Method for manufacturing all-solid-state battery and all-solid-state battery manufactured thereby

Abstract

The present invention relates to a method for manufacturing an all-solid-state battery and an all-solid-state battery manufactured thereby, the method comprising the steps of: (1) sequentially laminating a cathode current collector, a cathode layer, a solid electrolyte layer, an anode layer, and a first anode current collector to manufacture an all-solid-state battery; (2) charging and discharging the manufactured all-solid-state battery; (3) delaminating and removing the first anode current collector from the all-solid-state battery in a discharged state; and (4) disposing a second anode current collector to be in contact with the anode layer.

Description

Method for manufacturing an all-solid-state battery and an all-solid-state battery manufactured in this manner

[0001] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2023-0146371, dated October 30, 2023, and incorporates herein all the contents of the document disclosed in that Republic of Korea Patent Application.

[0002] The present invention relates to a method for manufacturing an all-solid-state battery and an all-solid-state battery manufactured in this manner.

[0003] Lithium secondary batteries have been mainly applied to small fields such as mobile devices and laptop computers, but recently, the research direction is expanding to medium and large fields such as energy storage systems (ESS) and electric vehicles (EVs).

[0004] For these medium and large-sized lithium secondary batteries, unlike small ones, the operating environment (e.g., temperature, shock) is harsher, and more batteries must be used, so safety must be secured along with excellent performance and an appropriate price.

[0005] Most commercially available lithium secondary batteries utilize organic liquid electrolytes, which consist of lithium salts dissolved in flammable organic solvents. This poses a potential risk of leakage, fire, and explosion. Therefore, replacing these liquid electrolytes with solid electrolytes is gaining attention as a viable solution to address these safety concerns.

[0006] Lithium secondary batteries using solid electrolytes offer increased safety, improved reliability by preventing electrolyte leakage, and the ease of manufacturing thin batteries. Furthermore, the use of lithium metal as the anode enhances energy density. Consequently, solid electrolytes are attracting attention as next-generation batteries, promising applications in both compact secondary batteries and high-capacity secondary batteries for electric vehicles.

[0007] However, lithium secondary batteries using solid electrolytes have lower ionic conductivity than liquid electrolytes, and their output characteristics deteriorate, especially at low temperatures. Furthermore, solid electrolytes have lower surface adhesion to active materials than liquid electrolytes, and the volume of the active material expands during the charge / discharge process, increasing interfacial resistance. Furthermore, solid electrolytes are distributed in a non-contact state with the electrode active material, which reduces output characteristics and capacity compared to the amount of conductive material introduced.

[0008] To solve these problems, lithium secondary batteries that typically use solid electrolytes, i.e., all-solid-state batteries, include a pressurizing process to improve the interfacial properties of the solid electrolyte and active material during the operation process.

[0009] However, when pressurizing in a harsh environment to increase the contact area between the active material particles and the solid electrolyte, there is a problem that the active material particles may break and uneven lithium dendrite precipitation may occur, so there is an urgent need to solve these problems.

[0010] [Prior Art Literature]

[0011] [Patent Document]

[0012] (Patent Document 1) Republic of Korea Patent Publication No. 10-2022-0012623 (February 4, 2022)

[0013] The purpose of the present invention is to provide a method for manufacturing an all-solid-state battery in which the capacity and life characteristics of the battery are improved by removing the negative electrode current collector of an all-solid-state battery in which initial charge and discharge have been performed and laminating a new negative electrode current collector, thereby resolving poor interface contact within the battery due to unevenness of the electrode caused by deformation of the current collector or unevenly deposited lithium dendrite.

[0014] Another object of the present invention is to provide an all-solid-state battery manufactured through the above-described method for manufacturing an all-solid-state battery.

[0015] One embodiment of the present invention provides a method for manufacturing an all-solid-state battery, including the steps of (1) manufacturing an all-solid-state battery by sequentially stacking a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a first negative electrode current collector, (2) charging and discharging the manufactured all-solid-state battery, (3) peeling and removing the first negative electrode current collector from the all-solid-state battery in a discharged state, and (4) arranging a second negative electrode current collector so as to be in contact with the negative electrode layer.

[0016] The step of peeling and removing the first negative electrode collector in the above step (3) can be performed when the discharge capacity is 80% or less of the discharge capacity after the first charge and discharge cycle during the charge and discharge in the above step (2).

[0017] In the above step (1), a pre-pressure pressing process may further be included in which the positive electrode current collector, the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the first negative electrode current collector are sequentially laminated and pressed together.

[0018] In the above step (4), a post-pressure pressing process may further be included in which the second negative electrode collector is placed in contact with the negative electrode layer and pressed.

[0019] The above-mentioned pre-pressure pressing process can be performed at 100 to 1,000 MPa.

[0020] The above post-pressure pressing process can be performed at 10 to 500 MPa.

[0021] The above anode layer may include at least one of a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer-based solid electrolyte, and a combination thereof.

[0022] The above pressurization may be performed through warm isostatic pressure.

[0023] The above charging and discharging can be performed in a voltage range of 2.5 to 4.5 V.

[0024] Another embodiment of the present invention provides an all-solid-state battery manufactured by the above manufacturing method, comprising a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a second negative electrode current collector.

[0025] According to the present invention, by peeling off the negative electrode current collector of an all-solid-state battery that has undergone initial charge and discharge and laminating a new negative electrode current collector, it is possible to improve the capacity and life characteristics of an all-solid-state battery by resolving poor interface contact within the battery due to unevenness of the electrode caused by deformation of the current collector or unevenly deposited lithium dendrite.

[0026] Figure 1 is a graph showing the life characteristics of an all-solid-state battery manufactured according to a method for manufacturing an all-solid-state battery according to one embodiment and a comparative example of the present invention.

[0027] Hereinafter, embodiments of the present invention will be described in detail. Prior to this, terms and words used in this specification and claims should not be interpreted as limited to their conventional or dictionary meanings. Rather, they should be interpreted with meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of a term to best explain his or her invention. Accordingly, the configurations described in the embodiments described in this specification are merely the most preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention. Therefore, it should be understood that various equivalents and modified examples may exist as of the time of this application.

[0028] Throughout this specification, whenever a part is said to 'include' a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0029] Additionally, the description that concretizes or adds components can be applied to all inventions unless there are special limitations, and is not limited to a specific invention.

[0030] Additionally, throughout the description and claims of the invention herein, the singular includes the plural unless otherwise stated.

[0031] Additionally, throughout the description and claims of the present invention, the term "or" includes "and" unless otherwise stated. Therefore, "comprising A or B" means all three cases of including A, including B, or including A and B.

[0032] Additionally, all numerical ranges include the extreme values ​​and all intermediate values ​​between them, unless explicitly stated otherwise.

[0033] Throughout this specification, the average particle diameter of the particles may be, for example, the median diameter (D50) measured using a laser particle size distribution meter.

[0034]

[0035] Method for manufacturing an all-solid-state battery

[0036] The method for manufacturing an all-solid-state battery of the present invention comprises (1) a step of manufacturing an all-solid-state battery by sequentially stacking a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a first negative electrode current collector, (2) a step of charging and discharging the manufactured all-solid-state battery, (3) a step of peeling and removing the first negative electrode current collector from the all-solid-state battery in a discharged state, and (4) a step of arranging a second negative electrode current collector so as to be in contact with the negative electrode layer.

[0037]

[0038] The method for manufacturing the all-solid-state battery of the present invention is specifically described step by step below.

[0039] First, (1) an all-solid-state battery is manufactured by stacking a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a first negative electrode current collector in that order.

[0040] The above-described positive electrode current collector may generally have a thickness of 3 to 500 μm. The positive electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. The positive electrode current collector may have fine unevenness on its surface to increase adhesion to the positive electrode layer described below, and may be in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0041] The above positive electrode layer may include a positive electrode active material, a solid electrolyte, a conductive material, and a binder.

[0042] The above-mentioned positive electrode active material is not particularly limited as long as it is a lithium composite oxide material capable of reversible insertion and de-insertion of lithium ions. For example, it may include at least one of a composite oxide of cobalt, manganese, nickel, iron, or a combination thereof; and lithium.

[0043] For a more specific example, as the positive electrode active material, a compound represented by any one of the following chemical formulas may be used: Li a A 1-b R b D2 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0 ≤ b ≤ 0.5); Li a E 1-b R b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); LiE 2-b R b O 4-c D c (In the above formula, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b R c D α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α ≤ 2); Li a Ni 1-b-c Co b R c O 2-α Z α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni 1-b-c Co b R c O 2-α Z2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Lia Ni 1-b-c Mn b R c D α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α ≤ 2); Li a Ni 1-b-c Mn b R c O 2-α Z α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni 1-b-c Mn b R c O 2-α Z2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni b E c G d O2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5 and 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d G e O2 (in the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, and 0 ≤ e ≤ 0.1); Li a NiG b O2 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (in the above formula, 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); Li a Mn2G bO4 (wherein 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiTO2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2); and LiFePO4.

[0044] In the above chemical formula, A is Ni, Co, Mn or a combination thereof; R 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; Z 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; T is Cr, V, Fe, Sc, Y or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu or a combination thereof.

[0045] The positive electrode active material may be included in an amount of 50 to 95 parts by weight based on 100 parts by weight of the entire positive electrode layer. In this case, the 100 parts by weight of the entire positive electrode layer may mean including the positive electrode active material, a conductive material, a sulfide-based solid electrolyte, a binder, and other additives, and specifically may mean 100 parts by weight of the entire positive electrode layer excluding the current collector, and the same may be applied to the content of each component included in the positive electrode.

[0046] For example, the content of the positive electrode active material may be 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 75 parts by weight or more, 78 parts by weight or more, or 80 parts by weight or more, and may be 95 parts by weight or less, 90 parts by weight or less, or 85 parts by weight or less, based on 100 parts by weight of the entire positive electrode layer.

[0047] If the content of the positive electrode active material is less than 50 parts by weight based on 100 parts by weight of the entire positive electrode layer, there may be a problem of a decrease in the capacity and total energy density of the electrode, and if it exceeds 95 parts by weight, there may be a problem of an increase in the interfacial resistance between the positive electrode active material and the solid electrolyte due to an increase in voids in the positive electrode layer. Therefore, in the case of the positive electrode layer of the all-solid-state battery according to the present invention, it is necessary to appropriately control the content of the positive electrode active material within the above range.

[0048] The conductive material is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fiber or metal fiber; metal powders such as fluorinated carbon, aluminum, and nickel powder; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives. The conductive material may be included in an amount of about 0.01 to 10 parts by weight, or 0.01 to 5 parts by weight, or 0.01 to 3 parts by weight based on 100 parts by weight of the entire positive electrode layer.

[0049] The above binder is a component added in consideration of the binding properties of the positive electrode active material, solid electrolyte, and conductive material included in the positive electrode layer, and may be any type of binder as long as it can be used for electrode formation in the technical field to which the present invention pertains. For example, the binder may be at least one selected from the group consisting of nitrile-butadiene rubber (NBR), polystyrene, and styrene-butadiene rubber (SBR), and preferably, the binder may be a butadiene rubber series binder such as nitrile-butadiene rubber (NBR) or styrene-butadiene rubber (SBR). The binder may be included in an amount of about 0.1 to 10 parts by weight based on 100 parts by weight of the entire positive electrode layer.

[0050] If the content of the above binder is less than 0.1 parts by weight based on 100 parts by weight of the entire positive electrode, the adhesive strength of the electrode may decrease, which may cause problems with the processability and stability of the coated product. If it exceeds 10 parts by weight, the resistance of the electrode may increase, which may reduce the cell life and output characteristics. Therefore, it is appropriately adjusted within the above range.

[0051] In one embodiment of the present invention, the solid electrolyte may include at least one of a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer-based solid electrolyte, and a combination thereof, and specifically, the solid electrolyte may include a sulfide-based solid electrolyte.

[0052] The sulfide-based solid electrolyte included in the above-mentioned positive electrode layer may be, for example, represented by the following chemical formula 1.

[0053] [Chemical Formula 1]

[0054] Li a M b S c X d

[0055] In the above chemical formula 1, M is Sn, Mg, Ba, B, Al, Ga, In, Si, Ge, Pb, N, P, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W, or La, X is F, Cl, Br, I, Se, Te, or O, and 0 <a≤6, 0<b≤6, 0<c≤6 및 0<d≤6이다.

[0056] For example, in the above chemical formula 1, M can be B, Si, Ge, P or N.

[0057] For example, in the above chemical formula 1, X can be F, Cl, Br, I or O.

[0058] For example, the sulfide-based solid electrolyte represented by the above chemical formula 1 may be Li2S-P2S5-LiBr, Li2S-P2S5-LiCl-LiBr, Li2S-SiS2-LiBr, Li2S-P2S5, Li2S-P2S5-LiCl, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-GeS2, Li2S-SiS2-Li3PO4, or a combination thereof.

[0059] The above sulfide-based solid electrolyte may have an argyrodite-type crystal structure. Since the sulfide-based solid electrolyte has an argyrodite-type crystal structure, the purity and crystallinity of the sulfide-based solid electrolyte are high, and a stable interfacial phase is formed, thereby achieving a high energy density while significantly improving potential stability and ionic conductivity.

[0060] The above sulfide-based solid electrolyte may be included in an amount of 5 to 49 parts by weight based on 100 parts by weight of the entire positive electrode layer.

[0061] The content of the above sulfide-based solid electrolyte may be, for example, 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, 9 parts by weight or more, 10 parts by weight or more, 11 parts by weight or more, 12 parts by weight or more, 13 parts by weight or more, 14 parts by weight or more, 15 parts by weight or more, 16 parts by weight or more, 17 parts by weight or more, 18 parts by weight or more, 19 parts by weight or more, 19.4 parts by weight or more, and may be 49 parts by weight or less, 45 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, 30 parts by weight or less, 25 parts by weight or less, 24 parts by weight or less, 23 parts by weight or less, 22 parts by weight or less, 21 parts by weight or less, or 20 parts by weight or less, based on 100 parts by weight of the entire positive electrode layer. Preferably, the content of the sulfide-based solid electrolyte may be included in an amount of 12 to 20 parts by weight based on 100 parts by weight of the entire positive electrode layer.

[0062] If the content of the above sulfide-based solid electrolyte is less than 5 parts by weight based on 100 parts by weight of the entire positive electrode layer, there may be a problem that the voids in the positive electrode layer increase, causing the interfacial resistance between the positive electrode active material and the solid electrolyte to increase, thereby lowering the capacity and overall energy density of the electrode. If it exceeds 49 parts by weight, there may be a problem that the capacity and overall energy density of the electrode to decrease. Therefore, it is necessary to appropriately adjust the content of the sulfide-based solid electrolyte within the above range.

[0063] The average particle diameter of the above sulfide-based solid electrolyte may be 0.1 to 5 μm. For example, the average particle diameter of the above sulfide-based solid electrolyte may be 0.1 to 3 μm, 0.1 to 2 μm, 0.1 to 1 μm, 0.1 to 0.9 μm, 0.1 to 0.8 μm, 0.1 to 0.7 μm, 0.1 to 0.6 μm, or 0.1 to 0.5 μm. The average particle diameter of the above sulfide-based solid electrolyte may be, for example, a volume-converted median diameter (D50) measured using a laser particle size distribution analyzer.

[0064] If the average particle size of the sulfide-based solid electrolyte is less than 0.1 ㎛, the sulfide-based solid electrolyte particles may easily clump together or may not be uniformly dispersed, causing them to become biased within the electrode, and there may be a problem that it may be difficult to form an effective interface between the positive electrode active material and the sulfide-based solid electrolyte. If it exceeds 5 ㎛, there may be a problem that pores may be generated in the positive electrode active material layer, causing a decrease in the ionic conductivity of the electrode. Therefore, it is desirable to appropriately adjust the sulfide-based solid electrolyte to have an average particle size within the above range.

[0065] The above-mentioned positive electrode layer can be manufactured according to a method widely known in the art, and is not limited to a specific manufacturing method, but for example, it can be manufactured by a dry electrode process method in which the positive electrode active material, sulfide-based solid electrolyte, conductive material, and binder are mixed to manufacture a dough and then the manufactured dough is sheeted, or a wet process in which the positive electrode mixture is manufactured in a slurry state by mixing in a solvent and then the positive electrode mixture is applied to a positive electrode current collector.

[0066] The above-described positive electrode layer may further include additives such as fillers, coating agents, dispersants, and ion-conducting aids in addition to the above-described positive electrode active material, solid electrolyte, conductive agent, and binder. The fillers, coating agents, dispersants, ion-conducting aids, and the like may be known materials generally used in electrodes of all-solid-state batteries.

[0067] The above solid electrolyte layer may be the same as or different from the solid electrolyte included in the above positive electrode layer.

[0068] The solid electrolyte included in the above solid electrolyte layer may include a sulfide-based solid electrolyte, and since the sulfide-based solid electrolyte is the same as that described in the above-described positive electrode layer, a detailed description thereof will be omitted.

[0069] The elastic modulus of the solid electrolyte layer, i.e., Young's modulus, may be, for example, 35 GPa or less, 30 GPa or less, 27 GPa or less, 25 GPa or less, or 23 GPa or less. The elastic modulus of the solid electrolyte layer, i.e., Young's modulus, may be, for example, 10 to 35 GPa, 15 to 35 GPa, 15 to 30 GPa, or 15 to 25 GPa. Since the solid electrolyte layer has an elastic modulus in this range, pressurization and / or sintering of the solid electrolyte included in the solid electrolyte layer may be performed more easily.

[0070] The above solid electrolyte layer further includes, for example, a binder. The binder included in the solid electrolyte layer is not limited to, but may include, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., and any binder used in the relevant technical field may be used. The binder of the solid electrolyte layer may be the same as or different from the binders of the positive electrode layer and the negative electrode layer.

[0071] The above negative electrode layer may include a negative electrode active material, and the negative electrode active material may include, for example, at least one selected from lithium metal, a lithium metal alloy, a carbon-based negative electrode active material, and a metal or metalloid negative electrode active material.

[0072] The above carbon-based negative electrode active material may include, in particular, amorphous carbon. Amorphous carbon includes, but is not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, etc., and any material classified as amorphous carbon in the relevant technical field may be used. Amorphous carbon is carbon that has no crystallinity or very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon.

[0073] The above metal or metalloid negative electrode active material includes at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), but is not necessarily limited thereto, and any metal or metalloid negative electrode active material that forms an alloy or compound with lithium in the relevant technical field may be used. For example, nickel (Ni) does not form an alloy with lithium and therefore is not a metal negative electrode active material.

[0074] The above-described negative electrode layer comprises a type of negative electrode active material among these negative electrode active materials, or comprises a mixture of a plurality of different negative electrode active materials. For example, the negative electrode active material layer comprises only amorphous carbon, or comprises at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Alternatively, the negative electrode active material layer comprises a mixture of amorphous carbon and at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio of amorphous carbon and silver (Ag) 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 this range and is selected according to the required characteristics of the all-solid-state battery. When the negative active material has this composition, the cycle characteristics of the all-solid-state battery are further improved.

[0075] The negative active material included in the above negative electrode layer includes a mixture of first particles made of, for example, amorphous carbon and second particles made of a metal or a metalloid. The metal or metalloid includes, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Alternatively, the metalloid is a semiconductor. The content of the second particles is 8 to 60 wt%, 10 to 50 wt%, 15 to 40 wt%, or 20 to 30 wt% based on the total weight of the mixture. When the second particles have a content in this range, the cycle characteristics of, for example, an all-solid-state battery are further improved.

[0076] The negative electrode active material included in the above negative electrode layer has, for example, a particle form. The average particle diameter of the negative electrode active material having a particle form is, for example, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or 900 nm or less. The average particle diameter of the negative electrode active material having a particle form is, 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 diameter in this range, reversible absorption and / or desorption of lithium can be facilitated during charge and discharge. The average particle diameter of the negative electrode active material can be, for example, a volume-converted median diameter (D50) measured using a laser particle size distribution analyzer.

[0077] The thickness of the negative electrode layer is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode layer. The thickness of the negative electrode layer is, for example, 1 ㎛ to 20 ㎛, 2 ㎛ to 10 ㎛, or 3 ㎛ to 7 ㎛. If the thickness of the negative electrode layer is too thin, lithium dendrites formed between the negative electrode layer and the negative electrode current collector cause the negative electrode layer to collapse, making it difficult to improve the cycle characteristics of the all-solid-state battery. If the thickness of the negative electrode layer increases excessively, the energy density of the all-solid-state battery decreases and the internal resistance of the all-solid-state battery due to the negative electrode layer increases, making it difficult to improve the cycle characteristics of the all-solid-state battery.

[0078] The cathode layer may include, for example, a binder. The binder may be, but is not limited to, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, or the like, and any binder used in the art may be used. The binder may be composed of a single binder or a plurality of different binders.

[0079] By including a binder in the above-described negative electrode layer, the negative electrode layer is stabilized on the negative electrode current collector. In addition, cracking of the negative electrode layer is suppressed despite changes in the volume and / or relative positions of the negative electrode active material layer during charge and discharge processes. For example, if the negative electrode layer does not include a binder, it is possible for the negative electrode layer to easily separate from the negative electrode current collector. The portion where the negative electrode layer separates from the negative electrode current collector exposes the negative electrode current collector and comes into contact with the solid electrolyte layer, increasing the possibility of a short circuit. The negative electrode layer is manufactured, for example, by applying a slurry in which the materials constituting the negative electrode layer are dispersed onto the negative electrode current collector and drying it. By including a binder in the negative electrode layer, stable dispersion of the negative electrode active material in the slurry is possible. For example, when applying the slurry onto the negative electrode current collector by screen printing, it is possible to suppress clogging of the screen (e.g., clogging by aggregates of the negative electrode active material).

[0080] The above first negative electrode current collector is composed of, for example, a material that does not react with lithium, i.e., does not form an alloy or a compound. The material constituting the first negative electrode current collector is, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not necessarily limited thereto, and any material that is used as an electrode current collector in the relevant technical field may be used. The first negative electrode current collector may be composed of one type of the above-described metal, or may be composed of an alloy or a coating material of two or more types of metals. The first negative electrode current collector is, for example, in the form of a plate or foil.

[0081] The above cathode layer may further include additives used in conventional all-solid-state batteries, such as fillers, dispersants, and ionic conductive agents.

[0082] The above all-solid-state battery can be manufactured by sequentially manufacturing the positive electrode current collector, positive electrode layer, solid electrolyte layer, negative electrode layer, and first negative electrode current collector.

[0083] In one embodiment of the present invention, the electrode assemblies stacked in the above order may be structured to be housed in a case such as a pouch. In addition, two or more electrode assemblies may be stacked to produce an all-solid-state battery.

[0084] The above-mentioned all-solid-state battery may further include an elastic sheet on the outer side of at least one of the positive electrode current collector and the first negative electrode current collector. The elastic sheet may be expressed as a buffer layer or an elastic layer, and may serve to ensure uniform transmission of pressure to the electrode stack to improve contact between solid components, and may also alleviate stress transmitted to the solid electrolyte, etc., and may serve to suppress cracks from occurring in the solid electrolyte due to stress accumulation according to changes in the thickness of the electrode during charge and discharge.

[0085] In one embodiment of the present invention, the step (1) may further include a pre-pressure pressing process of sequentially stacking a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a first negative electrode current collector, and pressing and pressing them.

[0086] The above-described pre-pressure pressing process may be carried out at a temperature of, for example, 25°C to 90°C, and at a pressure of 1,000 MPa or less, 800 MPa or less, or 600 MPa or less, for example, 100 to 500 MPa. The above-described pre-pressure pressing process may be carried out through, for example, isostatic pressing, roll pressing, or plate pressing, and specifically, may be carried out through warm isostatic pressing.

[0087]

[0088] Next, (2) the manufactured all-solid-state battery is charged and discharged.

[0089] An initial charge is performed by applying voltage to an all-solid-state battery manufactured by sequentially stacking the positive electrode current collector, positive electrode layer, solid electrolyte layer, negative electrode layer, and first negative electrode current collector manufactured in step (1) above.

[0090] By charging the above-mentioned all-solid-state battery to a voltage higher than that during normal use during the initial charge, the amorphous state of the alloy-based negative electrode active material can be promoted, thereby improving the capacity retention rate of the battery. More specifically, the amorphous portion preferentially reacts with Li, but by increasing the proportion of that portion and alleviating local stress concentration, the capacity retention rate can be improved.

[0091] The above-mentioned "initial" charge is clearly distinguished from the "first" charge, and the "initial" is a broad concept that includes the "first time." For example, the initial charge literally means the first charge, but the initial charge does not necessarily have to be the first charge. For example, even if several charge / discharge cycles are performed without sufficiently increasing the voltage of the all-solid-state battery, if charging is performed thereafter until the voltage of the all-solid-state battery reaches an appropriately high range, that process corresponds to the initial charge process in this specification. The initial charge is preferably, for example, the first or more and the tenth or less charge.

[0092] The above charging and discharging process can be repeated 1 to 500 times.

[0093]

[0094] Next, (3) the first negative electrode collector is peeled and removed from the all-solid-state battery in a discharged state, and (4) the second negative electrode collector is placed in contact with the negative electrode layer.

[0095] The above step (3) is to place the all-solid-state battery, which has undergone initial charging and discharging in the above step (2), in a final discharge state and to peel off the first negative electrode current collector from the all-solid-state battery.

[0096] In the case of an all-solid-state battery that has undergone repeated charging and discharging processes through the above step (2), the current collector may be deformed, or specifically, lithium may be deposited on the first negative current collector to form dendrites, the negative active material may swell to cause interfacial deterioration with the solid electrolyte, or the formed dendrites may form an uneven shape on the surface of the current collector, ultimately accelerating the interfacial resistance due to poor contact between the first negative current collector and the negative electrode layer.

[0097] In the past, to solve these problems, a method was mainly used to improve the interface characteristics by applying pressure during operation of the all-solid-state battery. However, if excessive pressure is continuously applied to the all-solid-state battery, there is a possibility that the active material may break or the battery may short-circuit due to the lithium dendrites generated.

[0098] The present invention has the characteristic of preventing a decrease in the capacity and life characteristics of a battery due to interface deterioration by peeling and removing the current collector itself that is unevenly deposited in an uneven shape and attached to the surface through the initial charge / discharge process of an all-solid-state battery, and newly arranging a new second negative current collector that did not participate in the initial charge / discharge process.

[0099] Through the above step (3), the first negative electrode collector used in the manufacture of the first all-solid-state battery is removed, and a new second negative electrode collector is placed in contact with the negative electrode layer of the all-solid-state battery.

[0100] The above second negative electrode collector may be different from or the same as the first negative electrode collector, but it is preferable that the shape, material, quality, etc. of the first negative electrode collector and the second negative electrode collector be the same.

[0101] In one embodiment of the present invention, the step (4) may further include a post-pressure pressing process of placing the second negative electrode current collector in contact with the negative electrode layer and pressing it.

[0102] The above post-pressure pressing process may be carried out at a temperature of, for example, 25°C to 90°C, and at a pressure of 500 MPa or less, 300 MPa or less, or 100 MPa or less, for example, 10 to 500 MPa. The above post-pressure pressing process may be carried out through, for example, isostatic pressing, roll pressing, or plate pressing, and specifically, may be carried out through warm isostatic pressing.

[0103] The pressure range of the above post-pressure pressing process may be equal to or less than the pressure range of the pre-pressure pressing process. If the pressure range of the post-pressure pressing fixing is greater than the pressure range of the pre-pressure pressing process, the pre-pressure pressing process may cause physical damage to the structure of the all-solid-state battery formed through the above step (1), such as breakage of the positive electrode active material.

[0104] In one embodiment of the present invention, the step of peeling and removing the first negative electrode collector in step (3) may be performed when the discharge capacity is 80% or less of the discharge capacity after the first charge and discharge cycle during the charge and discharge in step (2).

[0105] For example, the step of peeling and removing the first negative electrode collector in the above step (3) may be performed when the discharge capacity after the first charge and discharge cycle during the charge and discharge in the above step (2) is 80% or less, 81% or less, 82% or less, 83% or less, 84% or less, 85% or less, 86% or less, 87% or less, 88% or less, 89% or less, 90% or less, 91% or less, 92% or less, 93% or less, 94% or less, or 95% or less of the discharge capacity.

[0106] Another embodiment of the present invention provides an all-solid-state battery manufactured by the above-described manufacturing method, which includes a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a second negative electrode current collector.

[0107] The above positive electrode current collector, positive electrode layer, solid electrolyte layer, negative electrode layer, and second negative electrode current collector are the same as those described above, so their specific description is omitted.

[0108] As described above, the all-solid-state battery according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, and is therefore useful in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

[0109] Accordingly, according to another embodiment of the present invention, a battery module including the all-solid-state battery as a unit cell and a battery pack including the same are provided.

[0110] The above battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0111] Below, specific embodiments of the present invention are presented. However, the examples described below are intended only to specifically illustrate or explain the present invention and are not intended to limit the scope of the invention. Furthermore, any details not described herein are technically feasible for those skilled in the art, and thus their description is omitted.

[0112]

[0113] Example 1: Fabrication of an all-solid-state battery

[0114] 1. Manufacturing of the anode

[0115] Based on 100 parts by weight of the total positive electrode layer, LiNi having a particle size (D50) of 5㎛ as the positive electrode active material 0.8 Co 0.1 Mn 0.1 83 parts by weight of O2 powder, 15 parts by weight of lithium argyrodite-type solid electrolyte Li6PS5Cl, 0.2 parts by weight of carbon black conductive agent, and 1.5 parts by weight of polytetrafluoroethylene (PTFE) binder are mixed in a mortar, and then a sheet-shaped cathode layer is manufactured using a roll press.

[0116] The above-mentioned manufactured positive electrode layer is dried in a vacuum oven at 100°C for 8 hours, and placed on one side of an aluminum current collector having a thickness of 15 μm to manufacture a positive electrode.

[0117] 2. Manufacturing of solid electrolyte layer

[0118] A lithium argyrodite-type solid electrolyte Li6PS5Cl is added to a binder solution in which an acrylic binder (SX-A334, Zeon) is dissolved in an isobutyl isobutyrate (IBIB) solvent, and the solution is stirred in a sinky mixer to adjust the viscosity to an appropriate level. After adjusting the viscosity, 2 mm zirconia balls are added and stirred again in a sinky mixer to prepare a slurry. The slurry contains 98.5 wt% of the solid electrolyte and 1.5 wt% of the binder. The slurry is applied on a release PET film using a bar coater and dried at room temperature to prepare a solid electrolyte layer.

[0119] 3. Manufacturing of the cathode

[0120] A catalyst is prepared by mixing carbon black having a primary particle size (D50) of about 30 nm and silver (Ag) having an average particle size (D50) of about 60 nm in a weight ratio of 3:1, and 0.25 g of the catalyst is added to 2 g of an NMP solution containing 7 wt% of polyvinylidene fluoride binder and mixed to prepare a negative electrode layer composition. This is applied to a nickel foil current collector, which is a first negative electrode current collector, using a bar coater and vacuum-dried to prepare a negative electrode in which a negative electrode layer is formed on the current collector.

[0121] 4. Manufacturing of all-solid-state batteries

[0122] The prepared positive electrode, solid electrolyte layer, and negative electrode are cut, and the positive electrode, solid electrolyte layer, and negative electrode are laminated in that order, and then an elastic sheet is laminated on the negative electrode. This is sealed in a pouch shape and isostatically pressed (WIP) at a high temperature of 80°C and 500 MPa for 30 minutes (pre-pressure pressing process) to manufacture an all-solid-state battery. In a pressurized state, the positive electrode layer has a thickness of approximately 100 μm, the negative electrode layer has a thickness of approximately 7 μm, and the solid electrolyte layer has a thickness of approximately 60 μm.

[0123] 5. Peeling and removal of the first cathode collector

[0124] The above-mentioned all-solid-state battery was charged at a 0.33C rate until the battery voltage reached 4.25 V, and then discharged at a 0.33C rate until the battery voltage reached 3.0 V (1st cycle). The discharge capacity of the 1st cycle was measured using a charge / discharge evaluation device "TOSCAT-3000" (trade name, manufactured by Toyo Systems).

[0125] The above charge / discharge cycle was counted as one cycle, and the charge / discharge cycle was repeated 175 times. The discharge capacity for each cycle was measured. When the discharge capacity of the all-solid-state battery reached 90% of the discharge capacity of the first cycle, the charge and discharge steps were stopped, and the pouch was disassembled in the discharged state to peel off and remove the first negative electrode collector of the all-solid-state battery. The peeling of the first negative electrode collector was performed from one edge toward the other edge at an angle of 70° to the negative electrode layer, at a peeling speed of 1000 mm / min.

[0126] 6. Placement of the second cathode collector

[0127] In the solid-state battery from which the first negative electrode collector has been peeled and removed, a nickel foil current collector, which is a second negative electrode current collector of the same type and size as the first negative electrode current collector, is prepared, placed in contact with the negative electrode layer, sealed again in a pouch shape, and subjected to a warm isostatic press (WIP) at a high temperature of 80°C and 500 MPa for 30 minutes (post-pressure pressing process) to manufacture an all-solid-state battery.

[0128]

[0129] Comparative Example 1: Manufacturing of an All-Solid-State Battery

[0130] 1. Manufacturing of the anode

[0131] Based on 100 parts by weight of the total positive electrode layer, LiNi having a particle size (D50) of 5㎛ as the positive electrode active material 0.8 Co 0.1 Mn 0.1 83 parts by weight of O2 powder, 15 parts by weight of lithium argyrodite-type solid electrolyte Li6PS5Cl, 0.2 parts by weight of carbon black conductive agent, and 1.5 parts by weight of polytetrafluoroethylene (PTFE) binder are mixed in a mortar, and then a sheet-shaped cathode layer is manufactured using a roll press.

[0132] The above-mentioned manufactured positive electrode layer is dried in a vacuum oven at 100°C for 8 hours, and placed on one side of an aluminum current collector having a thickness of 15 μm to manufacture a positive electrode.

[0133] 2. Manufacturing of solid electrolyte layer

[0134] A lithium argyrodite-type solid electrolyte Li6PS5Cl is added to a binder solution in which an acrylic binder (SX-A334, Zeon) is dissolved in an isobutyl isobutyrate (IBIB) solvent, and the solution is stirred in a sinky mixer to adjust the viscosity to an appropriate level. After adjusting the viscosity, 2 mm zirconia balls are added and stirred again in a sinky mixer to prepare a slurry. The slurry contains 98.5 wt% of the solid electrolyte and 1.5 wt% of the binder. The slurry is applied on a release PET film using a bar coater and dried at room temperature to prepare a solid electrolyte layer.

[0135] 3. Manufacturing of the cathode

[0136] A catalyst is prepared by mixing carbon black having a primary particle size (D50) of about 30 nm and silver (Ag) having an average particle size (D50) of about 60 nm in a weight ratio of 3:1, and 0.25 g of the catalyst is added to 2 g of an NMP solution containing 7 wt% of polyvinylidene fluoride binder and mixed to prepare a cathode layer composition. This is applied to a nickel foil current collector, which is a cathode current collector, using a bar coater and vacuum-dried to prepare a cathode in which a cathode layer is formed on the current collector.

[0137] 4. Manufacturing of all-solid-state batteries

[0138] The prepared positive electrode, solid electrolyte layer, and negative electrode are cut, and the positive electrode, solid electrolyte layer, and negative electrode are laminated in that order, and then an elastic sheet is laminated on the negative electrode. This is sealed in a pouch shape and isostatically pressed (WIP) at a high temperature of 80°C and 500 MPa for 30 minutes (pre-pressure pressing process) to manufacture an all-solid-state battery. In a pressurized state, the positive electrode layer has a thickness of approximately 100 μm, the negative electrode layer has a thickness of approximately 7 μm, and the solid electrolyte layer has a thickness of approximately 60 μm.

[0139] 5. Charging and discharging of all-solid-state batteries

[0140] The above-mentioned manufactured all-solid-state battery was charged at a 0.33C rate until the battery voltage became 4.25 V, and then discharged at a 0.33C rate until the battery voltage became 3.0 V.

[0141] After repeating the above charge / discharge cycle 200 times, which is one cycle, the discharge capacity for each cycle was measured using a charge / discharge evaluation device “TOSCAT-3000” (product name, manufactured by Toyo Systems).

[0142]

[0143] The capacity retention rate of the discharge capacity of the all-solid-state battery according to Example 1 and Comparative Example 1 was measured, and the results are shown in Fig. 1.

[0144] Referring to FIG. 1, in the case of the all-solid-state battery according to Example 1, when the discharge capacity of the all-solid-state battery reaches 90% of the discharge capacity of the first cycle, the first negative electrode collector is peeled and removed, and a new second negative electrode collector is placed. As a result, it can be seen that the life characteristics are greatly improved compared to the all-solid-state battery including the first negative electrode collector.

[0145]

[0146] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

Claims

1. (1) A step of manufacturing an all-solid-state battery by sequentially stacking a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a first negative electrode current collector; (2) A step of charging and discharging the manufactured all-solid-state battery; (3) A step of peeling and removing the first negative electrode current collector from the all-solid-state battery in a discharged state; and (4) a step of arranging the second cathode current collector so as to be in contact with the cathode layer; including; Method for manufacturing an all-solid-state battery.

2. In paragraph 1, The step of peeling and removing the first negative electrode collector of the above step (3) is as follows: In the charging and discharging step (2) above, when the discharge capacity is 80% or less compared to the discharge capacity after the first charge and discharge cycle, Method for manufacturing an all-solid-state battery.

3. In paragraph 1, In the above step (1), the process further includes a pre-pressure pressing process of sequentially stacking the positive electrode current collector, the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the first negative electrode current collector, and pressing and pressing them. Method for manufacturing an all-solid-state battery.

4. In paragraph 1, In the above step (4), the second negative electrode current collector is placed in contact with the negative electrode layer, and a post-pressure pressing process is further included to pressurize and pressurize it. Method for manufacturing an all-solid-state battery.

5. In paragraph 3, The above-mentioned pre-pressure pressing process is performed at 100 to 1,000 MPa. Method for manufacturing an all-solid-state battery.

6. In paragraph 4, The above post-pressure pressing process is performed at 10 to 500 MPa. Method for manufacturing an all-solid-state battery.

7. In paragraph 1, The above anode layer comprises at least one of a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer-based solid electrolyte, and a combination thereof. Method for manufacturing an all-solid-state battery.

8. In paragraph 3 or 4, The above pressurization is carried out through warm isostatic pressure. Method for manufacturing an all-solid-state battery.

9. In paragraph 1, The above charging and discharging are carried out in a voltage range of 2.5 to 4.5 V. Method for manufacturing an all-solid-state battery.

10. A battery manufactured by the manufacturing method according to claim 1, comprising a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a second negative electrode current collector. All-solid-state battery.

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