or the like, and may include at least one of the above, but is not necessarily limited thereto. The positive electrode active materials may each be used alone, or may be a mixture of two or more types.

[0033] For example, the lithium transition metal oxide may be 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)、Li a 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-fThe compound is represented by one of the following: Fe2(PO4)3 (0≦f≦2) or LiFePO4, or contains one of these. In such a compound, the capital letter "A" is at least one of Ni, Co, or Mn, or a combination thereof, or contains one; the capital letter "B" is at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, or a rare earth element, or a combination thereof; the capital letter "D" is at least one of O, F, S, or P, or a combination thereof, or contains one; the capital letter "E" is at least one of Co or Mn, or a combination thereof, or contains one; the capital letter "F" is at least one of F, S, or P. Or a combination thereof, including the capital letter "G" is at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, including the capital letter "Q" is at least one of Ti, Mo, Mn, or a combination thereof, including the capital letter "I" is at least one of Cr, V, Fe, Sc, Y, or a combination thereof, including the capital letter "J" is at least one of V, Cr, Mn, Co, Ni, Cu, or a combination thereof, including the capital letter "J".

[0034] The positive electrode active material may include, for example, lithium salts of transition metal oxides having a layered rock salt type structure among the lithium transition metal oxides mentioned above. "Layered rock salt type structure" refers to, for example, a cubic rock salt type structure. <111> This structure consists of alternating, regular arrangements of oxygen and metal atomic layers in a directional pattern, where each atomic layer forms a two-dimensional plane. The "cubic rock salt type structure" is a type of crystalline structure, specifically a sodium chloride type (NaCl type) structure, where the face-centered cubic lattices (fcc) formed by the cations and anions 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 include, for example, LiNi x Co y Al zO₂(NCA) or LiNi x Co y Mn z O₂(NCM) (0<x<1, 0<y<1, 0<z<1, x+y+z=1) and other ternary lithium transition metal oxides. When the positive electrode active material contains a ternary lithium transition metal oxide having a layered rock salt structure, the energy density of the all-solid-state battery 10 can be increased, and the thermal stability can be improved.

[0035] The above-described compounds contained in the positive electrode active material may be covered with a coating layer (not shown). The positive electrode active material can also be a mixture of the above-described compound and a compound added with the coating layer. On the other hand, the coating layer provided on the surface of the positive electrode active material may contain, for example, oxides, hydroxides, oxyhydroxides, oxycarbonates, or hydroxycarbonates of the following coating elements. Compounds forming such a coating layer are amorphous or crystalline. The coating element contained in the coating layer may include at least one selected from Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The coating layer may contain, for example, Li₂O-ZrO₂ (LZO) and the like. The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. Examples of the coating layer forming method include spray coating, dipping method and the like.

[0036] When the positive electrode active material contains nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, the capacity density of the all-solid-state battery 10 can be increased, and metal elution of the positive electrode active material in a charged state can be reduced. As a result, the cycle characteristics of the all-solid-state battery 10 in a charged state are improved. On the other hand, "cycle characteristics" refers to characteristics indicating the degree to which the all-solid-state battery 10 deteriorates due to charge / discharge of the all-solid-state battery 10. An all-solid-state battery 10 with high cycle characteristics has a small degree of deterioration caused by charge / discharge, while an all-solid-state battery 10 with low cycle characteristics may have a large degree of deterioration caused by charge / discharge.

[0037] The positive electrode active material can have particle shapes such as spheres or ellipsoids. The particle size and content of the positive electrode active material are not particularly limited. In one embodiment, the positive electrode active material may be in a polycrystalline form and may include secondary particles formed by the aggregation of at least three or more primary particles. In other words, one first particle may contain a plurality of primary particles NNPs aggregated together. The first particles may be spherical or ellipsoidal.

[0038] A solid electrolyte can be dispersed between the positive electrode active materials. The solid electrolyte dispersed between the positive electrode active materials may have a particulate shape. The solid electrolyte dispersed between the positive electrode active materials may include sulfide-based solid electrolytes with excellent lithium-ion conductivity characteristics. Examples of sulfide-based solid electrolytes include 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 and n are positive numbers, uppercase "Z" means one or all of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are positive numbers, the uppercase letter "M" is one of P, Si, Ge, B, Al, or Gain, or contains one of them), 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 can contain at least one of the (0 ≤ x ≤ 2) values.

[0039] Sulfide-based solid electrolytes include, for example, Li 7-x PS 6-x Clx (0≦x≦2), Li 7-x PS 6-x Br x (0≦x≦2), and Li 7-x PS 6-x I x The compound is an argyrodite-type compound containing one or more (0≦x≦2) elements, or may contain them. In particular, sulfide-based solid electrolytes may be argyrodite-type compounds containing one or more Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0040] Alternatively, a sulfide-based solid electrolyte is Li 7-a-c M a PS 6-c X c The compound may be an argyrodite-type compound containing (0≦a≦2, (0≦c≦2)), where X is at least one of F, Br, Cl, or a combination thereof, or may contain them. M is scandium (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 At least one of the following, or a combination thereof, is included: kel (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), and bismuth (Bi).

[0041] The density of the algyrodite-type solid electrolyte may range from approximately 1.5 g / cc to approximately 2.0 g / cc. Having a density of approximately 1.5 g / cc or higher for the algyrodite-type solid electrolyte reduces the internal resistance of the all-solid-state battery, inhibiting or preventing defects such as penetration and short circuits of the solid electrolyte membrane due to lithium dendrite formation. The elastic modulus of the solid electrolyte may range, for example, from approximately 15 GPa to approximately 35 GPa.

[0042] The solid electrolyte in the positive electrode active material layer 120 may have a smaller intermediate particle size average (D50) than the solid electrolyte in the solid electrolyte layer 300, which will be described later. For example, the intermediate particle size average (D50) of the solid electrolyte contained 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 intermediate particle size average (D50) of the solid electrolyte contained in the solid electrolyte layer 300. For example, the intermediate particle size average (D50) may be the median diameter measured using a laser particle size distribution analyzer.

[0043] The positive electrode active material layer 120 may contain a conductive material. The conductive material may enhance the conductivity of the positive electrode active material and solid electrolyte without causing a chemical change in the all-solid-state battery 10. The conductive material may contain a carbon-based material. The conductive material may contain one or more of the following: graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0044] The positive electrode active material layer 120 may further contain a binder. The binder can bond the positive electrode active material, solid electrolyte, and conductive material within the positive electrode active material layer 120 to each other. The binder may include a substance to improve the bonding force between the positive electrode active material layer 120 and the positive electrode current collector 110. The binder may include at least one of the following: styrene-styrene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, vinylidene fluoridene / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0045] When using 100 parts by weight of the total positive electrode active material, solid electrolyte, conductive material, and binder as a reference, the positive electrode active material layer 120 may contain approximately 70 parts by weight or more and approximately 92 parts by weight of positive electrode active material. When using 100 parts by weight of the total positive electrode active material, solid electrolyte, conductive material, and binder as a reference, the positive electrode active material layer 120 may contain approximately 0.5 parts by weight or more and approximately 1.5 parts by weight of binder.

[0046] When using 100 parts by weight of the solid electrolyte in the positive electrode active material layer 120 as a reference, the positive electrode active material layer 120 may contain approximately 1 part by weight or more and approximately 50 parts by weight or less of conductive material. If the conductive material is included in the positive electrode active material layer 120 in an amount less than 1 part by weight based on 100 parts by weight of the solid electrolyte in the positive electrode active material layer 120, the proportion of conductive material will decrease, which may reduce the electrical conductivity of the positive electrode active material layer 120. If the conductive material is included in the positive electrode active material layer 120 in an amount exceeding 50 parts by weight based on 100 parts by weight of the solid electrolyte in the positive electrode active material layer 120, the proportion of conductive material will be substantially or excessively high, which may prevent the coating layer covering the surface of the solid electrolyte from being properly formed.

[0047] In addition to the positive electrode active material, solid electrolyte, conductive material, and binder described above, the positive electrode active material layer 120 may further include at least one additive, such as a filler, coating agent, dispersant, or ion conductivity enhancer.

[0048] The negative electrode layer 200 may include a negative electrode current collector 210 and a coating layer 220 on the negative electrode current collector 210. The negative electrode current collector 210 can provide a reference surface on which the coating layer 220 is placed. The negative electrode current collector 210 may include a material that does not react with lithium, i.e., does not form alloys or compounds with lithium. For example, the negative electrode current collector 210 may include at least one metal such as copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The thickness of the negative electrode current collector 210 may be about 1 μm to about 20 μm, for example 5 μm to 15 μm, or for example 7 μm to 10 μm.

[0049] The negative electrode current collector 210 is a composite substrate CPS described later, or may include it.

[0050] The coating layer 220 can be configured to allow lithium metal to grow between the all-solid-state battery 10 and the negative electrode current collector 210 during charging. The coating layer 220 constitutes a protective layer for lithium metal while simultaneously reducing or suppressing the deposition and growth of lithium dendrites.

[0051] The coating layer 220 may contain metal and carbon materials. For example, the coating layer 220 may contain at least one metal, including gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), or at least one of these. The coating layer 220 may contain at least one carbon, including carbon black, acetylene black, furnace black, ketzen black, and graphene, or at least one of these. In one embodiment, the coating layer 220 may contain a mixture of carbon black and silver (Ag).

[0052] The coating layer 220 may further contain other additives in addition to metal and carbon. The coating layer 220 may further contain at least one additive, such as a binder, filler, coating agent, dispersant, and ion conductivity enhancer, or at least one of these.

[0053] The coating layer 220 may be less thick than the positive electrode active material layer 120. The thickness of the coating layer 220 may be, for example, in the range of 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 coating layer 220 may be, for example, in the range of approximately 1 μm to 20 μm, 2 μm to 10 μm, or 3 μm to 7 μm. If the thickness of the coating layer 220 is excessively thin, i.e., less than approximately 1 μm, lithium dendrites formed between the coating layer 220 and the negative electrode current collector 210 may cause the coating layer 220 to collapse, degrading the cycle characteristics of the all-solid-state battery 10. If the thickness of the coating layer 220 is excessively increased, i.e., greater than approximately 20 μm, the energy density of the all-solid-state battery 10 may decrease, and the internal resistance of the all-solid-state battery 10 due to the coating layer 220 may increase, degrading the cycle characteristics of the all-solid-state battery 10.

[0054] On the other hand, although not shown in the diagram, a carbon layer may be further included between the coating layer 220 and the solid electrolyte layer 300 to improve adhesion.

[0055] The solid electrolyte layer 300 may be provided between the positive electrode layer 100 and the negative electrode layer 200. The solid electrolyte layer 300 may contain a sulfide-based solid electrolyte having desired or improved lithium-ion conductivity characteristics. The solid electrolyte in the solid electrolyte layer 300 may be identical to or different from any one of the substances contained in the solid electrolyte in the positive electrode active material layer 120 described above.

[0056] The solid electrolyte layer 300 may include a first solid electrolyte layer 310 and a second solid electrolyte layer 320. The first solid electrolyte layer 310 may be adjacent to the positive electrode layer 100, and the second solid electrolyte layer 320 may be adjacent to the negative electrode layer 200.

[0057] The second solid electrolyte layer 320 may be in direct contact with the coating layer 220. Accordingly, the second solid electrolyte layer 320 can reduce or suppress lithium dendrites formed between the coating layer 220 and the negative electrode current collector 210. The second solid electrolyte layer 320 can effectively reduce or suppress negative electrode side reactions. Therefore, the cell performance of the all-solid-state battery 10 according to the present invention can be improved.

[0058] The solid electrolyte in the solid electrolyte layer 300 may have a particle shape such as a sphere or an ellipsoid.

[0059] The solid electrolyte in the solid electrolyte layer 300 may include a sulfide-based solid electrolyte. The solid electrolyte in the solid electrolyte layer 300 may be amorphous, crystalline, or in a state where these are mixed. Further, the solid electrolyte may contain 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 a material containing Li2S-P2S5 is used as the sulfide-based solid electrolyte material forming the solid electrolyte, the mixing molar ratio of Li2S to P2S5 (represented as Li2S:P2S5) is, for example, in a range from about 50:50 to about 90:10.

[0060] For example, the sulfide-based solid electrolyte may be 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 xThe compound is an argyrodite-type compound containing at least one of (0≦x≦2), or may contain such a compound. In particular, sulfide-based solid electrolytes are argyrodite-type compounds containing at least one of Li6PS5Cl, Li6PS5, Br, and Li6PS5I, or may contain such a compound.

[0061] Alternatively, a sulfide-based solid electrolyte is Li 7-a-c M a PS 6-c X c A compound of the argyrodite-type containing (0≦a≦2, (0≦c≦2)), or potentially containing such a compound. Here, X is at least one of F, Br, Cl, or a combination thereof, or potentially containing such a compound. M is scandium (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), At least one of 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, or potentially containing such elements.

[0062] The density of the algyrodite-type solid electrolyte may be in the range of approximately 1.5 g / cc to approximately 2.0 g / cc. Having a density of approximately 1.5 g / cc or higher for the algyrodite-type solid electrolyte reduces the internal resistance of the all-solid-state battery, inhibiting or preventing defects such as penetration and short circuits of the solid electrolyte membrane due to lithium dendrite formation. The elastic modulus of the solid electrolyte within the solid electrolyte layer 300 is, for example, in the range of approximately 15 GPa to approximately 35 GPa.

[0063] The solid electrolyte layer 300 may further contain a binder. The binder contained in the solid electrolyte layer 300 is, but is not limited to, at least one of the following: styrene-styrene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc. The binder of the solid electrolyte layer 300 may be the same as or different from the binder contained in the positive electrode active material layer 120 or the binder contained in the coating layer 220.

[0064] Referring again to Figure 2, the first solid electrolyte layer 310 may have a first thickness t1, and the second solid electrolyte layer 320 may have a second thickness t2. The solid electrolyte layer 300 may have a third thickness t3. The first thickness t1 and the second thickness t2 may be different from each other. The second thickness t2 may be greater than the first thickness t1.

[0065] While a thinner solid electrolyte layer 300 results in a higher energy density, it also makes it more difficult to reduce or suppress the formation of lithium dendrites within the negative electrode, increasing the likelihood of short circuits.

[0066] Solid electrolytes can have gaps at the interface between the electrodes and the electrolyte, which can act as interfacial resistance and potentially degrade battery performance.

[0067] Interfacial resistance can be reduced by pressurizing both the electrode and the solid electrolyte layer. In one embodiment, since sulfide-based solid electrolytes have high ionic conductivity and at the same time mechanically weak properties, an all-solid-state battery can be manufactured with improved interfacial resistance through pressurization.

[0068] In one embodiment, the positive electrode layer 120 and the negative electrode layer 220 may include a pressurization process in the manufacturing process. In one embodiment, the pressurization process may be carried out by applying different pressures to each of the positive electrode layer 120 and the negative electrode layer 220 during manufacturing. In one embodiment, the positive electrode layer 120 may be manufactured under a relatively higher pressure than the negative electrode layer 220. For example, by applying nanoscale particles to the positive and negative electrode active materials, the contact area with the solid electrolyte can be increased and the interfacial resistance can be improved. In one embodiment, the positive electrode active material may include secondary particles formed by the aggregation of at least three or more primary particles in a polycrystalline form, for reasons such as improved bonding force with the electrode plate, capacity characteristics, and lifetime characteristics. In this case, the interfacial resistance between the positive electrode layer 120 and the first solid electrolyte layer 310 is observed to be greater than the interfacial resistance between the negative electrode layer 220 and the second solid electrolyte layer 320, and the positive electrode laminate may be manufactured under a relatively higher pressure compared to the negative electrode laminate. However, without limitation, the positive electrode layer 120 and the negative electrode layer 220 can be manufactured through pressurization processes that apply different pressures to each for various reasons.

[0069] One embodiment of the present invention addresses process problems that may arise due to differences in interfacial resistance between the positive electrode layer 120 and the negative electrode layer 220 and the second solid electrolyte layer 320, by dividing the solid electrolyte 300 into a first solid electrolyte layer 310 and a second solid electrolyte layer 320. For example, an all-solid-state battery manufactured according to the all-solid-state battery manufacturing method described later can provide an all-solid-state battery manufactured by applying different pressures to the positive electrode stack and the negative electrode stack, respectively.

[0070] In one embodiment of the present invention, the solid electrolyte layer 300 is divided into a first solid electrolyte layer 310 and a second solid electrolyte layer 320, and the thickness of each is adjusted to be different, thereby increasing the energy density while reducing or suppressing the formation of lithium dendrites in the negative electrode. Therefore, an all-solid-state battery 10 with improved stability against short-circuit risk and shock, and high energy density can be provided.

[0071] The ratio of the second thickness t2 to the first thickness t1 (t2 / t1) can be in the range of approximately 1 to 20. For example, the ratio of the second thickness t2 to the first thickness t1 (t2 / t1) may be approximately 2 to approximately 15, approximately 4 to approximately 11, or approximately 4.5 to approximately 5.5. When the ratio of the second thickness t2 to the first thickness t1 (t2 / t1) is within the numerical range mentioned, it is possible to provide an all-solid-state battery 10 with high energy density, while reducing or suppressing the formation of lithium-lithium dendrites in the negative electrode, thereby improving stability against short-circuit risk and shock.

[0072] The first thickness t1 may be approximately 30 μm or less. For example, the first thickness t1 may be approximately 25 μm or less, approximately 20 μm or less, approximately 14 μm or less, or approximately 10 μm or less. The first thickness t1 may be approximately 0.1 μm or more. For example, the first thickness t1 may be approximately 1 μm or more, approximately 2 μm or more, approximately 4 μm or more, or approximately 5 μm or more. If the first thickness t1 exceeds approximately 30 μm in the numerical range mentioned, the energy density of the all-solid-state battery 10 may decrease. If the first thickness t1 does not reach approximately 1 μm in the numerical range mentioned, interface formation may be difficult because the first thickness t1 does not reach the diameter of the active material molecules in the positive electrode.

[0073] The second thickness t2 may be approximately 30 μm or more. For example, it may be approximately 35 μm or more, approximately 40 μm or more, approximately 45 μm or more, approximately 50 μm or more, approximately 55 μm or more, or approximately 60 μm or more. The second thickness t2 may be approximately 120 μm or less. For example, the second thickness t2 may be approximately 90 μm or less, or 60 μm or less. If the second thickness t2 does not reach the numerical range of approximately 30 μm mentioned, it may be difficult to reduce or suppress the formation of lithium-lithium dendrites in the negative electrode, and a short circuit may occur. If the second thickness t2 exceeds the numerical range of approximately 120 μm mentioned, the energy density of the all-solid-state battery 10 may decrease.

[0074] The third thickness t3 may be approximately 120 μm or less. For example, the third thickness t3 may be 90 μm or less, or 60 μm or less. The third thickness t3 may be 10 μm or more. For example, the third thickness t3 may be approximately 30 μm or more, or approximately 50 μm or more. If the third thickness t3 exceeds the numerical range of approximately 120 μm, the energy density of the all-solid-state battery 10 may decrease.

[0075] Referring to Figures 2 and 3, the areas of the positive electrode layer 100 and the negative electrode layer 200 can be different from each other. For example, the area of ​​the negative electrode layer 200 may be larger than the area of ​​the positive electrode layer 100. The positive electrode layer 100 can completely overlap the negative electrode layer 200.

[0076] In one embodiment of the present invention, the first solid electrolyte layer 310 may have substantially the same area as the positive electrode layer 100. The second solid electrolyte layer 320 may have substantially the same area as the negative electrode layer 200.

[0077] Referring to Figures 2 and 3, the first solid electrolyte layer 310 may have a first width W1 in the first direction D1. The second solid electrolyte layer 320 may have a second width W2 in the first direction D1. The first width W1 may be smaller than the second width W2.

[0078] The difference between the second width W2 and the first width W1 may be approximately 10 mm or less. For example, the difference between the second width W2 and the first width W1 may be approximately 8 mm or less, approximately 5 mm or less, or approximately 3 mm or less. The difference between the second width W2 and the first width W1 may be approximately 0.1 mm or more, approximately 0.5 mm or more, or approximately 1 mm or more. If the difference between the second width W2 and the first width W1 exceeds the above numerical range, the size of the positive electrode layer 100 becomes relatively smaller, which may result in a lower discharge capacity and a decrease in the energy density of the all-solid-state battery 10. If the difference between the second width W2 and the first width W1 does not reach the above numerical range, it may be difficult to reduce or suppress the formation of lithium-lithium dendrites in the negative electrode, and a short circuit may occur.

[0079] The ratio of the second width W2 to the first width W1, W2 / W1, can be approximately 1 to approximately 1.6. For example, the ratio of the second width W2 to the first width W1, W2 / W1, may be in the range of approximately 1 to approximately 1.5, approximately 1 to approximately 1.4, approximately 1 to approximately 1.3, approximately 1 to approximately 1.2, or approximately 1 to approximately 1.1.

[0080] If the ratio of the second width W2 to the first width W1 (W2 / W1) exceeds a certain numerical range, the energy density of the all-solid-state battery 10 may decrease.

[0081] Referring to Figures 2 and 3, the first solid electrolyte layer 310 may have a third width W3 in the second direction D2. The second solid electrolyte layer 320 may have a fourth width W4 in the second direction D2. The third width W3 may be smaller than the fourth width W4.

[0082] The difference between the third width W3 and the fourth width W4 may be approximately 10 mm or less. For example, the difference between the third width W3 and the fourth width W4 may be approximately 8 mm or less, approximately 5 mm or less, or approximately 3 mm or less. The difference between the fourth width W4 and the third width W3 may be approximately 0.1 mm or more, approximately 0.5 mm or more, or approximately 1 mm or more. If the difference between the third width W3 and the fourth width W4 exceeds the above numerical range, the size of the positive electrode layer 100 becomes relatively smaller, which may result in a lower discharge capacity and a decrease in the energy density of the all-solid-state battery 10. If the difference between the third width W3 and the fourth width W4 does not reach the above numerical range, it may be difficult to reduce or suppress the formation of lithium-lithium dendrites in the negative electrode, and a short circuit may occur.

[0083] The ratio of the fourth width W4 to the third width W3, W4 / W3, can be approximately 1 to approximately 1.6. For example, the ratio of the fourth width W4 to the third width W3, W4 / W3, may be approximately 1 to approximately 1.5, approximately 1 to approximately 1.4, approximately 1 to approximately 1.3, approximately 1 to approximately 1.2, or approximately 1 to approximately 1.1.

[0084] If the ratio of the fourth width W4 to the third width W3 (W4 / W3) exceeds the above numerical range, the energy density of the all-solid-state battery 10 will decrease.

[0085] Figure 4 is a cross-sectional view illustrating an all-solid-state battery according to another embodiment of the present invention. In this embodiment, detailed explanations of technical features that overlap with those previously described with reference to Figures 2 and 3 are omitted, and the differences are described in detail.

[0086] Referring to Figure 4, the negative electrode layer 200 of the all-solid-state battery 10 may further include a lithium metal layer 400 between the negative electrode current collector 210 and the coating layer 220. The thickness of the lithium metal layer 400 can be further increased during charging of the all-solid-state battery 10. The coating layer 220 constitutes a protective layer for the lithium metal layer 400 and at the same time can suppress the growth of lithium dendrites from the lithium metal layer 400.

[0087] The lithium metal layer 400 is a thin metal film containing or may contain lithium or a lithium alloy. Lithium alloys include, but are not limited to, Li-Al alloys, Li-Sn alloys, Li-In alloys, Li-Ag alloys, Li-Au alloys, Li-Zn alloys, Li-Ge alloys, Li-Si alloys, etc., and any alloy used in lithium alloys is acceptable. The lithium metal layer 400 may contain lithium or one of such alloys. Alternatively, the lithium metal layer 400 may contain various types of alloys.

[0088] The lithium metal layer 400 may have a fifth width W5 in a first direction D1. The fifth width W5 may be the same as or greater than the first width W1. The fifth width W5 may be the same as or less than the second width W2. In one embodiment, the fifth width W5 may be greater than the first width W1 and less than the second width W2.

[0089] The following describes a composite substrate for a deposition-type anode according to one embodiment of the present invention, an anode including the composite substrate, and a lithium secondary battery including the composite substrate.

[0090] Figure 5 is a cross-sectional view illustrating a deposition-type anode according to one embodiment.

[0091] Referring to Figure 5, the precipitated negative electrode NAL can include a composite substrate CPS and a coating layer CTL on the composite substrate CPS.

[0092] The coating layer CTL may be configured to facilitate the uniform or substantially uniform formation of the lithium layer on the composite substrate CPS. The lithium layer may be formed between the coating layer CTL and the composite substrate CPS.

[0093] In one embodiment, the coating layer CTL may be the coating layer 220 described above with reference to Figure 2. That is, the coating layer CTL may contain metal and carbon materials.

[0094] Figure 6 is a cross-sectional view illustrating a composite substrate according to one embodiment. Figure 7 is an enlarged view of region M in Figure 6 to illustrate the elastic layer.

[0095] Referring to Figure 6, the composite substrate CPS can include an elastic layer ELL and a metal layer MEL on the elastic layer ELL.

[0096] The elastic layer ELL can absorb the volume change (expansion) of the lithium secondary battery due to charging and discharging. For example, the elastic layer ELL can prevent damage to the electrolyte by easing the stress generated in accordance with the thickness change during charging and discharging.

[0097] Referring to Figures 6 and 7, the elastic layer ELL can include polymer foam (PLM) and carbon-based conductive material (CDM).

[0098] Polymer foam (PLM) is a porous structure containing polymers and multiple pores, which can mitigate thickness changes in lithium secondary batteries including a precipitate-type anode.

[0099] In one embodiment, the elastic layer ELL may have an average gradient of 100 MPa or less at a displacement corresponding to 80% of its initial thickness under conditions of 25°C. In another embodiment, the average gradient of the stress-displacement curve may be 50 MPa or less at a displacement corresponding to 80% of its initial thickness under conditions of 25°C, or it may be 10 MPa or less at a displacement corresponding to 50% of its initial thickness. Having an elastic modulus within this range can effectively mitigate thickness changes due to lithium deposition.

[0100] In one embodiment, the elastic layer ELL may be a material for the polymer foam PLM and may include at least one of polyurethane resins, polyolefin resins, silicone resins, and thermoplastic elastomers.

[0101] The polyurethane resin is a monopolymer or copolymer containing urethane groups, or may contain them. In one embodiment, the urethane groups may be derived from polyether polyols, polyester polyols, or polycarbonate polyols.

[0102] Polyolefin resins are monopolymers of polyethylene or polypropylene, copolymers thereof, or may contain them.

[0103] The silicone resin is a monopolymer or copolymer containing siloxane groups, or may contain them. In one embodiment, the silicone resin may contain at least one of polydimethylsiloxane (PDMS), polymethylphenylsiloxane, and polydiphenylsiloxane.

[0104] In one embodiment, the thermoplastic elastomer may include vulcanized rubber.

[0105] The carbon-based conductive material can electrically connect the metal layer MEL and the elastic layer ELL by forming conductive paths within the elastic layer ELL. Through this configuration, the external electrode and the composite substrate CPS can be electrically connected via the elastic layer ELL.

[0106] In one embodiment, the carbon-based conductive material CDM may include at least one of graphite, carbon nanotubes, graphene, and carbon fibers.

[0107] In one embodiment, the content of the carbon-based conductive material CDM in the elastic layer ELL may be in the range of about 10% to about 60% by weight. In another embodiment, the content of the carbon-based conductive material CDM in the elastic layer ELL may be about 10% to about 50% by weight, or about 30% to about 50% by weight. Within this range of conductive material CDM content, the electrical conductivity of the elastic layer ELL can be improved.

[0108] In one embodiment, the carbon-based conductive material CDM may include carbon nanotubes CNT. The carbon nanotubes may include at least one selected from the group consisting of single-walled carbon nanotubes SWCNT, multi-walled carbon nanotubes MWCNT, and thin-walled carbon nanotubes TWCNT.

[0109] In one embodiment, the specific surface area of the carbon nanotubes is about 300 m 2 / g to about 1600 m 2 / g. For example, it may be about 400 m 2 / g to about 1500 m 2 / g, may be about 400 m 2 / g to about 1200 m 2 / g, or may be about 500 m 2 / g to about 800 m 2 / g.

[0110] In one embodiment, the aspect ratio of the carbon nanotubes may range from about 10 to about 3,000. For example, the aspect ratio of the carbon nanotubes may range from about 10 to about 2,500, may range from about 20 to about 2,000, or may range from about 30 to about 1,500. The aspect ratio of a carbon nanotube may be calculated as the ratio of the length of the carbon nanotube to the diameter thereof.

[0111] In one embodiment, the average length of the carbon nanotubes may range from about 1 μm to about 1,000 μm. For example, the average length of the carbon nanotubes may range from about 10 μm to about 800 μm, may range from about 10 μm to about 500 μm, may range from about 20 μm to about 200 μm, or may range from about 20 μm to about 100 μm.

[0112] In one embodiment, the average diameter of the carbon nanotubes may range from about 2 nm to about 10 nm. For example, the average diameter of the carbon nanotubes may range from about 2 nm to about 8 nm, or may range from about 4 nm to about 6 nm.

[0113] The elastic layer ELL can ensure desired or improved electrical conductivity by containing the carbon-based conductive material CDM described above. In one embodiment, the electrical conductivity of the elastic layer ELL is approximately 1.0 × 10⁻⁶. -1 S / cm to approx. 1.0×10 2 The conductivity can be in the range of S / cm. The elastic layer ELL having an electrical conductivity within this range allows for a low-resistance electrical connection between the external system and the metal layer MEL through the tab region described later.

[0114] Figure 8 is an exploded perspective view illustrating a composite substrate according to one embodiment. Figure 9A is an exploded perspective view illustrating a composite substrate according to another embodiment. Figure 9B is a cross-sectional view of the composite substrate of Figure 9A.

[0115] Referring to Figures 8, 9A, and 9B, in one embodiment, the elastic layer ELL may include a tab region TR formed at one end. The composite substrate CPS can be electrically connected to an external system through the tab region TR. The external system can perform energy storage, transmission, or control functions by utilizing a lithium secondary battery containing the composite substrate CPS. In one embodiment, the external system may be or include an external power source, load device, external equipment, etc.

[0116] Referring to Figure 8, in one embodiment, the tab region TR can protrude in one direction. The method for forming the tab region TR is not particularly limited, and in one embodiment, the tab region TR can be formed by integrally notching the metal layer MEL and the elastic layer ELL of the composite substrate CPS.

[0117] In one embodiment, the composite substrate CPS may further include a metal tab MTB. The metal tab MTB can be attached to a tab region TR of the elastic layer ELL. The metal tab MTB can be electrically connected to the tab region TR. That is, the metal tab MTB can electrically connect the composite substrate CPS to an external system via the elastic layer ELL.

[0118] In one embodiment, the metal tab MTB may include at least one metal, which is copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), or at least one of these.

[0119] Referring again to Figure 6, in one embodiment, the metal layer MEL of the composite substrate CPS may include at least one of copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), aluminum (Al), or an alloy thereof.

[0120] In one embodiment, the ratio of the thickness of the metal layer MEL to the total thickness of the composite substrate CPS may be in the range of about 0.05 to about 0.2. Having a thickness in this range makes it possible to improve the energy density of the lithium secondary battery containing the composite substrate while ensuring its structural stability.

[0121] In one embodiment, the thickness of the metal layer MEL may be in the range of approximately 0.1 μm to approximately 10 μm.

[0122] Figure 10A is a cross-sectional view illustrating a unit cell of a lithium secondary battery according to one embodiment. Referring to Figure 10A, in one embodiment, the unit cell may be in a bicell BIC configuration. In one embodiment, the bicell BIC may have a configuration in which negative electrode layers NALa and NALb are arranged on both sides of a positive electrode layer PAL, respectively. For example, the bicell BIC may include a positive electrode layer PAL; a first electrolyte layer EELa on the lower surface of the positive electrode layer PAL; a first negative electrode layer NALa on the lower surface of the first electrolyte layer EELa; a second electrolyte layer ELLb on the upper surface of the positive electrode layer PAL; and a second negative electrode layer NALb on the upper surface of the second electrolyte layer ELLb.

[0123] The positive electrode layer PAL may include a positive electrode current collector COL; a first positive electrode active material layer AML1 on one surface of the positive electrode current collector COL; and a second positive electrode active material layer AML2 on the other surface of the positive electrode current collector. The positive electrode current collector COL is the same as the positive electrode current collector COL described above with reference to Figure 1. Each of the first and second positive electrode active material layers AML1 and AML2 is the same as the positive electrode active material layer AML described above with reference to Figure 1. Each of the first and second negative electrode layers NALa and NALb may be any one of the negative electrode layers NAL described above with reference to Figures 1 to 9B.

[0124] For example, the first negative electrode layer NALa may include a first composite substrate CPSa and a first coating layer CTLa formed on one surface of the first composite substrate CPSa (see Figure 10A). The first composite substrate CPSa may include a first elastic layer ELLa and a first metal layer MELa. The first elastic layer ELLa may additionally include a first metal tab MTBa. The second negative electrode layer NALb may include a second composite substrate CPSb and a second coating layer CTLb formed on one surface of the second composite substrate CPSb. The second composite substrate CPSb may include a second elastic layer ELLb and a second metal layer MELb. The second elastic layer ELLb may additionally include a second metal tab MTBb. The first composite substrate CPSa and the second composite substrate CPSb may be any one of the composite substrates CPS described above with reference to Figures 1 to 9B. The first and second electrolyte layers EELa and EELb are each the same as the electrolyte layer EEL described above with reference to Figure 1.

[0125] The elastic layers ELLa and ELLb of the first negative electrode layer NALa and the second negative electrode layer NALb can absorb the volume change (expansion) of the lithium secondary battery due to charging and discharging. Therefore, no other elastic material is required.

[0126] Figure 10B is a cross-sectional view illustrating a stacked-cell lithium secondary battery according to one embodiment. Referring to Figure 10B, the stacked cell STC can include a plurality of bicells BIC as described above with reference to Figure 10A. For example, it can include a first bicell BICa; a second bicell BICb on the first bicell BICa; and a third bicell BICc on the second bicell BICb. Each of the first to third bicells BICa, BICb, and BICc can absorb the volume change (expansion) of the lithium secondary battery due to charging and discharging by including the elastic layer described above. Therefore, another elastic member may not be necessary.

[0127] The following describes a method for manufacturing a composite substrate according to an embodiment of the present invention. Figures 11 to 14 are cross-sectional views illustrating a composite substrate manufacturing method according to one embodiment.

[0128] Referring to Figure 11, a polymer solution POS can be prepared for the production of the elastic layer ELL. The polymer solution POS may contain a polymer precursor. In one embodiment, the polymer precursor may contain at least one of a polymer monomer MNO and a prepolymer.

[0129] In one embodiment, the polymer monomer MNO may be at least one monomer selected from a monomer for polyurethane resins, a monomer for polyolefin resins, a monomer for silicone resins, and a monomer for thermoplastic elastomers.

[0130] In one embodiment, the prepolymer may be at least one prepolymer selected from prepolymers for polyurethane resins, prepolymers for polyolefin resins, prepolymers for silicone resins, and prepolymers for thermoplastic elastomers. In one embodiment, the polymer solution POS may contain at least one prepolymer selected from polyether polyols, polyester polyols, and polycarbonate polyols.

[0131] In one embodiment, the polymer solution POS may further contain a crosslinking agent. In one embodiment, the crosslinking agent may include at least one of isocyanates, peroxides, and silane crosslinking agents. The peroxide may be, for example, dicumyl peroxide (DCP) or benzoyl peroxide (BPO). The silane crosslinking agent may be, for example, methyltriethoxysilane (MTES) or vinyltriethoxysilane (VTES).

[0132] In one embodiment, the polymer solution POS may further contain a polymerization initiator. In one embodiment, the polymerization initiator may include at least one of a thermal polymerization initiator or a photopolymerization initiator.

[0133] In one embodiment, the polymer solution POS may further contain a blowing agent. In one embodiment, the blowing agent may include at least one of water, carbon dioxide, nitrogen, and an azo-based blowing agent.

[0134] In one embodiment, the polymer solution POS may further contain a carbon-based conductive material.

[0135] In one embodiment, the carbon-based conductive material CDM may include at least one of graphite, carbon nanotubes, graphene, and carbon fibers.

[0136] The carbon-based conductive material CDM can be uniformly or substantially uniformly dispersed in a polymer foam produced by adding the carbon-based conductive material CDM together with a polymer solution POS. Through this, the electronic conductivity of the composite substrate can be improved.

[0137] By reacting materials within a polymer solution (POS), an elastic layer (ELL) can be formed.

[0138] Although not shown in the figures, the elastic layer of the composite substrate CPS according to the embodiment of the present invention may be manufactured by injection molding. For example, it can be manufactured by injecting at least one of polyurethane resin, polyolefin resin, silicone resin, and thermoplastic elastomer into an injection molding machine together with a foaming agent and a carbon-based conductive material. As a result, the elastic layer ELL can be formed.

[0139] In one embodiment, the carbon-based conductive material may include at least one of graphite, carbon nanotubes, graphene, and carbon fibers. For example, the carbon-based conductive material may include at least one of carbon nanotubes and graphene. The carbon nanotubes and graphene have desired or improved thermal stability and electronic conductivity.

[0140] Referring to Figures 12 and 13, a composite substrate CPS can be manufactured by forming a metal layer MEL on one surface of the elastic layer ELL. In one embodiment, a metal layer MEL can be formed by depositing metal onto one surface of the elastic layer ELL. The metal layer MEL can be formed on one surface of the elastic layer ELL by physical or chemical deposition.

[0141] Referring to Figure 14, a metal tab MTB can be formed at one end of the elastic layer ELL.

[0142] In one embodiment, a metal tab MTB can be attached to the tab region TR of the elastic layer ELL described above, with reference to Figures 8 and 9A. In another embodiment, a metal tab MTB can be attached to the tab region TR using an adhesive composition comprising a binder and a conductive material. The binder may include the positive or negative electrode binder described above. The adhesive composition may include the carbon-based conductive material described above.

[0143] Examples and comparative examples of the present invention are described below. However, the examples described below are merely one embodiment of the present invention, and the present invention is not limited to the examples described below.

[0144] Example 1 (composite base material) As a carbon-based conductive material, it has a wall thickness of approximately 1.0 nm and a specific surface area of ​​600 m². 2 Thin-walled carbon nanotubes (TWCNTs) with a density of / g and an aspect ratio of 120 were used.

[0145] Thermoplastic polyurethane (BASF, 1185A10FHF) and a carbon-based conductive material were injected into an injection molding machine in a weight ratio of 9:1. Then, nitrogen gas was used as a foaming agent to produce an elastic layer ELL with a thickness of approximately 50 μm.

[0146] Subsequently, a thin copper film was deposited on the upper surface of the elastic layer ELL to form a metal layer with a thickness of 8 μm. In other words, a composite substrate with a total thickness of approximately 58 μm was manufactured.

[0147] (Precipitation-type negative electrode) A coating layer slurry was prepared by mixing carbon black (CB) with a primary particle size of approximately 30 nm and silver (Ag) particles with an average particle size (D50) of approximately 60 nm in water in a weight ratio of 3:1. The coating layer slurry was applied to the metal layer of the composite substrate prepared above and dried to form a coating layer (CTL) with a thickness of approximately 7 μm. In other words, a composite substrate (CPS) and a deposition-type anode with a coating layer (CTL) formed on the composite substrate (CPS) were manufactured.

[0148] (positive electrode) A positive electrode slurry was prepared by mixing 98.5% by weight of large lithium cobalt oxide (LiCoO2, LCO) particles with an average particle size of approximately 12 μm, 1.0% by weight of a PVDF binder, and 0.5% by weight of a conductive material (carbon nanotubes) in an N-methylpyrrolidone solvent. The positive electrode slurry was applied to an aluminum current collector, dried, and rolled to produce the positive electrode. The positive electrode slurry was approximately 20 g / cm³. 2 The material was applied to the current collector to have a loading level. Rolling was carried out using a rolling mill so that the total thickness of the current collector and the positive electrode active material layer AML1 was approximately 62.5 μm.

[0149] (solid electrolyte membrane) A mixture was prepared by mixing polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) with a Li6PS5Cl sulfide-based solid electrolyte (D50=3μm, crystalline), which is an argyrodite-type crystalline material. After stirring the mixture to produce a dough, the prepared dough was passed through rollers to form a sheet. The thickness of the solid electrolyte film was approximately 70μm.

[0150] (Lithium secondary battery including a deposition-type negative electrode) After sequentially stacking the deposited negative electrode, solid electrolyte membrane, and positive electrode manufactured as described above, a lithium secondary battery was manufactured by pressing them into a flat plate at a pressure of 500 MPa.

[0151] Example 2 The negative electrode, positive electrode, solid electrolyte membrane, and lithium secondary battery were manufactured using the same method as in Example 1, except that the thermoplastic polyurethane (BASF, 1185A10FHF) and carbon-based conductive material were mixed in a weight ratio of 7:3 during the production of the elastic layer.

[0152] Example 3 The negative electrode, positive electrode, solid electrolyte membrane, and lithium secondary battery were manufactured using the same method as in Example 1, except that the thermoplastic polyurethane (BASF, 1185A10FHF) and carbon-based conductive material were mixed in a 5:5 weight ratio during the production of the elastic layer.

[0153] Example 4 The negative electrode, positive electrode, solid electrolyte membrane, and lithium secondary battery were manufactured using the same method as in Example 1, except that the thermoplastic polyurethane (BASF, 1185A10FHF) and carbon-based conductive material were mixed in a weight ratio of 4:6 during the production of the elastic layer.

[0154] Comparative Example 1 The negative electrode, positive electrode, solid electrolyte membrane, and lithium secondary battery were manufactured using the same method as in Example 1, except that poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS), a conductive polymer, was used instead of a carbon-based conductive material during the production of the elastic layer.

[0155] Evaluation Example 1: DC-iR Measurement The DC-iR of lithium secondary batteries (all-solid-state batteries) manufactured according to Examples 1 to 4 and Comparative Example 1 was measured. 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% of its total charge capacity, which in the context of discharge means 80% discharge) was measured. The DC internal resistance (DC-iR) was calculated from these results and is shown in Table 1.

[0156] Evaluation Example 2: Lifespan Evaluation Lithium secondary batteries (all-solid-state batteries) manufactured according to Examples 1 to 4 and Comparative Example 1 were placed in a test module and fixed with a force of 5000 gf. Initial charge-discharge was performed by charging to an upper voltage limit of 4.25 V with a constant current of 0.1 C at 45°C, and then discharging to a cutoff voltage of 2.5 V at 0.1 C. The batteries that underwent initial charge-discharge were repeatedly charged and discharged at 0.33 C in a voltage range of 2.5 V to 4.25 V at 45°C, and the lifespan was defined as the number of cycles at which the discharge capacity ratio to the initial discharge capacity decreased to less than 80%. The results are shown in Table 1 below.

[0157] [Table 1]

[0158] Referring to Table 1, it can be confirmed that the lithium secondary battery according to the embodiment has low internal resistance and a desired or improved lifespan by using carbon-based conductive material TWCNTs as the conductive material in the elastic layer of the composite substrate.

[0159] Lithium secondary batteries containing a deposited negative electrode undergo volume changes during charging and discharging. The composite substrate according to this disclosure can reduce such volume changes by including an elastic layer. Furthermore, unlike conventional substrates made solely of metal, the inclusion of an elastic layer allows for a lower density of the composite substrate, thereby improving the energy density of the battery. Moreover, since the composite substrate further contains a conductive material, the decrease in conductivity associated with the introduction of the elastic layer can be reduced or prevented. The lithium secondary battery according to this disclosure, by including the composite substrate, has desired or improved characteristics, including superior conductivity and cycle characteristics.

[0160] While this disclosure is described with reference to preferred embodiments, it should be understood that these embodiments are for illustrative purposes only and do not limit the scope of this disclosure. Various modifications and equivalent configurations are possible without departing from the spirit and scope of the appended claims. Therefore, the embodiments described should be considered as examples only and not as limitations on this disclosure. [Explanation of Symbols]

[0161] 10 All-solid-state battery 100 Positive electrode layer 110 Positive electrode current collector 120 Cathode active material layer 200 Negative electrode layer 210 Negative electrode current collector 220 Coating layer 300 solid electrolyte layer 310 First solid electrolyte layer 320 Second solid electrolyte layer 400 Lithium metal layer AML positive electrode active material layer CDM carbon-based conductive material COL positive electrode current collector CPS composite substrate CTL coating layer EEL electrolyte layer ELL elastic layer MEL metal layer MTB Metal Tab NAL negative electrode layer PAL positive electrode layer PLM polymer foam TR tab area

Claims

1. Elastic layer, The elastic layer includes a metal layer, The elastic layer comprises a polymer foam and a carbon-based conductive material, and is a composite substrate for a deposition-type anode.

2. The composite substrate for a precipitate-type anode according to claim 1, wherein the polymer foam comprises at least one of a polyurethane resin, a polyolefin resin, a silicone resin, and a thermoplastic elastomer.

3. The carbon-based conductive material comprises at least one of graphite, carbon nanotubes, graphene, and carbon fibers, as described in claim 1, for a composite substrate for a deposition-type anode.

4. The composite substrate for a precipitate-type anode according to claim 1, wherein the content of the carbon-based conductive material in the elastic layer is 10% by weight to 60% by weight.

5. The composite substrate for a deposition-type anode according to claim 1, wherein the ratio of the thickness of the metal layer to the total thickness of the composite substrate is in the range of 0.05 to 0.

2.

6. The electrical conductivity of the elastic layer is 1.0 × 10 -1 S / cm to 1.0×10 2 A composite substrate for a precipitate-type anode according to claim 1, wherein the S / cm range is...

7. The present invention further includes a metal tab attached to the elastic layer, The composite substrate for a deposition-type anode according to claim 1, wherein the elastic layer electrically connects the metal layer to an external system connected to the metal tab.

8. The composite substrate for a deposition-type anode according to claim 7, wherein the elastic layer includes a tab region formed at one end, and the metal tab is attached to the tab region.

9. Composite substrate and The composite substrate includes a coating layer, The composite substrate includes an elastic layer and a metal layer on the elastic layer, The elastic layer comprises a polymer foam and a carbon-based conductive material, and is a precipitate-type anode.

10. The deposition-type anode according to claim 9, wherein the polymer foam comprises at least one of polyurethane resin, polyolefin resin, silicone resin, and thermoplastic elastomer.

11. The deposition-type anode according to claim 9, wherein the carbon-based conductive material comprises at least one of graphite, carbon nanotubes, graphene, and carbon fibers.

12. The precipitate-type anode according to claim 9, wherein the content of the carbon-based conductive material in the elastic layer is in the range of 10% by weight to 60% by weight.

13. The present invention further includes a metal tab attached to the elastic layer, The deposition-type negative electrode according to claim 9, wherein the metal tab electrically connects the external circuit and the metal layer through the elastic layer.

14. The deposition-type anode according to claim 9, wherein the ratio of the thickness of the metal layer to the total thickness of the composite substrate is in the range of 0.05 to 0.

2.

15. The electrical conductivity of the elastic layer is 1.0 × 10 -1 S / cm to 1.0×10 2 A deposition-type anode according to claim 9, wherein the S / cm range.

16. The aforementioned coating layer is At least one metal from among gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), A precipitate-type anode according to claim 9, comprising at least one carbon material selected from carbon black, acetylene black, furnace black, Ketzen black, and graphene.

17. The positive electrode layer, A precipitate-type negative electrode layer, The electrolyte layer is interposed between the positive electrode layer and the negative electrode layer, The negative electrode layer includes a composite substrate, The composite substrate includes an elastic layer and a metal layer on the elastic layer, The elastic layer comprises a polymer foam and a carbon-based conductive material, in a lithium secondary battery.

18. The polymer foam comprises at least one of polyurethane resins, polyolefin resins, silicone resins, and thermoplastic elastomers. The lithium secondary battery according to claim 17, wherein the carbon-based conductive material comprises at least one of graphite, carbon nanotubes, graphene, and carbon fibers.

19. The lithium secondary battery according to claim 17, wherein the content of the carbon-based conductive material in the elastic layer is in the range of 10% by weight to 60% by weight.

20. The lithium secondary battery according to claim 17, wherein the electrolyte layer comprises a sulfide-based solid electrolyte.

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