Positive electrode for all-solid-state battery including mesh and method of manufacturing same

Abstract

Disclosed are a positive electrode for an all-solid-state battery including a mesh and a method of manufacturing the same.

Description

Technical Field

[0001] The present invention relates to a positive electrode for an all-solid-state battery comprising a mesh and a manufacturing method thereof. Background Art

[0002] Generally, an electrode of a lithium secondary battery is manufactured by a wet process in which a slurry including an active material is applied to a current collector or the like, and then the slurry is dried.

[0003] Recently, in order to increase the energy density of lithium secondary batteries, the electrodes of lithium secondary batteries tend to be thickened, but it is difficult to thicken the electrodes using the above-mentioned wet method. When the wet method is used, it is difficult to dry the electrodes because the electrodes become thicker and excessive binder is deposited on the electrode surface.

[0004] In order to solve these problems, many attempts to manufacture electrodes using dry methods are being made. In the conventional dry method, the electrode can be kept in the form of a film by applying shear stress to powders including active materials, adhesives, etc., and fibrillizing a suitable adhesive. However, in the above method, the shear stress is neither sufficient nor evenly transmitted, and therefore, the surface of the electrode may be wrinkled. The battery in a pressed cell unit that is less affected by the surface wrinkles and surface roughness of the electrode can work normally, but the battery in a pouch cell unit that is more affected by the surface wrinkles and surface roughness of the electrode may not work properly.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. Summary of the invention

[0006] In a preferred aspect, the present invention provides a positive electrode for an all-solid-state battery having no surface wrinkles and low surface roughness, and a method for manufacturing the same.

[0007] As used herein, the term "all-solid-state battery" refers to a rechargeable secondary battery that includes an electrolyte in a solid state for transferring ions between battery electrodes.

[0008] In one aspect, a positive electrode for an all-solid-state battery is provided, comprising: a first layer comprising a plurality of fibrous carbon materials and a first active material, and a second layer located on at least one surface of the first layer and comprising a second active material. In particular, the plurality of fibrous carbon materials form a network comprising pores, such that the first active material is disposed in the pores of the network.

[0009] The fibrous carbon material may include carbon nanotubes, vapor grown carbon fibers, carbon nanofibers, or combinations thereof.

[0010] The thickness of the mesh may be about 5 μm to 40 μm.

[0011] The BET surface area of ​​the mesh can be about 100 m 2 / g to 750m 2 / g

[0012] The total pore volume of the mesh can be about 0.5 cm 3 / g to 5cm 3 / g.

[0013] The tensile strength of the mesh may be about 2.5 MPa to 50 MPa.

[0014] The electron conductivity of the network can be equal to or greater than about 1×10 8 S / m.

[0015] The first active material may include a first positive electrode active material, a first solid electrolyte, and a first binder, and the second active material may include a second positive electrode active material, a second solid electrolyte, and a second binder.

[0016] As used herein, the term "binder" refers to a resin or polymeric material (eg, synthetic or natural) that can be polymerized or cured to form a polymeric matrix. Preferably, the binder according to the present invention may include polytetrafluoroethylene in its composition.

[0017] The first binder may include fibrillated polytetrafluoroethylene (PTFE).

[0018] The second binder may include fibrillated polytetrafluoroethylene (PTFE).

[0019] On the other hand, the present invention provides a method for manufacturing a positive electrode for an all-solid-state battery. The method comprises the following steps: preparing a starting material including a positive electrode active material, a solid electrolyte and a fibrous binder; supplying a plurality of fibrous carbon materials to a gap between a pair of rollers rotating in opposite directions, supplying the starting material to the plurality of fibrous carbon materials, and obtaining a positive electrode by film forming using the pair of rollers.

[0020] The starting material may be prepared by preparing a mixture including a positive electrode active material, a solid electrolyte, and a particulate binder, and fibrillating the particulate binder into a fibrous binder by applying a shear stress to the mixture.

[0021] The fibrous binder may include fibrillated polytetrafluoroethylene (PTFE).

[0022] In addition, the present invention provides an all-solid-state battery comprising the positive electrode as described herein.

[0023] Furthermore, a vehicle comprising an all-solid-state battery as described herein is provided.

[0024] Other aspects of the invention are discussed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other features of the present invention will now be described in detail with reference to certain exemplary embodiments of the invention shown in the accompanying drawings, which are given hereinafter only as examples and therefore do not limit the present invention, in which:

[0026] Figure 1 An exemplary all-solid-state battery according to an exemplary embodiment of the present invention is shown;

[0027] Figure 2 An exemplary positive electrode according to an exemplary embodiment of the present invention is shown;

[0028] Figure 3 An example of calendaring equipment is shown;

[0029] Figure 4 4 shows a field emission scanning electron microscope (FE-SEM) image showing the observation result of the positive electrode surface according to the comparative example;

[0030] Figure 5A and Figure 5B FE-SEM images are shown, which show that the Figure 4Observation results of the positive electrode surface portion other than the portion shown in ;

[0031] Figure 6 Showing load-displacement curves of the positive electrode according to the embodiment and the comparative example;

[0032] Figure 7 Shows the load test results of the positive electrodes according to the embodiments and the comparative examples;

[0033] Figure 8 The charging capacity of the all-solid-state battery including the positive electrode according to the embodiment and the comparative example is shown;

[0034] Fig. 9 The retention capacities of all-solid-state batteries including the positive electrodes according to the embodiments and the comparative examples are shown;

[0035] Fig.10 The coulombic efficiencies of all-solid-state batteries including the positive electrodes according to the embodiment and the comparative example are shown.

[0036] It should be understood that the accompanying drawings are not necessarily drawn to scale, but are simplified to a certain extent for various preferred features illustrating the basic principles of the present invention. The specific design features of the present invention disclosed herein, including, for example, specific size, orientation, position and shape, will depend in part on the specific intended application and use environment.

[0037] In the drawings, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. DETAILED DESCRIPTION

[0038] The above-mentioned purpose, other purposes, advantages and features of the present invention will become apparent from the description of the embodiments given below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed herein and can be implemented in various different forms. The embodiments are provided to make the description of the present invention thorough and to fully convey the protection scope of the present invention to those skilled in the art.

[0039] In the following description of the embodiment, even when depicted in different drawings, the same element is represented by the same reference numeral. In the accompanying drawings, for clarity of description, the size of the structure may be enlarged compared to its actual size. In the following description of the embodiment, terms such as "first" and "second" can be used to describe various elements, but these elements are not limited. These terms are only used to distinguish an element from other elements. For example, without departing from the scope and spirit of the present invention, the first element may also be referred to as the second element, and similarly, the second element may be referred to as the first element. Unless they have significantly different contextual meanings, singular expressions may also include plural expressions.

[0040] In the following description of the embodiments, terms such as “including,” “comprising,” and “having” will be interpreted as indicating the presence of the features, numbers, steps, operations, elements, or components, or a combination thereof, stated in the description, without excluding the presence of one or more other features, numbers, steps, operations, elements, components, or a combination thereof, or the possibility of adding these features, numbers, steps, operations, elements, components, or a combination thereof.

[0041] In addition, it should be understood that when a component (such as a layer, film, region, or panel, etc.) is referred to as being "on" another component, the component may be "directly" "on" the other component, or other components may be interposed between the two components. In the same way, it should be understood that when a component (such as a layer, film, region, or panel, etc.) is referred to as being "under" another component, the component may be "directly" "under" the other component, or other components may be interposed between the two components.

[0042] All the numbers, values ​​and / or expressions used in this specification that represent the amount of components, reaction conditions, polymer compositions and blends are approximate values, which reflect the various uncertainties in the measurements generated when these values ​​are obtained from essentially different things, so it should be understood that, unless otherwise stated, they are modified by the term "about". In addition, unless otherwise specified or obvious from the context, as used herein, the term "about" is understood to be within the normal tolerance range of this field, such as within 2 standard deviations of the mean value. "About" can be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05% or 0.01% of the value. Unless otherwise specified in the context, all numerical values ​​provided herein are modified by the term "about".

[0043] In addition, it should be understood that if a numerical range is disclosed in the specification, unless otherwise stated, the range includes all continuous values ​​from the minimum value of the range to the maximum value. In addition, if such a range refers to an integer, unless otherwise stated, the range includes all integers from the minimum integer to the maximum integer. In this specification, when describing the scope of a variable, it should be understood that the variable includes all values ​​of the endpoints described in the range. For example, the scope of "5 to 10" will be understood to include any sub-range, such as 6 to 10, 7 to 10, 6 to 9, 7 to 9, etc., and single values ​​such as 5, 6, 7, 8, 9 and 10, and will also be understood to include any value between the valid integers in the range, such as 5.5, 6.5, 7.5, 5.5 to 8.5, 6.5 to 9, etc. Similarly, for example, a range of "10% to 30%" will be understood to include sub-ranges such as 10% to 15%, 12% to 18%, 20% to 30%, etc., and all integers including values ​​of 10%, 11%, 12%, 13%, etc. up to 30%, and will also be understood to include any values ​​between the significant integers within the range, e.g., 10.5%, 15.5%, 25.5%, etc.

[0044] It should be understood that the term "vehicle" or "vehicular" or other similar terms used herein include general motor vehicles, such as passenger automobiles including sports utility vehicles (SUVs), buses, trucks, various commercial vehicles; watercraft including various boats and ships; aircraft, etc., and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel (e.g., fuels derived from resources other than petroleum) vehicles. As referred to herein, a hybrid vehicle is a vehicle with two or more power sources, such as gasoline-powered and electric-powered vehicles.

[0045] Figure 1 An all-solid-state battery 100 according to an exemplary embodiment of the present invention is shown. The all-solid-state battery 100 may include a positive electrode collector 10, a positive electrode 20, a solid electrolyte layer 30, an anode 40, and an anode collector 50. Positive current collector

[0046] The positive electrode collector 10 may include a plate-shaped base material having conductivity. The positive electrode collector 10 may appropriately include an aluminum foil.

[0047] The thickness of the positive electrode collector 10 is not limited to a specific value, and may be, for example, about 1 μm to 500 μm. positive electrode

[0048] Figure 2 An exemplary positive electrode 20 according to an exemplary embodiment of the present invention is shown. The positive electrode 20 may include a first layer 21 including a mesh 211 formed of a plurality of fibrous carbon materials placed or arranged to cross each other and a first active material 212 disposed in pores of the mesh 211, and a second layer 22 located on at least one surface of the first layer 21 and including a second active material.

[0049] When a plurality of fibrous carbon materials are arranged to cross each other, the mesh 211 can be appropriately formed.

[0050] The positive electrode 20 may be manufactured using a dry method. For example, the method of manufacturing the positive electrode 20 may include preparing a starting material including a positive electrode active material, a solid electrolyte, and a fibrous binder, providing a web 211 to a gap between a pair of rollers rotating in opposite directions, and providing the starting material to at least one surface of the web 211, and obtaining the positive electrode 20 by film formation using the pair of rollers.

[0051] The present invention is characterized in that, compared with the conventional dry method, by providing the mesh 211 as a buffer layer in the film forming process, wrinkles can be prevented from being formed on the surface of the positive electrode 20 due to uneven shear stress.

[0052] The preparing the starting material may include preparing a mixture including a positive electrode active material, a solid electrolyte, and a particulate binder, and fibrillating the particulate binder into a fibrous binder by applying a shear stress to the mixture.

[0053] The mixture may also include a dispersant, a conductive material, and the like.

[0054] The particle binder may suitably include polytetrafluoroethylene (PTFE) having a particle shape, such as spherical or ellipsoidal PTFE.

[0055] Polytetrafluoroethylene (PTFE) is a polymer obtained by replacing the hydrogen atoms of polyethylene (PE) with fluorine atoms. Polytetrafluoroethylene (PTFE) has an aliphatic main chain, but has excellent thermal stability and electrical stability, so it is widely used in the field of electronic materials. In particular, polytetrafluoroethylene (PTFE) has a low highest occupied molecular orbital (HOMO) level and therefore has high oxidation stability, so it is mainly used in the positive electrode. Polytetrafluoroethylene (PTFE) has a cylindrical structure, so even if it has a high glass transition temperature Tg, it can be fibrillated at low temperatures.

[0056] Polytetrafluoroethylene (PTFE) can have a specific gravity of about 2.185 or less. The lower limit of the specific gravity of polytetrafluoroethylene (PTFE) is not limited to a specific value, for example, can be equal to or greater than about 2. The relative molecular mass of polytetrafluoroethylene (PTFE) is measured using specific gravity. Specific gravity can be determined based on the program described in ASTM D4895. Samples to be tested can be sintered and cooled based on the sintering program described in ASTM D4895. The specific gravity of polytetrafluoroethylene (PTFE) is inversely proportional to its molecular weight. When the specific gravity of polytetrafluoroethylene (PTFE) is equal to or less than about 2.185, the molecular weight of polytetrafluoroethylene (PTFE) is high enough, so fibrillation can occur well.

[0057] The particulate binder may be in a powder state having an average particle size D50 of about 1 μm to 1000 μm.

[0058] The mixture may include a particulate binder in an amount of about 5 wt % or less based on the total weight of the mixture. When the content of the particulate binder is greater than about 5 wt %, the internal resistance of the all-solid-state battery 100 may increase. The lower limit of the content of the particulate binder is not limited to a specific value and may be equal to or greater than about 0.1 wt %.

[0059] The starting material including the positive electrode active material, the solid electrolyte and the fibrous binder can be obtained by applying shear stress to the mixture to fibrillate the particulate binder into the fibrous binder.

[0060] Applying shear stress to the mixture is not limited to a specific method. Shear stress can be applied using an apparatus or method commonly used in the technical field to which the present invention belongs. For example, a Taylor-Couette reactor can be used. The mixture can be placed in an outer cylinder having a cylindrical shape of a Taylor-Couette reactor, and the inner cylinder can be rotated rapidly to apply shear stress to the mixture. In addition, a shear stress device having shearing and pressing abilities, such as Micros (Nara Machinery Co., Ltd.) or a mechanical fusion system (Hosokawa Micron Corporation).

[0061] The time and temperature required for applying the shear stress can be appropriately adjusted according to the properties of the particle binder, the content of the particle binder, the specifications of the equipment, etc. For example, the shear stress can be applied to the mixture at a temperature of about 100° C. to 150° C. for about 1 minute to 1 hour.

[0062] The fibrous binder may include fibrillated polytetrafluoroethylene (PTFE). The fibrous binder may have a diameter of about 0.01 μm to 10 μm. The diameter represents the diameter of the cross section of the fibrous binder. The cross section represents the cross section of the fibrous binder cut in a direction perpendicular to the length direction of the fibrous binder. When the diameter is less than about 0.01 μm, the mechanical properties of the positive electrode 20 may be insufficient, and when the diameter is greater than about 10 μm, the lithium ion conductivity and electronic conductivity of the positive electrode 20 may be reduced.

[0063] The starting material obtained by applying shear stress to the mixture may be in a clay state due to the fibrous binder. In this state, it may be difficult to supply the starting material to subsequent processes. Therefore, preparing the starting material may also include obtaining a powdered starting material by crushing the starting material in a clay state.

[0064] The positive electrode 20 may be obtained by performing film formation through a calendaring process using the prepared starting material. Figure 3 An exemplary calendering apparatus is shown.

[0065] First, the web 211 may be supplied to a gap between a pair of rollers B and B′ rotating in opposite directions, and a starting material A may be provided to at least one surface of the web 211 .

[0066] The mesh 211 may be suitably formed of a plurality of fibrous carbon materials that are placed or arranged to cross each other. The mesh 211 may be porous and thus may include pores that are spaces between the plurality of fibrous carbon materials.

[0067] The fibrous carbon material may include carbon nanotubes, vapor-grown carbon fibers, carbon nanofibers, or a combination thereof.

[0068] The mesh 211 may have a thickness of about 5 μm to 40 μm. When the mesh 211 has a thickness less than 5 μm, the effect of improving the durability of the positive electrode 20 may not be obtained. When the mesh 211 has a thickness greater than about 40 μm, the mesh 211 may be exposed from the surface of the positive electrode 20.

[0069] The BET specific surface area of ​​the mesh 211 may be about 100 m 2 / g to 750m 2 / g. The total pore volume of the mesh 211 may be about 0.5 cm 3 / g to 5cm 3 / g. The BET specific surface area of ​​the mesh 211 was measured by nitrogen adsorption at 77K using AUTOSORB-1 (manufactured by Quanta Chrome Instruments). Prior to the measurement, the sample was degassed under dynamic vacuum at 423K for 6 hours and then used. The BET specific surface area was calculated by the Brunauer-Emmett-Teller (BET) method. At about P / P 0 =0.99, according to the adsorbed nitrogen (N 2 ) is used to estimate the total pore volume. When the BET specific surface area and / or the total pore volume of the mesh 211 is less than the above corresponding numerical range, the tensile strength of the mesh 211 is reduced, and thus the mesh 211 may be torn during the film forming process, or it may be difficult to obtain a uniform positive electrode 20. When the BET specific surface area and / or the total pore volume of the mesh 211 is greater than the corresponding numerical range, the tensile strength of the mesh 211 may become too high, and therefore, the film forming process may not be performed normally.

[0070] When the BET specific surface area and / or the total pore volume of the mesh 211 are within the above corresponding numerical ranges, the tensile strength of the mesh 211 may be approximately 2.5 MPa to 50 MPa.

[0071] The electronic conductivity of the mesh 211 may be equal to or greater than about 1×10 6 S / m or about 1×10 8 S / m. When the electronic conductivity of the mesh 211 is less than 1×10 6S / m, the electron conductivity of the positive electrode 20 may not be improved. The upper limit of the electron conductivity is not limited to a specific value.

[0072] The method of providing the starting material A to the web 211 is not limited to a specific method. For example, the starting material A may be put into a hopper and then may be dropped so as to be provided to at least one surface of the web 211.

[0073] The positive electrode 20 may be manufactured by operating a pair of rollers spaced about 0.1 mm to 0.5 mm from each other at a temperature of about 50° C. to 150° C. and at the same roller speed.

[0074] A portion of the starting material A may be disposed in the holes of the web 211, and the remaining starting material A may form a layer on at least one surface of the web 211 by the pair of rollers B and B'. This will be described later.

[0075] Shear stress may be applied to the starting material A through the pair of rollers B and B′, and in this process, the fibrous binder may also be fibrillated to increase the durability of the positive electrode 20 .

[0076] In contrast to the conventional dry method, by providing the web 211 , shear stress is uniformly applied to the starting material A by the pair of rollers B and B′, thereby preventing the formation of wrinkles on the surface of the positive electrode 20 or an increase in the surface roughness of the positive electrode 20 .

[0077] The positive electrode 20 manufactured by the above method may include a first layer 21 including a mesh 211 and a first active material 212 disposed in pores of the mesh 211 , and a second layer 22 located on at least one surface of the first layer 21 and including a second active material.

[0078] The first active material 212 and the second active material may be derived from the starting material A.

[0079] The first active material 212 may include a first positive active material, a first solid electrolyte, and a first binder.

[0080] The second active material may include a second positive electrode active material, a second solid electrolyte, and a second binder.

[0081] Each of the first positive active material and the second positive active material may include a rock-salt-layer-type active material, such as LiCoO 2 、LiMnO 2 、LiNiO 2 、LiVO 2 or Li 1+x Ni 1 / 3 Co1 / 3 Mn 1 / 3 O 2 ; Spinel-type active materials, such as LiMn 2 O 4 or Li(Ni 0.5 Mn 1.5 )O 4 ; Inverse-spinel-type active materials, such as LiNiVO 4 or LiCoVO 4 ; Olivine-type active materials, such as LiFePO 4 、LiMnPO 4 、LiCoPO 4 or LiNiPO 4 ; Rock-salt-layer-type active materials in which a part of the transition metals are replaced by different kinds of metals, such as LiNi 0.8 Co (0.2-x) Al x O 2 (0 < x < 0.2), spinel-type active materials in which a part of the transition metals are replaced by different kinds of metals, such as Li 1+x Mn 2-x-y M y O 4 (M is at least one of Al, Mg, Co, Fe, Ni or Zn, and 0 < x + y < 2); Lithium titanate, such as Li 4 Ti 5 O 12 etc.

[0082] Each of the first solid electrolyte and the second solid electrolyte may include an oxide-based solid electrolyte, a sulfide-based solid electrolyte, etc.

[0083] The oxide-based solid electrolyte may include perovskite-type LLTO (Li 3x La 2 / 3-x TiO 3 ), phosphate-based NASICON-type LATP (Li 1+x Al x Ti 2-x (PO 4 ) 3 ) etc.

[0084] The sulfide-based solid electrolyte may include Li 2 S-P 2 S 5 、Li 2 S-P 2 S 5 -LiI、Li2 SP 2 S 5 -LiCl, Li 2 SP 2 S 5 -LiBr, Li 2 SP 2 S 5 -Li 2 O. Li 2 SP 2 S 5 -Li 2 O-LiI、Li 2 S-SiS 2 , Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2 -LiCl, Li 2 S-SiS 2 -B 2 S 3 -LiI, Li 2 S-SiS 2 -P 2 S 5 -LiI, Li 2 SB 2 S 3 , Li 2 SP 2 S 5 -Z m S n (m and n are positive numbers, and Z is one of Ge, Zn and Ga), Li 2 S-GeS 2 , Li 2 S-SiS 2 -Li 3 PO 4 , Li 2 S-SiS 2 -Li x MO y (x and y are positive numbers and M is one of P, Si, Ge, B, Al, Ga and In), Li 10 G 2 S 12 wait.

[0085] The first binder and the second binder may include the above-mentioned fibrillated polytetrafluoroethylene (PTFE). Solid electrolyte layer

[0086] The solid electrolyte layer 30 may be interposed between the positive electrode 20 and the negative electrode 40 , and may include a solid electrolyte having lithium ion conductivity.

[0087] The solid electrolyte may include an oxide-based solid electrolyte, a sulfide-based solid electrolyte, or the like.

[0088] Oxide-based solid electrolytes may include perovskite-type LLTO (Li 3x La 2 / 3-x TiO 3 ), phosphate-based NASICON-type LATP (Li 1+x Al x Ti 2-x (PO 4 ) 3 )wait.

[0089] Sulfide-based solid electrolytes may include Li 2 SP 2 S 5 , Li 2 SP 2 S 5 -LiI, Li 2 SP 2 S 5 -LiCl, Li 2 SP 2 S 5 -LiBr, Li 2 SP 2 S 5 -Li 2 O. Li 2 SP 2 S 5 -Li 2 O-LiI、Li 2 S-SiS 2 , Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2 -LiCl, Li 2 S-SiS 2 -B 2 S 3 -LiI, Li 2 S-SiS 2 -P 2 S 5 -LiI, Li 2 SB 2 S 3 , Li2 S-P 2 S 5 -Z m S n (where m and n are positive numbers, and Z is one of Ge, Zn, and Ga), Li 2 S-GeS 2 、Li 2 S-SiS 2 -Li 3 PO 4 、Li 2 S-SiS 2 -Li x MO y (where x and y are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, and In), Li 10 GeP 2 S 12 etc. negative electrode

[0090] The negative electrode 40 according to an exemplary embodiment may be a composite negative electrode including a negative electrode active material and a solid electrolyte.

[0091] The negative electrode active material may include a carbon-based active material, a silicon-based active material, or a combination thereof. In particular, the negative electrode active material may include a combination of a carbon-based active material and a silicon-based active material, and may be formed, for example, by coating cores including a carbon-based active material with shells including a silicon-based active material.

[0092] The carbon-based active material may include natural graphite, artificial graphite, etc.

[0093] The silicon-based active material may include Si, SiO x (0 < x < 2), etc.

[0094] The average particle size D50 of the negative electrode active material may not be limited to a specific value, and may be, for example, about 8 μm to 10 μm.

[0095] The solid electrolyte may include an oxide-based solid electrolyte, a sulfide-based solid electrolyte, etc.

[0096] The oxide-based solid electrolyte may include perovskite-type LLTO (Li 3x La 2 / 3-x TiO 3 ), phosphate-based NASICON-type LATP (Li 1+x Al x Ti 2-x (PO 4 ) 3 ), etc.

[0097] Sulfide-based solid electrolytes may include Li 2 SP 2 S 5 , Li 2 SP 2 S 5 -LiI, Li 2 SP 2 S 5 -LiCl, Li 2 SP 2 S 5 -LiBr, Li 2 SP 2 S 5 -Li 2 O. Li 2 SP 2 S 5 -Li 2 O-LiI、Li 2 S-SiS 2 , Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2 -LiCl, Li 2 S-SiS 2 -B 2 S 3 -LiI, Li 2 S-SiS 2 -P 2 S 5 -LiI, Li 2 SB 2 S 3 , Li 2 SP 2 S 5 -Z m S n (m and n are positive numbers, and Z is one of Ge, Zn and Ga), Li 2 S-GeS 2 , Li 2 S-SiS 2 -Li 3 PO 4 , Li 2 S-SiS 2 -Li x MO y (x and y are positive numbers, and M is one of P, Si, Ge, B, Al, Ga and In), Li 10 G2 S 12 wait.

[0098] The negative electrode 40 according to the exemplary embodiment may include lithium metal or a lithium metal alloy.

[0099] The lithium metal alloy may include an alloy of lithium and a metal or metalloid capable of alloying with lithium. The metal or metalloid capable of alloying with lithium may include Si, Sn, Al, Ge, Pb, Bi, Sb, and the like.

[0100] The negative electrode 40 according to the exemplary embodiment may not include a negative electrode active material and a component having substantially the same function as the negative electrode active layer. When the all-solid-state battery is charged, lithium ions migrated from the positive electrode 20 may be deposited in the form of lithium metal and stored between the negative electrode 40 and the negative electrode current collector 50.

[0101] The negative electrode 40 may include amorphous carbon and a metal capable of alloying with lithium.

[0102] The amorphous carbon may include at least one selected from furnace black, acetylene black, Ketjen black, graphene, and combinations thereof.

[0103] The metal may include one or more selected from gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Negative current collector

[0104] The negative electrode current collector 50 may include a material that does not react with lithium. Specifically, the negative electrode current collector 50 may include at least one selected from nickel (Ni), copper (Cu), stainless steel, and a combination thereof.

[0105] The thickness of the negative electrode collector 50 is not limited to a specific value, and may be, for example, about 1 μm to 500 μm. Example

[0106] Hereinafter, the present invention will be described in more detail by the following examples. The following examples are only used to exemplarily describe the present invention and are not intended to limit the scope of the present invention. Example

[0107] The mixture is obtained by mixing a positive electrode active material, a sulfide-based solid electrolyte, and polytetrafluoroethylene (PTFE) in a particle state using a mixing device.

[0108] The polytetrafluoroethylene (PTFE) in a particle state was fibrillated by placing the mixture in a mortar and applying shear stress to the mixture with a pestle. Here, the shear stress was applied to the mixture at a temperature of about 120° C. for about 30 minutes.

[0109] By pulverizing the starting material in a clay state obtained by the above method, a starting material in a powder state is obtained.

[0110] By using Figure 3 The positive electrode is manufactured by film forming using the calendering device shown in . For example, a carbon nanotube sheet used as a mesh is provided to the gap between a pair of rollers spaced about 0.1 mm apart from each other, and rotated at the same speed at a temperature of about 80° C., and a starting material in a powder state is provided on both surfaces of the mesh. Thereafter, the positive electrode discharged from the pair of rollers is collected. Comparative Example

[0111] A positive electrode was manufactured using the same raw material in the same manner as in Example, except that no network was provided in the gap between the pair of rollers.

[0112] Figure 4 Field emission scanning electron microscope (FE-SEM) images are shown, which show the observation results of the positive electrode surface according to the comparative example. The left image shows the surface height difference depending on the position based on the line. The surface height difference is about 4 μm. The right image shows the surface height difference by color. Similarly, there is also a surface height difference.

[0113] Figure 5A and Figure 5B FE-SEM images are shown, which show that the Figure 4 Observation results of the positive electrode surface other than the portion shown in FIG. Wrinkles having a predetermined width of about 30 μm to 60 μm were repeatedly formed on the positive electrode surface.

[0114] Therefore, without the mesh according to the exemplary embodiment of the present invention, the surface of the positive electrode is wrinkled and the surface roughness of the positive electrode is increased. Test Example 1

[0115] The adhesive strength of the positive electrodes according to the examples and the comparative examples was evaluated. The adhesive strength was measured by the following method using a tensile strength tester (manufactured by DAESUNG precision Co., Ltd.).

[0116] Each positive electrode is adhered to a slide glass using double-sided tape. Each positive electrode is cut so that its width fits the width of the slide glass, but its length is greater than the length of the slide glass. A portion of the positive electrode adhered to the double-sided tape and another portion of the positive electrode not adhered to the double-sided tape are fixed to the load cell of the tensile strength tester respectively. The load value (load value) depending on the displacement (displacement) is measured by applying tensile strength to the positive electrode, and the stress value is calculated based on the load value. The stress value is called bonding strength.

[0117] Figure 6 The load-displacement curves of the positive electrodes according to the embodiments and the comparative examples are shown. Compared with the positive electrodes according to the comparative examples, the positive electrodes according to the embodiments have excellent bonding strength. The reason for this is that the positive electrodes according to the embodiments have excellent mechanical properties due to good film formation and have low surface roughness. Test Example 2

[0118] The positive electrodes according to the examples and comparative examples were subjected to a load test. The load test was performed by the following method using a 2 roll-type rolling mill (manufactured by Intech Systems).

[0119] In the film forming process using the web and the mixture in a powder state, the Δ gap (ΔGap) and the pressure automatically applied between two calendars in a load test device while forming the film were measured and recorded.

[0120] Figure 7 The results of the load test on the positive electrode according to the embodiment and the comparative example are shown. The positive electrode according to the embodiment has a low and uniform Δ gap compared with the positive electrode according to the comparative example. The reason is that the pressure applied to the load test device for testing the positive electrode according to the embodiment is less than the pressure applied to the load test device for testing the positive electrode according to the comparative example. These results mean that the positive electrode according to the embodiment has excellent mechanical properties due to good film formation and has low surface roughness. Test Example 3

[0121] The cell performance of the all-solid-state batteries including the positive electrodes according to the embodiments and comparative examples was evaluated. The charge capacity, retention capacity and coulombic efficiency of each all-solid-state battery were measured while charging and discharging each all-solid-state battery at a temperature of 30°C and 0.05C (CC-CV).

[0122] Figure 8 The charging capacity of the all-solid-state batteries including the positive electrodes according to the embodiment and the comparative example is shown. Fig. 9The retention capacities of all-solid-state batteries including the positive electrodes according to the examples and comparative examples are shown. Fig.10 The coulombic efficiency of the all-solid-state batteries including the positive electrodes according to the embodiment and the comparative example is shown.

[0123] Therefore, compared with the positive electrode according to the comparative example, the positive electrode according to the embodiment can also increase the charging capacity, retention capacity and coulombic efficiency of the all-solid-state battery. Test Example 4

[0124] The electron conductivity and lithium ion conductivity of the positive electrodes according to the examples and comparative examples were measured.

[0125] The electronic conductivity and lithium ion conductivity of the positive electrode were measured by applying an AC voltage of 10 mV to each positive electrode and then 6 The impedance value of the positive electrode was measured by performing a frequency sweep from 0.1 Hz to 100 Hz. The measurement results are listed in Table 1 below. Table 1

[0126] As shown in Table 1, the application of the mesh has no negative effect on the lithium ion conductivity of the positive electrode. In addition, the positive electrode according to the example exhibits significantly higher electronic conductivity than the positive electrode according to the comparative example.

[0127] As is apparent from the above description, according to various exemplary embodiments of the present invention, a positive electrode for an all-solid-state battery having no surface wrinkles and low surface roughness and a method of manufacturing the same may be provided.

[0128] The present invention has been described in detail with reference to the exemplary embodiments of the present invention. However, those skilled in the art will appreciate that these embodiments may be modified without departing from the principles and spirit of the present invention, and the scope of the present invention will be defined in the appended claims and their equivalents.

Claims

1. A positive electrode for an all-solid-state battery, include: a first layer comprising a plurality of fibrous carbon materials and a first active material; and a second layer, the second layer being located on at least one surface of the first layer and comprising a second active material, and The plurality of fibrous carbon materials form a network including pores, and the first active material is disposed in the pores of the network. 2 . The positive electrode according to claim 1 , wherein the fibrous carbon material comprises carbon nanotubes, vapor-grown carbon fibers, carbon nanofibers, or a combination thereof. 3 . The cathode according to claim 1 , wherein the mesh has a thickness of about 5 μm to 40 μm.

4. The positive electrode according to claim 1, wherein the BET specific surface area of ​​the network is about 100 m 2 / g to 750m 2 / g.

5. The positive electrode of claim 1, wherein the total pore volume of the network is about 0.5 cm 3 / g to 5cm 3 / g. The cathode of claim 1 , wherein the mesh has a tensile strength of about 2.5 MPa to 50 MPa.

7. The positive electrode according to claim 1, wherein the electronic conductivity of the network is equal to or greater than about 1×10 8 S / m.

8. The positive electrode according to claim 1, in: The first active material includes a first positive electrode active material, a first solid electrolyte and a first binder; and The second active material includes a second positive electrode active material, a second solid electrolyte, and a second binder. 9 . The cathode of claim 8 , wherein the first binder comprises fibrillated polytetrafluoroethylene (PTFE). 10 . The cathode of claim 8 , wherein the second binder comprises fibrillated polytetrafluoroethylene (PTFE).

11. A method for manufacturing a positive electrode for an all-solid-state battery, wherein include: preparing a starting material comprising a positive electrode active material, a solid electrolyte and a fibrous binder; supplying a plurality of fibrous carbon materials to a gap between a pair of rollers rotating in opposite directions, and providing the starting material to the plurality of fibrous carbon materials; and The positive electrode is obtained by performing film formation using the pair of rollers, The positive electrode comprises: a first layer comprising the plurality of fibrous carbon materials and a first active material, wherein the plurality of fibrous carbon materials form a mesh including pores, and the first active material is disposed in the pores of the mesh; and The second layer is located on at least one surface of the first layer and includes a second active material.

12. The method according to claim 11, wherein the starting material is prepared include: preparing a mixture comprising the positive electrode active material, the solid electrolyte and a particle binder; and The particulate binder is fibrillated into the fibrous binder by applying shear stress to the mixture.

13. The method of claim 11, wherein the fibrous binder comprises fibrillated polytetrafluoroethylene (PTFE).

14. The method of claim 11, wherein the fibrous carbon material comprises carbon nanotubes, vapor-grown carbon fibers, carbon nanofibers, or a combination thereof.

15. The method of claim 11, wherein the mesh has a thickness of about 5 μm to 40 μm.

16. The method of claim 11, wherein the mesh has a BET specific surface area of ​​about 100 m 2 / g to 750m 2 / g.

17. The method of claim 11, wherein the total pore volume of the web is about 0.5 cm 3 / g to 5cm 3 / g.

18. The method of claim 11, wherein the web has a tensile strength of about 2.5 MPa to 50 MPa.

19. The method of claim 11, wherein the electronic conductivity of the mesh is equal to or greater than about 1×10 8 S / m.

20. An all-solid-state battery comprising the positive electrode according to claim 1.

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