All-solid-state battery

Abstract

The present invention relates to an all-solid-state battery and, more specifically, to an all-solid-state battery including: a cell stack including a plurality of stacked unit cells; and a spring pad provided on at least one of a lower part and an upper part of the cell stack. The spring pad includes a plate and a plurality of springs on the plate, each of the plurality of springs includes a first spring having a first diameter and a second spring having a second diameter smaller than the first diameter, and the second spring is positioned inside the first spring.

Description

All-solid-state batteries

[0001] The present invention relates to an all-solid-state battery, and more particularly, to an all-solid-state battery including a spring pad capable of uniformly pressurizing a cell.

[0002]

[0003] Recent industrial demands have led to the active development of batteries with high energy density and safety. For example, lithium-ion batteries are being used not only in information and communication devices, but also in the automotive sector. Safety is particularly important in the automotive sector, as it is directly related to life.

[0004] All-solid-state batteries do not use flammable organic dispersion media, significantly reducing the risk of fire or explosion even if a short circuit occurs. Consequently, these all-solid-state batteries can boast excellent safety.

[0005]

[0006] The problem to be solved by the present invention is to provide an all-solid-state battery with improved durability.

[0007]

[0008] According to the concept of the present invention, an all-solid-state battery may include a cell stack including a plurality of stacked unit cells; and a spring pad provided at least on one of the bottom and top of the cell stack. The spring pad includes a plate and a plurality of springs on the plate, each of the plurality of springs including a first spring having a first diameter and a second spring having a second diameter smaller than the first diameter, and the second spring may be located inside the first spring.

[0009] According to another concept of the present invention, an all-solid-state battery may include a cell of the all-solid-state battery; and a spring pad provided at least at one of the bottom and top of the cell. The spring pad includes a first plate, a second plate, and a double spring between the first and second plates, the double spring including a first spring having a first diameter and a second spring having a second diameter smaller than the first diameter, and the second spring may be located inside the first spring.

[0010]

[0011] The present invention provides an all-solid-state battery that can be used at both high and low temperatures and has excellent lifespan characteristics. The spring pad according to the present invention can uniformly and stably pressurize the cells of the all-solid-state battery. Specifically, the present invention can maintain uniform pressure in the cells by uniformly arranging small springs on a plate. Since each spring has a double spring structure, it can stably withstand high pressure (or load) even with a small diameter.

[0012]

[0013] FIG. 1 is a plan view of an all-solid-state battery according to embodiments of the present invention.

[0014] Figure 2 is a cross-sectional view taken along line A-A' of Figure 1.

[0015] FIG. 3 is a cross-sectional view taken along line A-A' of FIG. 1 to explain an all-solid-state battery according to another embodiment of the present invention.

[0016] FIG. 4 is a cross-sectional view taken along line A-A' of FIG. 1 to explain an all-solid-state battery according to another embodiment of the present invention.

[0017] FIG. 5 is a plan view illustrating a spring pad according to embodiments of the present invention.

[0018] Fig. 6 is a cross-sectional view taken along line AA' of Fig. 5.

[0019] Figure 7 is a graph of stress versus strain of a double spring according to an embodiment of the present invention and a single spring according to a comparative example of the present invention.

[0020] FIG. 8 is a cross-sectional view taken along line AA' of FIG. 5 to explain a spring pad according to another embodiment of the present invention.

[0021] Figure 9 is a cross-sectional view illustrating an all-solid-state battery according to one embodiment of the present invention.

[0022] FIG. 10 and FIG. 11 are each cross-sectional views illustrating an all-solid-state battery according to another embodiment of the present invention.

[0023] Figure 12 is a graph showing the physical characteristics of a pad according to an embodiment of the present invention.

[0024] Figure 13 is a graph showing the results of repeating the press and release of a pad 100 times according to an embodiment of the present invention.

[0025] Figure 14 is a graph showing the results of repeating the press and release of a pad 10 times according to an embodiment of the present invention.

[0026] Figures 15a and 15b are graphs showing the results of repeating compression 10 times in a strain range of 30% of a pad according to an embodiment of the present invention.

[0027]

[0028] 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.

[0029] 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.

[0030] 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.

[0031] The terminology used herein is for the purpose of describing embodiments and is not intended to limit the present invention. In this specification, the singular also includes the plural unless specifically stated otherwise. As used herein, the words "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components.

[0032] 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.

[0033]

[0034] 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.

[0035] Referring to FIGS. 1 and 2, a unit cell (CEL) of an all-solid-state battery 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 unit cell (CEL) 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).

[0036] 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.

[0037] 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.

[0038] Meanwhile, unlike that illustrated in FIG. 1, 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).

[0039] 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.

[0040] 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.

[0041] 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, 단위 셀(CEL)의 에너지 밀도가 커지고 열안정성이 향상될 수 있다.

[0042] 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.

[0043] When the cathode active material is a ternary lithium transition metal oxide such as NCA or NCM and contains nickel (Ni), it is possible to increase the capacity density of the unit cell (CEL) and reduce metal dissolution of the cathode active material in a charged state. As a result, the cycle characteristics of the unit cell (CEL) in a charged state are improved. Meanwhile, the "cycle characteristics" are characteristics indicating the degree to which the unit cell (CEL) is deteriorated due to charge / discharge of the unit cell (CEL). A unit cell (CEL) with high cycle characteristics may have a small degree of deterioration of the unit cell (CEL) due to charge / discharge, and a unit cell (CEL) with low cycle characteristics may have a large degree of deterioration of the unit cell (CEL) due to charge / discharge.

[0044] 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.

[0045] 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).

[0046] 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-x PS6-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 Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] The positive electrode active material layer (120) may include a conductive material. The conductive material may be conductive without causing chemical changes in the unit cell (CEL), thereby increasing the conductivity of the positive electrode active material and the solid electrolyte. The conductive material may include a carbon-based material. For example, the conductive material may include one or more selected from graphite, carbon black, acetylene black, carbon nanofibers, and carbon nanotubes.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] The negative electrode layer (200) may include a negative electrode current collector (210) and a negative electrode coating layer (220) on the negative electrode current collector (210). The negative electrode current collector (210) may provide a reference surface on which the negative electrode coating layer (220) is 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.

[0056] 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.

[0057] The cathode coating layer (220) can allow lithium metal to grow between the cathode current collector (210) and the unit cell (CEL) when charging. The cathode coating layer (220) can act as a protective layer for the lithium metal and simultaneously suppress the precipitation and growth of lithium dendrites.

[0058] The cathode coating layer (220) may include a metal and carbon. For example, the cathode coating layer (220) may include at least one metal selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The cathode coating layer (220) may include at least one carbon selected from the group consisting of carbon black, acetylene black, furnace black, ketjen black, and graphene. In one embodiment, the cathode coating layer (220) may include a mixture of carbon black and silver (Ag).

[0059] The cathode coating layer (220) may further include additives other than metal and carbon. The cathode coating layer (220) may further include, for example, at least one additive selected from the group consisting of a binder, a filler, a coating agent, a dispersant, and an ion conductive additive.

[0060] The negative electrode coating layer (220) may have a smaller thickness than the positive electrode active material layer (120). The thickness of the negative electrode coating layer (220) may be, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer (120). The thickness of the negative electrode coating layer (220) may be, for example, 1 um to 20 um, 2 um to 10 um, or 3 um to 7 um. If the thickness of the negative electrode coating layer (220) is too thin, lithium dendrites formed between the negative electrode coating layer (220) and the negative electrode current collector (210) may collapse the negative electrode coating layer (220), thereby deteriorating the cycle characteristics of the unit cell (CEL). If the thickness of the cathode coating layer (220) increases excessively, the energy density of the unit cell (CEL) may decrease and the internal resistance of the unit cell (CEL) due to the cathode coating layer (220) may increase, thereby deteriorating the cycle characteristics of the cell.

[0061] Meanwhile, although not shown, a carbon layer may be further included to improve adhesion between the cathode coating layer (220) and the solid electrolyte layer (300).

[0062] 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.

[0063] 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).

[0064] 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.

[0065] In one embodiment, the first solid electrolyte is 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 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.

[0066] In another embodiment, the first solid electrolyte is Li 7-a M a PS 6-c X c It may include an argyrodite-type compound including X, 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.

[0067] 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.

[0068] 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 negative electrode coating layer (220).

[0069] 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.

[0070] 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.

[0071] The second solid electrolyte can be in direct contact with the negative electrode coating layer (220). As a result, the second solid electrolyte can suppress lithium dendrites formed between the negative electrode coating 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 according to the present invention can be improved.

[0072] 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).

[0073] 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).

[0074] 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).

[0075] 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).

[0076] 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).

[0077] A unit cell (CEL) according to the present embodiment can be manufactured by forming a cathode composite layer (ASH) on a first carrier film, forming a cathode composite layer (CSH) on a second carrier film, and then laminating the cathode composite layer (ASH) and the cathode composite layer (CSH).

[0078] In the embodiments described below, detailed descriptions of technical features that overlap with those described previously with reference to FIGS. 1 and 2 will be omitted, and differences will be described in detail.

[0079] FIG. 3 is a cross-sectional view taken along line A-A' of FIG. 1 to explain an all-solid-state battery according to another embodiment of the present invention. Referring to FIG. 3, a unit cell (CEL) according to the present invention may further include a gasket (GSK). The gasket (GSK) may be provided to surround a cathode composite layer (CSH). The gasket (GSK) may fill a step in the side surface of the unit cell (CEL) caused by a difference in area between the cathode composite layer (ASH) and the cathode composite layer (CSH). The gasket (GSK) may surround 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).

[0080] 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.

[0081] FIG. 4 is a cross-sectional view taken along line A-A' of FIG. 1 to explain an all-solid-state battery according to another embodiment of the present invention. Referring to FIG. 4, the negative electrode layer (200) of the unit cell (CEL) may further include a lithium metal layer (400) between the negative electrode current collector (210) and the negative electrode coating layer (220). The thickness of the lithium metal layer (400) may further increase when the unit cell (CEL) is charged. The negative electrode coating layer (220) serves as a protective layer for the lithium metal layer (400), and at the same time, may suppress the growth of lithium dendrites from the lithium metal layer (400).

[0082] The lithium metal layer (400) may be a metal thin film containing lithium or a lithium alloy. The lithium alloy may include, but is not limited to, a Li-Al alloy, a Li-Sn alloy, a Li-In alloy, a Li-Ag alloy, a Li-Au alloy, a Li-Zn alloy, a Li-Ge alloy, a Li-Si alloy, etc., and any lithium alloy may be used. The lithium metal layer (400) may contain one of these alloys or lithium. Alternatively, the lithium metal layer (400) may contain various types of alloys.

[0083] The lithium metal layer (400) may have a fifth width (WI5) in the first direction (D1). The fifth width (WI5) may be equal to or greater than the first width (WI1). The fifth width (WI5) may be equal to or less than the second width (WI2). For example, the fifth width (WI5) may be greater than the first width (WI1) and less than the second width (WI2).

[0084]

[0085] Fig. 5 is a plan view illustrating a spring pad according to embodiments of the present invention. Fig. 6 is a cross-sectional view taken along line AA' of Fig. 5.

[0086] Referring to FIGS. 5 and 6, a spring pad (MSP) may be provided to uniformly pressurize the interior of an all-solid-state battery. The spring pad (MSP) may include a plate (PLT). The plate (PLT) may include a first plate (PLT1) and a second plate (PLT2). The first plate (PLT1) may be a lower plate of the spring pad (MSP), and the second plate (PLT2) may be an upper plate of the spring pad (MSP). Each of the first and second plates (PLT1, PLT2) may include at least one metal selected from aluminum and stainless steel, a polymer, an amorphous material, or a ceramic.

[0087] A plurality of springs (ELB) may be interposed between the first and second plates (PLT1, PLT2). As shown in Fig. 5, the plurality of springs (ELB) may be two-dimensionally arranged on the plate (PLT). For example, the plurality of springs (ELB) may be arranged in a row along the first direction (D1) and the second direction (D2). The arrangement of the plurality of springs (ELB) according to the present invention is not limited to that shown in Fig. 5. The plurality of springs (ELB) may also be arranged in various other arrangements (for example, a zigzag arrangement).

[0088] For example, the spacing between springs (ELB) adjacent to each other in the first direction (D1) may be greater than 0 mm and less than or equal to 3 mm. The spacing between springs (ELB) adjacent to each other in the second direction (D2) may be greater than 0 mm and less than or equal to 3 mm.

[0089] Each of the springs (ELB) may include a first spring (ELB1) and a second spring (ELB2). The first spring (ELB1) may be larger than the second spring (ELB2). Specifically, a first diameter (DI1) of the first spring (ELB1) may be larger than a second diameter (DI2) of the second spring (ELB2). A first thickness (TK1) of the first spring (ELB1) may be larger than a second thickness (TK2) of the second spring (ELB2). In the present invention, the thickness of the spring may refer to the thickness of a metal wire constituting the spring (see FIGS. 5 and 6).

[0090] The second spring (ELB2) may be located within the first spring (ELB1). Specifically, the interior of the first spring (ELB1) may be an empty space. The second spring (ELB2) may be provided within the empty space within the first spring (ELB1). Thus, the spring (ELB) composed of the first spring (ELB1) and the second spring (ELB2) may have a double spring structure.

[0091] In one embodiment, the elastic modulus of the first spring (ELB1) and the elastic modulus of the second spring (ELB2) may be different from each other. For example, the elastic modulus of the first spring (ELB1) may be greater than the elastic modulus of the second spring (ELB2). The elastic modulus of the spring (ELB) composed of the first and second springs (ELB1, ELB2) may be substantially equal to the sum of the elastic modulus of the first spring (ELB1) and the elastic modulus of the second spring (ELB2).

[0092] The first diameter (DI1) of the first spring (ELB1) may be 10 mm to 20 mm. The second diameter (DI2) of the second spring (ELB2) may be 5 mm to 10 mm. Each of the springs (ELB) may have a relatively small diameter, thereby allowing a plurality of springs (ELB) to be uniformly arranged at a high density on the plate (PLT).

[0093] The spring pad (MSP) according to the present invention has superior durability and maintains consistent elasticity compared to the elastic sheet described below. Furthermore, since small-sized springs (ELB) are uniformly arranged at a high density on the plate (PLT), uniform pressure can be applied to the cell stack within the all-solid-state battery.

[0094] In one embodiment, each of the first and second springs (ELB1, ELB2), i.e., the spring (ELB), may be a metal coil spring. The spring (ELB) may include a coil spring in which coils of symmetrical shapes are laminated and extended in a direction in which an elastic restoring force is generated. The spring (ELB) may include, but is not limited to, a crest-to-crest coil spring.

[0095] The spring (ELB) according to the present embodiment includes a coil spring in which coils of symmetrical shapes are laminated and extended in a direction in which elastic restoring force is generated, thereby improving the lifespan compared to a flat type coil spring and suppressing the generation of powder due to friction caused by spring elastic recovery.

[0096] In another embodiment, the spring (ELB) may include a coil spring in which a single-layer coil is extended in a ring shape. The spring (ELB) may include, but is not limited to, a single-turn coil spring. By including a coil spring in which a single-layer coil is extended in a ring shape, the spring (ELB) may have an improved lifespan and a reduced thickness compared to a flat-type coil spring.

[0097] In another embodiment, the spring (ELB) may include a coil spring in which coils of the same shape are laminated and extended in a direction in which an elastic restoring force is generated. The spring (ELB) may include, but is not limited to, a nested coil spring. By including a coil spring in which coils of the same shape are laminated and extended in a direction in which an elastic restoring force is generated, the spring (ELB) may have an improved lifespan, a reduced thickness, and improved elastic restoring force compared to a flat type coil spring.

[0098] Referring to Fig. 7, a graph of stress versus strain of a double spring according to an embodiment of the present invention and a single spring according to a comparative example of the present invention is shown. When the single spring of the comparative example, for example, the first spring (ELB1), is used alone, there is a problem that the elastic modulus is relatively small and thus the stress that can be endured is relatively small. On the other hand, when the double spring according to the present embodiment, for example, a combination of the first and second springs (ELB1, ELB2), is used, there is an advantage that the elastic modulus is relatively large and thus the stress that can be endured is relatively large.

[0099]

[0100] FIG. 8 is a cross-sectional view taken along line AA' of FIG. 5 to explain a spring pad according to another embodiment of the present invention.

[0101] Referring to FIGS. 5 and 8, the first plate (PLT1) may include a first recessed portion (RSR1) for accommodating a second spring (ELB2). The second plate (PLT1) may include a second recessed portion (RSR2) for accommodating a second spring (ELB2). The first recessed portion (RSR1) and the second recessed portion (RSR2) may vertically overlap each other. The diameter of each of the first and second recessed portions (RSR1, RSR2) may be substantially the same as the second diameter (DI2) of the second spring (ELB2) described above with reference to FIG. 6.

[0102] A second spring (ELB2) may be provided within the first and second recessed portions (RSR1, RSR2). The first spring (ELB1) may have a first height (HE1) between the first and second plates (PLT1, PLT2). The second spring (ELB2) may have a second height (HE2) between the first and second recessed portions (RSR1, RSR2). The second height (HE2) may be greater than the first height (HE1).

[0103] By inserting and supporting the second spring (ELB2) into the first and second recessed portions (RSR1, RSR2), the second spring (ELB2) can be stably fixed inside the first spring (ELB1). The first and second recessed portions (RSR1, RSR2) can prevent the second spring (ELB2) from coming off.

[0104] In one embodiment of the present invention, at least one of the first and second plates (PLT1, PLT2) may further include a recessed portion for accommodating a first spring (ELB1). For example, each of the first and second plates (PLT1, PLT2) may have a double recessed structure for securing a double spring.

[0105]

[0106] Fig. 9 is a cross-sectional view illustrating an all-solid-state battery according to one embodiment of the present invention. Referring to Fig. 9, the all-solid-state battery may include a case (CHO) and a cell stack (LAM) within the case (CHO).

[0107] A cell stack (LAM) may include a plurality of unit cells (CEL) and a plurality of elastic pads (EPD). In one embodiment, the plurality of unit cells (CEL) and the plurality of elastic pads (EPD) may be alternately stacked along a third direction (D3). Each of the plurality of unit cells (CEL) may be substantially identical to the unit cell (CEL) described above with reference to FIGS. 1 to 4.

[0108] Each of the elastic pads (EPD) may include an insulating material. The elastic pad (EPD) may include an elastic material. For example, the elastic pad (EPD) may include at least one selected from the group consisting of epoxy resin, acrylic resin, polyimide resin, polyester resin, polypropylene resin, polyamide resin, polystyrene resin, polyvinyl chloride resin, polycarbonate resin, fluororesin such as PTFE, and silicone rubber. In one embodiment, the lowermost elastic pad (EPD) may be provided at the lowermost portion of the cell stack (LAM). The uppermost elastic pad (EPD) may be provided at the uppermost portion of the cell stack (LAM).

[0109] The all-solid-state battery according to the present invention may further include at least one spring pad (MSP) provided inside the case (CHO). For example, a first spring pad (MSP1) may be provided below the cell stack (LAM), and a second spring pad (MSP2) may be provided above the cell stack (LAM). The cell stack (LAM) may be interposed between the first and second spring pads (MSP1, MSP2). Each of the first and second spring pads (MSP1, MSP2) may be substantially the same as the spring pad (MSP) described above with reference to FIGS. 5 to 9.

[0110] The case (CHO) can accommodate a cell stack (LMA) in its internal space. In one embodiment, the case (CHO) may have a metal can shape, but is not limited thereto. The case (CHO) may have a square prism shape, but is not limited thereto, and may have a polygonal prism shape such as a triangular prism shape, a pentagonal prism shape, a hexagonal prism shape, a heptagonal prism shape, an octagonal prism shape, a circular prism shape, an elliptical prism shape, or a loop prism shape. Various known coating layers may be coated on the inner and outer surfaces of the case (CHO).

[0111] A first spring pad (MSP1) may be interposed between the bottom surface of the case (CHO) and the cell stack (LAM). A second spring pad (MSP2) may be interposed between the top surface of the case (CHO) and the cell stack (LAM). The first and second spring pads (MSP1, MSP2) may apply uniform pressure to the cell stack (LAM). The first and second spring pads (MSP1, MSP2) may accommodate a change in the volume of the cell stack (LAM) that occurs during charging / discharging of the battery.

[0112] FIG. 10 and FIG. 11 are each cross-sectional views illustrating an all-solid-state battery according to another embodiment of the present invention.

[0113] Referring to FIG. 10, the all-solid-state battery may include a pouch (PCH) and a layered organic light emitting diode (LAM) within the pouch (PCH). The layered organic light emitting diode (LAM) may include a plurality of unit cells (CELs) and a plurality of elastic pads (EPDs) that are alternately stacked.

[0114] The all-solid-state battery according to the present embodiment may further include at least one spring pad (MSP) provided inside the pouch (PCH). For example, a first spring pad (MSP1) may be provided below the cell stack (LAM), and a second spring pad (MSP2) may be provided above the cell stack (LAM). The cell stack (LAM) may be interposed between the first and second spring pads (MSP1, MSP2). The pouch (PCH) may enclose the stack (LAM1), the first spring pad (MSP1), and the second spring pad (MSP2) together.

[0115] The pouch (PCH) may be interposed between a first end plate (ENP1) and a second end plate (ENP2). The first end plate (ENP1) may be positioned below the first spring pad (MSP1). The second end plate (ENP2) may be positioned above the second spring pad (MSP2).

[0116] A fastening member (CPP) connecting a first end plate (ENP1) and a second end plate (ENP2) to each other may be provided. The fastening member (CPP) may fasten the first and second end plates (ENP1, ENP2) to each other. The first and second end plates (ENP1, ENP2) are coupled to each other by the fastening member (CPP), thereby pressurizing a cell stack (LAM) therein. The first and second spring pads (MSP1, MSP2) may uniformly transmit the pressure formed by the first and second end plates (ENP1, ENP2) to the cell stack (LAM).

[0117] Referring to FIG. 11, the all-solid-state battery may include a first cell stack (LAM1) and a second cell stack (LAM2). The second cell stack (LAM2) may be stacked on the first cell stack (LAM1).

[0118] The first cell stack (LAM1) may include a plurality of first unit cells (CEL1) and a plurality of first elastic pads (EPD1) that are alternately stacked. The second cell stack (LAM2) may include a plurality of second unit cells (CEL2) and a plurality of second elastic pads (EPD2) that are alternately stacked.

[0119] A first pouch (PCH1) may surround a first cell stack (LAM1). A second pouch (PCH2) may surround a second cell stack (LAM2). A spring pad (MSP) may be provided between the first cell stack (LAM1) and the second cell stack (LAM2).

[0120] A first end plate (ENP1) may be provided below a first cell stack (LAM1). A second end plate (ENP2) may be provided above a second cell stack (LAM2). A fastening portion (CPP) may be provided to connect the first end plate (ENP1) and the second end plate (ENP2) to each other. The first and second end plates (ENP1, ENP2) are coupled to each other by the fastening portion (CPP), thereby pressurizing the first and second cell stacks (LAM1, LAM2) therein. The spring pad (MSP) may uniformly transmit the pressure formed by the first and second end plates (ENP1, ENP2) to the first and second cell stacks (LAM1, LAM2).

[0121]

[0122] Hereinafter, the present invention will be described in more detail through examples. However, these examples are intended to exemplify the present invention and the scope of the present invention is not limited to these examples.

[0123] Example

[0124] A metal spring pad comprising metal springs and metal plates was prepared. The metal springs were positioned between two metal plates and arranged in a checkerboard pattern on one metal plate. Adjacent metal springs were spaced at intervals of less than 2 mm. Each metal spring had a dual spring structure, with a first spring having a diameter of 15 mm and a second spring having a diameter of 7 mm. Each of the first and second springs was a coil spring. Each metal spring was made of stainless steel (SUS). The thickness of the metal spring pad ranged from 3 mm to 20 mm.

[0125]

[0126] Experimental Example 1: Investigation of the usable temperature of the pad

[0127] Using the pad of the example, physical properties were investigated at various temperatures. The physical properties were investigated by pressing and releasing at a speed of 0.01 mm / s up to 7.5 MPa at a specific temperature. The results are shown in Fig. 12. Referring to Fig. 12, it was confirmed that the pad of the example maintained its physical properties at both high and low temperatures.

[0128]

[0129] Experimental Example 2: Investigation of the lifespan of the pad

[0130] The lifespan of the pad of the example was investigated through a compression test. The compression test was conducted by measuring the force or pressure applied externally when the pad of the example was contracted. The process of pressing to y mm at a speed of 0.1 mm / s and releasing to y mm at a speed of 0.1 mm / s was repeated 100 times, and the results are shown in Fig. 13. The process of pressing to b mm at a speed of 0.01 mm / s and releasing to b mm at a speed of 0.01 mm / s was repeated 10 times, and the results are shown in Fig. 14.

[0131] Referring to FIGS. 13 and 14, the pad according to the embodiment maintained the force without a significant decrease (about 95% decrease).

[0132] Referring to Fig. 15a, the pad according to the embodiment did not undergo permanent deformation even after 10 repetitions of compression within a strain range of 30%. Referring to Fig. 15b, the pad according to the embodiment did not exhibit significant changes in response to externally applied force even after repeated compression.

[0133] Through the above experimental results, it was confirmed that the pad according to the example had an excellent lifespan.

Claims

1. A cell stack comprising a plurality of stacked unit cells; and Including a spring pad provided at least one of the bottom and top of the cell stack, The spring pad comprises a plate and a plurality of springs on the plate, Each of the plurality of springs includes a first spring having a first diameter and a second spring having a second diameter smaller than the first diameter, An all-solid-state battery, wherein the second spring is located inside the first spring.

2. In paragraph 1, An all-solid-state battery, wherein the elastic modulus of the first spring is greater than the elastic modulus of the second spring.

3. In paragraph 1, An all-solid-state battery, wherein the thickness of the first spring is greater than the thickness of the second spring.

4. In paragraph 1, An all-solid-state battery, wherein the height of the first spring is smaller than the height of the second spring.

5. In paragraph 4, An all-solid-state battery, wherein the plate includes a recess configured to receive the second spring.

6. In paragraph 1, An all-solid-state battery, wherein the elastic coefficient of each of the plurality of springs is substantially equal to the sum of the elastic coefficient of the first spring and the elastic coefficient of the second spring.

7. In paragraph 1, The above plurality of springs are arranged in a row along the first direction, An all-solid-state battery, wherein the plurality of springs are arranged in a row along a second direction intersecting the first direction.

8. In paragraph 1, An all-solid-state battery, wherein the gap between adjacent springs among the plurality of springs is greater than 0 mm and less than or equal to 3 mm.

9. In paragraph 1, Further comprising a case accommodating the cell stack and the spring pad, The above case is an all-solid-state battery including a metal can.

10. In paragraph 1, A pouch surrounding the cell stack and the spring pad; 1st end plate; a second end plate; and Further comprising a fastening member for fastening the first and second end plates to each other, An all-solid-state battery, wherein the pouch is interposed between the first and second end plates.

11. In paragraph 1, An all-solid-state battery, wherein each of the plurality of unit cells includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer.

12. In paragraph 10, The above positive electrode layer includes a positive electrode current collector and a positive electrode active material layer on the positive electrode current collector, An all-solid-state battery, wherein the negative electrode layer comprises a negative electrode current collector and a negative electrode coating layer on the negative electrode current collector.

13. In paragraph 1, An all-solid-state battery, wherein the cell stack further includes a plurality of elastic pads each interposed between the plurality of unit cells.

14. In paragraph 13, An all-solid-state battery, wherein each of the plurality of elastic pads comprises at least one selected from the group consisting of epoxy resin, acrylic resin, polyimide resin, polyester resin, polypropylene resin, polyamide resin, polystyrene resin, polyvinyl chloride resin, polycarbonate resin, fluororesin such as PTFE, and silicone rubber.

15. Cells of all-solid-state batteries; and Including a spring pad provided at least one of the bottom and top of the above cell, The spring pad comprises a first plate, a second plate, and a double spring between the first and second plates, The above double spring includes a first spring having a first diameter and a second spring having a second diameter smaller than the first diameter, An all-solid-state battery, wherein the second spring is located inside the first spring.

16. In paragraph 15, An all-solid-state battery, wherein the elastic modulus of the first spring is greater than the elastic modulus of the second spring.

17. In paragraph 15, An all-solid-state battery, wherein the thickness of the first spring is greater than the thickness of the second spring.

18. In paragraph 15, An all-solid-state battery, wherein the height of the first spring is smaller than the height of the second spring.

19. In paragraph 18, An all-solid-state battery, wherein at least one of the first and second plates includes a recess configured to receive the second spring.

20. In paragraph 15, An all-solid-state battery, wherein the elastic modulus of the double spring is substantially equal to the sum of the elastic modulus of the first spring and the elastic modulus of the second spring.

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