All-solid-state battery and manufacturing method thereof

Abstract

The invention relates to an all-solid-state battery and a manufacturing method thereof. More specifically, the all-solid-state battery of the present disclosure is formed such that the positive electrode active material layer is surrounded by the positive electrode current collector and the solid electrolyte layer, thereby preventing stretching of the positive electrode active material layer during pressurization and ensuring structural stability of the battery.

Description

Technical Field

[0001] This application claims the priority benefit of Korean Patent Application No. 10-2023-0166203, filed on November 27, 2023, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present disclosure relates to all-solid-state batteries and methods for manufacturing the same. Background Art

[0003] Various batteries are being studied to overcome the limitations of current lithium secondary batteries in terms of capacity, safety, output, large-scale and miniaturization.

[0004] Representative examples include: metal-air batteries, which have a very high theoretical capacity compared to lithium secondary batteries; all-solid-state batteries, which have no explosion risk and are safe; supercapacitors in terms of output; NaS batteries or redox flow batteries (RFBs) for large-scale applications; and thin-film batteries for miniaturization. These technologies are being continuously studied in academia and industry.

[0005] An all-solid-state battery is a battery in which a solid electrolyte is used instead of the liquid electrolyte used in a conventional lithium secondary battery, and since a flammable solvent is not used in the battery, there is no possibility of fire or explosion due to the decomposition reaction of the conventional electrolyte, which greatly improves safety. It also has the advantage of being able to use Li metal or Li alloy as the negative electrode material, which can significantly improve the energy density with respect to the mass and volume of the battery.

[0006] Traditionally, in order to manufacture an all-solid-state battery composed entirely of solid materials, a battery is manufactured by sequentially stacking a positive electrode, a solid electrolyte layer, and a negative electrode to form a laminate, and then applying pressure to the housing after positioning the laminate. The electrodes and solid electrolyte layers used in all-solid-state batteries are not all of the same size. Therefore, during the pressing process, the size difference between the electrodes or solid electrolyte layers may cause end cracking. In addition, the positive electrode is not rigid and has high spreadability due to the binder contained therein. During the pressing process, when pressure is applied unidirectionally, a part of the positive electrode can be pushed to the non-loaded side, resulting in its non-uniform stretching and reducing the performance of the battery.

[0007] Figure 1 It is a schematic diagram of a longitudinal section of a prior art all-solid-state battery.

[0008] The unit cell 100 of a prior art all-solid-state battery has a structure in which a positive electrode current collector 111, a positive electrode active material layer 112, a solid electrolyte layer 120, and a negative electrode layer 130 are stacked in sequence. The stacked cell 200 is formed by stacking a plurality of unit cells 100, for example, two or more unit cells 100 stacked together. When manufacturing the unit cell 100, compared with the adjacent solid electrolyte layer 120, the area of the positive electrode layer 110 including the positive electrode current collector 111 and the positive electrode active material layer 112 is smaller, so it is not easy to align the solid electrolyte layer 120 on the positive electrode layer 110, which may cause misalignment. In addition, after laminating the components as described above, during pressing, due to the area difference between the adjacent positive electrode active material layer 112 and the solid electrolyte layer 120, cracks C may be generated in the solid electrolyte layer 120, and when the laminated structure itself collapses, contact D between the positive electrode and the negative electrode layer may occur.

[0009] Therefore, it is necessary to develop a technology that can ensure the structural stability of all-solid-state batteries to prevent cracks and positive electrode stretching during the pressing process of cell assembly.

[0010] [Prior Art Documents]

[0011] [Patent Documents]

[0012] (Patent Document 1) Japanese Patent Application Laid-Open No. 2022-186164 Summary of the Invention

[0013] [Technical Problem]

[0014] The inventor of the present application has conducted various studies to solve the above problems, and as a result, it has been found that in an all-solid-state battery including a unit cell or a stacked cell in which a plurality of unit cells are stacked, in a unit cell including a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, and a negative electrode layer, the relatively small-sized positive electrode active material layer is surrounded by the positive electrode current collector and the solid electrolyte layer, and each component included in the unit cell has no deviation in size and has structural stability, thereby preventing problems such as cracks and positive electrode stretching during the pressing process.

[0015] Therefore, an object of the present disclosure is to provide an all-solid-state battery having structural stability and a manufacturing method thereof.

[0016] [Technical Solution]

[0017] To achieve the above object, the present disclosure provides an all-solid-state battery, which includes a unit cell,

[0018] wherein the unit cell includes a positive electrode layer, a solid electrolyte layer formed on the positive electrode layer, and a negative electrode layer formed on the solid electrolyte layer,

[0019] Among them, the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer. The positive electrode current collector has a receiving portion designed to accommodate a part of the positive electrode active material layer, and the positive electrode active material layer is accommodated in the receiving portion.

[0020] Among them, the solid electrolyte layer is formed in contact with the positive electrode current collector and the positive electrode active material layer.

[0021] In an example of the present disclosure, a all-solid-state battery is provided, in which the height of the receiving portion is less than the height of the positive electrode active material layer.

[0022] In an example of the present disclosure, a all-solid-state battery is provided, in which a part of the side surface of the positive electrode active material layer is in contact with the positive electrode current collector, and a part is in contact with the solid electrolyte layer. The part of the side surface of the positive electrode active material layer in contact with the positive electrode current collector is less than the part in contact with the solid electrolyte layer.

[0023] In an example of the present disclosure, a all-solid-state battery is provided, in which the negative electrode layer includes a negative electrode current collector; and a negative electrode active material layer formed on the negative electrode current collector, and the negative electrode active material layer is laminated adjacent to the solid electrolyte layer.

[0024] In an example of the present disclosure, a all-solid-state battery is provided, in which the negative electrode layer includes a negative electrode current collector; and an anodeless coating layer formed on the negative electrode current collector, and the anodeless coating layer is laminated adjacent to the solid electrolyte layer.

[0025] In an example of the present disclosure, a all-solid-state battery is provided, in which two or more unit battery cells are stacked.

[0026] The present disclosure provides a method for manufacturing a all-solid-state battery, which includes a unit battery cell manufacturing process. The unit battery cell manufacturing process includes: (S1) forming a positive electrode active material layer on a positive electrode current collector, the positive electrode current collector having a receiving portion designed to accommodate a part of the positive electrode active material layer;

[0027] (S2) forming a solid electrolyte layer on the positive electrode current collector and the positive electrode active material layer except for the receiving portion;

[0028] (S3) forming a negative electrode layer on the solid electrolyte layer; and

[0029] (S4) pressing and bonding the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer in the stacking direction.

[0030] In an example of the present disclosure, a method for manufacturing a all-solid-state battery is provided, in which the pressure is 400 Mpa to 700 MPa.

[0031] [Beneficial effects]

[0032] The unit cell included in the all-solid-state battery of the present disclosure has a structure in which a positive electrode layer, a solid electrolyte layer, and a negative electrode layer are stacked in sequence, such that the relatively small positive electrode active material layer is surrounded by the positive electrode current collector and the solid electrolyte layer, making the cross-sectional area of the unit cell constant and the unit cell having structural stability, which has the effect of preventing cracks from occurring even during the pressing process.

[0033] In addition, since a part of the positive electrode active material layer is received and adjacent to the positive electrode current collector, and another part of the positive electrode active material layer is surrounded by the solid electrolyte layer, it has the effect of preventing the positive electrode active material layer from stretching during the pressing process. Description of the drawings

[0034] Figure 1 is a schematic longitudinal cross-sectional view of an all-solid-state battery of the prior art.

[0035] Figure 2 is a schematic longitudinal cross-sectional view of an all-solid-state battery of an example of the present invention.

[0036] Figures 3a to 3d is a schematic view showing the cross-sectional structure of the all-solid-state batteries manufactured in the examples and comparative examples.

[0037] Figure 4 is a graph showing the experimental results of the life characteristics of the all-solid-state batteries manufactured in the examples and comparative examples.

[0038] Figures 5a to 5c shows scanning electron microscope (SEM) photographs of the cross-sections of the all-solid-state batteries manufactured in the examples and comparative examples. Detailed description of the embodiments

[0039] Hereinafter, the present disclosure will be described in more detail to provide a better understanding.

[0040] The terms and words used in this specification and the claims should not be construed in their ordinary or dictionary meanings, but rather based on the principle that the inventor can define the concept of the term as he / she deems most suitable to best describe his / her invention, and be construed in a meaning and concept consistent with the technical concept of the present disclosure.

[0041] All-solid-state battery

[0042] The present disclosure relates to an all-solid-state battery.

[0043] The all-solid-state battery of the present invention includes unit battery cells. Among them, the unit battery cell includes a positive electrode layer, a solid electrolyte layer formed on the positive electrode layer, and a negative electrode layer formed on the solid electrolyte layer. Among them, the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer. The positive electrode current collector has a receiving portion designed to accommodate a part of the positive electrode active material layer, and the positive electrode active material layer is accommodated in the receiving portion. The solid electrolyte layer is formed adjacent to the positive electrode current collector and the positive electrode active material layer.

[0044] The shape of the unit battery cell is square, and the cross-sectional areas of the positive electrode layer, the solid electrolyte layer, and the negative electrode layer are equal. Here, the cross-section of the positive electrode layer can be the cross-section of the positive electrode current collector, can be the cross-section of the positive electrode active material layer and the part of the positive electrode current collector including the positive electrode active material layer adjacent thereto, or can be the cross-section of the positive electrode active material layer and the solid electrolyte layer adjacent to the positive electrode active material layer.

[0045] In addition, since the unit battery cell does not contain any heterogeneous materials or blank spaces except for the positive electrode layer, the solid electrolyte layer, and the negative electrode layer, problems such as structural instability or battery performance deterioration caused by heterogeneous materials or blank spaces can be avoided. Therefore, the unit battery cell of the all-solid-state battery can include a positive electrode layer, a solid electrolyte layer, and a negative electrode layer.

[0046] In one example of the present disclosure, two or more unit battery cells can be stacked.

[0047] In the case of a stacked battery cell in which two or more of the above unit battery cells are stacked, it also does not contain any heterogeneous materials or blank spaces. The stacked battery cell can also have a square shape.

[0048] Figure 2 It is a schematic diagram of a longitudinal section of an all-solid-state battery which is an example of the present invention.

[0049] Reference Figure 2 , the all-solid-state battery 10 can be in the form of a stacked battery cell 200 in which two unit battery cells 100 are stacked. Compared with the solid electrolyte layer 120 and the negative electrode layer 130, the size of the positive electrode active material layer 112 is relatively small. By designing the outer periphery of the positive electrode active material layer 112 to be surrounded by the positive electrode current collector 111 and the solid electrolyte layer 120, the step caused by the size difference between the positive electrode active material layer 112 and the solid electrolyte layer 120 and the negative electrode layer 130 can be compensated.

[0050] The positive electrode current collector 111 includes a main body portion 111a and a receiving portion 111b for accommodating the positive electrode active material layer 112. The receiving portion 111b is formed as a recess in the main body portion 111a. A part of the positive electrode active material layer 112 is accommodated in the receiving portion 111b. The positive electrode active material layer 112 accommodated in the receiving portion 111b is surrounded by the positive electrode current collector 111.

[0051] In the side length (H1 + H2) of the positive electrode active material layer 112, the side length H1 adjacent to the positive electrode current collector 111 may be smaller than the side length H2 adjacent to the solid electrolyte layer 120. If the side length H1 adjacent to the positive electrode current collector 111 is large, the possibility of contact with the negative electrode layer 130 increases, and short circuit may occur.

[0052] Since the receiving portion 111b houses a part of the positive electrode active material layer 112, the remaining positive electrode active material layer 112 not housed in the receiving portion 111b is surrounded by the solid electrolyte layer 120. The solid electrolyte layer 120 is formed on the positive electrode active material layer 112. The solid electrolyte layer 120 is formed to surround the remaining portion of the positive electrode active material layer 112 not accommodated in the receiving portion 111b. Therefore, the solid electrolyte layer 120 is also formed on the main body portion 111a other than the receiving portion 111b in the positive electrode current collector 111.

[0053] The positive electrode active material layer 112, which is relatively small in size compared to the solid electrolyte layer 120 and the negative electrode layer 130, is surrounded by the positive electrode current collector 111 and the solid electrolyte layer 120 to compensate for the size difference, so that the unit cell 100 has a square shape. As a result, the stacked cell 200 in which the unit cells 100 are stacked also has a square shape.

[0054] When performing a pressing process by applying pressure to the square-shaped unit cell 100 or stacked cell 110 in a certain direction, problems such as cracks and positive electrode stretching can be prevented, thereby achieving structural stability. In addition, it is challenging to achieve a desired shape and area because the positive electrode is stretched irregularly and spreads unevenly. However, in the present disclosure, positive electrode stretching can be prevented, so that it can be controlled to a desired shape and area.

[0055] In an example of the present disclosure, the height of the receiving portion may be smaller than the height of the positive electrode active material layer.

[0056] Since only a part of the positive electrode active material layer is housed in the receiving portion, it is desirable that the height of the receiving portion is relatively small with respect to the height of the positive electrode active material layer. Since the positive electrode active material layer is housed in the receiving portion, the positive electrode active material layer is fixed by the positive electrode active material layer, so that positive electrode stretching does not occur even in the pressing process.

[0057] In an example of the present invention, a part of the side of the positive electrode active material layer is in contact with the positive electrode current collector, and a part of the side is in contact with the solid electrolyte layer, but the side length of the positive electrode active material layer in contact with the positive electrode current collector may also be smaller than the side length in contact with the solid electrolyte layer.

[0058] Regarding the side surface of the positive electrode active material layer, a part of the side surface of the positive electrode active material layer is received in the receiving portion of the positive electrode current collector and is in contact with the positive electrode current collector, and the remaining part is in contact with the solid electrolyte layer. If the length of the side surface of the positive electrode active material layer in contact with the positive electrode current collector is greater than the length of the side surface in contact with the solid electrolyte layer, the possibility of the positive electrode current collector contacting the negative electrode increases, and a short circuit may occur.

[0059] In one example of the present disclosure, the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer formed on one side surface of the positive electrode current collector.

[0060] The positive electrode current collector supports the positive electrode active material layer and functions to transfer electrons between the external wire and the positive electrode active material layer.

[0061] Furthermore, there is no particular limitation on the positive electrode current collector as long as it has high electron conductivity and does not cause chemical changes in the all-solid-state battery. For example, as the positive electrode current collector, copper, stainless steel, aluminum, nickel, titanium, palladium, calcined carbon, copper, stainless steel, copper or stainless steel treated with carbon, nickel or silver on the surface, aluminum cadmium alloy, etc. can be used.

[0062] In addition, the positive electrode current collector may have a fine uneven structure on the surface of the positive electrode current collector or adopt a three-dimensional porous structure to strengthen the bonding force with the positive electrode active material layer. Therefore, the positive electrode current collector can include various forms, such as films, sheets, foils, meshes, nets, porous materials, foams, non-woven materials, etc.

[0063] The positive electrode active material layer may be smaller in area than the positive electrode current collector and be located on the positive electrode current collector.

[0064] The positive electrode active material layer includes a positive electrode active material, a conductive material, and a binder. In addition, the positive electrode active material layer may further include a solid electrolyte.

[0065] In addition, the positive electrode active material can be any material capable of reversibly adsorbing and releasing lithium ions, such as but not particularly limited to: layered compounds, such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), Li[Ni x Co y Mn z M v O2 (where M is any one or more elements selected from Al, Ga, and In; and 0.3 ≤ x < 1.0, 0 ≤ y, z ≤ 0.5, 0 ≤ v ≤ 0.1, and x + y + z + v = 1), Li(Li a M b-a-b' M' b' )O 2-c A c(where 0 ≤ a ≤ 0.2, 0.6 ≤ b ≤ 1, 0 ≤ b' ≤ 0.2, and 0 ≤ c ≤ 0.2; M includes at least one selected from Mn, Ni, Co, Fe, Cr, V, Cu, Zn, and Ti; M' includes at least one selected from Al, Mg, and B; and A includes at least one selected from P, F, S, and N), or a compound substituted with one or more transition metals; lithium manganese oxides, such as the compound of formula Li 1+y Mn 2-y O4 (where y is from 0 to 0.33), LiMnO3, LiMn2O3, or LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides, such as LiV3O8, LiFe3O4, V2O5, or Cu2V2O7; Ni-site type lithium nickel oxides represented by the formula LiNi 1-y M y O2 (where M is Co, Mn, Al, Cu, Fe, Mg, B, or Ga, and y is from 0.01 to 0.3); lithium manganese composite oxides represented by the formula LiMn 2- y M y O2 (where M is Co, Ni, Fe, Cr, Zn, or Ta, and y is from 0.01 to 0.1) or Li2Mn3MO8 (where M is Fe, Co, Ni, Cu, or Zn); LiMn2O4, in which a part of Li is substituted by alkaline earth metal ions; disulfides; Fe2(MoO4)3; and so on, but not limited thereto.

[0066] In addition, based on the total weight of the positive electrode active material layer, the content of the positive electrode active material can be 60% by weight to 80% by weight. Specifically, the content of the positive electrode active material can be 60% by weight, more than 65% by weight, or more than 68% by weight, and less than 72% by weight, less than 75% by weight, or less than 80% by weight. If the content of the positive electrode active material is less than 60% by weight, the battery performance may decrease, and if the content is greater than 80% by weight, the mass transfer resistance may increase.

[0067] In addition, the solid electrolyte can have a thioargentite structure. More specifically, it can include a sulfide-based solid electrolyte, a halide-based solid electrolyte, or an oxide-based solid electrolyte.

[0068] The sulfide-based solid electrolyte can include a compound represented by the following formula 1 or a mixture thereof:

[0069] <Formula 1>

[0070] Li a M b S c X d

[0071] where M is selected from P, Sn, Sb, As, and Ge;

[0072] where X is selected from Cl, Br, and I,

[0073] 5 ≤ a ≤ 7.5, 0.5 < b ≤ 1.5, 4 < c ≤ 6, and 0.5 < d ≤ 2.

[0074] The halide-based solid electrolyte can be represented by the following formula 2:

[0075] <Formula 2>

[0076] Li 6-3a M a Br b Cl c

[0077] where M is a metal other than Li, 0 < a < 2, 0 ≤ b ≤ 6, 0 ≤ c ≤ 6, and b + c = 6.

[0078] For example, the halide-based solid electrolyte may include at least one selected from the group consisting of Li3YBr6, Li3YCl6, and Li3YBr2Cl4.

[0079] The oxide-based solid electrolyte can be suitably selected from, but not limited to: LLT-based compounds having a perovskite structure such as Li 3x La 2 / 3-x TiO3; LISICON such as Li 14 Zn(GeO4)4; LATP-based compounds such as Li 1.3 Al 0.3 Ti 1.7 (PO4)3; LAGP-based compounds such as (Li 1+x Ge 2-x Al x (PO4)3); phosphate-based compounds such as LiPON, etc.

[0080] In addition, the conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery and has excellent conductivity without causing chemical changes in the battery. As representative examples, graphite or conductive carbon can be used. For example: graphite, such as natural graphite, artificial graphite, etc.; carbon black, such as carbon black, acetylene black, Ketjen black, Denka black, thermal cracking carbon black, channel black, furnace black, lamp black, thermal black (summer black), etc.; carbon-based materials having a crystal structure of graphene or graphite; conductive fibers, such as carbon fibers, metal fibers, etc.; carbon fluoride; metal powders, such as aluminum powder, nickel powder, etc.; conductive whiskers, such as zinc oxide, potassium titanate, etc.; conductive oxides, such as titanium oxide; and conductive polymers, such as polyphenylene derivatives; which can be used alone or in a mixture of two or more of the foregoing, but are not necessarily limited thereto. Preferably, the conductive material may include vapor-grown carbon fiber (VGCF).

[0081] In addition, based on the total weight of the positive electrode active material layer, the content of the conductive material can be 1 wt% to 5 wt%. More specifically, the content of the conductive material can be 1 wt% or more, 1.5 wt% or more, 2 wt% or more, and can be 4 wt% or less, 4.5 wt% or less, or 5 wt% or less. If the content of the conductive material is too small, for example less than 1 wt%, it is difficult to expect the effect of improving conductivity or the electrochemical performance of the battery may decrease, and if the content of the conductive material is too large, for example more than 5 wt%, the amount of the positive electrode active material may be relatively small, resulting in a decrease in capacity and energy density. The method of adding the conductive material to the positive electrode is basically not limited, and any conventional method known in the art can be used, such as mixing with the positive electrode active material or coating the positive electrode active material.

[0082] A binder is a component that helps to bond the positive electrode active material and the conductive material or bond with the current collector, and may include those selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, poly(ethylene oxide), chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, cyanoethyl sucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropylene copolymer. Preferably, the binder may include polytetrafluoroethylene (PTFE).

[0083] In addition, based on the total weight of the positive electrode active material layer, the content of the binder may be from 0.5 wt% to 4 wt%, more specifically, the content of the binder may be 0.5 wt% or more, 1 wt% or more, 1.5 wt% or more, 3 wt% or less, 3.5 wt% or less, or 4 wt% or less. If the binder content is less than 0.5 wt%, the adhesion of the positive electrode active material to the positive electrode current collector may be reduced, and if the binder content is greater than 4 wt%, the adhesion can be improved, but the content of the positive electrode active material may be reduced, resulting in a decrease in battery capacity.

[0084] In one example of the present disclosure, the solid electrolyte layer may be larger in area than the positive electrode active material layer. Here, the area of the solid electrolyte layer and the area of the positive electrode active material layer represent the areas when looking down on the solid electrolyte layer and the positive electrode active material layer.

[0085] Since the solid electrolyte layer wraps the positive electrode active material layer, the lithium ion transfer area increases, which may be advantageous in terms of ionic conductivity.

[0086] In addition, the solid electrolyte layer may include a sulfide-based solid electrolyte, a halide-based solid electrolyte, or an oxide-based solid electrolyte. In terms of lithium ion conductivity, the solid electrolyte layer may include a sulfide-based solid electrolyte having a thio-LISICON crystal structure.

[0087] The sulfide-based solid electrolyte may include a compound represented by the following formula 1 or a mixture thereof:

[0088] <Formula 1>

[0089] Li a M b A c X d

[0090] wherein M is selected from P, Sn, Sb, As, and Ge;

[0091] wherein A is selected from S, Se, and Te;

[0092] wherein X is selected from Cl, Br, and I,

[0093] 5 ≤ a ≤ 7.5, 0.5 < b ≤ 1.5, 4 < c ≤ 6, and 0.5 < d ≤ 2.

[0094] The halide-based solid electrolyte can be represented by Formula 2 below:

[0095] <Formula 2>

[0096] Li 6-3a M a Br b Cl c

[0097] wherein M is a metal other than Li, 0 < a < 2, 0 ≤ b ≤ 6, 0 ≤ c ≤ 6, and b + c = 6.

[0098] For example, the halide-based solid electrolyte may include at least one selected from the group consisting of Li3YBr6, Li3YCl6, and Li3YBr2Cl4.

[0099] The oxide-based solid electrolyte may be suitably selected from, but not limited to: LLT-based compounds having a perovskite structure such as Li 3x La 2 / 3-x TiO3; LISICON such as Li 14 Zn(GeO4)4; LATP-based compounds such as Li 1.3 Al 0.3 Ti 1.7 (PO4)3; LAGP-based compounds such as (Li 1+x Ge 2-x Al x (PO4)3); phosphate-based compounds such as LiPON, etc.

[0100] In one example of the present disclosure, the negative electrode layer includes: a negative electrode current collector; and a negative electrode active material layer formed on the negative electrode current collector, wherein the negative electrode active material layer may be laminated adjacent to the solid electrolyte layer.

[0101] Alternatively, the negative electrode layer may include: a negative electrode current collector; and an anodeless coating formed on the negative electrode current collector, wherein the anodeless coating is laminated adjacent to the solid electrolyte layer.

[0102] The negative electrode active material layer contains a negative electrode active material, a binder, and a conductive material.

[0103] The negative electrode active material may include a material capable of reversibly inserting or extracting lithium (Li + ), a material capable of reacting with lithium ions to reversibly form a lithium-containing compound, lithium metal, or a lithium alloy.

[0104] Lithium ions (Li + ) The material capable of reversibly inserting or extracting may be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. The material capable of reacting with lithium ions (Li + ) to reversibly form a lithium-containing compound may be, for example, tin oxide, titanium nitrate, or silicon. The lithium alloy may be, for example, an alloy of lithium (Li) and a metal selected from the group consisting of indium (In), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), francium (Fr), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), aluminum (Al), and tin (Sn).

[0105] Preferably, the negative electrode active material may be lithium metal or a lithium-indium alloy (Li-In). More specifically, it may be in the form of lithium metal, a lithium thin film, a lithium-indium alloy thin film, or powder.

[0106] Based on the total weight of the negative electrode active material layer, the content of the negative electrode active material may be 40% by weight to 80% by weight. Specifically, the content of the negative electrode active material may be 40% by weight or more, 50% by weight or more, or may be 70% by weight or less or 80% by weight or less. If the content of the negative electrode active material is less than 40% by weight, the connectivity between the wet negative electrode active material layer and the dry negative electrode active material layer may be insufficient, and if the content is greater than 80% by weight, the mass transfer resistance may be greater.

[0107] The binder is a component that helps to bond the positive electrode active material and the conductive material or bond with the current collector, and may include those selected from styrene-butadiene rubber, acrylated styrene-butadiene rubber, acrylonitrile copolymer, acrylonitrile-butadiene rubber, nitrile rubber, acrylonitrile-styrene-butadiene copolymer, acrylic rubber, butyl rubber, fluororubber, polytetrafluoroethylene, polyethylene, polypropylene, ethylene / propylene copolymer, polybutadiene, poly(ethylene oxide), chlorosulfonated polyethylene, polyvinylpyrrolidone, polyvinylpyridine, polyvinyl alcohol, polyvinyl acetate, polyepichlorohydrin, polyphosphazene, polyacrylonitrile, polystyrene, latex, acrylic resin, phenolic resin, epoxy resin, carboxymethyl cellulose, hydroxypropyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cyanoethyl cellulose, cyanoethyl sucrose, polyester, polyamide, polyether, polyimide, polycarboxylate, polycarboxylic acid, polyacrylic acid, polyacrylate, lithium polyacrylate, polymethacrylic acid, polymethacrylate, polyacrylamide, polyurethane, polyvinylidene fluoride, and poly(vinylidene fluoride)-hexafluoropropylene copolymer. Preferably, the binder may include polytetrafluoroethylene (PTFE).

[0108] In addition, based on the total weight of the negative electrode active material layer, the content of the binder may be 0.5 wt% to 4 wt%, more specifically, the content of the binder may be 0.5 wt% or more, 1 wt% or more, 1.5 wt% or more, 3 wt% or less, 3.5 wt% or less, or 4 wt% or less. If the binder content is less than 0.5 wt%, the adhesion of the negative electrode active material to the negative electrode current collector may decrease, and if the binder content is greater than 4 wt%, the adhesion can be improved, but the content of the negative electrode active material may decrease, resulting in a reduction in battery capacity.

[0109] In addition, the above-mentioned conductive material is not particularly limited as long as it prevents side reactions in the internal environment of the all-solid-state battery and has excellent conductivity without causing chemical changes in the battery. As representative examples, graphite or conductive carbon can be used, such as: graphite, such as natural graphite, artificial graphite, etc.; carbon black, such as carbon black, acetylene black, Ketjen black, Denka black, thermal cracking carbon black, channel black, furnace black, lamp black, thermal black (summer black), etc.; carbon-based materials having a crystal structure of graphene or graphite; conductive fibers, such as carbon fibers, metal fibers, etc.; carbon fluoride; metal powders, such as aluminum powder, nickel powder, etc.; conductive whiskers, such as zinc oxide, potassium titanate, etc.; conductive oxides, such as titanium oxide; and conductive polymers, such as polyphenylene derivatives; They can be used alone or in a mixture of two or more of the foregoing, but are not limited thereto. Preferably, the conductive material may include vapor-grown carbon fiber (VGCF).

[0110] In addition, based on the total weight of the negative electrode active material layer, the content of the conductive material can be from 1 wt% to 5 wt%. More specifically, the content of the conductive material can be 1 wt% or more, 1.5 wt% or more, 2 wt% or more, and can be 4 wt% or less, 4.5 wt% or less, or 5 wt% or less. If the content of the conductive material is too small, for example, less than 1 wt%, it is difficult to expect the effect of improving conductivity or the electrochemical performance of the battery may decrease. And if the content of the conductive material is too large, for example, more than 5 wt%, the amount of the negative electrode active material may be relatively small, resulting in a decrease in capacity and energy density. The method of adding the conductive material to the negative electrode is basically not limited, and any conventional method known in the art can be used, such as mixing with the negative electrode active material or coating the negative electrode active material.

[0111] In addition, the negative electrode current collector is not particularly limited as long as it has conductivity and does not cause chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, carbon-treated surface, copper or stainless steel treated with nickel or silver, aluminum cadmium alloy, etc. can be used. In addition, like the positive electrode current collector, the negative electrode current collector can be in various forms, such as a film, sheet, foil, net, porous material, foam, non-woven material, etc. having fine irregularities formed on the surface.

[0112] The manufacturing method of the negative electrode is not particularly limited, and it can be manufactured by forming a negative electrode active material layer on the negative electrode current collector by using a conventional method of forming a layer or film. For example, methods such as pressing, coating, or deposition can be used. The negative electrode of the present disclosure also includes the case where a lithium thin film is not formed on the negative electrode current collector, and a metallic lithium thin film is formed on the metal plate by initial charging after assembling the battery.

[0113] In addition, the anodeless coating does not include the negative electrode active material, and the negative electrode active material can be formed in the anodeless coating by charging. For example, when the battery is charged, lithium ions may move out from the positive electrode, causing lithium metal to precipitate at the negative electrode. In other words, the anodeless coating can be a film that induces lithium precipitation.

[0114] The anodeless coating can include metal particles and carbon material particles, and more specifically, can include a carbon material-metal composite.

[0115] The carbon material particles can be, for example, amorphous carbon material particles. However, the carbon material particles are not limited to amorphous particles. Specific examples of the amorphous carbon material can include carbon black, such as acetylene black, furnace black, Ketjen black, graphene, or a combination thereof.

[0116] In addition, the metal particles can form an alloy with lithium, and the metal particles can be one or more particles selected from silver (Ag), gold, platinum, palladium, silicon, aluminum, bismuth, tin, indium, and zinc. The anodeless coating can be formed into a very thin film having a very small thickness, for example, a thickness of 10 μm or less.

[0117] Preferably, the anodeless coating may include an Ag-C composite as a carbon material-metal composite, and during the first charge, lithium may deposit between the negative electrode current collector and the coating containing the Ag-C composite.

[0118] In one example of the present disclosure, the all-solid-state battery may be a pouch-type all-solid-state battery.

[0119] Method for manufacturing an all-solid-state battery

[0120] The present disclosure also relates to a method for manufacturing an all-solid-state battery.

[0121] The method for manufacturing the all-solid-state battery of the present disclosure includes a unit cell manufacturing process, which includes the following steps (S1) to (S4):

[0122] (S1) Form a positive electrode active material layer on a positive electrode current collector having a receiving portion designed to accommodate a part of the positive electrode active material layer;

[0123] (S2) Form a solid electrolyte layer on the positive electrode current collector and the positive electrode active material layer except for the receiving portion;

[0124] (S3) Form a negative electrode layer on the solid electrolyte layer; and

[0125] (S4) Press and bond the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer in the stacking direction.

[0126] The configurations and shapes of the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer are as described above.

[0127] Hereinafter, the method for manufacturing the all-solid-state battery of the present disclosure will be described in more detail through each step.

[0128] In one example of the present disclosure, in the above step (S1), a positive electrode active material layer may be formed on a positive electrode current collector having a receiving portion for accommodating a part of the positive electrode active material layer.

[0129] The positive electrode active material layer can be prepared by wet or dry methods respectively. The positive electrodes prepared by the manufacturing process of the above positive electrode active material layer can be called wet positive electrodes and dry positive electrodes respectively.

[0130] When performing a wet process, the positive electrode active material layer can be formed by applying a slurry for forming the positive electrode active material layer to the positive electrode current collector. Specifically, the positive electrode active material layer can be prepared by coating a slurry for forming the positive electrode active material layer, which is prepared by mixing a positive electrode active material, a conductive material, and a binder in an organic solvent, on the receiving portion of the positive electrode current collector and drying it. At this time, an organic solvent that can uniformly disperse the positive electrode active material, the binder, and the conductive material and is easily evaporated is preferably used. Specifically, examples include acetonitrile, methanol, ethanol, tetrahydrofuran, water, and isopropyl alcohol.

[0131] In addition, when performing a dry process, the positive electrode active material layer can be separately manufactured in the form of a sheet, and then stamped to fit the size of the receiving portion of the positive electrode current collector and bonded to the receiving portion of the positive electrode current collector. In this case, a sheet can be prepared in a conventional manner using the slurry for forming the positive electrode active material layer as described above.

[0132] In one example of the present disclosure, in the above step (S2), a solid electrolyte layer can also be formed on the positive electrode current collector and the positive electrode active material layer other than the receiving portion.

[0133] The positive electrode current collector includes a main body portion and a receiving portion formed as a recess in the main body portion. The positive electrode active material layer is formed on the receiving portion. Therefore, when the solid electrolyte layer is formed on the positive electrode active material layer, the solid electrolyte layer can also be formed on the main body portion of the positive electrode current collector other than the receiving portion.

[0134] The solid electrolyte layer can be prepared by applying a slurry obtained by mixing a solid electrolyte and a binder in a solvent to the positive electrode active material layer and then drying it.

[0135] As described above, the solid electrolyte can include at least one selected from the group consisting of sulfide-based solid electrolytes, halide-based solid electrolytes, and oxide-based solid electrolytes. Preferably, the solid electrolyte can include a sulfide-based solid electrolyte having a thiargyrite-type crystal structure.

[0136] In addition, the binder resin can include at least one selected from acrylic copolymers, acrylic block copolymers, and random copolymers of acrylic monomers or oligomers.

[0137] In addition, based on 100 parts by weight of the solid electrolyte, 5 to 15 parts by weight of the binder can be included. Specifically, the content of the binder can be 5 parts by weight or more, 7 parts by weight or more, or 9 parts by weight or more, or 11 parts by weight or less, 13 parts by weight or less, or 15 parts by weight or less. If the content of the binder is less than 5 parts by weight, it may be difficult to form the solid electrolyte layer, and if it is greater than 15 parts by weight, the ionic conductivity may decrease.

[0138] Furthermore, there is no particular limitation on the solvent as long as it can dissolve and / or disperse the solid electrolyte and / or the binder to form a slurry. For example, the solvent can be at least one selected from dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, xylene, N,N-dimethylformamide (DMF), benzene, tetrahydrofuran (THF), and water. The amount of the solvent is adjusted in consideration of the thickness of the coating, the properties of the prepared solid electrolyte, etc.

[0139] The coating method can be bar coating, roll coating, spin coating, slot coating, die coating, knife coating, comma coating, slot die coating, lip coating, or solution casting, but is not limited thereto, as long as the coating can form a layer.

[0140] There is no particular limitation on drying as long as the drying method can evaporate the solvent after coating to form a layer. For example, drying can be carried out at a temperature below 300°C. Specifically, the drying temperature can be below 300°C, below 200°C, below 150°C, or below 100°C.

[0141] In one example of the present disclosure, in the above step (S3), a negative electrode layer can be formed on the solid electrolyte layer.

[0142] The method of forming the negative electrode layer on the solid electrolyte layer is not particularly limited as long as it is a method commonly practiced in the art, and methods such as lamination can be used.

[0143] In one example of the present disclosure, in the above step (S4), they can be joined by applying pressure in the stacking direction of the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, and the negative electrode layer.

[0144] The above step (S4) refers to the process of applying pressure after manufacturing the unit cell, but the pressure can also be applied after manufacturing the stacked cell, or the pressure can be applied inside the casing.

[0145] The pressure can be 400 Mpa to 700 MPa. More specifically, it can be 400 Mpa or more, 450 Mpa or more, or 500 Mpa or more, and can be 600 Mpa or less, 650 Mpa or less, or 700 Mpa or less. If the pressure is less than 400 MPa, the pressure is insufficient to manufacture the all-solid-state battery, or there may be pores remaining inside the positive electrode, increasing the resistance; if the pressure is greater than 700 Mpa, the pressure may be higher than necessary, resulting in cracking of a part of the battery.

[0146] [Examples]

[0147] In the following, preferred embodiments of the present disclosure are described for the purpose of explaining the present disclosure. However, it will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the present disclosure and the technical concept, and these changes and modifications fall within the scope of the appended patent claims.

[0148] Example 1

[0149] Manufacture a all-solid-state battery 10 having a cross-sectional structure as Figure 3a shown.

[0150] Prepare an aluminum foil as the positive electrode current collector 111. The aluminum foil includes a main body portion and a receiving portion formed as a recess in the main body portion.

[0151] After attaching a dry sheet containing NMC (Ni, Co, Mn)O2 to the receiving portion, a positive electrode layer 110 is prepared by forming a positive electrode active material layer 112.

[0152] Then, a slurry for forming a solid electrolyte is dip-coated on the main body portion and the positive electrode active material layer 112, and then dried to form a solid electrolyte layer 120. The main body portion is the portion of the positive electrode current collector 111 other than the receiving portion. The slurry for forming a solid electrolyte is prepared by mixing a sulfide-based solid electrolyte having a thioargentite-based crystal structure and a rubber-based binder at a weight ratio of 1:1 and adding it to an N-methylpyrrolidone (NMP) solvent.

[0153] The positive electrode active material layer 112 is formed to be surrounded by the positive electrode current collector 111 and the solid electrolyte layer 120. In the side surface of the positive electrode active material layer 112, the length of the portion in contact with the positive electrode current collector 111 is less than the length of the portion in contact with the solid electrolyte layer 120.

[0154] After that, a negative electrode layer 130 is stacked on the solid electrolyte layer 120 and pressed to a pressure of 500 Mpa to prepare the all-solid-state battery 10 in the form of a unit cell. The negative electrode layer 130 is anode-free, and an Ag-C composite is formed on one side of the Cu current collector.

[0155] Example 2

[0156] Fabricate a all-solid-state battery 10 having Figure 3b the cross-sectional structure shown.

[0157] Prepare an aluminum foil as the positive electrode current collector 111. The aluminum foil includes a main body portion and a receiving portion formed as a recess in the main body portion.

[0158] The positive electrode 110 is prepared by coating a slurry containing NMC (Ni, Co, Mn)O2 on the receiving portion to form a positive electrode active material layer 112.

[0159] Then, the slurry for forming the solid electrolyte is dip-coated on the main body portion and the positive electrode active material layer 112, and then dried to form the solid electrolyte layer 120. The main body portion is the part of the positive electrode current collector 111 other than the receiving portion. The slurry for forming the solid electrolyte is prepared by mixing a sulfide-based solid electrolyte having a thiogermanate-based crystal structure and a rubber-based binder at a weight ratio of 1:1 and adding it to an N-methylpyrrolidone (NMP) solvent.

[0160] The positive electrode active material layer 112 is formed to be surrounded by the positive electrode current collector 111 and the solid electrolyte layer 120. Among the side surfaces of the positive electrode active material layer 112, the length of the portion in contact with the positive electrode current collector 111 is shorter than the length of the portion in contact with the solid electrolyte layer 120.

[0161] After that, the negative electrode layer 130 is stacked on the solid electrolyte layer 120 and pressed to a pressure of 500 Mpa to prepare the all-solid-state battery 10 in the form of a unit cell. The negative electrode layer is anode-free, and an Ag-C composite is formed on one side of the Cu current collector.

[0162] Comparative Example 1

[0163] Manufacture an all-solid-state battery having Figure 3c the cross-sectional structure shown.

[0164] The positive electrode layer 110, the solid electrolyte layer 120, and the negative electrode layer 130 are laminated and pressed to a pressure of 500 Mpa, whereby the all-solid-state battery 10 is fabricated. Here, the positive electrode layer 110, the solid electrolyte layer 120, and the negative electrode layer 130 are all in the form of sheets, and their sizes are in the order of positive electrode layer 110 < negative electrode layer 130 < solid electrolyte layer 120. In addition, the configurations of the positive electrode layer 110, the solid electrolyte layer 120, and the negative electrode layer 130 are the same as those in Example 2.

[0165] Comparative Example 2

[0166] Manufacture an all-solid-state battery having Figure 3d the cross-sectional structure shown in

[0167] An all-solid-state battery is prepared in the same manner as in Comparative Example 1, except that the positive electrode layer 110, the solid electrolyte layer 120, and the negative electrode layer 130 are all of the same size.

[0168] Experimental Example 1: Performance Evaluation Experiment of All-Solid-State Battery

[0169] A performance evaluation experiment was conducted on the all-solid-state battery.

[0170] To evaluate the performance of the all-solid-state battery, the life characteristics were evaluated by measuring the discharge capacity during cycling at 0.33C / 0.33C.

[0171] As a result, as Figure 4 shown, it can be seen that Examples 1 and 2 have significantly better life characteristics compared to Comparative Examples 1 and 2. These results can be attributed to the structural stability of the all-solid-state battery.

[0172] Experimental Example 2: Crack confirmation

[0173] The cracks in the all-solid-state battery were inspected during the pressing process.

[0174] The cross-sections of the unit cells of Examples 1 and 2 and Comparative Examples 1 and 2 were observed by scanning electron microscopy (SEM).

[0175] Figures 5a to 5c Scanning electron microscopy (SEM) photographs of the cross-sections of the all-solid-state batteries manufactured in the Examples and Comparative Examples are shown.

[0176] Figure 5a A cross-sectional view of the battery is shown, which is substantially free of damage including cracks.

[0177] In addition, referring to Figure 5b and 5c , it can be seen that the positive electrode layer 110 was stretched and cracked, causing the cracks to extend to the solid electrolyte layer 130.

[0178] Although the present disclosure has been described above by way of limited examples and drawings, the present invention is not limited thereto, and those of ordinary skill in the art can make various modifications and variations within the equivalent scope of the technical concept of the present invention and the patent claims set forth below.

[0179] [Reference Signs]

[0180] 10: All-solid-state battery

[0181] 100: Unit cell

[0182] 110: Positive electrode layer

[0183] 111: Positive electrode current collector

[0184] 111a: Main body portion

[0185] 111b: Receiving portion

[0186] 112: Positive electrode active material layer

[0187] 120: Solid electrolyte layer

[0188] 130: Negative electrode layer

[0189] 131: Negative electrode current collector

[0190] 132: Negative electrode active material layer

[0191] 200: Stacked battery cells

[0192] C: Crack

[0193] D: Disintegration

Claims

1. A all-solid-state battery, which includes a unit cell, Among them, The unit cell includes a positive electrode layer, a solid electrolyte layer formed on the positive electrode layer, and a negative electrode layer formed on the solid electrolyte layer, wherein, the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer, the positive electrode current collector has a receiving portion designed to accommodate a part of the positive electrode active material layer, and the positive electrode active material layer is accommodated in the receiving portion, wherein, the solid electrolyte layer is formed to be in contact with the positive electrode current collector and the positive electrode active material layer.

2. The all-solid-state battery according to claim 1, Among them, The height of the receiving portion is less than the height of the positive electrode active material layer.

3. The all-solid-state battery according to claim 1, Among them, A part of the side surface of the positive electrode active material layer contacts the positive electrode current collector, and a part is adjacent to the solid electrolyte layer, wherein, the part of the side surface of the positive electrode active material layer in contact with the positive electrode current collector is less than the part in contact with the solid electrolyte layer.

4. The all-solid-state battery according to claim 1, Among them, The negative electrode layer includes: a negative electrode current collector; and a negative electrode active material layer formed on the negative electrode current collector, wherein, the negative electrode active material layer is laminated to contact the solid electrolyte layer.

5. The all-solid-state battery according to claim 1, Among them, The negative electrode layer includes: a negative electrode current collector; and an anodeless coating formed on the negative electrode current collector, wherein, the anodeless coating is laminated to contact the solid electrolyte layer.

6. The all-solid-state battery according to claim 1, Among them, Two or more unit cells are stacked.

7. A manufacturing method of an all-solid-state battery, which includes a unit cell manufacturing process, and the unit cell manufacturing process includes: (S1) Form a positive electrode active material layer on the positive electrode current collector, the positive electrode current collector having a receiving portion designed to accommodate a part of the positive electrode active material layer; (S2) Form a solid electrolyte layer on the positive electrode current collector and the positive electrode active material layer except for the receiving portion; (S3) Form a negative electrode layer on the solid electrolyte layer; and (S4) Press and bond the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer and the negative electrode layer in the stacking direction.

8. The manufacturing method of the all-solid-state battery according to claim 7, Among them, The pressure is 400 Mpa to 700 MPa.

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