Negative electrode for secondary battery and all-solid-state battery comprising same

Abstract

The present invention relates to a negative electrode for a secondary battery, comprising: a negative electrode current collector; a functional layer coating the surface of the negative electrode current collector; and an electrodeposition layer disposed on the functional layer, wherein the functional layer contains conductive carbon, and the functional layer is configured to stabilize the interface with the electrodeposition layer. The electrodeposition layer comprises: an amorphous carbon matrix; and composite particles dispersed in the amorphous carbon matrix and containing crystalline carbon.

Description

Anode for secondary battery and all-solid-state battery containing same

[0001] It's about all-solid-state batteries.

[0002] Recent industrial demands have led to the active development of batteries with high energy density and safety. Recently, all-solid-state batteries, which replace the electrolyte with a solid electrolyte, have been proposed. All-solid-state batteries are made by laminating a cathode, solid electrolyte, and anode, then pressurizing and densifying them. These batteries utilize solid electrolytes instead of the electrolytes found in conventional secondary batteries. By eliminating the use of flammable organic dispersion media, all-solid-state batteries significantly reduce the risk of fire or explosion in the event of a short circuit. Consequently, these all-solid-state batteries can exhibit high safety.

[0003] One embodiment provides a negative electrode for a secondary battery capable of stabilizing an interface of a lithium metal layer grown during charging and an all-solid-state battery including the same.

[0004] One embodiment provides a negative electrode for a secondary battery capable of suppressing dendrite growth of lithium metal on the negative electrode surface and an all-solid-state battery including the same.

[0005] According to one embodiment, a negative electrode for a secondary battery may include: an negative electrode current collector; a functional layer coating a surface of the negative electrode current collector; and an electrodeposition layer disposed on the functional layer. The functional layer may include conductive carbon. The functional layer may be configured to stabilize an interface between the electrodeposition layer and the functional layer. The electrodeposition layer may include an amorphous carbon matrix; and composite particles dispersed within the amorphous carbon matrix and including crystalline carbon.

[0006] According to another embodiment, an all-solid-state battery may include a positive electrode layer; a negative electrode layer facing the positive electrode layer; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer. The negative electrode layer may include a negative electrode current collector; a functional layer coating a surface of the negative electrode current collector; and an electrodeposition layer on the functional layer. The functional layer may include conductive carbon. The electrodeposition layer may include an amorphous carbon matrix.

[0007] The above-mentioned electrodeposition layer may further include composite particles dispersed within the amorphous carbon matrix and including crystalline carbon.

[0008] According to another embodiment, an all-solid-state battery may include a positive electrode layer; a negative electrode layer facing the positive electrode layer; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer. The negative electrode layer may include a negative electrode current collector; a first functional layer coating a surface of the negative electrode current collector; an electrodeposition layer on the first functional layer; and a second functional layer on the electrodeposition layer. Each of the first functional layer and the second functional layer may include conductive carbon. The electrodeposition layer may include an amorphous carbon matrix and composite particles dispersed within the amorphous carbon matrix and including crystalline carbon.

[0009] According to one embodiment, a negative electrode for a secondary battery can stabilize the interface of a lithium metal layer grown during charging by coating a functional layer on the surface of a negative electrode current collector.

[0010] A negative electrode for a secondary battery according to one embodiment can suppress internal short circuits of the battery by suppressing dendrite growth of lithium metal on the surface.

[0011] An all-solid-state battery according to one embodiment can minimize electrolyte deterioration and uneven lithium growth due to high interfacial energy by blocking direct contact between lithium and a solid electrolyte and lithium and a negative electrode current collector.

[0012] Figure 1 is a plan view of an all-solid-state battery according to one embodiment.

[0013] Figure 2 is a front view of an all-solid-state battery according to one embodiment.

[0014] Figure 3 is a front view of an all-solid-state battery according to another embodiment.

[0015] Figure 4 is a cross-sectional view of a negative electrode for a secondary battery according to one embodiment.

[0016] Figures 5 to 9 are cross-sectional views of a negative electrode for a secondary battery according to another embodiment.

[0017] Figures 10 to 16 are cross-sectional views of an all-solid-state battery according to another embodiment.

[0018] Figures 17 and 18 are SEM photographs of cross-sections of cathodes according to comparative examples.

[0019] Figures 19 and 20 show 2 mAh cm -2 These are SEM photographs of the electrodeposited layer of the negative electrode according to the examples and comparative examples when lithium deposition was performed.

[0020] Figures 21 and 22 are graphs showing the cycle characteristics of all-solid-state batteries of examples and comparative examples.

[0021] To fully understand the structure and effects of the present invention, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various forms and subject to various modifications. However, the description of these embodiments is provided solely to ensure a complete disclosure of the present invention and to fully inform those skilled in the art of the invention of the scope of the invention.

[0022] In this specification, when a component is referred to as being on another component, it means that it can be formed directly on the other component, or a third component may be interposed between them. Furthermore, in the drawings, the thicknesses of the components are exaggerated for the sake of clarity. Parts designated by the same reference numerals throughout the specification represent the same components.

[0023] Embodiments described herein will be described with reference to cross-sectional and / or plan views, which are ideal illustrations of the present invention. In the drawings, the thicknesses of films and regions are exaggerated for the purpose of effectively explaining the technical contents. Accordingly, the regions illustrated in the drawings have a schematic nature, and the shapes of the regions illustrated in the drawings are intended to illustrate specific shapes of regions of the device and are not intended to limit the scope of the invention. Although terms such as first, second, and third are used to describe various components in various embodiments of the present specification, these components should not be limited by such terms. These terms are used only to distinguish one component from another. The embodiments described and illustrated herein also include complementary embodiments thereof.

[0024] Unless otherwise specified herein, the singular may also include the plural. Furthermore, unless otherwise specified, "A or B" may mean "including A, including B, or including A and B." As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components.

[0025] As used herein, “combination thereof” may mean mixtures, laminates, composites, copolymers, alloys, blends, and reaction products of the components.

[0026] Unless otherwise defined herein, the particle size may be the average particle size. In addition, the particle size refers to the average particle size (D50), which means the diameter of particles with a cumulative volume of 50% by volume in a particle size distribution. The average particle size (D50) can be measured by a method well known to those skilled in the art, for example, by measuring with a particle size analyzer, or by measuring with a transmission electron microscope (TEM) photograph or a scanning electron microscope (SEM) photograph. Alternatively, the average particle size (D50) value can be obtained by measuring with a measuring device that utilizes dynamic light-scattering, performing data analysis to count the number of particles for each particle size range, and calculating from the counted number. Alternatively, the average particle size (D50) value can be obtained by measuring with a laser diffraction method. When measuring by laser diffraction, more specifically, after the particles to be measured are dispersed in a dispersion medium, they are introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000) and irradiated with ultrasonic waves of approximately 28 kHz at an output of 60 W, and the average particle size (D50) based on 50% of the particle size distribution in the measuring device can be calculated.

[0027] Fig. 1 is a plan view of an all-solid-state battery according to embodiments of the present invention. Fig. 2 is a cross-sectional view taken along line A-A' of Fig. 1.

[0028] Referring to FIGS. 1 and 2, the all-solid-state battery (10) according to the present invention 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, the present invention is not limited thereto, and 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).

[0029] A positive electrode layer (100) according to one embodiment of the present invention may include a positive electrode current collector (110) and a positive electrode active material layer (120) disposed on the positive electrode current collector (110). 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 arranged. The positive electrode current collector (110) can include a plate or foil including, 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 an alloy thereof.

[0031] Meanwhile, unlike that illustrated in FIG. 2, in one embodiment of the present invention, the positive electrode current collector (110) may be omitted. Although not illustrated, a carbon layer having a thickness of 0.1 μm to 4 μm may be additionally disposed between the positive electrode current collector (110) and the positive electrode active material layer (120) to increase the bonding strength between the positive electrode current collector (110) and the positive electrode active material layer (120).

[0032] The positive electrode active material of the positive electrode active material layer (120) may include a material that can reversibly absorb and desorb lithium ions. The positive electrode active material may include a plurality of particles. The positive electrode 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, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but is not necessarily limited thereto. The positive electrode active materials may be each alone or may be a mixture of two or more types.

[0033] Lithium transition metal oxides include, 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), Li a Ni 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 Ni 1-b-cMn 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-fA compound represented by any one of Fe2(PO4)3(0≤f≤2), LiFePO4. In these compounds, the capital letter “A” is Ni, Co, Mn, or a combination thereof, the capital letter “B” is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof, the capital letter “D” is O, F, S, P, or a combination thereof, the capital letter “E” is Co, Mn, or a combination thereof, the capital letter “F” is F, S, P, or a combination thereof, the capital letter “G” is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof, the capital letter “Q” is Ti, Mo, Mn, or a combination thereof, the capital letter “I” is Cr, V, Fe, Sc, Y, or a combination thereof, and the capital letter “J” is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0034] 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 atomic layers and metal atomic layers are alternately and regularly arranged in a direction, and thereby each atomic layer forms a two-dimensional plane. The "cubic rock salt structure" refers to the sodium chloride type (NaCl type) structure, which is a type of crystal structure, and specifically refers to a structure in which the face-centered cubic lattice (fcc) formed by each cation and anion is arranged with a displacement of half of the ridge of the unit lattice. Lithium transition metal oxides having this layered rock salt structure include, 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. 양극 활물질이 층상암염형 구조를 갖는 삼원계 리튬전이금속산화물을 포함하는 경우, 전고체 전지(10)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0035] The above-described compound included in the positive electrode active material may be covered by a coating layer (not shown). The positive electrode active material may also be a mixture of the above-described compound and a compound to which a coating layer is added. Meanwhile, the coating layer added to the surface of the positive electrode active material may include, for example, an oxide, a hydroxide, an oxyhydroxide, an oxycarbonate, or a hydroxycarbonate of the coating elements below. The compound forming the coating layer is 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 positive electrode active material. The method for forming the coating layer includes, for example, spray coating, dipping, etc.

[0036] When the positive electrode active material includes nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, for example, the capacity density of the all-solid-state battery (10) can be increased, thereby reducing metal dissolution of the positive electrode active material in a charged state. As a result, the cycle characteristics of the all-solid-state battery (10) in a charged state are improved. Meanwhile, the "cycle characteristics" are characteristics indicating the degree to which the all-solid-state battery (10) is deteriorated by charge / discharge of the all-solid-state battery (10). An all-solid-state battery (10) with high cycle characteristics may have a small degree of deterioration of the all-solid-state battery (10) due to charge / discharge, and an all-solid-state battery (10) with low cycle characteristics may have a large degree of deterioration of the all-solid-state battery (10) due to charge / discharge.

[0037] The positive electrode active material may have a particle shape such as a sphere or an ellipsoid, for example. The particle size and content of the positive electrode active material are not particularly limited.

[0038] The solid electrolyte of the positive electrode active material layer (120) may have a particle shape. The solid electrolyte may be dispersed between the positive electrode active materials. The solid electrolyte may include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. Examples of the sulfide-based solid electrolyte include Li2S-P2S5, Li2S-P2S5-LiX (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, Li2S-P2S5-Z m S n (m, n are positive numbers, capital letter “Z” represents Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p, q are positive numbers, capital letter “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).

[0039] Sulfide-based solid electrolytes include, 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-xPS 6-x I x It may be an argyrodite-type compound including at least one selected from (0≤x≤2). In particular, the sulfide-based solid electrolyte may be an argyrodite-type compound including at least one selected from Li3PS4Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0040] Alternatively, the sulfide-based solid electrolyte is Li 7-a M a PS 6-c X c It may be an argyrodite-type compound containing (0≤a≤2, (0≤c≤2)), where X may be F, Br, Cl, or a combination thereof. M is 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. Can be.

[0041] The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the solid electrolyte may be, for example, 15 GPa to 35 GPa.

[0042] The solid electrolyte in the positive electrode active material layer (120) may have a smaller average particle diameter than the first and second solid electrolytes in the solid electrolyte layer (300) described later. For example, the average particle diameter of the solid electrolyte 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 diameter of the solid electrolyte in the solid electrolyte layer (300). Meanwhile, the average particle diameter may be a median diameter measured using a laser particle size distribution meter.

[0043] The positive electrode active material layer (120) may include a conductive material. The conductive material may have conductivity without causing a chemical change in the all-solid-state battery (10), thereby increasing the conductivity of the positive electrode 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.

[0044] The positive electrode active material layer (120) may further include a binder. The binder may bind the positive electrode active material, the solid electrolyte, and the conductive material within the positive electrode active material layer (120) to each other. The binder may include a material for improving the bonding strength between the positive electrode active material layer (120) and the positive electrode 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.

[0045] Based on 100 parts by weight of the total of the positive electrode active material, the solid electrolyte, the conductive material, and the binder, the positive electrode active material layer (120) may include 85 parts by weight or more and 92 parts by weight or less of the positive electrode active material. Based on 100 parts by weight of the total of the positive electrode active material, the solid electrolyte, the conductive material, and the binder, the positive electrode active material layer (120) may include 0.5 parts by weight or more and 1.5 parts by weight or less of the binder.

[0046] Based on 100 parts by weight of the solid electrolyte, the positive electrode active material layer (120) may include 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 electrode active material layer (120) in an amount of less than 1 part by weight based on 100 parts by weight of the solid electrolyte, the proportion of the conductive material may decrease, thereby lowering 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 of more than 50 parts by weight based on 100 parts by weight of the solid electrolyte, the proportion of the conductive material may be excessively high, so that a covering layer covering the surface of the solid electrolyte may not be properly formed.

[0047] The positive electrode active material layer (120) may further include additives such as fillers, coating agents, dispersants, and ion conductive aids in addition to the above-described positive electrode active material, solid electrolyte, conductive agent, and binder.

[0048] The negative electrode layer (200) may include a negative electrode current collector (210) and an electrodeposition layer (220) on the negative electrode current collector (210). The negative electrode current collector (210) may provide a reference surface on which the electrodeposition layer (220) is disposed. The negative electrode current collector (210) may include, for example, a material that does not react with lithium, i.e., does not form an alloy or a compound 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.

[0049] The negative electrode current collector (210) may be composed of one of the above-described metals, or may include an alloy or coating material of two or more metals. The negative electrode current collector (210) may have, for example, a plate shape or a foil shape. Meanwhile, in one embodiment, the negative electrode current collector (210) may be omitted.

[0050] The electrodeposition layer (220) can allow lithium metal to grow inside the electrodeposition layer (220) when the all-solid-state battery (10) is charged. The electrodeposition layer (220) can act as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0051] The electrodeposition layer (220) may include a metal and carbon. For example, the electrodeposition 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 electrodeposition layer (220) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In one embodiment, the electrodeposition layer (220) may include a mixture of carbon black and silver (Ag).

[0052] The electrodeposition layer (220) may further include additives other than metal and carbon. For example, the electrodeposition layer (220) may further include at least one additive selected from the group consisting of a binder, a filler, a coating agent, a dispersant, and an ion-conducting aid.

[0053] The binder included in the above-described deposition layer (220) may include at least one of styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride (PVDF), polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0054] The binder may be included in an amount of 1 to 30 parts by weight based on 100 parts by weight of the electrodeposition layer (220). For example, the binder may be included in an amount of 5 to 15 parts by weight based on 100 parts by weight of the electrodeposition layer (220).

[0055] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the electrodeposition layer (220) and the solid electrolyte layer (300).

[0056] A 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 include a sulfide-based solid electrolyte having excellent lithium ion conductivity characteristics. The solid electrolyte in the solid electrolyte layer (300) may be the same as or different from any one of the materials included in the solid electrolyte in the positive electrode active material layer (120) described above.

[0057] 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).

[0058] Referring to FIG. 2, the first solid electrolyte layer (310) may include a first solid electrolyte. The first solid electrolyte may have a particle shape such as a sphere or an ellipsoid. The first solid electrolyte may include a sulfide-based solid electrolyte. The first solid electrolyte may be amorphous, crystalline, or a mixture thereof. In addition, the solid electrolyte may include, for example, at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements among the above-described sulfide-based solid electrolyte materials. For example, the solid electrolyte may be a material including Li2S-P2S5. When using a sulfide-based solid electrolyte material including Li2S-P2S5 to form the solid electrolyte, the mixing molar ratio of Li2S and P2S5 is, for example, in the range of Li2S:P2S5=50:50 to 90:10.

[0059] In one embodiment, the first solid electrolyte is 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 first solid electrolyte may include an argyrodite-type compound including at least one selected from (0≤x≤2). The first solid electrolyte may include an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0060] In another embodiment, the first solid electrolyte is Li 7-a M a PS 6-c X c Argyrodite-type compounds may include, wherein X may be Cl, Br, or a combination thereof. M may be Na, K, Fe, Mg, Ca, Ag, Cu, Zr, Zn, or a combination thereof. Each of a and c may be a real number between 0 and 2.

[0061] The density of the argyrodite-type solid electrolyte may be 1.5 g / cc to 2.0 g / cc. When the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state battery is reduced, and the defect of the solid electrolyte membrane being penetrated and short-circuited due to the formation of lithium dendrites can be prevented. The elastic modulus of the first solid electrolyte is, for example, 15 GPa to 35 GPa.

[0062] The first solid electrolyte layer (310) may further include a binder. The binder included in the solid electrolyte layer (300) may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited thereto. The binder of the first solid electrolyte layer (310) 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 electrodeposition layer (220).

[0063] The second solid electrolyte layer (320) may include a second solid electrolyte. The second solid electrolyte may have a particle shape such as a sphere or ellipsoid.

[0064] The second solid electrolyte may include a sulfide-based solid electrolyte. The description of the second solid electrolyte may be the same as or similar to that described above for the first solid electrolyte. In one embodiment, the second solid electrolyte may have substantially the same composition as the first solid electrolyte. In another embodiment, the second solid electrolyte may have a similar composition to the first solid electrolyte.

[0065] The second solid electrolyte can be in direct contact with the electrodeposition layer (220). As a result, the second solid electrolyte can suppress lithium dendrites formed between the electrodeposition layer (220) and the negative electrode current collector (210). The second solid electrolyte can effectively suppress negative electrode side reactions. As a result, the cell performance of the all-solid-state battery (10) according to the present invention can be improved.

[0066] The first solid electrolyte layer (310) may have a first thickness (TK1), and the second solid electrolyte layer (320) may have a second thickness (TK2). The first thickness (TK1) and the second thickness (TK2) may be the same or different. In one embodiment, the first thickness (TK1) may be greater than the second thickness (TK2). For example, the first thickness (TK1) may be 1.1 to 5 times the second thickness (TK2).

[0067] Referring back to FIGS. 1 and 2, the positive electrode layer (100) and the first solid electrolyte layer (310) may form a positive electrode composite layer (CSH). The negative electrode layer (200) and the second solid electrolyte layer (320) may form a negative electrode composite layer (ASH). The positive electrode composite layer (CSH) may be laminated on the negative electrode composite layer (ASH).

[0068] The area of ​​the cathode composite layer (ASH) and the area of ​​the cathode composite layer (CSH) may be different. Specifically, the area of ​​the cathode composite layer (ASH) may be larger than that of the cathode composite layer (CSH). The cathode composite layer (CSH) may be completely overlapped within the cathode composite layer (ASH).

[0069] 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).

[0070] Specifically, the positive electrode composite layer (CSH) may have a first width (WI1) in a first direction (D1). The negative electrode composite layer (ASH) may have a second width (WI2) in the first direction (D1). The first width (WI1) may be smaller than the second width (WI2). The positive electrode composite layer (CSH) may have a third width (WI3) in the second direction (D2). The negative electrode composite layer (ASH) may have a fourth width (WI4) in the second direction (D2). The third width (WI3) may be smaller than the fourth width (WI4).

[0071] The all-solid-state battery (10) according to the present embodiment can be manufactured by forming a negative electrode composite layer (ASH) on a first carrier film, forming a positive electrode composite layer (CSH) on a second carrier film, and then laminating the negative electrode composite layer (ASH) and the positive electrode composite layer (CSH).

[0072] FIG. 3 is a cross-sectional view taken along line A-A' of FIG. 1, illustrating an all-solid-state battery according to another embodiment of the present invention. In the embodiments described below, detailed descriptions of technical features overlapping with those previously described with reference to FIGS. 1 and 2 will be omitted, and differences will be described in detail.

[0073] Referring to FIG. 3, the all-solid-state battery (10) according to the present invention may further include a gasket (GSK). The gasket (GSK) may be provided to surround the cathode composite layer (CSH). The gasket (GSK) may fill the step on the side of the all-solid-state battery (10) caused by the difference in area between the anode composite layer (ASH) and the cathode composite layer (CSH). The gasket (GSK) may surround the four side surfaces of the cathode composite layer (CSH). For example, the thickness of the gasket (GSK) may be substantially the same as the thickness of the cathode composite layer (CSH).

[0074] The upper surface of the second solid electrolyte layer (320) may include a first region in contact with the first solid electrolyte layer (310) and a second region in contact with the gasket (GSK). The second region may be a peripheral region of the upper surface of the second solid electrolyte layer (320). The second region may surround the first region.

[0075]

[0076] Hereinafter, a negative electrode for a secondary battery according to an embodiment will be described in detail with reference to FIG. 4. The negative electrode for a secondary battery according to an embodiment may include a negative electrode layer (200). The negative electrode layer (200) may include a negative electrode current collector (210), a functional layer (400) coating the surface of the negative electrode current collector, and an electrodeposition layer (220) disposed on the functional layer (400).

[0077] The above functional layer (400) may be configured to stabilize the interface between the above electrodeposition layer (220) and the above functional layer (400).

[0078] The above functional layer (400) can prevent lithium metal from growing at the interface between the electrodeposition layer (220) and the negative electrode current collector (210) by separating the composite particles (222) included in the electrodeposition layer (220) from the negative electrode current collector (210). The functional layer (400) can minimize the influence of unstable lithium deposition due to high interfacial energy at the interface of the negative electrode current collector (210).

[0079] The above functional layer (400) may include conductive carbon having high electrical conductivity.

[0080] The above conductive carbon has an electrical conductivity of 1×10 S / cm to 1×10 5 S / cm. The electrical conductivity of the conductive carbon is 10 S / cm or more, 1×10 2 S / cm or more, 1×10 3 S / cm or more, or 1×10 4 It may be S / cm or more (room temperature conditions, 20°C to 30°C). This is a range in which lithium ions can easily move within the functional layer (400). If it falls short of the above range, it is difficult to secure excellent effects of the functional layer (400).

[0081] The conductive carbon may include at least one selected from the group consisting of amorphous carbon, graphite, graphene, graphene oxide, reduced graphene oxide, and combinations thereof.

[0082] The amorphous carbon may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, and ketjen black.

[0083] In one embodiment, the conductive carbon may be, but is not limited to, carbon black or graphite.

[0084] The content of the conductive carbon may be included in a range of 75 wt% to 98 wt% relative to the total weight of the functional layer. When the content of the conductive carbon satisfies the above-described range, the interface between the electrodeposition layer (220) and the functional layer (400) can be effectively stabilized.

[0085] The conductive carbon included in the above functional layer (400) may have the same or different components as the amorphous carbon matrix (221) included in the electrodeposition layer (220).

[0086] The functional layer (400) may further include a binder. The binder content may range from 2 wt% to 15 wt% based on the total weight of the functional layer. If the binder content is too low, the functional layer (400) may not be formed stably. On the other hand, if the binder content is too high, the ionic conductivity of the all-solid-state battery may deteriorate, and the capacity of the battery may decrease.

[0087] The binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene, styrene butadiene rubber (SBR), polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate.

[0088] In one embodiment, the binder may be, but is not limited to, polyvinylidene fluoride (PVDF).

[0089] For example, the functional layer (400) can be manufactured by coating a slurry containing the above-described conductive carbon, binder, and organic solvent on the negative electrode current collector (210). For example, the lithium functional layer (400) can be manufactured by bar coating a slurry containing the above-described conductive carbon, binder, and organic solvent on the negative electrode current collector (210).

[0090] The above-mentioned electrodeposition layer (220) may include an amorphous carbon matrix (221) and composite particles (222) dispersed within the amorphous carbon matrix (221) and including crystalline carbon.

[0091] The weight ratio of the composite particles (222) and the amorphous carbon matrix (221) may be 1:1 to 1:5. For example, the weight ratio of the composite particles (222) and the amorphous carbon matrix (221) may be 1:1 to 1:3. When the above range is satisfied, the formation of the electrodeposition layer (220) in which the composite particles (222) are dispersed within the amorphous carbon matrix (221) may be facilitated.

[0092] The BET specific surface area of ​​the above electrodeposition layer (220) is 30 to 70 m 2 / g may be. For example, the BET specific surface area of ​​the electrodeposition layer (220) may be 40 to 60 m 2 / g can be 45 to 50 m 2 / g may be.

[0093] The content of the composite particles (222) may be 15 wt% to 50 wt% with respect to the total weight of the electrodeposition layer (220). For example, the content of the composite particles (222) may be 25 wt% to 50 wt% with respect to the total weight of the electrodeposition layer (220). When the above range is satisfied, the formation of the electrodeposition layer (220) in which the composite particles (222) are dispersed within the amorphous carbon matrix (221) may be facilitated.

[0094] The amorphous carbon matrix (221) forms the body of the electrodeposition layer (220). The amorphous carbon matrix (221) may include composite particles (222) therein. The amorphous carbon matrix (221) may surround each composite particle (222).

[0095] The amorphous carbon matrix (221) can be in direct contact with the negative electrode current collector (210). The amorphous carbon matrix (221) can be in direct contact with the solid electrolyte layer (300).

[0096] In one embodiment, the composite particles (222) may be spaced apart from the negative electrode current collector (210). The composite particles (222) may be spaced apart from the solid electrolyte layer (300).

[0097] The amorphous carbon matrix (221) can prevent lithium metal from growing at the interface between the electrodeposition layer (220) and the negative electrode current collector (210) by separating the composite particles (222) from the negative electrode current collector (210). The amorphous carbon matrix (221) can minimize the influence of unstable lithium deposition due to high interfacial energy at the interface of the negative electrode current collector (210).

[0098] The amorphous carbon matrix (221) can prevent lithium metal from growing at the interface between the electrodeposition layer (220) and the solid electrolyte layer (300) by separating the composite particles (222) from the solid electrolyte layer (300). The amorphous carbon matrix (221) can prevent electrolyte deterioration and inhibit the precipitation and growth of lithium dendrites by preventing lithium metal from growing into the solid electrolyte layer (300).

[0099] The amorphous carbon matrix (221) may include amorphous carbon. The amorphous carbon included in the amorphous carbon matrix (221) may include a material selected from soft carbon, hard carbon, pitch carbide, mesophase pitch carbide, calcined coke, polymer carbide, and combinations thereof. The amorphous carbon may be formed by carbonizing a carbon precursor, such as coal pitch, mesophase pitch, petroleum pitch, coal oil, petroleum heavy oil, organic synthetic pitch, or a polymer resin such as a phenol resin, a furan resin, or a polyimide resin, through a heat treatment process. The heat treatment temperature during carbonization can be controlled in the range of 500°C to 1400°C.

[0100] The amorphous carbon included in the amorphous carbon matrix (221) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, and ketjen black. Compared to crystalline carbon, the amorphous carbon has relatively low hardness and toughness, and can effectively suppress the volume expansion of the composite particles (222) dispersed within the amorphous carbon matrix (221), thereby improving the cycle life characteristics.

[0101] The BET surface area of ​​the amorphous carbon matrix (221) is 50 to 70 m 2 / g may be. For example, the BET specific surface area of ​​the amorphous carbon matrix (221) is 55 to 60 m 2 / g. When the above range is satisfied, the amorphous carbon matrix (221) may have appropriate ionic conductivity, making it easy to transfer lithium ions to the surface or interior of the composite particle (222).

[0102] The composite particle (222) may include crystalline carbon. The crystalline carbon may have a special structure, such as a porous structure or a graphene structure, and thus may provide an environment conducive to the adsorption and storage of lithium ions.

[0103] In one embodiment, the crystalline carbon may include graphite, such as natural graphite or artificial graphite, in an amorphous, plate-like, flake-like, spherical, or fibrous form. When the crystalline carbon includes natural graphite, a relatively inexpensive negative electrode with a large capacity can be manufactured. When the crystalline carbon includes artificial graphite, a negative electrode with relatively improved cycle characteristics can be manufactured.

[0104] The composite particle (222) may further include at least one of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). In one embodiment, the composite particle (222) may include a mixture of carbon black and silver (Ag). The composite particle (222) may include the above-described materials or mixtures together with crystalline carbon to provide a convenient environment for adsorbing and storing lithium ions.

[0105] The average particle diameter (D50) of the composite particles (222) may be 10 μm to 30 μm. For example, the average particle diameter (D50) of the composite particles (222) may be 20 μm to 30 μm. When the above range is satisfied, the composite particles (D50) can appropriately provide a space on the surface or inside where lithium ions can be absorbed.

[0106] The BET surface area of ​​the composite particles (222) is 10 to 30 m 2 / g may be. For example, the BET specific surface area of ​​the composite particles (222) may be 15 to 20 m 2 / g. When the above range is satisfied, the composite particle (222) has a relatively low BET surface area compared to the amorphous matrix (221), and thus can relatively well adsorb lithium ions (L) on the surface or inside.

[0107] Referring to FIG. 4, the functional layer (400) may have a third thickness (TK3), and the electrodeposition layer (220) may have a fourth thickness (TK4).

[0108] For example, the thickness of the functional layer (400) may be, for example, 1 μm to 10 μm, 2 μm to 8 μm, or 3 μm to 6 μm.

[0109] If the thickness of the functional layer (400) is thinner than the range described above, lithium metal cannot be evenly precipitated, a problem occurs in which the lithium metal comes into contact with the negative electrode current collector (210), and the functional layer cannot function as a protective layer. In addition, if the thickness of the functional layer (400) is thinner than the range described above, the thickness of the functional layer (400) may be very thin, resulting in a decrease in coulombic efficiency. On the other hand, if the thickness of the functional layer (400) is thicker than the range described above, the energy density of the all-solid-state battery may decrease.

[0110] The functional layer (400) can extend the life of the all-solid-state battery by protecting the expanding lithium metal layer and suppressing the precipitation and growth of lithium dendrites.

[0111] The electrodeposition layer (220) may have a fourth thickness (TK4). The thickness of the electrodeposition layer (220) may be equal to or thicker than the thickness of the functional layer (400).

[0112] For example, the thickness of the electrodeposition layer (220) may be, for example, 1 μm to 10 μm.

[0113] In particular, when the thickness of the electrodeposition layer (220) is thinner than the range described above, lithium metal may not be formed within the electrodeposition layer (220), so lithium may penetrate outside the electrodeposition layer (220) and precipitate, and dendrite may be formed in the direction of the solid electrolyte layer (300). On the other hand, when the thickness of the electrodeposition layer (220) is thicker than the range described above, the energy density of the all-solid-state battery may decrease and the internal resistance of the all-solid-state battery due to the electrodeposition layer (220) may increase, thereby deteriorating the cycle characteristics of the all-solid-state battery.

[0114] The third thickness (TK3) and the fourth thickness (TK4) may be the same or different. In one embodiment, the third thickness (TK3) may be greater than the fourth thickness (TK4). For example, the thickness ratio of the third thickness (TK3) to the fourth thickness (TK4) may be 1:1 to 1:3.

[0115] When the thickness ratio of the third thickness (TK3) to the fourth thickness (TK4) is within the above-mentioned numerical range, an all-solid-state battery with improved lifespan can be provided by stabilizing the interface of lithium metal grown during charging.

[0116]

[0117] Referring to FIG. 5, the composite particle (222) according to one embodiment may include lithium ions (L) absorbed on the surface or inside of the composite particle (222). The lithium ions (L) may be capable of reversible intercalation and deintercalation (lithiated intercalation). In the electrodeposition layer (220) according to one embodiment, the lithium ions (L) that move to the negative electrode during the charging process may be preferentially absorbed on the surface or inside of the composite particle (222) rather than in the amorphous carbon matrix (221).

[0118] Referring to FIG. 6, according to one embodiment, a composite particle (222) may have lithium ions (L) absorbed to a limit on the surface or inside thereof, and then lithium may be precipitated on the surface of the composite particle (222) to form a lithium layer (LM). The lithium layer (LM) on the surface of the composite particle (222) may be capable of reversible intercalation and deintercalation, and thus may function as the capacity of a battery.

[0119] Referring to FIG. 6, the composite particle (222) according to one embodiment may further include a lithium layer (LM) covering a portion of the surface of the composite particle (222). The lithium layer (LM) may include at least one of lithium metal, lithium alloy, lithium powder, or precipitated lithium.

[0120] The surface of the composite particle (222) according to an exemplary embodiment may include an upper surface adjacent to the solid electrolyte layer (300) in the third direction (D3) and a lower surface adjacent to the functional layer (400) in the third direction (D3). Referring to FIG. 6, the lithium layer (LM) according to an exemplary embodiment may cover all or part of the upper surface of the composite particle (222). Referring to FIG. 6, the lithium layer (LM) according to an exemplary embodiment may not cover the lower surface of the composite particle (222). The lithium layer (LM) according to an exemplary embodiment may cover the lower surface of the composite particle (222). The lithium layer (LM) according to an exemplary embodiment may cover a part of the lower surface of the composite particle (222).

[0121] Referring to FIG. 7, a lithium layer (LM) according to an embodiment may grow in a third direction (D3) by precipitating lithium. Referring to FIG. 8, a lithium layer (LM) according to an embodiment may grow in a direction substantially perpendicular to the third direction (D3) by precipitating lithium. According to an exemplary embodiment, the growth of the lithium layer (LM) may first grow in the third direction (D3) and then grow in a direction substantially perpendicular to the third direction (D3). Referring to FIG. 8, a lithium layer (LM) grown in the third direction (D3) and in a direction substantially perpendicular to the third direction (D3) may form a lithium metal layer (2213).

[0122] Referring to FIG. 8, a lithium metal layer (2213) according to an exemplary embodiment may divide an amorphous carbon matrix (221) into a first amorphous carbon layer (2211) and a second amorphous carbon layer (2212). The first amorphous carbon layer (2211) and the second amorphous carbon layer (2212) according to an exemplary embodiment may be spaced apart from each other in a third direction (D3).

[0123] According to an exemplary embodiment, the first amorphous carbon layer (2211) may be arranged to be in direct contact with the lithium metal layer (2213). According to an exemplary embodiment, the first amorphous carbon layer (2211) may be arranged to be spaced apart from the composite particles (222).

[0124] According to an exemplary embodiment, the second amorphous carbon layer (2212) may be arranged to be in direct contact with the lithium metal layer (2213). According to an exemplary embodiment, the second amorphous carbon layer (2212) may be arranged to be in direct contact with some of the composite particles (222) among the plurality of composite particles (222).

[0125] According to an exemplary embodiment, a lithium metal layer (2213) may be disposed between the first amorphous carbon layer (2211) and the second amorphous carbon layer (2212) and may be in direct contact with the composite particles (222). According to an exemplary embodiment, the lithium metal layer (2213) may surround at least one of the plurality of composite particles (222). According to an exemplary embodiment, the lithium metal layer (2213) may surround a portion of a surface of at least one of the plurality of composite particles (222).

[0126]

[0127] Referring to FIG. 9, the functional layer (400) of the present embodiment can alleviate physical stress resulting from a large volume change due to lithium deposition inside the electrodeposition layer (220).

[0128] The functional layer (400) of the present embodiment can prevent lithium metal from growing at the interface between the electrodeposition layer (220) and the negative electrode current collector (210) by separating the composite particles (222) included in the electrodeposition layer (220) from the negative electrode current collector (210). The functional layer (400) can minimize the influence of unstable lithium deposition due to high interfacial energy at the interface of the negative electrode current collector (210).

[0129] Referring to FIG. 9, the functional layer (400) may include lithium ions (L) stored therein. The lithium ions (L) may be capable of reversible intercalation and deintercalation (lithiated intercalation). In one embodiment, the functional layer (400) may allow lithium ions (L) moving during the charging process to be stored on the surface or inside of the conductive carbon.

[0130] The functional layer (400) of the present embodiment may use conductive carbon that does not impede the movement of electrons and can relieve physical stress.

[0131] For example, when the electrodeposition layer (220) expands in volume due to lithium deposition, lithium metal may penetrate the electrodeposition layer (220) and precipitate to the outside.

[0132] The functional layer (400) protects the lithium metal layer (2213) deposited outside the electrodeposition layer (220), and at the same time, lithiation occurs through contact with the lithium metal layer (2213), thereby exhibiting the effect of increasing lithium affinity and electrical conductivity.

[0133] The above functional layer (400) can have high lithium affinity through the lithiation process, thereby minimizing the interfacial energy between carbon and lithium.

[0134] The negative electrode current collector (210) coated with the above functional layer (400) has a low contact angle due to low interfacial energy with lithium, thereby enabling the formation of a stable interface. Accordingly, the functional layer (400) of the present embodiment can form a more stable interface than the conventional technology in which the negative electrode current collector (210) and the lithium metal layer (2213) are in direct contact.

[0135]

[0136] Referring to FIG. 10, an all-solid-state battery (10) according to another 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). The negative electrode layer (200) may include a negative electrode current collector (210), a functional layer (400) coating the surface of the negative electrode current collector, and an electrodeposition layer (220) on the functional layer.

[0137] The functional layer (400) includes conductive carbon, and the electrodeposition layer (220) may include an amorphous carbon matrix (221). The electrodeposition layer (220) may further include composite particles (222) dispersed within the amorphous carbon matrix (221) and including crystalline carbon.

[0138] For example, the above-mentioned electrodeposition layer (220) may be formed solely of an amorphous carbon matrix (221), or may be formed by mixing an amorphous carbon matrix (221) and composite particles (222).

[0139] Detailed descriptions of technical features that overlap with those previously described with reference to FIGS. 1 to 9 will be omitted, and differences will be described in detail.

[0140] Referring to FIG. 11, the composite particle (222) may include lithium ions (L) absorbed on the surface or inside of the composite particle (222). The lithium ions (L) may be derived from the positive electrode layer (100). In an embodiment, the all-solid-state battery (10) may be configured so that lithium ions (L) transferred to the negative electrode during the charging process may be preferentially absorbed on the surface or inside of the composite particle (222) rather than in the amorphous carbon matrix (221).

[0141] Referring to FIG. 12, the composite particle (222) may include at least one of lithium metal (LM), a lithium alloy, lithium powder, or precipitated lithium on the surface of the composite particle (222). After lithium ions (L) are absorbed to a limit on the surface or inside of the composite particle (222), lithium may be precipitated on the surface of the composite particle (222) to form a lithium layer (LM). The lithium layer (LM) on the surface of the composite particle (222) may be subject to reversible intercalation and deintercalation, thereby functioning as the capacity of the battery. Regarding the deposition behavior of the lithium metal (LM), the contents described with reference to FIGS. 1 to 9 may be applied as is.

[0142] Referring to FIG. 13, an all-solid-state battery (10) according to another 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). The negative electrode layer (200) may include a negative electrode current collector (210), a functional layer (400) coating a surface of the negative electrode current collector (210), a first amorphous carbon layer (2211) disposed on the functional layer (400), a lithium metal layer (2213) disposed on the first amorphous carbon layer (2211) and having at least one composite particle (222) including crystalline carbon dispersed therein, and a second amorphous carbon layer (2212) disposed on the lithium metal layer (2213). Detailed descriptions of technical features that overlap with those previously described with reference to FIGS. 1 to 9 will be omitted, and differences will be described in detail.

[0143] The first amorphous carbon layer (2211) and the second amorphous carbon layer (2212) may have substantially the same composition as the amorphous carbon matrix (221) described above. The first amorphous carbon layer (2211) and the second amorphous carbon layer (2212) may have different compositions from the amorphous carbon matrix (221) described above.

[0144] The first amorphous carbon layer (2211) can prevent lithium metal from growing on the surface of the negative electrode current collector (210) by separating the lithium metal layer (2213) from the negative electrode current collector (210). The first amorphous carbon layer (2211) can minimize the influence of unstable lithium deposition due to high energy on the surface of the negative electrode current collector (210).

[0145] The second amorphous carbon layer (2212) can prevent lithium metal from growing inside the solid electrolyte layer (300) by separating the lithium metal layer (2213) from the solid electrolyte layer (300). The second amorphous carbon layer (2212) can prevent electrolyte deterioration and inhibit lithium metal from growing into the solid electrolyte layer (300), thereby suppressing the precipitation and growth of lithium dendrites.

[0146] The lithium metal layer (2213) can store lithium derived from the positive electrode layer (100) in the form of ions and metals. The lithium metal layer (2213) can prevent lithium derived from the positive electrode layer (100) from reaching the negative electrode current collector (210), thereby preventing lithium metal from growing on the surface of the negative electrode current collector (210).

[0147] Referring to FIG. 14, the functional layer (400) of the present embodiment can alleviate physical stress resulting from a large volume change due to lithium deposition inside the electrodeposition layer (220).

[0148] The functional layer (400) of the present embodiment can prevent lithium metal from growing at the interface between the electrodeposition layer (220) and the negative electrode current collector (210) by separating the composite particles (222) included in the electrodeposition layer (220) from the negative electrode current collector (210). The functional layer (400) can minimize the influence of unstable lithium deposition due to high interfacial energy at the interface of the negative electrode current collector (210).

[0149] Referring to FIG. 14, the functional layer (400) may include lithium ions (L) stored therein. The lithium ions (L) may be capable of reversible intercalation and deintercalation (lithiated intercalation). In one embodiment, the functional layer (400) may allow lithium ions (L) moving during the charging process to be stored on the surface or inside of the conductive carbon.

[0150] The functional layer (400) of the present embodiment may use conductive carbon that does not impede the movement of electrons and can relieve physical stress.

[0151] For example, when the electrodeposition layer (220) expands in volume due to lithium deposition, lithium metal may penetrate the electrodeposition layer (220) and precipitate to the outside.

[0152] The functional layer (400) protects the lithium metal layer (2213) deposited outside the electrodeposition layer (220), and at the same time, lithiation occurs through contact with the lithium metal layer (2213), thereby exhibiting the effect of increasing lithium affinity and electrical conductivity.

[0153] The above functional layer (400) can have high lithium affinity through the lithiation process, thereby minimizing the interfacial energy between carbon and lithium.

[0154]

[0155] Referring to FIG. 15, an all-solid-state battery (10) according to another 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).

[0156] A plurality of functional layers can be formed between the solid electrolyte layer (300) and the negative electrode current collector (210).

[0157] For example, a negative electrode for a secondary battery according to another embodiment may include: a negative electrode current collector (210); a first functional layer (410) coating a surface of the negative electrode current collector (210); an electrodeposition layer (220) on the first functional layer (410); and a second functional layer (420) on the electrodeposition layer (220).

[0158] In this implementation example, detailed descriptions of technical features that overlap with those described with reference to FIGS. 1 to 9 above will be omitted, and differences will be described in detail.

[0159] Each of the first functional layer (410) and the second functional layer (420) may include conductive carbon.

[0160] The above-mentioned electrodeposition layer (220) may include an amorphous carbon matrix (221) and composite particles (222) dispersed within the amorphous carbon matrix (221) and including crystalline carbon.

[0161] The conductive carbon included in the first functional layer (410) may have substantially the same composition as the amorphous carbon matrix (221) included in the electrodeposition layer (220). The conductive carbon included in the first functional layer (410) may have substantially different composition from the amorphous carbon matrix (221) included in the electrodeposition layer (220).

[0162] The conductive carbon included in the second functional layer (420) may include amorphous carbon having a particle size of about 1 nm to 500 nm. For example, the amorphous carbon may be carbon black. If the particle size of the conductive carbon exceeds the above range, a problem may occur in which lithium metal is precipitated at the interface of the solid electrolyte layer (300) beyond the second functional layer (420).

[0163]

[0164] Referring to FIG. 16, the functional layer (410) of the present embodiment can alleviate physical stress resulting from a large volume change due to lithium deposition inside the electrodeposition layer (220).

[0165] The first functional layer (410) of the present embodiment can prevent lithium metal from growing at the interface between the electrodeposition layer (220) and the negative electrode current collector (210) by separating the composite particles (222) included in the electrodeposition layer (220) from the negative electrode current collector (210). The functional layer (410) can minimize the influence of unstable lithium deposition due to high interfacial energy at the interface of the negative electrode current collector (210).

[0166] Referring to FIG. 16, the first functional layer (410) may include lithium ions (L) stored therein. The lithium ions (L) may be capable of reversible intercalation and deintercalation (litiated intercalation). According to one embodiment, the first functional layer (410) may allow lithium ions (L) moving during the charging process to be stored on the surface or inside of the conductive carbon.

[0167] The first functional layer (410) of this other embodiment may use conductive carbon that does not impede the movement of electrons and can relieve physical stress.

[0168] For example, when the electrodeposition layer (220) expands in volume due to lithium deposition, lithium metal may penetrate the electrodeposition layer (220) and precipitate to the outside.

[0169] The first functional layer (410) protects the lithium metal layer (2213) deposited outside the electrodeposition layer (220), and at the same time, lithiation occurs through contact with the lithium metal layer (2213), thereby exhibiting the effect of increasing lithium affinity and electrical conductivity.

[0170] The above first functional layer (410) can have high lithium affinity through the lithiation process, thereby minimizing the interfacial energy between carbon and lithium.

[0171] The second functional layer (420) can protect the lithium metal layer (2213) deposited outside the electrodeposition layer (220).

[0172] The second functional layer (420) can prevent lithium metal from growing at the interface between the electrodeposition layer (220) and the solid electrolyte layer (300) by separating the composite particles (222) from the solid electrolyte layer (300). The second functional layer (420) can prevent electrolyte deterioration and inhibit the precipitation and growth of lithium dendrites by preventing lithium metal from growing into the solid electrolyte layer (300).

[0173]

[0174] Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are merely examples of the present invention, and the present invention is not limited to the following examples.

[0175]

[0176] Example 1

[0177] Crystalline carbon, artificial graphite, and polyvinylidene fluoride (PVDF) binder were mixed in a mass ratio of 9:1, dispersed in N-methylpyrrolidone (NMP), and a functional layer slurry was prepared using a ball mill device.

[0178] Next, natural graphite was separated or crushed with crystalline carbon to prepare crystalline graphite powder with an average particle size of 10 μm to 30 μm and carbon black (CAS#1333-86-4) powder with amorphous carbon. The prepared crystalline graphite powder and carbon black powder (BET: 56.934 m 2 / g) were mixed in a mass ratio of 1:2, and the powder thus obtained was mixed with polyvinylidene fluoride (PVDF) binder in a mass ratio of 9:1, and then dispersed in N-methylpyrrolidone (NMP), and a ball mill device was used to prepare a slurry for the electrodeposition layer (BET: 48.6099 m 2 / g) was manufactured.

[0179] The manufactured functional layer slurry was applied onto a SUS foil having a thickness of 10 μm, an electrodeposition layer was coated on the current collector, and then dried to coat the functional layer on the current collector with a thickness of 3 μm.

[0180] The prepared electrodeposition layer slurry was applied to a thickness of 3 μm on the functional layer and then dried, and the electrodeposition layer was coated on the functional layer to produce a cathode layer with a thickness of approximately 6 μm. The coating was performed using a doctor blade method.

[0181] 90 mg of a sulfide-based solid electrolyte containing Li3PS4 was placed in a mold with a diameter of 10 mm, and cold-pressed at 200 MPa to produce a solid electrolyte layer. The thickness of the solid electrolyte layer thus produced was 600 μm.

[0182] A negative electrode layer was manufactured on the manufactured solid electrolyte layer, and then cold-pressed at 380 MPa, and then lithium metal with a thickness of 400 μm was laminated to manufacture a half-cell.

[0183] The fabricated half-cell was placed in a fixing jig, and a charge-discharge test was performed using a test cell capable of determining the driving pressure via a spring. The charge-discharge test was performed under a driving pressure of 5 MPa.

[0184]

[0185] Example 2

[0186] A half-cell was manufactured using the same method as Example 1, except that carbon black (CAS#1333-86-4) was used instead of artificial graphite when manufacturing the functional layer slurry, and a charge / discharge test was performed.

[0187]

[0188] Example 3

[0189] A half-cell was manufactured in the same manner as Example 1, except that the functional layer was coated with a thickness of 5 to 6 μm, and a charge-discharge test was performed.

[0190]

[0191] Example 4

[0192] A half-cell was manufactured using the same method as Example 1, except that only carbon black powder was used instead of the mixed powder when manufacturing the electrodeposition layer slurry, and a charge-discharge test was performed.

[0193]

[0194] Comparative Example 1

[0195] A half-cell was manufactured using the same method as Example 1, and a charge-discharge test was performed, except that the electrodeposition layer was directly coated on the current collector instead of coating the functional layer on the current collector, and only carbon black powder was used when preparing the electrodeposition layer slurry.

[0196]

[0197] Comparative Example 2

[0198] A half-cell was manufactured using the same method as Example 1, except that the electrodeposition layer was directly coated on the current collector instead of coating the functional layer on the current collector, and a charge-discharge test was performed.

[0199]

[0200] Evaluation Example 1: Analysis of the cathode cross-section

[0201] Figures 17a and 18a are images of the negative electrode observed through SEM while charging a half-cell manufactured according to Comparative Example 2. Figures 17a and 18a show that lithium is 0.5 mAh cm, respectively. -2 , 2 mAh cm -2 This is a cross-sectional SEM image of the cathode when deposited.

[0202] Figure 17b is an enlarged view of area A of Figure 17a, and Figure 18b is an enlarged view of area B of Figure 18a.

[0203] Referring to Figures 17a and 17b, lithium is 0.5 mAh cm -2 When deposited, lithium was confirmed to be deposited in a shape similar to the diameter of the composite particles. In the early stages of lithium deposition, lithium was confirmed to grow longitudinally.

[0204] Referring to Figures 18a and 18b, lithium is 2 mAh cm -2 When deposited, it was confirmed that some lithium that was not accommodated inside the electrode spread laterally as the deposition capacity increased.

[0205] Figure 19 shows the 2 mAh cm of a half cell manufactured according to Comparative Example 2. -2 This is a perspective SEM image of the electrodeposited layer when deposited.

[0206] Referring to Figure 19, it was confirmed that the lithium spreading laterally comes into direct contact with the current collector.

[0207]

[0208] Evaluation Example 2: Evaluation of Lithium Deposition Behavior

[0209] Figures 20a to 20c show 2 mAh cm of half cells manufactured according to the examples and comparative examples. -2 This is a perspective SEM image of the electrodeposited layer when deposited.

[0210] Figure 20a shows the 2 mAh cm of a half cell manufactured according to Comparative Example 2. -2A perspective SEM image of the electrodeposited layer when deposited. Figure 20b shows the 2 mAh cm of a half-cell manufactured according to Example 1. -2 A perspective SEM image of the electrodeposited layer when deposited. Figure 20c shows the 2 mAh cm of a half-cell manufactured according to Example 2. -2 This is a perspective SEM image of the electrodeposited layer when deposited.

[0211] Referring to Figure 20a, it was confirmed that as the deposition capacity increased, lithium protruded laterally and came into direct contact with the current collector.

[0212] Referring to FIGS. 20b and 20c, it was confirmed that the protrusions due to lithium deposition in the electrodeposition layer were covered by the functional layer.

[0213] Referring to Fig. 20c, it can be confirmed that the particles of the functional layer protecting the lithium deposition layer are lithiated and have a golden color. This suggests that chemical lithiation occurs in the functional layer upon contact with the lithium deposition layer.

[0214]

[0215] Evaluation Example 3: Cycle Characteristics Evaluation

[0216] The half-cells manufactured in the examples and comparative examples were 0.5 mAcm -2 Current density of 2 mAhcm -2 By repeatedly charging and discharging at a capacity of 1 V, a cut-off voltage of 1 V, and a temperature of 60°C, the coulombic efficiency (%) according to the number of cycles (cycle number, #) was measured to determine when a short circuit occurred, and the results are shown in Figs. 21 and 22. In the above measurement results, the point in time when the coulombic efficiency rapidly increases was determined to be the point in time when a short circuit occurred.

[0217] Referring to Figure 21, in the case of Comparative Example 1, the time of occurrence of a short circuit according to a charge / discharge test was earlier than in Examples 1 to 3. This is understood to be due to lithium dendrites grown on the surface of the negative electrode current collector and at the interface between the electrodeposited layer and the solid electrolyte layer causing the short circuit.

[0218] In the case of Comparative Example 2, it was confirmed that the battery life was not good compared to Examples 1 to 3 due to the formation of an unstable interface as a part of the lithium metal layer that continued to grow during charging came into contact with the current collector.

[0219] On the other hand, in the case of Examples 1 to 3, it can be confirmed that lithium metal grows from the center of the electrodeposition layer due to the composite particles inside the amorphous carbon matrix, and the thickly grown lithium metal layer is protected by the functional layer, thereby forming a stable interface and improving the lifespan.

[0220] Referring to Figure 22, it can be confirmed that Examples 1 and 4 exhibit superior Coulombic efficiency compared to Comparative Example 1. This indicates that the functional layer according to the present invention improves lifespan characteristics even in an electrodeposited layer composed solely of amorphous carbon. Therefore, it can be confirmed that the functional layer according to the present invention can be applied to general electrodeposited layers as well.

[0221]

[0222] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

Claims

1. Negative current collector; A functional layer coating the surface of the above negative electrode collector; and Including an electrodeposition layer disposed on the above functional layer, The functional layer comprises conductive carbon, and the functional layer is configured to stabilize the interface between the electrodeposition layer and the functional layer. The above electrodeposition layer: amorphous carbon matrix; and Comprising composite particles dispersed within the amorphous carbon matrix and containing crystalline carbon, Cathode for secondary batteries.

2. In paragraph 1, The above conductive carbon has an electrical conductivity of 1×10 S / cm to 1×10 5 S / cm, Cathode for secondary batteries.

3. In paragraph 1, The conductive carbon comprises at least one selected from the group consisting of amorphous carbon, graphite, graphene, graphene oxide, reduced graphene oxide, and combinations thereof. Cathode for secondary batteries.

4. In paragraph 1, The above functional layer further includes a binder, The binder comprises at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene, styrene butadiene rubber (SBR), polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate. Cathode for secondary batteries.

5. In paragraph 1, The content of the conductive carbon is 75 wt% to 98 wt% of the total weight of the functional layer. Cathode for secondary batteries.

6. In paragraph 1, The above electrodeposition layer has a weight ratio of the composite particles and the amorphous carbon matrix of 1:1 to 1:

5. Cathode for secondary batteries.

7. In paragraph 1, The above crystalline carbon includes artificial graphite or natural graphite, The average particle diameter (D50) of the above composite particles is 10 μm to 30 μm. Cathode for secondary batteries.

8. In paragraph 1, The above composite particles further include at least one of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Cathode for secondary batteries.

9. In paragraph 1, The BET specific surface area of ​​the above composite particles is 10 to 30 m 2 / g and, The BET specific surface area of ​​the above amorphous carbon matrix is ​​50 to 70 m 2 / g person, Cathode for secondary batteries.

10. In paragraph 1, The BET specific surface area of ​​the above electrodeposition layer is 30 to 70 m 2 / g person, Cathode for secondary batteries.

11. In paragraph 1, The thickness of the functional layer is 1 μm to 10 μm, The thickness of the above-mentioned electrodeposition layer is 1 μm to 10 μm, Cathode for secondary batteries.

12. In paragraph 1, The thickness ratio of the functional layer to the electrodeposited layer is 1:1 to 1:3, Cathode for all-solid-state batteries.

13. In paragraph 1, The amorphous carbon matrix comprises a first amorphous carbon layer and a second amorphous carbon layer, Further comprising a lithium metal layer disposed between the first amorphous carbon layer and the second amorphous carbon layer and in direct contact with the composite particles. Cathode for secondary batteries.

14. In paragraph 1, The functional layer comprises stored lithium ions, Cathode for secondary batteries.

15. Bipolar layer; a cathode layer opposite to the anode layer; and Including a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; The above cathode layer: negative current collector; A functional layer coating the surface of the above negative electrode collector; and Including an electrodeposition layer on the above functional layer, The above functional layer includes conductive carbon, The above electrodeposition layer comprises an amorphous carbon matrix, All-solid-state battery.

16. In paragraph 15, The conductive carbon comprises at least one selected from the group consisting of amorphous carbon, graphite, graphene, graphene oxide, reduced graphene oxide, and combinations thereof. All-solid-state battery.

17. In paragraph 15, The above functional layer is an all-solid-state battery containing absorbed lithium ions.

18. In paragraph 15, The above electrodeposition layer further comprises composite particles dispersed within the amorphous carbon matrix and containing crystalline carbon, The amorphous carbon matrix comprises a first amorphous carbon layer and a second amorphous carbon layer, An all-solid-state battery further comprising a lithium metal layer disposed between the first amorphous carbon layer and the second amorphous carbon layer and in direct contact with the composite particles.

19. Bipolar layer; a cathode layer opposite to the anode layer; and Including a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; The above cathode layer: negative current collector; A first functional layer coating the surface of the above negative electrode collector; an electrodeposition layer on the first functional layer; and Including a second functional layer on the above-mentioned electrodeposition layer, Each of the first functional layer and the second functional layer includes conductive carbon, The above-mentioned electrodeposition layer comprises an amorphous carbon matrix and composite particles dispersed within the amorphous carbon matrix and containing crystalline carbon. All-solid-state battery.

20. In paragraph 19, The conductive carbon comprises at least one selected from the group consisting of amorphous carbon, graphite, graphene, graphene oxide, reduced graphene oxide, and combinations thereof. All-solid-state battery.

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