KR20230144416A - All-solid-state battery and manufacturing method for all-solid-state battery - Google Patents

Abstract

The present invention relates to an all-solid-state secondary battery and a manufacturing method of the all-solid-state secondary battery. According to an embodiment of the present invention, the manufacturing method of the all-solid secondary battery comprises the following steps of: forming a unit cell by stacking an anode layer, a cathode layer, and a solid electrolyte layer; and pressing the unit cell by arranging one pair of pressurizing parts on one surface and the other side of the unit cell, respectively; and forming a housing surrounding the unit cell while pressing the unit cell.

Description

All-solid secondary battery and manufacturing method for all-solid secondary battery {All-solid-state battery and manufacturing method for all-solid-state battery}

The present invention relates to an all-solid secondary battery and an all-solid secondary battery manufacturing method, and more specifically, to an all-solid secondary battery manufacturing method of manufacturing a housing after arranging a unit stack cell structure, and to an all-solid secondary battery manufactured thereby. It is an invention about

Recently, in response to industrial demands, the development of batteries with high energy density and safety has been actively conducted. For example, lithium-ion batteries are being put into practical use not only in the fields of information-related devices and communication devices, but also in the automobile field. Meanwhile, in the automotive field, the safety of lithium-ion batteries is important because it can be directly related to the lives of passengers.

Lithium-ion batteries currently on the market use electrolytes containing flammable organic solvents, so there is a risk of overheating and fire in the event of a short circuit. In response to this, an all-solid secondary battery using a solid electrolyte instead of an electrolyte has been proposed. By not using flammable organic solvents, all-solid-state secondary batteries can greatly reduce the possibility of fire or explosion even if a short circuit occurs. Therefore, these all-solid-state secondary batteries can greatly increase safety compared to lithium-ion batteries that use electrolytes.

Generally, lithium is used as a negative electrode to increase the energy density of all-solid-state secondary batteries. Lithium has problems due to volume expansion during use and irreversible growth during charging and discharging. To solve this problem, a method of placing a lithium precipitate layer that deposits lithium on the current collector is used. In order to manufacture an all-solid-state secondary battery including a precipitated negative electrode, a certain pressure (for example, 8 MPa or less) must be applied inside the cell. However, it is difficult to include a process of maintaining such pressure in the cell during the manufacturing process of an all-solid-state secondary battery, and even if a pressurizing process is included, there is a problem in that an additional pressurizing device must be provided after manufacturing the all-solid-state secondary battery in a pouch form.

In the present invention, in manufacturing an all-solid-state secondary battery composed of a material that is sensitive to air exposure and physical properties as it contains a precipitated negative electrode, the housing is adopted as a can type, and the unit cell is not inserted into the can. A method of manufacturing an all-solid secondary battery using a can manufacturing method and an all-solid secondary battery resulting therefrom can be provided.

A method of manufacturing an all-solid-state secondary battery according to an embodiment of the present invention includes forming a unit cell by stacking a positive electrode layer, a negative electrode layer, and a solid electrolyte layer, and disposing a pair of pressing parts on one side and the other side of the unit cell, respectively. Thus, it includes the steps of pressurizing the unit cell and forming a housing surrounding the unit cell in a pressurized state.

In the method of manufacturing an all-solid-state secondary battery according to an embodiment of the present invention, the step of pressurizing the unit cell includes placing the pair of pressurizing parts on one side and the other side of the unit cell, respectively, facing each other. It can be pressurized in either direction.

In the method of manufacturing an all-solid-state secondary battery according to an embodiment of the present invention, the step of pressurizing the unit cell may pressurize the unit cell at a pressure of 1 to 8 MPa.

In the method of manufacturing an all-solid-state secondary battery according to an embodiment of the present invention, the step of pressurizing the unit cell further includes arranging a cushioning sheet between the unit cell and at least one of the pair of pressurizing parts. It can be included.

In the method of manufacturing an all-solid-state secondary battery according to an embodiment of the present invention, the step of forming the housing may be performed by connecting one side and the other side of one or more fixing parts to the pair of pressurizing parts, respectively, to form the housing. there is.

In the method of manufacturing an all-solid-state secondary battery according to an embodiment of the present invention, the step of forming the housing involves forming a can-shaped housing in the shape of a rectangular parallelepiped with the one or more fixing parts connecting the pair of pressing parts as sides. You can.

In the method of manufacturing an all-solid-state secondary battery according to an embodiment of the present invention, forming the housing may further include placing a cover on the housing.

In the method of manufacturing an all-solid-state secondary battery according to an embodiment of the present invention, the step of forming the housing includes forming the one or more fixing parts so that the ends of the pair of pressing parts are connected to the inner surface of the one or more fixing parts. It can be placed.

In the method of manufacturing an all-solid-state secondary battery according to an embodiment of the present invention, the step of forming the unit cell may include disposing a lithium precipitate layer between the negative electrode current collector layer and the negative electrode active material layer included in the negative electrode layer. .

An all-solid-state secondary battery according to an embodiment of the present invention is an all-solid-state secondary battery manufactured by the manufacturing method according to the present invention.

The method of manufacturing an all-solid-state secondary battery according to an embodiment of the present invention can form a housing itself by connecting a fixing part to the pressing part while pressing the unit cell with the pressing part. Accordingly, the pressurized state of the unit cell can be easily maintained. In addition, the housing can be formed with the member that compresses the unit cell itself, without the process of inserting the unit cell into a separate housing while pressing it. Accordingly, a rectangular can-type all-solid-state secondary battery can be manufactured using unit cells in a compressed state more easily than with conventional manufacturing methods. Therefore, the number of stacks of unit cells can be increased, and can-type housings with excellent airtightness and physical stability can be applied to all-solid-state secondary batteries.

Additionally, when the unit cell includes a lithium precipitate layer, the housing can be formed while maintaining the unit cell in a pressurized state, making it possible to more easily manufacture a can-type all-solid-state secondary battery.

1 to 5 show a method of manufacturing an all-solid-state secondary battery according to an embodiment of the present invention.

The present inventive concept described below can be subjected to various transformations and can have various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit this creative idea to a specific embodiment, and should be understood to include all transformations, equivalents, or substitutes included in the technical scope of this creative idea.

The terms used below are only used to describe specific embodiments and are not intended to limit the creative idea. Singular expressions include plural expressions unless the context clearly dictates otherwise. Hereinafter, terms such as "comprise" or "have" are intended to indicate the presence of features, numbers, steps, operations, components, parts, ingredients, materials, or combinations thereof described in the specification, but are intended to indicate the presence of one or more of the It should be understood that this does not exclude in advance the presence or addition of other features, numbers, steps, operations, components, parts, components, materials, or combinations thereof. “/” used below may be interpreted as “and” or “or” depending on the situation.

In order to clearly express various layers and areas in the drawing, the thickness is enlarged or reduced. Throughout the specification, similar parts are given the same reference numerals. Throughout the specification, when a part such as a layer, membrane, region, plate, etc. is said to be “on” or “on” another part, this includes not only the case where it is directly on top of the other part, but also the case where there is another part in between. . Throughout the specification, terms such as first and second may be used to describe various components, but the components should not be limited by the terms. Terms are used only to distinguish one component from another.

1 to 5 show a method of manufacturing an all-solid-state secondary battery 1 according to an embodiment of the present invention.

The manufacturing method of the all-solid-state secondary battery 1 according to an embodiment of the present invention includes forming a unit cell 10 by stacking a positive electrode layer 100, a negative electrode layer 200, and a solid electrolyte layer 300, Placing a pair of pressurizing parts 400 on one side and the other side of the unit cell 10, respectively, pressuring the unit cell 10 and surrounding the unit cell 10 while pressing the unit cell 10. may include forming the housing 20.

First, the anode layer 100, the cathode layer 200, and the solid electrolyte layer 300 are stacked to form the unit cell 10. For example, as shown in FIG. 1, after the cathode layer 200 is disposed below, the solid electrolyte layer 300 and the anode layer 100 are sequentially disposed to form the unit cell 10. Alternatively, the solid electrolyte layer 300 and the cathode layer 200 may be placed in that order after the anode layer 100 is placed below.

In one embodiment, the positive electrode layer 100 may include a positive electrode current collector 110 and a positive electrode active material layer 120. For example, the positive electrode current collector 110 includes indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), and zinc ( It may be made of at least one of a plate or foil made of Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. In another embodiment, the positive electrode current collector 110 may be omitted.

The positive electrode active material layer 120 may include, for example, a positive electrode active material and a solid electrolyte. The solid electrolyte included in the positive electrode active material layer 120 may be similar to or different from the solid electrolyte included in the solid electrolyte layer 300.

The positive electrode active material can reversibly absorb and desorb lithium ions. Positive electrode active materials include, for example, lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), and lithium nickel cobalt manganese oxide (NCM). , lithium transition metal oxides such as lithium manganate, lithium iron phosphate, nickel sulfide, copper sulfide, lithium sulfide, iron oxide, or vanadium oxide, but must be limited to these. It is not possible and any material used as a positive electrode active material in the relevant technical field is possible. The positive electrode active material may be used alone or in a mixture of two or more types.

In one embodiment, lithium transition metal oxide is LiaA1-bBbD2 (in the above formula, 0.90 a ≤ 1, and 0 b ≤ 0.5); LiaE1-bBbO2-cDc (in the above equation, 0.90 a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE2-bBbO4-cDc (where 0 b ≤ 0.5, 0 ≤ c ≤ 0.05); LiaNi1-b-cCobBcDα (in the above formula, 0.90 a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); LiaNi1-b-cCobBcO2-αFα (in the above formula, 0.90 a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); LiaNi1-b-cCobBcO2-αF2 (in the above formula, 0.90 a ≤ 1, 0 ≤ b ≤ 0.5, 0 c ≤ 0.05, 0 < α <2); LiaNi1-b-cMnbBcDα (in the above formula, 0.90 a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); LiaNi1-b-cMnbBcO2-αFα (in the above formula, 0.90 a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α <2); LiaNi1-b-cMnbBcO2-αF2 (in the above formula, 0.90 a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c 0.05, 0 < α <2); LiaNibEcGdO2 (in the above equation, 0.90 a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1.); LiaNibCocMndGeO2 (in the above equation, 0.90 a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤0.5, 0.001 ≤ e ≤ 0.1.); LiaNiGbO2 (in the above equation, 0.90 a ≤ 1, 0.001 ≤ b ≤ 0.1); LiaCoGbO2 (in the above equation, 0.90 a ≤ 1, 0.001 ≤ b ≤ 0.1); LiaMnGbO2 (in the above equation, 0.90 a ≤ 1, 0.001 ≤ b ≤ 0.1); LiaMn2GbO4 (in the above equation, 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-f)Fe2(PO4)3(0 ≤ f ≤ 2); It is a compound expressed in one of the chemical formulas of LiFePO4. In these compounds, A is Ni, Co, Mn, or combinations thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. It is also possible to use a compound to which a coating layer is added to the surface of such a compound, and it is also possible to use a mixture of the above-described compound and a compound to which a coating layer is added. The coating layer added to the surface of such a compound includes, for example, a coating element compound of an oxide, hydroxide, oxyhydroxide of the coating element, oxycarbonate of the coating element, or hydroxycarbonate of the coating element. The compounds that make up this coating layer are amorphous or crystalline. Coating elements included in the coating layer include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The method of forming the coating layer is selected within a range that does not adversely affect the physical properties of the positive electrode active material. Coating methods include, for example, spray coating, dipping method, etc. Since the specific coating method can be easily understood by those skilled in the art, detailed explanation will be omitted.

In one embodiment, the positive electrode active material may include, for example, a lithium salt of the above-described lithium transition metal oxide having a layered rock salt type structure. “Layered rock salt structure” is, for example, a cubic rock salt structure in which oxygen atomic layers and metal atomic layers are alternately and regularly arranged in the <111> direction, whereby each atomic layer forms a two-dimensional plane. It is a structure that is being formed. “Cubic rock salt structure” refers to a sodium chloride type (NaCl type) structure, which is a type of crystal structure. Specifically, the face centered cubic lattice (fcc) formed by cations and anions, respectively, forms a unit lattice. It represents a structure arranged offset by 1/2 of the ridge. The lithium transition metal oxide having this layered rock salt structure is, for example, LiNixCoyAlzO2 (NCA) or LiNixCoyMnzO2 (NCM) (0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1) and other ternary lithium transition metal oxides. When the positive electrode active material includes a ternary lithium transition metal oxide having a layered rock salt-type structure, the energy density and thermal stability of the all-solid-state secondary battery 1 are further improved.

The positive electrode active material may be covered by a coating layer. The coating layer may be any coating layer known as a coating layer for the positive electrode active material of an all-solid-state secondary battery. For example, the coating layer may be made of Li2O-ZrO2 (LZO), etc.

In one embodiment, when the positive electrode active material contains nickel (Ni) as a ternary lithium transition metal oxide such as NCA or NCM, the capacity density of the all-solid-state secondary battery 1 is increased to reduce metal elution from the positive electrode active material in the charged state. reduction is possible. As a result, the cycle characteristics of the all-solid-state secondary battery 1 in a charged state are improved.

In one embodiment, the positive electrode active material may have a particle shape such as a sphere or an elliptical sphere. The particle size of the electrode active material is not particularly limited and is within the range applicable to the positive electrode active material of conventional all-solid-state secondary batteries. The content of the positive electrode active material in the positive electrode layer 100 is also not particularly limited and is within a range applicable to the positive electrode of a conventional all-solid-state secondary battery.

In one embodiment, the solid electrolyte included in the positive electrode active material layer 120 may have a smaller average particle diameter (D50) than the solid electrolyte included in the solid electrolyte layer 300. For example, the D50 of the solid electrolyte included in the positive electrode active material layer 120 is 90% or less, 80% or less, 70% or less, 60% or less, and 50% of the D50 of the solid electrolyte included in the solid electrolyte layer 300. It may be less than, 40% or less, 30% or less, or 20% or less.

In one embodiment, the positive electrode active material layer 120 may include a binder. The binder may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc.

In one embodiment, the positive active material layer 120 may include a conductive material. The conductive material may be, for example, graphite, carbon black, acetylene black, Ketjen black, carbon fiber, metal powder, etc.

In one embodiment, the positive electrode layer 100 may further include additives such as fillers, coating agents, dispersants, and ion conductivity auxiliaries in addition to the positive electrode active material, solid electrolyte, binder, and conductive material. As fillers, coating agents, dispersants, ion conductive auxiliaries, etc. that the positive electrode layer 100 may contain, known materials generally used in electrodes of all-solid-state secondary batteries can be used.

The negative electrode layer 200 may include a negative electrode current collector 210 and a negative electrode active material layer 220.

The negative electrode current collector 210 is made of a material that does not react with lithium, that is, does not form any alloy or compound. Materials constituting the negative electrode current collector 210 include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but are not necessarily limited to these. Anything that can be used as an electrode current collector in the relevant technical field is possible. In one embodiment, the thickness of the negative electrode current collector 210 is 1 to 20 μm, 5 to 15 μm, for example, 7 to 10 μm.

The negative electrode active material layer 220 may include, for example, a negative electrode active material and a binder. The negative electrode active material may have a particle form. The average particle diameter of the negative electrode active material in particle form may be 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or 900 nm or less. Alternatively, the average particle diameter of the negative electrode active material may be, for example, 10 nm to 4 μm or less, 10 nm to 3 μm or less, 10 nm to 2 μm or less, 10 nm to 1 μm or less, or 10 nm to 900 nm or less. When the negative electrode active material has an average particle size in this range, reversible absorption and/or desorption of lithium can be facilitated more easily during charging and discharging. The average particle size of the negative electrode active material may be the median particle size (D50) measured using a laser particle size distribution meter.

The negative electrode active material included in the negative electrode active material layer 220 may include one or more selected from carbon-based negative electrode active materials and metal or metalloid negative electrode active materials.

The carbon-based negative electrode active material is particularly amorphous carbon. Amorphous carbon is, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), and graphene. ), etc., but is not necessarily limited to these, and any carbon that is classified as amorphous carbon in the relevant technical field is possible. Amorphous carbon is carbon that does not have crystallinity or has very low crystallinity and is distinguished from crystalline carbon or graphitic carbon.

Metal or metalloid anode active materials include gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). ), but is not necessarily limited to these, and any metal negative active material or metalloid negative active material that forms an alloy or compound with lithium in the relevant technical field can be used. For example, nickel (Ni) does not form an alloy with lithium and is therefore not a metal anode active material.

The negative electrode active material layer 220 includes one type of negative electrode active material among these negative electrode active materials, or a mixture of a plurality of different negative electrode active materials. For example, the negative active material layer 220 contains only amorphous carbon, or gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), and bismuth (Bi). ), tin (Sn), and zinc (Zn). Alternatively, the negative electrode active material layer 22 is made of amorphous carbon, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), and tin ( It includes a mixture with one or more selected from the group consisting of Sn) and zinc (Zn). The mixing ratio of the mixture of amorphous carbon and gold, etc. is a weight ratio, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1, but is not necessarily limited to these ranges and may vary depending on the required amount. It is selected according to the characteristics of the solid secondary battery (1). When the negative electrode active material has this composition, the cycle characteristics of the all-solid-state secondary battery 1 can be further improved.

The negative electrode active material included in the negative electrode active material layer 220 may include a mixture of first particles made of amorphous carbon and second particles made of metal or metalloid. Metals or metalloids include gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). may include. Metalloids may alternatively be semiconductors. The content of the second particles may be 8 to 60% by weight, 10 to 50% by weight, 15 to 40% by weight, or 20 to 30% by weight, based on the total weight of the mixture. By having the content of the second particles in this range, the cycle characteristics of the all-solid-state secondary battery 1 can be further improved.

In one embodiment, the negative electrode active material layer 220 may further include a binder. For example, binders include styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride/hexafluoropropylene copolymer, and polyacrylic. Ronitrile, polymethyl methacrylate, carboxymethyl cellulose (CMC), etc. are not necessarily limited to these, and any binder used in the relevant technical field can be used. The binder may be single or composed of multiple different binders.

Since the negative electrode active material layer 220 includes a binder, the negative electrode active material layer 220 is stabilized on the negative electrode current collector 210. In addition, cracking of the negative electrode active material layer 220 is suppressed despite changes in the volume and/or relative position of the negative electrode active material layer 220 during the charging and discharging process. For example, when the negative electrode active material layer 220 does not include a binder, the negative electrode active material layer 220 can be easily separated from the negative electrode current collector 210. As the negative electrode active material layer 220 separates from the negative electrode current collector 210, there is a possibility that the negative electrode current collector 210 may contact the solid electrolyte layer 300 in the exposed portion of the negative electrode current collector 210, resulting in a short circuit. increases. The negative electrode active material layer 220 is manufactured by applying a slurry in which the material constituting the negative electrode active material layer 220 is dispersed onto the negative electrode current collector 210 and drying it. By including a binder in the negative electrode active material layer 220, the negative electrode active material can be stably dispersed in the slurry. For example, when the slurry is applied on the negative electrode current collector 21 by screen printing, clogging of the screen (for example, clogging by aggregates of the negative electrode active material) can be suppressed.

In one embodiment, the negative electrode active material layer 220 may further include additives used in conventional all-solid-state secondary batteries, such as fillers, coating agents, dispersants, and ion conductivity auxiliaries.

In one embodiment, the thickness of the negative electrode active material layer 220 may be 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 active material layer 220 may be, for example, 1 μm to 20 μm, 2 μm to 10 μm, or 3 μm to 7 μm. If the thickness of the negative electrode active material layer 220 is too thin, the lithium dendrites formed between the negative electrode active material layer 220 and the negative electrode current collector 210 will collapse the negative electrode active material layer 220, causing the all-solid-state secondary battery (1) It is difficult to improve the cycle characteristics of If the thickness of the anode active material layer 220 increases excessively, the energy density of the all-solid-state secondary battery 1 decreases and the internal resistance of the all-solid-state secondary battery 1 due to the anode active material layer 220 increases, thereby reducing the all-solid-state secondary battery. It is difficult to improve the cycle characteristics of (1).

As the thickness of the negative electrode active material layer 220 decreases, the charging capacity of the negative electrode active material layer 220 also decreases. The charge capacity of the negative electrode active material layer 220 may be, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, or 2% or less of the charge capacity of the positive electrode active material layer 120. You can. Alternatively, the charge capacity of the negative electrode active material layer 220 is, for example, 0.1% to 50%, 0.1% to 40%, 0.1% to 30%, 0.1% to 20%, 0.1% of the charge capacity of the positive electrode active material layer 12. to 10%, 0.1% to 5%, or 0.1% to 2%.

As shown in FIG. 1, the negative electrode current collector 210 may be placed at the bottom of the unit cell 10, and the negative electrode active material layer 220 may be placed thereon. A solid electrolyte layer 300, a positive electrode active material layer 120, and a positive electrode current collector 110 may be arranged in order on the negative electrode active material layer 220.

In one embodiment, the cathode layer 200 may further include a lithium precipitation layer 230. More specifically, all-solid-state secondary batteries containing lithium in the negative electrode may experience volume expansion problems due to lithium during charging and discharging. To prevent this, a lithium precipitation layer 230 may be formed on the cathode layer 200. The lithium precipitation layer 230 is disposed between the negative electrode current collector 210 and the negative electrode active material layer 220, and may be formed due to lithium moving from the positive electrode layer 100 to the negative electrode layer 200 during charging. In this way, by including the lithium precipitation layer 230, volume expansion of the all-solid-state secondary battery 1 can be suppressed and irreversible loss of lithium can be prevented.

In one embodiment, the thickness of the lithium precipitation layer 230 may be 0 ㎛ to 50 ㎛. For example, the thickness of the lithium precipitation layer 230 may be 10 ㎛ or more, 20 ㎛ or more, 30 ㎛ or more, or 40 ㎛ or more and 50 ㎛ or less, 40 ㎛ or less, 30 ㎛ or less, or 20 ㎛ or less.

The solid electrolyte layer 300 is disposed between the anode layer 100 and the cathode layer 200 and may include a sulfide-based solid electrolyte.

Sulfide-based solid electrolytes are, for example, Li2S-P2S5, Li2S-P2S5-LiX, -LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-ZmSn, m, n are positive numbers, Z is Ge, Zn or Ga one of Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-LipMOq, p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga In, Li7-xPS6-xClx, 0 x≤2, Li7-xPS6-xBrx, 0≤x≤2, and Li7-xPS6-xIx, 0 One or more selected from x≤2. Sulfide-based solid electrolytes are manufactured by processing starting materials such as Li2S, P2S5, etc. by melting quenching or mechanical milling. Additionally, after this treatment, heat treatment can be performed. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. In addition, the solid electrolyte may include, for example, sulfur (S), phosphorus (P), and lithium (Li) as constituent elements at least among the sulfide-based solid electrolyte materials described above. For example, the solid electrolyte may be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material containing Li2S-P2S5 to form a solid electrolyte, the mixing molar ratio of Li2S and P2S5 is, for example, Li2S:P2S5 = 50:50 to 90:10.

Sulfide-based solid electrolytes are, for example, Li7-xPS6-xClx, 0 x≤2, Li7-xPS6-xBrx, 0≤x≤2, and Li7-xPS6-xIx, 0 It may be an argyrodite-type compound containing one or more selected from x≤2. In particular, the sulfide-based solid electrolyte may be an ajirodite-type compound containing one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

The density of the azirodite-type solid electrolyte may be 1.5 to 2.0 g/cc. As the ajirodite-type solid electrolyte has a density of 1.5 g/cc or more, the internal resistance of the all-solid secondary battery is reduced, and penetration of the solid electrolyte by Li can be effectively suppressed. The elastic modulus of the solid electrolyte is, for example, 15 to 35 GPa.

In one embodiment, the solid electrolyte layer 300 may include, for example, a binder. For example, the binder is not limited to styrene butadiene rubber (SBR), poly tetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., and any binder used in the relevant technical field can be used. The binder of the solid electrolyte layer 300 may be the same as or different from the binder included in the positive electrode active material layer 120 and the negative electrode active material layer 220.

Next, the pressurizing part 400 is placed on the unit cell 10. For example, as shown in FIG. 2, a pair of pressing parts 400 is provided, and the unit cell 10 is placed on one pressing part 400, and the other pressing part 10 is placed on the unit cell 10. (400) can be placed. Accordingly, one side and the other side of the unit cell 10 each come into contact with the pressing portion 400. Here, the unit cell 10 may have a height H1.

The shape and size of the pressing portion 400 are not particularly limited. For example, the pressing part 400 may be a flat plate made of metal or the like. Additionally, the pressing portion 400 may have a wider width than the unit cell 10.

In one embodiment, the pressing part 400 may be a high-strength plate that can withstand high pressure. For example, the pressing unit 400 may be a high-strength plate that can withstand the high pressure (1 to 8 MPa) applied in the step of pressing the unit cell 10, which will be described later.

Next, the unit cell 10 is pressurized using the pressurizing unit 400. For example, as shown in FIG. 3, the unit cell 10 can be pressed by pressing a pair of pressing parts 400 in opposite directions. Here, the pressure P applied to the pressurizing unit 400 is not particularly limited and may be the pressure necessary for the above-described lithium precipitation layer 230 to operate. For example, the pressure P applied to the pressing unit 400 may be 1 MPa to 8 MPa. The height of the unit cell 10 can be compressed from H1 to H2 by the pressurizing unit 400.

The method of pressing the pressing unit 400 is not particularly limited. For example, the unit cell 10 can be pressurized by pressurizing the pair of pressurizing parts 400 using a hydraulic actuator or the like. Alternatively, the unit cell 10 can be pressed by fixing the position of the pair of pressing parts 400 using a jig.

In one embodiment, pressurizing the unit cell 10 may further include arranging one or more cushioning sheets 500 between the pressing unit 400 and the unit cell 10. For example, a cushioning sheet 500 may be placed between the pressurizing portion 400 disposed below and the cathode layer 200 of the unit cell 10. Additionally, a cushioning sheet 500 may be placed between the pressurizing portion 400 disposed above and the anode layer 100 of the unit cell 10. The cushioning sheet 500 prevents the unit cell 10 from coming into direct contact with the pressurizing part 400, and the pressurizing part 400 prevents the anode layer 100 and the cathode layer 200 of the unit cell 10 from contacting each other directly. It can prevent shock.

In one embodiment, the cushioning sheet 500 may be made of an elastic material. For example, elastic materials forming the cushioning sheet 500 include polyurethane, natural rubber, spandex, butyl rubber (Isobutylene Isoprene Rubber, IIR), fluoroelastomer, elastomer, ethylene-propylene rubber (EPR), and styrene-butadiene rubber. (SBR), chloroprene, elastin, rubber epichlorohydrin, nylon, terpene, isoprene rubber, polybutadiene, nitrile rubber, thermoplastic elastomer, silicone rubber, ethylene-propylene-diene rubber (EPDM), ethylene vinyl acetate (EVA), It may include one or more selected from the group consisting of halogenated butyl rubber, neoprene, and copolymers thereof, but is not limited thereto, and any material having elasticity may be used without limitation. For example, the cushioning sheet 500 may be made of silicone rubber, cellulose fiber, polyolefin resin, polyurethane resin, acrylic resin, etc. In one embodiment, the cushioning sheet 500 may be made of acrylic resin or urethane resin.

Next, a housing 20 surrounding the unit cell 10 is formed. For example, as shown in FIG. 4, in a state in which the unit cell 10 is pressed by a pair of pressing parts 400, one or more fixing parts 600 are attached to the pressing part so that the unit cell 10 is disposed inside. By connecting with (400), the housing (20) can be formed.

The shape and size of the fixing part 600 are not particularly limited, and it is sufficient as long as it is connected to a pair of pressing parts 400 to maintain the pressurized state of the unit cell 10. For example, the fixing part 600 may be a flat plate with a height corresponding to the height of the pair of pressing parts 400. Alternatively, the fixing part 600 may be a collection of a plurality of bars supporting a pair of pressing parts 400.

The number of fixing parts 600 is not particularly limited, and it is sufficient to maintain the position of the pair of pressing parts 400 that pressurize the unit cell 10. For example, one fixing part 600 may be disposed on one side of a pair of pressing parts 400. Alternatively, a total of two fixing parts 600 may be arranged, one at each end in the longitudinal direction of the pair of pressing parts 400. Alternatively, one more fixing part 600 may be arranged on the upper or lower surface of the pair of pressing parts 400, for a total of three.

In one embodiment, the fixing part 600 may be made of a material with the same or different strength as the pressing part 400. For example, the fixing part 600 may be made of a material with a lower strength than the pressing part 400, and in this case, the cost is lower than when the entire rectangular can-shaped housing 20 is formed with the pressing part 400 made of a high-strength material. can save.

The fixing part 600 may be disposed on one side and/or the other side of the pair of pressing parts 400 to maintain the pair of pressing parts 400 pressing the unit cell 10. Once the fixing part 600 is disposed, the member (for example, a hydraulic cylinder or jig, etc.) that presses the pair of pressing parts 400 can be dismantled.

In one embodiment, one side and the other side of one or more fixing parts 600 may be connected to a pair of pressing parts 400, respectively. For example, one side of the fixing part 600 may be connected to the pressing part 400 placed below, and the other side of the fixing part 600 may be connected to the pressing part 400 placed above. Accordingly, the fixing part 600 can maintain the state in which the unit cell 10 is pressed by the pair of pressing parts 400.

In one embodiment, the step of forming the housing 20 may include arranging the fixing parts 600 so that the pair of pressing parts 400 and one or more fixing parts 600 form a rectangular parallelepiped shape. For example, as shown in FIG. 4, the fixing part 600 is placed on the left side of the pair of pressing parts 400, and the fixing part 600 is placed on the right side of the pair of pressing parts 400 to face it. It can be placed. Accordingly, the fixing part 600 connected to the pair of pressing parts 400 may form the side surface of a rectangular parallelepiped. In this way, the manufacturing method of the all-solid-state secondary battery 10 according to an embodiment of the present invention can form a can-type housing 20, especially a square can-type housing.

In one embodiment, the step of forming the housing 20 may include arranging the fixing parts 600 so that the ends of the pair of pressing parts 400 are connected to the inner surfaces of one or more fixing parts 600. For example, as shown in FIG. 4, the fixing part 600 is disposed outside the pressing part 400 in the longitudinal direction, so that the inner surfaces of both ends of the fixing part 600 are connected to the ends of the pressing part 400. You can.

In one embodiment, the step of forming the housing 20 may connect one or more fixing parts 600 to the pressing part 400 through welding. For example, as shown in FIG. 4, one side and the other side of the fixing part 600 may be placed on a pair of pressing parts 400, and then the contacting parts may be welded to form a welded part 700.

In another embodiment, the step of forming the housing 20 may be performed by coupling the fixing part 600 to the pressing part 400 through bolting. Alternatively, in the step of forming the housing 20, the fixing part 600 may be coupled to the pressing part 400 using a separate mechanical device or an adhesive member.

In one embodiment, forming the housing 20 may further include placing the cover 800 on the housing 20. For example, as shown in FIG. 5, with the fixing parts 600 disposed on both sides of the pair of pressing parts 400, the cover 800 is arranged to cover the open surface of the housing 20. can do. One or more covers 800 may be arranged to cover the upper and/or lower surfaces of the rectangular housing 20.

The method of placing the cover 800 on the housing 20 is not particularly limited. The cover 800 can be welded along the upper edges of the pressing part 400 and the fixing part 600. Alternatively, the cover 800 can be placed on the housing 20 using a separate clamp member or adhesive member. Accordingly, the can-type housing 20 can be manufactured.

In this way, the method of manufacturing the all-solid-state secondary battery 1 according to an embodiment of the present invention involves pressing the unit cell 10 with the pressing part 400 and connecting the fixing part 600 to the pressing part 400. Thus, the housing 20 can be formed by itself. Accordingly, a square can-type housing 20 surrounding the unit cell 10 with or without the lithium precipitate layer 230 in a compressed state can be easily manufactured.

The manufacturing method of the all-solid-state secondary battery 1 according to an embodiment of the present invention pressurizes the unit cell 10 using the pressurizing part 400, and connects the fixing part 600 to the pressing part 400 to pressurize the unit cell 10. The pressurized state of (10) can be easily maintained. In addition, the housing 20 can be formed with the member that compresses the unit cell 10 itself, without the process of inserting the unit cell 10 into a separate housing in a compressed state. Accordingly, the all-solid-state secondary battery 1 of the square can type can be manufactured using the unit cell 10 in a compressed state more easily than the conventional manufacturing method.

In the above, an embodiment has been described with reference to the drawings and examples, but this is merely an example, and those skilled in the art will understand that various modifications and other equivalent implementations are possible therefrom. will be. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims (10)

Forming a unit cell by stacking an anode layer, a cathode layer, and a solid electrolyte layer; and
Placing a pair of pressing parts on one side and the other side of the unit cell, respectively, to pressurize the unit cell; and
A method of manufacturing an all-solid-state secondary battery comprising: forming a housing surrounding the unit cell while pressing the unit cell. According to paragraph 1,
The step of pressurizing the unit cell includes placing the pair of pressure boots on one side and the other side of the unit cell, respectively, and pressing them in directions facing each other. According to paragraph 2,
The step of pressurizing the unit cell is a method of manufacturing an all-solid-state secondary battery, in which the unit cell is pressed with a pressure of 1 to 8 MPa. According to paragraph 1,
The step of pressurizing the unit cell further includes the step of disposing a cushioning sheet between the unit cell and at least one of the pair of pressurizing parts. According to paragraph 1,
The step of forming the housing is a method of manufacturing an all-solid-state secondary battery, wherein the housing is formed by connecting one side and the other side of one or more fixing parts with the pair of pressing parts, respectively. According to clause 5,
The step of forming the housing is a method of manufacturing an all-solid-state secondary battery, wherein the can-shaped housing is formed in a rectangular parallelepiped shape with the one or more fixing parts connecting the pair of press parts as sides. According to clause 6,
Forming the housing further includes placing a cover on the housing. According to clause 5,
The forming of the housing includes arranging the one or more fixing parts so that the ends of the pair of pressing parts are connected to the inner surface of the one or more fixing parts. According to paragraph 1,
The step of forming the unit cell is a method of manufacturing an all-solid-state secondary battery, wherein a lithium precipitate layer is disposed between a negative electrode current collector layer and a negative electrode active material layer included in the negative electrode layer. An all-solid-state secondary battery manufactured by the method according to any one of claims 1 to 9.

Images