All-solid-state battery and battery module including all-solid-state battery

Abstract

The present invention relates to an all-solid battery including: a positive electrode including a positive electrode current collector coated with a positive electrode mixture layer; a negative electrode including a negative electrode current collector having a porous structure; a solid electrolyte layer located between the positive electrode and the negative electrode; a stopper provided at an outer circumference of the negative electrode; a battery case in which the stopper and an electrode assembly including the positive electrode, the negative electrode, and the solid electrolyte layer are accommodated; and a pressing member provided at both surfaces of the battery case parallel to a plane of the positive electrode and the negative electrode and pressing the positive electrode and the negative electrode toward an inside of the battery case, wherein a height of the stopper is equal to or less than a thickness of the negative electrode before being pressed. The all-solid battery suppresses formation of lithium dendrites and thus improves safety.

Description

Technical Field

[0001] This application claims priority to Korean Patent Application No. 2021-0041333, filed on March 30, 2021, the disclosure of which is incorporated herein by reference in its entirety.

[0002] This invention relates to an all-solid-state battery including a porous current collector and a battery module including the all-solid-state battery. More specifically, this invention relates to an all-solid-state battery including a porous current collector and a battery module including the all-solid-state battery, which is configured to reduce the variation in battery thickness caused by lithium plating and peeling. Background Technology

[0003] Rechargeable lithium-ion batteries with high energy density have attracted attention as an environmentally friendly new energy source because they not only significantly reduce the use of fossil fuels, but also do not produce byproducts from energy use.

[0004] Lithium-ion batteries have also attracted attention as a power source for devices with high output and high energy density, such as electric vehicles, as well as wearable or portable devices. As a result, research on lithium-ion batteries with high operating voltage and energy density has been rapidly underway.

[0005] Lithium-ion secondary batteries, including electrolytes and separators, have the disadvantage of high risks of electrolyte leakage and fire / explosion. As an alternative, an all-solid-state battery has been proposed, which uses a non-flammable solid as the electrolyte, thereby reducing the risk of fire / explosion.

[0006] The advantages of all-solid-state batteries are improved safety. Due to the use of solid electrolytes, lithium ions move at high speeds and the thickness of the negative electrode is reduced, thereby increasing energy density.

[0007] As a means of increasing the energy density of all-solid-state batteries, a negative electrode consisting only of a current collector has been proposed without including a negative electrode mixture layer.

[0008] When an all-solid-state battery, including a negative electrode without a negative electrode mixture layer, is charged, lithium ions move from the positive electrode to the negative electrode, and lithium is deposited on the negative electrode current collector at the point where the negative electrode current collector and the solid electrolyte layer come into contact with each other. When the all-solid-state battery discharges, the lithium deposited on the negative electrode current collector is stripped off. This process may alter the volume of the all-solid-state battery.

[0009] Furthermore, due to the repeated charging and discharging of all-solid-state batteries, the size of lithium deposited on the negative electrode current collector may gradually increase, and lithium dendrites may grow through the pores of the solid electrolyte layer. Lithium dendrites may cause short circuits in the battery or may reduce the battery's capacity.

[0010] In other words, as the contact interface between the negative electrode current collector and the solid electrolyte layer becomes smaller, the possibility of lithium dendrite growth may further increase.

[0011] Relatedly, Patent Document 1 relates to a current collector having a three-dimensional structure with holes, wherein a seed metal is deposited on the lower surface of the current collector, such that the lower surface of the current collector has a lower reduction potential than the upper surface of the current collector. Due to the reduction potential difference between the upper and lower surfaces of the current collector, lithium ions move to the lower surface of the current collector, thereby preventing the growth of lithium dendrites.

[0012] Although Patent Document 1 proposes a three-dimensional current collector structure with pores to prevent lithium dendrite growth, this current collector is for lithium-ion secondary batteries and does not propose a method to widen the contact interface between the negative electrode and the solid electrolyte layer.

[0013] Therefore, technologies are needed to reduce volume changes in all-solid-state batteries and prevent lithium dendrite growth, thereby improving the safety of all-solid-state batteries.

[0014] (Existing technical literature)

[0015] (Patent Document 1) Korean Patent Application Publication No. 2019-0143710 (2019.12.31) Summary of the Invention

[0016] Technical issues

[0017] The present invention was made in view of the above-mentioned problems, and the object of the present invention is to provide an all-solid-state battery including a porous current collector and a battery module including the all-solid-state battery, which is configured such that the plating and stripping of lithium moving to the negative electrode occurs in the negative current collector, thereby preventing volume changes of the all-solid-state battery.

[0018] Technical solution

[0019] An all-solid-state battery according to the invention for achieving the above-mentioned objectives, the all-solid-state battery comprising: a positive electrode including a positive current collector coated with a positive electrode mixture layer; a negative electrode including a negative current collector having a porous structure; a solid electrolyte layer located between the positive and negative electrodes; a first stop member disposed at the outer periphery of the negative electrode; a battery housing configured to house an electrode assembly and the first stop member, the electrode assembly including a positive electrode, a negative electrode, and the solid electrolyte layer; and a pressing member disposed at each of the opposing surfaces of the battery housing parallel to the planes of the positive and negative electrodes, the pressing member being configured to press in a direction toward the interior of the battery housing, wherein the height of the first stop member is equal to or less than the thickness of the negative electrode before pressing.

[0020] The negative current collector can be made of metallic materials.

[0021] All-solid-state batteries may also include a second stop located at the outer periphery of the positive electrode.

[0022] The first stop can be configured to be perpendicular to the pressing surface of the pressing member.

[0023] The height of the first stop can be less than the thickness of the negative electrode before pressing.

[0024] The length of the first stop can correspond to the length of the outer perimeter of the negative electrode where the first stop is located.

[0025] When the battery casing is pressed by the pressing member, the initial shape of the first stop can be maintained.

[0026] All-solid-state batteries do not undergo volume changes due to charging and discharging.

[0027] Lithium plating and stripping can occur in the holes of the negative current collector.

[0028] The negative electrode can be made of a negative electrode current collector with a porous structure.

[0029] This invention provides a battery module that includes all-solid-state batteries as unit cells.

[0030] Furthermore, the present invention can provide various combinations of the above-mentioned solutions.

[0031] Beneficial effects

[0032] As is apparent from the above description, in this invention, a porous negative electrode current collector with pores formed therein is provided, whereby lithium can be grown in the pores of the negative electrode current collector, and thus the thickness of the all-solid-state battery can be prevented from increasing.

[0033] In addition, since lithium grows in the holes of the negative electrode current collector, lithium dendrites can be prevented from growing toward the positive electrode.

[0034] In addition, the pressing component is located on the outer surface of the battery casing, which increases the contact surface between the negative electrode and the solid electrolyte, and thus reduces the resistance of the all-solid-state battery.

[0035] In addition, the stop is located on the outside of the negative current collector, which can prevent the porous negative current collector from deforming due to the pressing force of the pressing component. Attached Figure Description

[0036] Figure 1 This is a vertical cross-sectional view of an all-solid-state battery according to an embodiment.

[0037] Figure 2 yes Figure 1 A three-dimensional image.

[0038] Figure 3 yes Figure 1 A magnified view of a portion of the image.

[0039] Figure 4 yes Figure 1 A magnified view of a portion of the image.

[0040] Figure 5 yes Figure 2 An exploded 3D diagram.

[0041] Figure 6 This is an exploded perspective view of an all-solid-state battery according to another embodiment. Detailed Implementation

[0042] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, enabling those skilled in the art to readily implement the invention. However, in describing the operational principles of the preferred embodiments of the invention in detail, detailed descriptions of known functions and configurations incorporated herein may obscure the subject matter of the invention, and will therefore be omitted.

[0043] Furthermore, the same reference numerals are used throughout the accompanying drawings to denote components that perform similar functions or operations. Where one component is referred to in the specification as being connected to another component, this means not only that the one component can be directly connected to the other component, but also that the one component can be indirectly connected to the other component via yet another component. Additionally, unless otherwise stated, including one element does not mean excluding other elements, but rather means that these elements can be further included.

[0044] Furthermore, unless otherwise specified, the description of implementing elements by limitation or addition can be applied to all inventions and does not limit any particular invention.

[0045] Furthermore, in the specification and claims of this invention, unless otherwise stated, the singular form is intended to include the plural form.

[0046] Furthermore, in the specification and claims of this invention, unless otherwise stated, "or" includes "and". Therefore, "including A or B" refers to three cases: including A, including B, and including both A and B.

[0047] Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0048] Figure 1 This is a vertical cross-sectional view of an all-solid-state battery according to the present invention, and Figure 2 yes Figure 1 A three-dimensional image.

[0049] Reference Figure 1 and Figure 2 The all-solid-state battery according to the present invention includes: a positive electrode 110 including a positive current collector 111 coated with a positive electrode mixture layer 112; a negative electrode 120 including a negative current collector having a porous structure; a solid electrolyte layer 130 located between the positive electrode 110 and the negative electrode 120; a stop member 140 disposed at the outer periphery of the negative electrode 120; a battery housing 101 configured to accommodate an electrode assembly including the positive electrode 110, the negative electrode 120, the solid electrolyte layer 130 and the stop member 140; and a pressing member 150 disposed at each of the opposing surfaces of the battery housing 101 parallel to the planes of the positive electrode 110 and the negative electrode 120, the pressing member 150 being configured to press in a direction toward the interior of the battery housing 101.

[0050] For example, a positive electrode is manufactured by applying a positive electrode mixture, including a positive electrode active material, to a positive electrode current collector and drying the positive electrode mixture. Optionally, the positive electrode mixture may also include a binder, a conductive agent, and a filler, as needed.

[0051] The positive current collector is not particularly limited, as long as it exhibits high conductivity and does not cause any chemical changes in the battery in which it is used. For example, the positive current collector can be made of stainless steel, aluminum, nickel, titanium, or sintered carbon. Alternatively, it can be made of aluminum or stainless steel with a surface treated with carbon, nickel, titanium, or silver. Furthermore, the positive current collector can have micron-scale non-uniform patterns formed on its surface to increase the adhesion of the positive electrode active material. The positive current collector can be configured in any of a variety of forms, such as membranes, sheets, foils, meshes, porous bodies, foams, and nonwoven fabrics.

[0052] Positive electrode active materials are materials capable of inducing electrochemical reactions, and may include at least one of the positive electrode active materials represented by the following chemical formulas 1 to 3.

[0053] Li a Co 1-x M x O2(1)

[0054] Li a Mn 2-y M y O4(2)

[0055] Li a Fe 1-z M z PO4(3)

[0056] In the above formula, 0.8 ≤ a ≤ 1.2, 0 ≤ x ≤ 0.8, 0 ≤ y ≤ 0.6, and 0 ≤ z ≤ 0.5.

[0057] M is at least one selected from the group consisting of Ti, Cd, Cu, Cr, Mo, Mg, Mn, Al, Ni, Nb, V, and Zr.

[0058] In other words, the positive electrode active material may include at least one material selected from the group consisting of lithium metal oxide having a layered structure represented by chemical formula 1, lithium-manganese-based oxide having a spinel structure represented by chemical formula 2, and lithium phosphate having an olivine structure represented by chemical formula 3.

[0059] Although there is no limitation on the type of lithium metal oxide having a layered structure, at least one of the following can be used, for example: lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium cobalt-nickel oxide, lithium cobalt-manganese oxide, lithium manganese-nickel oxide, lithium nickel-cobalt-manganese oxide, and materials derived therefrom by replacing or doping with another element.

[0060] Lithium nickel-cobalt-manganese oxide can be represented as Li 1+z Ni b Co c Mn 1-(b+c+d) M d O (2-e) A e (Where, -0.5≤z≤0.5, 0.1≤b≤0.8, 0.1≤c≤0.8, 0≤d≤0.2, 0≤e≤0.2, b+c+d<1, M=Al, Mg, Cr, Ti, Si or Y, and A=F, P or Cl).

[0061] Although there is no limitation on the type of lithium-manganese-based oxide with a spinel structure, at least one of the following groups can be used, for example: lithium manganese oxide, lithium nickel manganese oxide, and materials derived therefrom by substitution or doping with another element.

[0062] Furthermore, although there are no restrictions on the types of lithium phosphates with an olivine structure, for example, at least one of the following groups can be used: lithium iron phosphate and materials derived therefrom by replacing or doping with another element.

[0063] Other elements may be at least one selected from the group consisting of Al, Mg, Mn, Ni, Co, Cr, V and Fe.

[0064] Adhesives are components that facilitate adhesion between active materials and conductive agents, as well as adhesion to current collectors. Based on the total weight of the mixture including the positive electrode active material, adhesives are typically added in amounts from 1% to 30% by weight. For example, adhesives may include at least one selected from the group consisting of polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene propylene diene monomer (EPDM), styrene-butene rubber, fluororubber, and copolymers thereof.

[0065] A conductive agent is typically added, making up 1% to 30% by weight of the total weight of the mixture, including the positive electrode active material. There are no particular limitations on the conductive agent, as long as it exhibits high conductivity without causing any chemical changes in the battery in which it is applied. For example, the following materials can be used as conductive agents: graphite, such as natural or artificial graphite; carbon black, such as ethylene black, acetylene black, Ketjen black, channel black, furnace black, lamp black, or thermally cracked carbon black; conductive fibers, such as carbon fibers or metal fibers; metal powders, such as fluorinated carbon powder, aluminum powder, or nickel powder; conductive whiskers, such as zinc oxide or potassium titanate; conductive metal oxides, such as titanium oxide; conductive materials, such as polyphenylene derivatives; graphene; or carbon nanotubes.

[0066] Fillers are optional components used to suppress electrode expansion. There are no particular restrictions on fillers, as long as they are made of fibrous materials and do not cause chemical changes in the battery to which they are applied. For example, materials such as polyolefin-based polymers, such as polyethylene or polypropylene, or fibrous materials, such as glass fiber or carbon fiber, can be used as fillers.

[0067] The negative current collector is configured to have a porous structure in which openings are formed, and is made of a metallic material that exhibits conductivity (such as copper, nickel, aluminum, stainless steel, or alloys thereof). For example, nickel (Ni) foam can be used as a negative current collector.

[0068] In a specific example, the negative electrode may include lithium metal, which can be added to the outer surface of a negative electrode current collector having a porous structure. There are no particular limitations on the method of adding lithium metal. For example, lithium metal can be added using deposition methods selected from the group consisting of thermal deposition, electron beam deposition, chemical vapor deposition, and physical vapor deposition.

[0069] The solid electrolyte that constitutes the solid electrolyte layer can be a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a polymer-based solid electrolyte.

[0070] Sulfide-based solid electrolytes may contain sulfur atoms (S), exhibit ionic conductivity characteristic of metals belonging to Group 1 or Group 2 of the periodic table, and may also exhibit electronic insulation. Sulfide-based solid electrolytes preferably contain at least Li, S, and P as elements and exhibit high lithium-ion conductivity; however, depending on the purpose or environment, elements other than Li, S, and P may be included.

[0071] Specifically, Li6PS5Cl, Li2S-P2S5, Li2S-P2S5-LiCl, Li2S-P2S5-H2S, Li2S-P2S5-H2S-LiCl, Li2S-LiI-P2S5, Li2S-LiI-Li2O-P2S5, Li2S-LiB r-P2S5, Li2SLi2O-P2S5, Li2S-Li3PO4-P2S5, Li2S-P2S5-P2O5, Li2S-P2S5-SiS2, Li2S-P2S5-SiS2-LiCl, Li2S-P2S5-SnS, Li2S-P2S5- Al2S3, Li2S-GeS2, Li2S-GeS2-ZnS, Li2S-Ga2S3, Li2S-GeS2-Ga2S3, Li2S-GeS2-P2S5, Li2S-GeS2-Sb2S5, Li2S-GeS2-Al2S3, Li2SSiS2 , Li2S-Al2S3, Li2S-SiS2-Al2S3, Li2S-SiS2-P2S5, Li2S-SiS2-P2S5-LiI, Li2S-SiS2-LiI, Li2S-SiS2-Li4SiO4, Li2SSiS2-Li3PO4 or Li 10 GeP2S 12 It can be used as a sulfide-based inorganic solid electrolyte.

[0072] Amorphization methods can be used to synthesize sulfide-based inorganic solid electrolyte materials. Examples of amorphization methods include mechanical grinding, solution processing, and rapid melt cooling. These processes can be performed at room temperature (25°C), thus simplifying the manufacturing process.

[0073] The oxide-based solid electrolyte is preferably a compound containing oxygen atoms (O), exhibiting ionic conductivity of metals belonging to Group 1 or Group 2 of the periodic table, and exhibiting electronic insulation.

[0074] As an oxide-based solid electrolyte, for example, Li can be used xa La ya TiO3 (xa = 0.3 to 0.7, and ya = 0.3 to 0.7) (LLT), Li xb La yb Zr zbM bb mb O nb (where Mbb is at least one of Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, and Sn, xb satisfies 5 ≤ xb ≤ 10, yb satisfies 1 ≤ yb ≤ 4, zb satisfies 1 ≤ zb ≤ 4, mb satisfies 0 ≤ mb ≤ 2, and nb satisfies 5 ≤ nb ≤ 20), Li xc B yc M cc zc O nc (where M cc is at least one of C, S, Al, Si, Ga, Ge, In, and Sn, xc satisfies 0 ≤ xc ≤ 5, yc satisfies 0 ≤ yc ≤ 1, zc satisfies 0 ≤ zc ≤ 1, and nc satisfies 0 ≤ nc ≤ 6), Li xd (Al,Ga) yd (Ti,Ge) zd Si ad P md O nd (where 1 ≤ xd ≤ 3, 0 ≤ yd ≤ 1, 0 ≤ zd ≤ 2, 0 ≤ ad ≤ 1, 1 ≤ md ≤ 7, and 3 ≤ nd ≤ 13), Li (3-2xe) M ee xe D ee O (where xe indicates a number between 0 and 0.1, M ee indicates a divalent metal atom, and D ee indicates a halogen atom or a combination of two or more halogen atoms), Li xf Si yf O zf (1 ≤ xf ≤ 5, 0 < yf ≤ 3, and 1 ≤ zf ≤ 10), Li xg S yg O zg (1 ≤ xg ≤ 3, 0 < yg ≤ 2, and 1 ≤ zg ≤ 10), Li3BO3 - Li2SO4, Li2O - B2O3 - P2O5, Li2O - SiO2, Li6BaLa2Ta2O 12 、Li3PO (4-3 / 2w) N w (w < 1), Li with a lithium superionic conductor (LISICON) - type crystal structure 3.5 Zn 0.25 GeO4, La with a perovskite - type crystal structure 0.55 Li 0.35 TiO3, LiTi2P3O with a sodium superionic conductor (NASICON) - type crystal structure 12 、Li 1+xh+yh(Al,Ga) xh (Ti,Ge) 2-xh Si yh P 3-yh O 12 (where 0 ≤ xh ≤ 1 and 0 ≤ yh ≤ 1), or Li7La3Zr2O with a garnet-type crystal structure 12 (LLZ). Alternatively, phosphorus compounds comprising Li, P, and O may be used. For example, lithium phosphate (Li3PO4), LiPON (in which some oxygen in lithium phosphate is replaced by nitrogen), or LiPOD may be used. 1 (D 1 (It is selected from at least one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, and Au). Alternatively, LiA may also be used. l ON(A l It is selected from at least one of Si, B, Ge, Al, C and Ga.

[0075] Polymer-based solid electrolytes can be solid polymer electrolytes formed by adding polymer resin to independently solvated lithium salts or polymer gel electrolytes formed by impregnating polymer resin with an organic electrolyte containing organic solvent and lithium salt.

[0076] Solid polymer electrolytes are not particularly limited, as long as they are composed of polymeric materials, such as those with ionic conductivity, and are typically used as solid electrolyte materials in all-solid-state batteries. Examples of solid polymer electrolytes may include polyether-based polymers, polycarbonate-based polymers, acrylate-based polymers, polysiloxane-based polymers, phosphazene-based polymers, polyethylene oxide, polyethylene derivatives, epoxy alkyl derivatives, phosphate ester polymers, polylysine, polyester sulfides, polyvinyl alcohol, polyvinylidene fluoride, and polymers containing ionic dissociative groups. Alternatively, solid polymer electrolytes may include branched copolymers formed by copolymerizing amorphous polymers (such as polymethyl methacrylate (PMMA), polycarbonate, polysiloxane, and / or phosphazene) as comonomers in the backbone of polyethylene oxide (PEO), which are polymer resins, comb-like polymer resins, and crosslinked polymer resins.

[0077] Polymer gel electrolytes comprise an organic electrolyte containing lithium salts and polymer resins, wherein the content of the organic electrolyte is 60 to 400 parts by weight, based on the weight of the polymer resin. While the polymer resin used in the polymer gel electrolyte is not limited to specific components, it may include, for example, polyvinyl chloride (PVC)-based resins, polymethyl methacrylate (PMMA)-based resins, polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), and polyvinylidene fluoride hexafluoropropylene (PVDF-HFP).

[0078] The all-solid-state battery according to the present invention includes a negative electrode current collector with a porous structure. Compared with a negative electrode current collector with a non-porous structure, the all-solid-state battery is more likely to deform due to damage to the negative electrode current collector. Therefore, in order to prevent deformation of the negative electrode current collector, a stop member can be provided on the outer periphery of the negative electrode current collector.

[0079] The stop members can be arranged around the four directions of the negative current collector, and can be arranged in pairs parallel to each other on the outer periphery of the negative current collector.

[0080] Figure 1 The negative electrode 120 shown is composed solely of a negative electrode current collector with a porous structure. For example, Ni foam can be used as the negative electrode current collector.

[0081] A pair of stops 140 are disposed at opposite ends of the negative electrode 120 in the y-axis direction. The stops 140 may be configured such that the outer surface of the stops in the x-axis direction is perpendicular to the solid electrolyte layer and also perpendicular to the pressing surface of the pressing member 150.

[0082] When the area difference between the positive electrode 110 and the negative electrode 120 is large, the performance of the battery cell may be reduced. Therefore, it is preferable to minimize the dimension of the stop in the y-axis direction, as long as the desired strength can be ensured.

[0083] For example, the area of ​​the pressing surface of the positive electrode 110 parallel to the pressing member 150 can be configured to correspond to the area of ​​the pressing surfaces of the outer surface of the negative electrode 120 and the outer surface of the stop member parallel to the pressing member 150. Therefore, the pressure-bearing area of ​​the negative electrode can be formed to be smaller than the pressure-bearing area of ​​the positive electrode.

[0084] Furthermore, in existing lithium-ion secondary batteries that use liquid electrolytes, the area of ​​the negative electrode can be formed to be larger than that of the positive electrode in order to prevent lithium from depositing at the edge of the negative electrode during charging.

[0085] However, for all-solid-state batteries, especially when a porous negative electrode current collector is included as in this invention, and a Li plating / stripping mechanism is applied, lithium is plated into the pores of the negative electrode current collector during charging, thereby preventing lithium deposition at the edges of the negative electrode. Therefore, the area of ​​the negative electrode does not need to be larger than the area of ​​the positive electrode.

[0086] The all-solid-state battery according to the invention can be configured to have a structure in which electrode assemblies are housed in a pouch-shaped battery casing made of a laminate comprising a metal layer and a resin layer.

[0087] Some lithium ions that migrate to the negative electrode may be deposited on the surface of the negative electrode to form lithium nuclei, and the lithium nuclei may grow into dendritic lithium dendrites.

[0088] If lithium dendrites that form and grow on the negative electrode surface come into contact with the positive electrode, a short circuit may occur in the lithium secondary battery. This may shorten the life of the lithium secondary battery and may hinder the assurance of stable performance.

[0089] Furthermore, all-solid-state batteries with high energy density suffer from frequent short circuits due to the low strength of the solid electrolyte membrane disposed between the positive and negative electrodes.

[0090] Lithium ions are plated on the portion of the negative electrode current collector that comes into contact with the solid electrolyte layer. If the contact area between the negative electrode current collector and the solid electrolyte layer is narrow, lithium ions are plated locally, thereby forming lithium dendrites.

[0091] Therefore, in this invention, a pair of pressing members 150 are respectively disposed on opposite surfaces of the battery housing 101 that are parallel to the planes of the positive electrode 110 and the negative electrode 120, and the pressing members 150 press in a direction toward the interior of the battery housing 101, thereby increasing the contact area between the negative electrode 120 and the solid electrolyte layer 130.

[0092] Reference Figure 2 A pair of stop members 140 are respectively disposed at both ends of the negative electrode 120 in the y-axis direction, and each stop member 140 has sufficient rigidity to maintain its original shape when the battery casing is pressed by the pressing member 150, thereby maintaining the distance between the solid electrolyte layer 130 and the pressing member 150. Therefore, the volume of the negative electrode 120 can be no smaller than the height of the stop member 140 by the pressing force of the pressing member 150.

[0093] Despite from Figure 1 and Figure 2 The positive and negative electrode terminals are omitted from the text, but for ease of description, the electrode terminals connected to the positive and negative terminals can extend outward from the battery casing to serve as electrode terminals. Specifically, the positive terminal connector protruding from the positive terminal and the negative terminal connector protruding from the negative terminal can be connected to the positive lead and the negative lead, respectively, and the positive lead and the negative lead can extend outward from the battery casing to serve as electrode terminals.

[0094] The battery casing can be a pouch-shaped battery casing made of a laminate consisting of metal and resin layers, or a prismatic casing made of metal material.

[0095] Figure 3 yes Figure 1 A magnified view of a portion of the image.

[0096] Reference Figure 3 , Figure 1 and Figure 2 The battery casing and pressing component shown are from Figure 3 Omitted in .

[0097] A positive current collector 111 coated with a positive electrode mixture layer 112, a solid electrolyte layer 130, and a negative electrode 120 having a hole 121 configured to allow the interior and exterior of the negative current collector to communicate with each other through it are stacked in sequence, and a stop member 140 is provided at the outer periphery of the negative electrode 120.

[0098] During the charging of the all-solid-state battery, lithium ions removed from the positive electrode are inserted into the hole 121 of the negative electrode current collector, thereby depositing lithium 122 in the hole 121.

[0099] During the discharge of the all-solid-state battery, the lithium 122 plated in the hole 121 of the negative electrode current collector is stripped off and moves toward the positive electrode 110.

[0100] In this invention, because a negative current collector with a porous structure is used, lithium plating and stripping occur in the pores of the negative current collector during the charging and discharging of the all-solid-state battery.

[0101] Therefore, considering the volume of the negative electrode current collector's orifice to adjust the density and loading of the positive electrode mixture layer, the amount of lithium plated in the orifice of the negative electrode current collector does not exceed the total volume of the orifice, and the surface of the negative electrode current collector is not plated with lithium.

[0102] In this case, an all-solid-state battery can be provided that does not undergo volume changes due to charging and discharging.

[0103] Figure 4 yes Figure 1 A magnified view of a portion of the image.

[0104] Reference Figure 4 The pressing member 150 can increase the contact surface between the solid electrolyte layer 130 and the negative electrode 120 while applying pressure P in the direction toward the battery housing 101. At this time, a stop member 140 is provided to prevent the negative electrode, including the negative electrode current collector with a porous structure, from deforming due to the pressing pressure P of the pressing member 150.

[0105] When the height h1 of the stop member 140 is equal to the thickness h2 of the negative electrode 12 before pressing, lithium will be deposited on the negative electrode during charging, thereby increasing the thickness of the negative electrode. However, since the pressing member 150 presses the all-solid-state battery, the initial thickness of the negative electrode and the thickness of the negative electrode after charging can be equal to each other. In addition, since the stop member and the pressing member prevent the thickness of the negative electrode from increasing during charging, the contact surface between the solid electrolyte layer 130 and the negative electrode 120 can be increased.

[0106] When the height h1 of the stop member 140 is less than the thickness h2 of the negative electrode 120 before pressing, the electrode assembly can be housed in the battery casing, and the all-solid-state battery can be further pressed by the pressing member 150, thereby increasing the contact surface between the solid electrolyte layer 130 and the negative electrode 120 to be larger than before the electrode assembly is housed in the battery casing 101.

[0107] Figure 5 yes Figure 2 An exploded 3D diagram.

[0108] Reference Figure 5 The length w1 of the stop member corresponds to the length w2 of the outer periphery of the stop member 140 on the negative electrode.

[0109] Since the lengths of the pair of pressing members 150 added to the opposing surfaces of the battery housing 101 in the z-axis direction are equal to or greater than the lengths of the battery housing 101 in the z-axis direction and the lengths of the pressing members 150 in the y-axis direction are equal to or greater than the lengths of the battery housing 101 in the y-axis direction, the battery housing 101 can be pressed evenly over the entire opposing surfaces of the battery.

[0110] Therefore, a contact surface can be uniformly formed on the entire surface of the solid electrolyte layer 130 and the negative electrode 120 facing each other, thereby minimizing the growth of lithium dendrites.

[0111] Figure 6 This is an exploded perspective view of an all-solid-state battery according to another embodiment.

[0112] Reference Figure 6 A stop 141 is disposed on the outer periphery of the positive electrode 110, which includes a positive current collector 111 coated with a positive electrode mixture layer 112. Compared with the stop 140 located on the outer periphery of the negative electrode, the surface of the stop 141 parallel to the pressing surface of the pressing member can have the same size, and with the solid electrolyte layer 130 inserted between the positive and negative electrodes, the stop can resist the pressing force of the pressing member 150 to support the positive and negative electrodes.

[0113] The height of the stop member 141 in the x-axis direction can be equal to or less than the thickness of the positive electrode in the x-axis direction. When the height of the stop member is equal to the thickness of the positive electrode, it can prevent the thickness of the positive electrode in the x-axis direction from being greater than its initial thickness during charging and discharging. When the height of the stop member is less than the thickness of the positive electrode, the electrode assembly is pressed by the pressing member 150, thereby increasing the contact surface between the positive electrode and the solid electrolyte layer.

[0114] Figure 1 The description of the all-solid-state battery shown can also be applied to... Figure 5Other structures of the all-solid-state battery are shown.

[0115] The present invention provides a battery module that includes an all-solid-state battery as a unit cell, and the battery module can be used as an energy source for medium and large-scale devices that require high-temperature stability, long cycle characteristics and high stability.

[0116] Examples of medium to large-sized devices include battery-powered motor-driven power tools, electric vehicles (including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs)), electric two-wheelers (including electric bicycles (E-bikes) and electric scooters (E-scooters)), electric golf carts, and energy storage systems. However, the invention is not limited thereto.

[0117] The present invention will be described below with reference to the following embodiments. These embodiments are provided merely for the purpose of facilitating a better understanding of the invention and should not be construed as limiting the scope of the invention.

[0118] <Experiment Example 1> Material thickness varies with pressure

[0119] To examine the thickness variation of the negative current collector and the stop, the thickness variation was measured under the pressure of the pressing member, with the negative current collector used alone (A), the stop used alone (B), and both the negative current collector and the stop used simultaneously (C). The results are shown in Table 1 below.

[0120] Ni foam with 91% porosity was used as the negative electrode current collector, and PET film was used as a stop.

[0121] The PET film has a thickness of 50 μm. In case (C), four PET films are stacked to correspond to the thickness of the Ni foam, resulting in a total thickness of 200 μm for the PET film stack. The PET film stack is used as a stop.

[0122] [Table 1]

[0123] Pressing force (MPa) of the pressing component 0 2.5 5.0 10.0 (A) Ni foam (μm) 202 183 168 136 (B) Stop (μm) 50 50 50 50 (C) Ni foam + stop (μm) 202 201 200 200

[0124] Referring to Table 1 above, in case (A), the thickness gradually decreases as the pressing force of the pressing member increases, while in case (B), the thickness remains unchanged even if the pressing force of the pressing member increases. In case (C), pressure is applied to the PET film used at the stop, and the PET film acts as a support, thus maintaining the thickness at 200 μm, i.e., the thickness of the stop, even if the pressing force increases. Therefore, it can be seen that when the stop is applied to Ni foam, it can prevent the thickness of the Ni foam from decreasing.

[0125] <Example 1>

[0126] NCM811(LiNi) will be used as the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2), silver-germanium sulfide (Li6PS5Cl) as the solid electrolyte, carbon black as the conductive agent, and polytetrafluoroethylene as the binder were prepared in a weight ratio of 77.5:19.5:1.5:1.5 and dispersed in anisole to form a positive electrode slurry. The positive electrode slurry was applied to a 15 μm thick aluminum current collector by a doctor blade and dried at 100 °C for 12 hours under vacuum to manufacture the positive electrode.

[0127] To fabricate the solid electrolyte layer, silver-germanium sulfide (Li6PS5Cl) as the solid electrolyte and polytetrafluoroethylene (PTFE) as the binder were dispersed in anisole at a weight ratio of 95:5 and stirred to prepare a solid electrolyte layer slurry. This solid electrolyte layer slurry was applied to a polyethylene terephthalate release film and dried under vacuum at 100°C for 12 hours to form a solid electrolyte layer with a thickness of 30 μm.

[0128] As a negative electrode current collector with a porous structure, Ni foam with a thickness of 202 μm is used as the negative electrode.

[0129] Electrode assemblies are manufactured by sequentially stacking a positive electrode, a solid electrolyte layer, and a negative electrode.

[0130] A 50 μm thick PET film was used as a stop at the outer periphery of the negative electrode. Four PET films were stacked to make the thickness of the stop correspond to the thickness of the Ni foam, thereby manufacturing and using a stop with a thickness of 200 μm.

[0131] Electrode assemblies are housed in a pouch-shaped battery casing, and the battery casing is hermetically sealed to manufacture an all-solid-state battery.

[0132] <Example 2>

[0133] In addition to further placing the same stop as the stop at the negative electrode at the outer periphery of the positive electrode during the manufacturing of all-solid-state batteries (e.g. Figure 6 The structure shown is different from Example 1, and the all-solid-state battery is manufactured using the same method as Example 1.

[0134] <Comparative Example 1>

[0135] Except for using nickel foil instead of Ni foam as the negative electrode and not applying a stop (unlike Example 1), the all-solid-state battery is manufactured using the same method as in Embodiment 1.

[0136] <Comparative Example 2>

[0137] Except that no stop is used when manufacturing the all-solid-state battery and only Ni foam is applied as the negative electrode (unlike Example 1), the all-solid-state battery is manufactured using the same method as in Embodiment 1.

[0138] <Comparative Example 3>

[0139] Except for the five PET films stacked together to serve as stoppers (unlike in Example 1), the all-solid-state battery is manufactured using the same method as in Example 1.

[0140] <Experimental Example 2> Measurement experiment on the thickness increase rate of all-solid-state batteries

[0141] All-solid-state batteries manufactured according to Examples 1, 2 and Comparative Examples 1 to 3 are fastened to the pressing member and a pressure of 5 MPa is applied to them.

[0142] In this state, the thickness change of the all-solid-state battery is measured while it is being charged and discharged.

[0143] The thickness of the all-solid-state battery was measured while it was charged at 60°C in CC / CV mode (4.25V, 0.05C and 0.01C cutoff current) and discharged to 3V at 0.05C in 3CC mode.

[0144] The thickness change rate is calculated by (battery thickness after charging / battery thickness before charging) × 100, and the calculation results are shown in Table 2 below.

[0145] [Table 2]

[0146]

[0147] Referring to Table 2 above, in the all-solid-state batteries manufactured according to Examples 1 and 2, the thickness of the Ni foam did not become smaller than the height of the stop member, but remained uniform because the stop member configured to receive pressure from the pressing member was provided in the battery as a support member, so that the measured thickness of the all-solid-state battery before and after charging was equal to each other.

[0148] Therefore, it can be seen that the lithium moving to the negative electrode is plated / stripped in the pores of the Ni foam.

[0149] Furthermore, in Examples 1 and 2, more than 10 charge and discharge cycles were performed compared to the comparative example, indicating that the lifespan characteristics of the all-solid-state battery manufactured according to the examples are improved.

[0150] In Comparative Example 1, because lithium plating occurs on the Ni foil, the thickness increase rate after the first charge is large, and short circuits occur quickly, resulting in low lifetime characteristics.

[0151] In Comparative Example 2, since no stop was provided even though the same Ni foam was applied as in the embodiment, the thickness of the Ni foam thinned due to the pressure of the pressing member. In Comparative Example 2, the thickness change rate after the first charge was small; however, a short circuit occurred during the tenth charge and discharge.

[0152] In Comparative Example 3, where the thickness of the stop member was greater than the thickness of the Ni foam, although the thickness of the negative electrode was not increased to exceed the thickness of the Ni foam, the pressure from the pressing member was not transmitted to the electrode assembly, thus preventing extensive contact between the positive electrode, the solid electrolyte layer, and the Ni foam. As a result, the all-solid-state battery could not function properly.

[0153] Therefore, as in this invention, when a negative electrode is provided, including a negative current collector with a porous structure, a stop member, and a pressing member, an all-solid-state battery with significantly improved lifespan characteristics can be provided.

[0154] Those skilled in the art will understand that, based on the above description, various applications and modifications can be made within the scope of this invention.

[0155] (Explanation of reference numerals in the attached diagram)

[0156] 101: Battery casing

[0157] 110: Positive electrode

[0158] 111: Positive current collector

[0159] 112: Positive electrode mixture layer

[0160] 120: Negative electrode

[0161] 121: Kong

[0162] 122: Lithium

[0163] 130: Solid electrolyte layer

[0164] 140, 141: Stop components

[0165] 150: Pressing component

[0166] h1: Height of the stop component

[0167] h2: Thickness of the negative electrode before pressing

[0168] w1: Length of the stop component

[0169] w2: Length of the outer perimeter of the negative electrode

Claims

1. A solid-state battery comprising: a positive electrode including a positive electrode current collector coated with a positive electrode mixture layer; a negative electrode including a negative electrode current collector having a porous structure; a solid electrolyte layer between the positive electrode and the negative electrode; a first stopper provided at an outer periphery of the negative electrode; a battery case configured to accommodate an electrode assembly including the positive electrode, the negative electrode, and the solid electrolyte layer, and the first stopper; and a pressing member provided at each of opposite surfaces of the battery case parallel to a plane of the positive electrode and the negative electrode, the pressing member being configured to be pressed in a direction toward an inside of the battery case, wherein a height of the first stopper is equal to or less than a thickness of the negative electrode before pressing, wherein the first stopper is provided to prevent the negative electrode including the negative electrode current collector having the porous structure from being deformed due to a pressing force of the pressing member.

2. The all-solid battery according to claim 1, wherein The negative electrode current collector is made of a metal material. 3.The solid-state battery of claim 1, further comprising a second stopper provided at an outer periphery of the positive electrode.

4. The all-solid battery according to claim 1, wherein The first stopper is provided perpendicular to a pressing surface of the pressing member.

5. The all-solid battery according to claim 1, wherein The height of the first stopper is less than the thickness of the negative electrode before pressing.

6. The all-solid battery according to claim 1, wherein A length of the first stopper corresponds to a length of the outer periphery of the negative electrode where the first stopper is provided.

7. The all-solid battery according to claim 1, wherein The first stopper maintains an original shape when the battery case is pressed by the pressing member.

8. The all-solid battery according to claim 1, wherein The solid-state battery has no volume change due to charging and discharging.

9. The all-solid battery according to claim 1, wherein Lithium plating and peeling occur in pores in the negative electrode current collector.

10. The all-solid battery according to claim 1, wherein Ni foam is used as the negative electrode current collector having the porous structure. 11.A battery module including the solid-state battery of any one of claims 1 to 10 as a unit cell.

Images