Cathode for all-solid-state battery and all-solid-state battery including the same

Abstract

The present invention relates to a positive electrode for an all-solid-state battery, the positive electrode comprising a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a binder, the sulfide-based solid electrolyte comprising a first sulfide-based solid electrolyte containing a bromine (Br) element and a second sulfide-based solid electrolyte not containing the bromine (Br) element, the positive electrode active material comprising a core capable of reversibly absorbing and releasing lithium ions; and a coating layer formed on a surface of the core, the coating layer comprising the first sulfide-based solid electrolyte, and the all-solid-state battery comprising the positive electrode.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0146682 filed on November 7, 2022, and includes all the contents disclosed in the document of the Korean Patent Application as part of this specification.

[0002] The present invention relates to a positive electrode for an all-solid-state battery and an all-solid-state battery including the same.

Background Art

[0003] Lithium secondary batteries have mainly been applied to small fields such as mobile devices and notebook computers. Recently, however, the research direction has been expanding to medium and large fields such as energy storage systems (ESS) and electric vehicles (EV).

[0004] In the case of such medium and large lithium secondary batteries, unlike small ones, not only is the operating environment (e.g., temperature, shock) severe, but more batteries have to be used. Therefore, it is necessary to ensure safety along with excellent performance and an appropriate price.

[0005] Most of the currently commercially available lithium secondary batteries use an organic liquid electrolyte in which a lithium salt is dissolved in a flammable organic solvent, and thus have potential risks such as leakage, ignition, and explosion. Accordingly, using a solid electrolyte instead of the organic liquid electrolyte has been attracting attention as an alternative to overcome the safety problem.

[0006] An all-solid-state battery is composed of a positive electrode, a solid electrolyte, and a negative electrode. As the solid electrolyte of the all-solid-state battery, sulfides, oxides, etc. can be used, but sulfide-based solid electrolytes are the most promising materials from the viewpoint of lithium ion conductivity.

[0007] By the way, when using a sulfide-based solid electrolyte, due to the reaction between cobalt and sulfur, generally, a cathode active material coated with cobalt (Co) is not used for the cathode.

[0008] In addition, during the charge and discharge cycles of all-solid-state batteries, reactions occur at the interface between the cathode active material and the sulfide-based solid electrolyte, and component diffusion such as Co, P, and S occurs from the interface, resulting in deterioration of the life characteristics. Therefore, improvement is necessary.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] An object of the present invention is to provide a cathode for an all-solid-state battery that includes both a sulfide-based solid electrolyte containing bromine (Br) element and a sulfide-based solid electrolyte not containing bromine element, and by applying the sulfide-based solid electrolyte containing bromine element to the coating layer of the cathode active material, an all-solid-state battery cathode with improved ionic conductivity and interface characteristics between the active material and the solid electrolyte is provided.

[0011] Another object of the present invention is to provide an all-solid-state battery with improved electrochemical characteristics and life characteristics by applying the cathode for an all-solid-state battery.

Means for Solving the Problems

[0012] One embodiment of the present invention is a positive electrode for an all-solid-state battery including a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a binder, wherein the sulfide-based solid electrolyte includes a first sulfide-based solid electrolyte containing a bromine (Br) element and a second sulfide-based solid electrolyte not containing a bromine (Br) element, the positive electrode active material includes a core capable of reversibly occluding and releasing lithium ions; and a coating layer formed on the surface of the core, and the coating layer includes the first sulfide-based solid electrolyte, and provides a positive electrode for an all-solid-state battery.

[0013] The first sulfide-based solid electrolyte is represented by the following Chemical Formula 1.

[0014] [Chemical Formula 1] Li a M 1 b S c X 1 d Br e

[0015] In Chemical Formula 1, M 1 is Sn, Mg, Ba, B, Al, Ga, In, In, Si, Ge, Pb, N, P, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W, or La, and X 1 is F, Cl, Br, I, Se, Te, or O, and 0 < a ≤ 6, 0 < b ≤ 6, 0 < c ≤ 6, 0 ≤ d ≤ 6, and 0 < e ≤ 6.

[0016] The second sulfide-based solid electrolyte is represented by the following Chemical Formula 2.

[0017] [Chemical Formula 2] Li k M 2 l S m X 2 n

[0018] In Formula 2, M 2is Sn, Mg, Ba, B, Al, Ga, In, In, Si, Ge, Pb, N, P, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W, or La, and X 2 is F, Cl, I, Se, Te, or O, where 0 < k ≦ 6, 0 < l ≦ 6, 0 < m ≦ 6, and 0 ≦ n ≦ 6.

[0019] The sulfide-based solid electrolyte may have an argyrodite-type crystal structure.

[0020] The first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte can be contained in a weight ratio of 95:5 to 5:95.

[0021] The positive electrode active material can be contained in an amount of 50 to 95 parts by weight based on 100 parts by weight of the entire positive electrode.

[0022] The sulfide-based solid electrolyte can be contained in an amount of 5 to 49 parts by weight based on 100 parts by weight of the entire positive electrode.

[0023] The positive electrode active material may be coated with 1 to 20 parts by weight of the first sulfide-based solid electrolyte based on 100 parts by weight of the entire positive electrode active material including the core and the coating layer.

[0024] The average particle size of the first sulfide-based solid electrolyte is 0.1 to 5 μm.

[0025] The average particle size of the second sulfide-based solid electrolyte is 0.1 to 5 μm.

[0026] Another embodiment of the present invention provides a all-solid-state battery including a positive electrode; a negative electrode; and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein the positive electrode includes the positive electrode for the all-solid-state battery.

Advantages of the Invention

[0027] According to the present invention, the positive electrode for all-solid-state battery contains a positive electrode active material and a sulfide-based solid electrolyte. The sulfide-based solid electrolyte simultaneously contains a first sulfide-based solid electrolyte containing bromine (Br) element and a second sulfide-based solid electrolyte not containing bromine element. By applying the first sulfide-based solid electrolyte to the coating layer of the positive electrode active material, it is possible to maintain flexible deformation characteristics with respect to the pressing process during the manufacture of the all-solid-state battery. As a result of the increased contact area between the positive electrode active material and the solid electrolyte, excellent interfacial characteristics can be exhibited. Further, by including the second sulfide-based solid electrolyte not containing bromine element together in the positive electrode for all-solid-state battery, the dispersibility of the positive electrode is enhanced, and as a result of the improved resistance of the electrode, the ion conductivity of the all-solid-state battery can be improved.

Brief Description of Drawings

[0028]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Best Mode for Carrying Out the Invention

[0029] Hereinafter, embodiments of the present invention will be described in detail. Prior to this, the terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. Based on the principle that the inventor can appropriately define the concept of terms in order to explain his invention in the best way, they must be construed in meanings and concepts consistent with the technical idea of the present invention. Therefore, the configurations described in the embodiments described in this specification are merely the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. At the time of filing this application, it should be understood that there are various equivalents and modifications that can replace these.

[0030] Throughout this specification, when a certain part states that a certain component "includes", this means that, unless otherwise stated to the contrary, it does not exclude other components, but can further include other components.

[0031] Throughout this specification, the average particle size of the particles may be, for example, the median diameter (D50) measured using a laser particle size distribution analyzer.

[0032] Hereinafter, a positive electrode for an all-solid-state battery according to an embodiment of the present invention will be described.

[0033] The present invention relates to an all-solid-state battery positive electrode that improves the ionic conductivity of an all-solid-state battery and has improved interfacial characteristics between a positive electrode active material and a solid electrolyte in the positive electrode for an all-solid-state battery.

[0034] Normally, in the case of an all-solid-state battery, unlike a general lithium secondary battery, since a liquid electrolyte is not used, in addition to the solid electrolyte layer, the positive electrode active material layer also contains a solid electrolyte.

[0035] At this time, in order to ensure stable ionic conductivity, it is important for the positive electrode active material and the solid electrolyte contained in the positive electrode active material layer to effectively contact each other to form a high effective contact area, which acts as a crucial factor for improving the charge-discharge capacity and efficiency of all-solid-state batteries. In order to improve the effective contact area between the positive electrode active material and the solid electrolyte in this way, a pressure of about 500 Mpa or more is applied during the manufacturing process of all-solid-state batteries. In order to solve the problems caused by the pressurization process, attempts have been made to introduce a coating layer of solid electrolyte on the positive electrode active material to improve it.

[0036] However, when a coating layer is introduced into the positive electrode active material as described above, although the effective contact area between the positive electrode active material and the solid electrolyte increases and the resistance of the electrode decreases, the contact between the solid electrolyte formed by the coating layer of the positive electrode active material and the solid electrolyte existing in the positive electrode active material layer that is not formed by the coating layer decreases, and there is a possibility that the ionic conductivity of the battery decreases. In addition, when the positive electrode is manufactured by coating all the positive electrode active material with a solid electrolyte, voids are generated in the positive electrode active material layer, so there is also a possibility that the ionic conductivity and charge-discharge efficiency of the battery will finally decrease.

[0037] In contrast, in order to solve the above problems, the positive electrode for all-solid-state batteries of the present invention includes a positive electrode and a sulfide-based solid electrolyte. The sulfide-based solid electrolyte includes both 1) a first sulfide-based solid electrolyte containing bromine (Br) element and 2) a second sulfide-based solid electrolyte not containing bromine element. By including the first sulfide-based solid electrolyte in the coating layer of the positive electrode active material, it is possible to maintain flexible deformation characteristics with respect to the pressurization process during the manufacture of all-solid-state batteries. As a result of the increased contact area between the positive electrode active material and the solid electrolyte, excellent interfacial characteristics are shown, the dispersibility of the positive electrode is enhanced, the resistance of the electrode is improved, and it is confirmed that the ionic conductivity and charge-discharge capacity can be improved, thus completing the present invention.

[0038] Figures 1 and 2 show SEM images of the cross-section of the positive electrode for all-solid-state batteries according to an embodiment of the present invention.

[0039] Referring to FIGS. 1 and 2, a positive electrode for an all-solid-state battery according to an embodiment of the present invention is a positive electrode for an all-solid-state battery including a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a binder. The sulfide-based solid electrolyte includes a first sulfide-based solid electrolyte containing bromine (Br) element and a second sulfide-based solid electrolyte not containing bromine (Br) element. The positive electrode active material includes a core capable of reversibly occluding and releasing lithium ions; and a coating layer formed on the surface of the core, and the coating layer includes the first sulfide-based solid electrolyte.

[0040] The positive electrode for the all-solid-state battery simultaneously includes a first sulfide-based solid electrolyte containing bromine (Br) element and a second sulfide-based solid electrolyte not containing bromine element. By applying the first sulfide-based solid electrolyte to the coating layer of the positive electrode active material, it is possible to maintain flexible deformation characteristics with respect to the pressing process during the manufacture of the all-solid-state battery. As a result of the increased contact area between the positive electrode active material and the solid electrolyte, excellent interfacial characteristics can be exhibited. Further, by including the second sulfide-based solid electrolyte not containing bromine element in the positive electrode for the all-solid-state battery together, the dispersibility of the positive electrode is increased, and as a result of the improved resistance of the electrode, the ion conductivity of the all-solid-state battery can be improved.

[0041] Although not limited to a specific theory, since the first sulfide-based solid electrolyte contained in the positive electrode active material coating layer contains bromine element, a specific crystal structure will be formed, and thereby, it can be understood that the effect of suppressing side reactions at the interface between the positive electrode active material and the solid electrolyte is shown. Therefore, when the sulfide-based solid electrolyte essentially containing the bromine is coated on the surface of the positive electrode active material and applied to the positive electrode, the interfacial resistance between the positive electrode active material and the solid electrolyte can be reduced, and the effect of increasing the ion conductivity can be shown.

[0042] In addition, the positive electrode for all-solid-state battery according to the present invention includes, in addition to the first sulfide-based solid electrolyte containing bromine, a second sulfide-based solid electrolyte not containing bromine. Since the second sulfide-based solid electrolyte can exhibit excellent ductility against external pressure, the contact force between solid electrolytes can be maintained even for an increase in internal pressure generated during the pressing process in the manufacturing process of the all-solid-state battery or during the driving process of the all-solid-state battery, so that the ionic conductivity of the all-solid-state battery can be improved.

[0043] In one embodiment of the present invention, the first sulfide-based solid electrolyte may be represented by the following Chemical Formula 1.

[0044] [Chemical Formula 1] Li a M 1 b S c X 1 d Br e

[0045] In Formula 1 above, M 1 is Sn, Mg, Ba, B, Al, Ga, In, In, Si, Ge, Pb, N, P, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W or La, and X 1 is F, Cl, Br, I, Se, Te, or O, and 0 < a ≤ 6, 0 < b ≤ 6, 0 < c ≤ 6, 0 ≤ d ≤ 6 and 0 < e ≤ 6.

[0046] For example, in Chemical Formula 1 above, M 1 may be B, Si, Ge, P or N.

[0047] <l For example, in Chemical Formula 1 above, X 1 may be F, Cl, Br, I or O.

[0048] For example, the first sulfide-based solid electrolyte represented by the chemical formula 1 may be Li2S-P2S5-LiBr, Li2S-P2S5-LiCl-LiBr, Li2S-SiS2-LiBr, or a combination thereof.

[0049] In one embodiment of the present invention, the second sulfide-based solid electrolyte may be represented by the following chemical formula 2.

[0050] [Chemical formula 2] Li k M 2 l S m X 2 n

[0051] In the formula 2, M 2 is Sn, Mg, Ba, B, Al, Ga, In, In, Si, Ge, Pb, N, P, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W, or La, and X 2 is F, Cl, I, Se, Te, or O, and 0 < k ≦ 6, 0 < l ≦ 6, 0 < m ≦ 6, and 0 ≦ n ≦ 6.

[0052] For example, in the chemical formula 2, M 2 may be B, Si, Ge, P, or N.

[0053] For example, in the chemical formula 2, X 2 may be F, Cl, I, or O.

[0054] For example, the second sulfide-based solid electrolyte represented by the chemical formula 2 may be Li2S-P2S5, Li2S-P2S5-LiCl, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-GeS2, Li2S-SiS2-Li3PO4, or a combination thereof.

[0055] In one embodiment of the present invention, the sulfide-based solid electrolyte, that is, the first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte, may have an argyrodite-type crystal structure.

[0056] Since the sulfide-based solid electrolyte has an argyrodite-type crystal structure, the purity and crystallinity of the sulfide-based solid electrolyte are high, a stable interfacial phase is formed, and the potential stability and ionic conductivity can be significantly improved while having a high energy density.

[0057] In one embodiment of the present invention, the first sulfide-based solid electrolyte may be contained in an amount of 5 to 25 parts by weight based on 100 parts by weight of the total of the first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte. For example, the first sulfide-based solid electrolyte may be 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, 9 parts by weight or more, or 10 parts by weight or more, and 25 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, 14 parts by weight or less, 13 parts by weight or less, 12 parts by weight or less, or 11 parts by weight or less based on 100 parts by weight of the total of the first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte. Preferably, the first sulfide-based solid electrolyte can be contained in an amount of 7 to 10 parts by weight based on 100 parts by weight of the total of the first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte.

[0058] In the positive electrode for all-solid-state battery according to the present invention, when the content range of the first sulfide-based solid electrolyte is less than 5 parts by weight based on 100 parts by weight in total of the first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte contained in the positive electrode for all-solid-state battery, the content of the first sulfide-based solid electrolyte contained in the positive electrode active material coating layer decreases, resulting in a decrease in the inhibitory effect of side reactions at the interface between the positive electrode active material and the solid electrolyte, an increase in the interfacial resistance between the positive electrode active material and the solid electrolyte, and a possibility of a decrease in the ionic conductivity of the all-solid-state battery. When the content range of the first sulfide-based solid electrolyte exceeds 25 parts by weight based on 100 parts by weight in total of the first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte contained in the positive electrode for all-solid-state battery, the thickness of the coating layer containing the first sulfide-based solid electrolyte increases excessively, and as a result, the positive electrode active material is isolated in the first sulfide-based solid electrolyte which is a constituent component of the coating layer, causing a problem of an increase in the resistance of the electrode.

[0059] In the positive electrode for all-solid-state battery according to the present invention, when the content range of the second sulfide-based solid electrolyte is less than 75 parts by weight based on 100 parts by weight in total of the first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte contained in the positive electrode for all-solid-state battery, there is a problem that voids are generated in the positive electrode active material layer and the ionic conductivity of the electrode decreases. When it exceeds 95 parts by weight, the problem in the case where the content of the first sulfide-based solid electrolyte is less than 5 parts by weight can be reversed.

[0060] Therefore, in order to improve the ionic conductivity and potential stability of the positive electrode for all-solid-state battery according to the present invention and stably ensure the charge-discharge capacity and life characteristics of the all-solid-state battery including the same, it is preferable to adjust the contents of the first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte within the above ranges.

[0061] In one embodiment of the present invention, the positive electrode active material can be contained in an amount of 50 to 95 parts by weight based on 100 parts by weight of the entire positive electrode. For example, the content of the positive electrode active material may be 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 75 parts by weight or more, or 80 parts by weight or more based on 100 parts by weight of the entire positive electrode, and may be 95 parts by weight or less, 90 parts by weight or less, or 85 parts by weight or less.

[0062] When the content of the positive electrode active material is less than 50 parts by weight based on 100 parts by weight of the entire positive electrode, there is a problem that the capacity and the overall energy density of the electrode decrease. When it exceeds 95 parts by weight, there are many voids in the positive electrode active material layer, and there is a problem that the interfacial resistance between the positive electrode active material and the solid electrolyte increases. Therefore, in the case of the positive electrode for an all-solid-state battery according to the present invention, it is necessary to appropriately adjust the content of the positive electrode active material within the above range.

[0063] In one embodiment of the present invention, the sulfide-based solid electrolyte can be contained in an amount of 5 to 49 parts by weight based on 100 parts by weight of the entire positive electrode. The content of the sulfide-based solid electrolyte means the total content of the first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte contained in the positive electrode. For example, based on 100 parts by weight of the entire positive electrode, it can be 5 parts by weight or more, 6 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, 9 parts by weight or more, 10 parts by weight or more, 11 parts by weight or more, 12 parts by weight or more, 13 parts by weight or more, 14 parts by weight or more, or 15 parts by weight or more, and can be 49 parts by weight or less, 45 parts by weight or less, 40 parts by weight or less, 35 parts by weight or less, 30 parts by weight or less, 25 parts by weight or less, 24 parts by weight or less, 23 parts by weight or less, 22 parts by weight or less, 21 parts by weight or less, or 20 parts by weight or less. Preferably, the content of the sulfide-based solid electrolyte can be contained in an amount of 12 to 20 parts by weight based on 100 parts by weight of the entire positive electrode.

[0064] When the content of the sulfide-based solid electrolyte is less than 5 parts by weight based on 100 parts by weight of the entire cathode, there are problems such as an increase in voids in the cathode active material layer, an increase in the interfacial resistance between the cathode active material and the solid electrolyte, and a decrease in the capacity and overall energy density of the electrode. When it exceeds 49 parts by weight, there is a problem of a decrease in the capacity and overall energy density of the electrode. Therefore, in the case of the cathode for an all-solid-state battery according to the present invention, it is necessary to appropriately adjust the total content of the sulfide-based solid electrolyte, that is, the first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte, within the above range.

[0065] In one embodiment of the present invention, the cathode active material may be coated with 1 to 20 parts by weight of the first sulfide-based solid electrolyte based on 100 parts by weight of the entire cathode active material including the core and the coating layer. For example, it may be coated with 1 part by weight or more, 2 parts by weight or more, or 3 parts by weight or more based on 100 parts by weight of the entire cathode active material including the core and the coating layer, and may be coated with 20 parts by weight or less, 15 parts by weight or less, 10 parts by weight or less, 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, 6 parts by weight or less, or 5 parts by weight or less.

[0066] In one embodiment of the present invention, the average particle size of the first sulfide-based solid electrolyte may be 0.1 to 5 μm. For example, the average particle size of the first sulfide-based solid electrolyte may be 0.1 to 3 μm, 0.1 to 2 μm, 0.1 to 1 μm, 0.1 to 0.9 μm, 0.1 to 0.8 μm, 0.1 to 0.7 μm, 0.1 to 0.6 μm, or 0.1 to 0.5 μm.

[0067] When the average particle size of the first sulfide-based solid electrolyte is less than 0.1 μm, there is a problem that the first sulfide-based solid electrolyte particles are easily scattered and the formation of the coating layer does not proceed smoothly. When it exceeds 5 μm, there is a problem that the thickness of the coating layer excessively increases and the coating layer is not formed uniformly. Therefore, it is preferable to appropriately adjust the first sulfide-based solid electrolyte of the cathode for an all-solid-state battery according to the present invention to have an average particle size within the same range as described above.

[0068] In one embodiment of the present invention, the average particle size of the second sulfide-based solid electrolyte may be 0.1 to 5 μm. For example, the average particle size of the second sulfide-based solid electrolyte may be 0.1 to 3 μm, 0.1 to 2 μm, 0.1 to 1 μm, 0.1 to 0.9 μm, 0.1 to 0.8 μm, or 0.2 to 0.8 μm.

[0069] When the average particle size of the second sulfide-based solid electrolyte is less than 0.1 μm, the second sulfide-based solid electrolyte particles may easily aggregate, may not be uniformly dispersed, and may be concentrated in the electrode, making it difficult to form an effective interface between the positive electrode active material and the second sulfide-based solid electrolyte. When it exceeds 5 μm, voids may occur in the positive electrode active material layer, which may cause a problem of a decrease in the ionic conductivity of the electrode. Therefore, it is desirable to appropriately adjust the second sulfide-based solid electrolyte of the positive electrode for all-solid-state batteries according to the present invention so that it has an average particle size within the same range as described above.

[0070] In one embodiment of the present invention, the thickness of the coating layer formed on the surface of the positive electrode active material may be 0.05 to 0.2 μm. For example, the thickness of the coating layer may be 0.05 μm or more, 0.06 μm or more, 0.07 μm or more, 0.09 μm or more, or 0.1 μm or more, and may be 0.2 μm or less, 0.18 μm or less, 0.16 μm or less, or 0.15 μm or less.

[0071] When the thickness of the coating layer is less than 0.05 μm, the content of the first sulfide-based solid electrolyte that can be included in the positive electrode active material coating layer decreases, the effect of suppressing side reactions at the interface between the positive electrode active material and the solid electrolyte decreases, the interfacial resistance between the positive electrode active material and the solid electrolyte increases, and the ionic conductivity of the all-solid-state battery may decrease. When the thickness of the coating layer exceeds 0.2 μm, the positive electrode active material is isolated by the first sulfide-based solid electrolyte that is a constituent component of the coating layer, resulting in a problem of an increase in the resistance of the electrode.

[0072] In one embodiment of the present invention, the positive electrode for all-solid-state batteries may further include a conductive material and a binder.

[0073] The conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery. For example, graphite such as natural graphite and artificial graphite; carbon black such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc.; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, nickel powder, etc.; conductive whiskers such as zinc oxide, potassium titanate, etc.; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives, etc. can be used. The conductive material can be contained in an amount of about 0.01 to 10 parts by weight, or 0.01 to 5 parts by weight, or 0.01 to 3 parts by weight based on 100 parts by weight of the entire positive electrode.

[0074] The binder is a component added in consideration of the adhesion of the positive electrode active material, sulfide-based solid electrolyte, and conductive material to the positive electrode for the all-solid-state battery, and any polymer binder known to be usable for electrode formation in the technical field to which the present invention belongs can be used without particular limitation.

[0075] Examples of such polymer binders include acrylic binders, polyvinylidene fluoride (PVDF) binders, polytetrafluoroethylene (PTFE) binders, or butadiene rubber binders such as nitrile butadiene rubber (NBR), etc., and of course, various other polymer binders can also be used. The binder can be contained in an amount of about 0.01 to 10 parts by weight, or 0.01 to 5 parts by weight, or 0.01 to 3 parts by weight based on 100 parts by weight of the entire positive electrode.

[0076] The positive electrode for an all-solid-state battery according to an embodiment of the present invention can include a current collector and a positive electrode active material layer formed on at least one side surface of the current collector, and the positive electrode active material layer can include the positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a binder.

[0077] The positive electrode can be manufactured according to methods widely known in the art and is not limited to a specific manufacturing method. For example, the positive electrode active material, sulfide-based solid electrolyte, conductive material, binder, etc. can be mixed in a solvent to be manufactured as a slurry-like positive electrode mixture, and this positive electrode mixture can be applied to a positive electrode current collector for manufacturing.

[0078] On the other hand, in the case of the positive electrode active material, it is not particularly limited as long as it is a lithium composite oxide material capable of reversible insertion and extraction of lithium ions. For example, it may contain one or more of composite oxides of metals such as cobalt, manganese, nickel, iron, or combinations thereof; and lithium.

[0079] As a more specific example, as the positive electrode active material, a compound represented by any of the following chemical formulas can be used. Li a A 1-b R b D2 (in the above formula, 0.90 ≦ a ≦ 1.8 and 0 ≦ b ≦ 0.5); Li a E 1-b R b O 2-c D c (in the above formula, 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, and 0 ≦ c ≦ 0.05); LiE 2-b R b O 4-c D c (in the above formula, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05); Li a Ni 1-b-c Co b R c D α (in the above formula, 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05, 0 < α ≦ 2); Li a Ni 1-b-c Co b R c O 2-α Z α (in the above formula, 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05 and 0 < α < 2); Li a Ni 1-b-c Co b Rc O 2-α Z2 (in the formula, 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05 and 0 < α < 2); Li a Ni 1-b-c Mn b R c D α (in the formula, 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05 and 0 < α ≦ 2); Li a Ni 1-b-c Mn b R c O 2-α Z2 (in the formula, 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05 and 0 < α < 2); Li a Ni 1-b-c [[ID=*27]]Mn b R c O 2-α Z2 (in the formula, 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.5, 0 ≦ c ≦ 0.05 and 0 < α < 2); Li a Ni b E c G d O2 (in the formula, 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.5 and 0.001 ≦ d ≦ 0.1); Li a Ni b Co c Mn d G e O2 (in the formula, 0.90 ≦ a ≦ 1.8, 0 ≦ b ≦ 0.9, 0 ≦ c ≦ 0.5, 0 ≦ d ≦ 0.5 and 0 ≦ e ≦ 0.1); Li a NiG b O2 (in the formula, 0.90 ≦ a ≦ 1.8 and 0.001 ≦ b ≦ 0.1); Li a CoG b O2 (in the formula, 0.90 ≦ a ≦ 1.8 and 0.001 ≦ b ≦ 0.1); Li a MnG b O2 (in the formula, 0.90 ≦ a ≦ 1.8 and 0.001 ≦ b ≦ 0.1); Li a Mn2G b It should be noted that there may be some inaccuracies in the translation due to the lack of clear context for some symbols and abbreviations. If possible, it is recommended to provide more detailed information for a more accurate translation. Also, the '*' in line 27 is just for highlighting the possible error in the original text, which seems to be a duplicate of line 7.O4 (in the above formula, 0.90 ≦ a ≦ 1.8 and 0.001 ≦ b ≦ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiTO2; LiNiVO4; Li (3-f) J2(PO4)3 (0 ≦ f ≦ 2); Li (3-f) Fe2(PO4)3 (0 ≦ f ≦ 2); and LiFePO4.

[0080] In the above chemical formula, A is Ni, Co, Mn, or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Fe, Mg, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; Z is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; T is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0081] Regarding the sulfide-based solid electrolyte, since it is the same as the content described above, hereinafter, the sulfide-based solid electrolyte included in the positive electrode for all-solid-state batteries according to the present invention will be omitted from detailed description in this specification.

[0082] The positive electrode current collector generally has a thickness of 3 to 500 μm. Such a positive electrode current collector is not particularly limited as long as it does not cause a chemical change in the battery and has high conductivity. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or those obtained by surface treatment of the surface of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. can be used. The current collector can also form fine irregularities on its surface to enhance the adhesive force of the positive electrode active material, and various forms such as films, sheets, foils, nets, porous bodies, foams, non-woven fabrics, etc. are possible.

[0083] In addition to the positive electrode active material, sulfide-based solid electrolyte, conductive material, and binder, the positive electrode can further contain additives such as, for example, a filler, coating agent, dispersant, and ionic conductivity auxiliary agent. As the filler, coating agent, dispersant, ionic conductivity auxiliary agent, etc., known materials generally used for electrodes of all-solid-state secondary batteries can be used.

[0084] The thickness of the positive electrode may be, for example, 70 to 150 μm.

[0085] Another embodiment of the present invention provides an all-solid-state battery including a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive electrode and the negative electrode at all times, wherein the positive electrode is the positive electrode for the all-solid-state battery.

[0086] Regarding the positive electrode included in the all-solid-state battery, since it is as described above, hereinafter, the negative electrode and solid electrolyte included in the all-solid-state battery will be described in detail.

[0087] The solid electrolyte layer disposed between the positive electrode and the negative electrode can include, for example, a sulfide-based solid electrolyte. The sulfide-based solid electrolyte may be the same as or different from the sulfide-based solid electrolyte included in the positive electrode.

[0088] For specific details regarding the sulfide-based solid electrolyte, refer to the aforementioned positive electrode part.

[0089] The elastic modulus of the solid electrolyte, that is, Young's modulus, is, for example, 35 GPa or less, 30 GPa or less, 27 GPa or less, 25 GPa or less, 23 GPa or less. The elastic modulus of the solid electrolyte, that is, Young's modulus, is, for example, 10 to 35 GPa, 15 to 35 GPa, 15 to 30 GPa, or 15 to 25 GPa. When the solid electrolyte has an elastic modulus within this range, the pressurization and / or sintering of the solid electrolyte can be performed more easily.

[0090] The solid electrolyte layer further contains, for example, a binder. The binder contained in the solid electrolyte layer is, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited thereto, and any material that can be used as a binder in the relevant technical field is possible. The binder in the solid electrolyte layer may be the same as or different from the binders in the positive electrode active material layer and the negative electrode active material layer.

[0091] Next, the negative electrode of the all-solid-state battery can include a negative electrode current collector and a negative electrode active material layer.

[0092] The thickness of the negative electrode active material layer is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer. The thickness of the negative electrode active material layer is, for example, 1 μm to 20 μm, 2 μm to 10 μm, or 3 μm to 7 μm. If the thickness of the negative electrode active material layer is too thin, the lithium dendrite formed between the negative electrode active material layer and the negative electrode current collector will disintegrate the negative electrode active material layer, and it is difficult to improve the cycle characteristics of the all-solid-state battery. If the thickness of the negative electrode active material layer increases excessively, the energy density of the all-solid-state battery will decrease, the internal resistance of the all-solid-state battery due to the negative electrode active material layer will increase, and it is difficult to improve the cycle characteristics of the all-solid-state battery.

[0093] The negative electrode active material layer contains, for example, a negative electrode active material that forms an alloy or a compound with lithium.

[0094] The negative electrode active material included in the negative electrode active material layer has, for example, a particulate shape. The average particle diameter of the negative electrode active material having a particulate form is, for example, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, or 900 nm or less. The average particle diameter of the negative electrode active material having a particulate form is, for example, from 10 nm to 4 μm or less, from 10 nm to 3 μm or less, from 10 nm to 2 μm or less, from 10 nm to 1 μm or less, or from 10 nm to 900 nm or less. By having an average particle diameter within this range, the reversible absorption (absorbing) and / or desorption (desorbing) of lithium during charge and discharge becomes easier. The average particle diameter of the negative electrode active material is, for example, the volume-converted median diameter (D50) measured using a laser particle size distribution analyzer.

[0095] The negative electrode active material included in the negative electrode active material layer includes, for example, one or more selected from carbon-based negative electrode active materials and metal or semi-metal negative electrode active materials.

[0096] The carbon-based negative electrode active material is particularly amorphous carbon. The amorphous carbon is, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, etc., but is not necessarily limited thereto, and any material classified as amorphous carbon in the technical field is possible. Amorphous carbon is carbon that has no crystallinity or very low crystallinity and is distinguished from crystalline carbon or graphite-based carbon.

[0097] The metal or semi-metal negative electrode active material includes one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), but is not necessarily limited thereto, and any material can be used as long as it is a metal negative electrode active material or semi-metal negative electrode active material that forms an alloy or compound with lithium in the relevant technical field. For example, nickel (Ni) does not form an alloy with lithium, so it is not a metal negative electrode active material.

[0098] The negative electrode active material layer contains a certain negative electrode active material among these negative electrode active materials, or a mixture of a plurality of different negative electrode active materials. For example, the negative electrode active material layer contains only amorphous carbon, or contains one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). In another aspect, the negative electrode active material layer contains a mixture of amorphous carbon and one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio of the mixture such as amorphous carbon and silver (Ag) is, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1 as a weight ratio, but is not necessarily limited to this range and is selected according to the required characteristics of the entire solid-state battery. When the positive electrode active material has such a composition, the cycle characteristics of the entire solid-state battery are further improved.

[0099] The negative electrode active material contained in the negative electrode active material layer includes, for example, a mixture of first particles made of amorphous carbon and second particles made of a metal or a semi-metal. The metal or semi-metal includes, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), etc. The semi-metal is also a semiconductor. The content of the second particles is 8 to 60% by weight, 10 to 50% by weight, 15 to 40% by weight, or 20 to 30% by weight based on the total weight of the mixture. By the second particles having a content within this range, for example, the cycle characteristics of all-solid-state batteries are further improved.

[0100] The negative electrode active material layer includes, for example, a binder. The binder is, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but is not necessarily limited to these, and any material used as a binder in the technical field is possible. The binder can be composed of a single or a plurality of different binders.

[0101] Since the negative electrode active material layer contains a binder, the negative electrode active material layer is stabilized on the negative electrode current collector. Further, even in the case of volume change and / or change in relative position of the negative electrode active material layer during the charge and discharge process, cracking of the negative electrode active material layer is suppressed. For example, when the negative electrode active material layer does not contain a binder, the negative electrode active material layer can be easily separated from the negative electrode current collector. The portion where the negative electrode active material layer has detached from the negative electrode current collector exposes the negative electrode current collector and comes into contact with the solid electrolyte layer, increasing the likelihood of a short circuit. The negative electrode active material layer is produced, for example, by applying a slurry in which materials constituting the negative electrode active material layer are dispersed onto the negative electrode current collector and drying it. By including a binder in the negative electrode active material layer, stable dispersion of the negative electrode active material in the slurry becomes possible. For example, when applying the slurry onto the negative electrode current collector by the screen printing method, it is possible to suppress clogging of the screen (for example, clogging due to aggregates of the negative electrode active material).

[0102] The negative electrode current collector is made of a material that does not react with lithium, that is, does not form both alloys and compounds. The material constituting the negative electrode current collector is, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), etc., but is not necessarily limited to these, and any material that can be used as an electrode current collector in the relevant technical field is possible. The negative electrode current collector may be composed of one of the above metals, or may be composed of an alloy or coating material of two or more metals. The negative electrode current collector is, for example, plate-shaped or foil-shaped.

[0103] The positive electrode active material layer can further contain additives used in conventional all-solid-state batteries, such as fillers, dispersants, ion conductors, etc.

[0104] The all-solid-state battery can be manufactured, for example, by manufacturing the positive electrode, negative electrode, and solid electrolyte layer respectively and then laminating these layers.

[0105] The present invention provides a battery module including the all-solid-state battery as a unit cell, a battery pack including the battery module, and a device including the battery pack as a power source.

[0106] At this time, specific examples of the device include a power tool powered by an electric motor; an electric vehicle including an Electric Vehicle (EV), a Hybrid Electric Vehicle (HEV), a Plug-in Hybrid Electric Vehicle (PHEV), etc.; an electric two-wheeler including an electric bicycle (E-bike) and an electric scooter (E-scooter); an electric golf cart; a power storage system, etc., but are not limited thereto.

[0107] Hereinafter, specific examples of the present invention will be shown. However, the examples described below are merely for specifically exemplifying or explaining the present invention, and the present invention is not limited thereby. Also, since those skilled in the art can sufficiently technically infer the content not described herein, the description thereof will be omitted.

[0108] Production Example 1: Production of a positive electrode for an all-solid-state battery (1) 78 g of LiNi 0.8 Co 0.1 Mn 0.1 O2 powder with a particle size (D50) of 5 μm and 3.9 g of Li6PS5Cl 0.5 Br 0.5 powder with a particle size (D50) of 0.4 μm as the first sulfide-based solid electrolyte were put into a container and mixed at 5,000 rpm for 1 minute using a Lab Blender (Waring) without using a separate solvent (primary mixing). Next, the mixture was subjected to high-shear mixing (NOB-130, Hosokawa Micron) at 3,000 rpm for 10 minutes to produce a positive electrode active material composite in which a first sulfide-based solid electrolyte coating layer was formed on the surface of the positive electrode active material.

[0109] (2) 81.9 parts by weight of the manufactured positive electrode active material composite, 15.6 parts by weight of Li6PS5Cl as the second sulfide-based solid electrolyte, 1.5 parts by weight of carbon black powder as the conductive material, and 1 part by weight of polytetrafluoroethylene (PTFE) as the binder were put into a container and mixed at 5,000 rpm for 1 minute using a Lab Blender (Waring) without using a solvent separately (primary mixing). Next, a shear force of 100 N was applied to the mixture and high-shear mixing (PBV-0.1L, Irie Shokai) was performed to produce a positive electrode slurry (secondary mixing).

[0110] (3) The manufactured positive electrode slurry was used to produce a free-standing film using a Two roll mill MR-3 (Inoue). Thereafter, the film was placed on one surface of an aluminum current collector with a thickness of 15 μm and pressed to produce a positive electrode for an all-solid-state battery.

[0111] Production Example 2: Production of a positive electrode for an all-solid-state battery In the process of producing the positive electrode slurry, an all-solid-state battery was produced in the same manner as in Production Example 1, except that Li6PS5Cl 0.5 Br 0.5 was used instead of Li6PS5Cl as the second sulfide-based solid electrolyte.

[0112] Production Example 3: Production of a positive electrode for an all-solid-state battery In the process of producing the positive electrode active material composite, an all-solid-state battery was produced in the same manner as in Production Example 1, except that Li6PS5Cl 0.5 Br 0.5 was used instead of Li6PS5Cl as the first sulfide-based solid electrolyte.

[0113] Production Example 4: Production of a positive electrode for an all-solid-state battery In the process of producing the positive electrode slurry, Li6PS5Cl was used instead of Li6PS5Cl 0.5 Br 0.5 as the first sulfide-based solid electrolyte, and Li6PS5Cl was used instead of Li6PS5Cl as the second sulfide-based solid electrolyte.0.5 Br 0.5 A solid-state battery was manufactured in the same manner as in Production Example 1, except that Br was used.

[0114] Example 1: Manufacture of a solid-state battery Lithium metal with a thickness of 100 μm was used as the negative electrode, and a Li2S-P2S5 solid electrolyte film with a thickness of 50 μm was interposed between the positive electrode and the negative electrode manufactured in Production Example 1 to produce a jig cell having a capacity of 5 mAh / cm 2 capacity.

[0115] Comparative Example 1: Manufacture of a solid-state battery A solid-state battery was manufactured in the same manner as in Example 1, except that the positive electrode manufactured in Production Example 2 was used instead of the positive electrode manufactured in Production Example 1.

[0116] Comparative Example 2: Manufacture of a solid-state battery A solid-state battery was manufactured in the same manner as in Example 1, except that the positive electrode manufactured in Production Example 3 was used instead of the positive electrode manufactured in Production Example 1.

[0117] Comparative Example 3: Manufacture of a solid-state battery A solid-state battery was manufactured in the same manner as in Example 1, except that the positive electrode manufactured in Production Example 4 was used instead of the positive electrode manufactured in Production Example 1.

[0118] Evaluation Example 1: SEM and TEM analysis of the positive electrode for a solid-state battery SEM (Scanning electron microscopy) analysis was performed on the positive electrode for a solid-state battery manufactured according to Production Example 1, and the results are shown in FIGS. 1 and 2. The SEM analysis was performed using a JEM-ARM200F microscope manufactured by JEOL Ltd.

[0119] Referring to FIG. 1, in the case of the positive electrode for a solid-state battery manufactured according to Production Example 1, it can be confirmed that a coating layer of a first sulfide-based solid electrolyte containing bromine is uniformly formed on the surface of the positive electrode active material.

[0120] Also, referring to FIG. 2, in the case of the positive electrode for all-solid-state battery manufactured according to Production Example 1, since the bromine-free second sulfide-based solid electrolyte is densely located between the positive electrode active materials, it can be confirmed that they are in close contact at the interface between the positive electrode active material and the second sulfide-based solid electrolyte.

[0121] Evaluation Example 2: TEM (Transmission electron microscopy) and EDX (Energy dispersive X-ray spectroscopy) analysis of the positive electrode for all-solid-state battery (1) In the positive electrode for all-solid-state battery manufactured according to Production Example 1, TEM (Transmission electron microscopy) analysis was performed to measure the presence or absence of the coating layer of the positive electrode active material, and the results are shown in FIG. 3. The TEM analysis was performed using Titan G2 80-200 of FEI Company.

[0122] Referring to FIG. 3, in the case of the positive electrode for all-solid-state battery manufactured according to Production Example 1 of the present invention, it can be confirmed that the coating layer of the sulfide-based solid electrolyte is uniformly formed on the surface of the positive electrode active material.

[0123] (2) Also, in the positive electrode for all-solid-state battery manufactured according to Production Example 1, an EDX (Energy dispersive X-ray spectroscopy) experiment was performed to measure the bromine (Br) composition of the first sulfide-based solid electrolyte contained in the positive electrode active material coating layer, and the results are shown in FIG. 4. The EDX measuring instrument was measured using JSM7900F of JEOL Ltd.

[0124] As shown in FIG. 4, in the case of the positive electrode for all-solid-state battery manufactured according to Production Example 1, it was found that the first sulfide-based solid electrolyte exists in a bromine-rich composition in the coating layer formed on the surface of the positive electrode active material.

[0125] Evaluation Example 3: Charge and discharge characteristics analysis For each of the all-solid-state batteries of Example 1, Comparative Example 1 to Comparative Example 3, the charge and discharge characteristics were evaluated by the following charge and discharge tests.

[0126] After charging at a rate of 0.1 C (C-rate) until the voltage reached 4.25 V (vs. Li), it was cut off at a rate of 0.05 C while maintaining 4.25 V (vs. Li). Subsequently, it was discharged at a rate of 0.1 C (C-rate) until the voltage reached 3.0 V (vs. Li) during discharge (1 st cycle). The results are shown in Figure 5 below.

[0127] Referring to Figure 5, in the case of the all-solid-state battery according to Example 1, it was confirmed that it exhibited a reversible capacity and an energy density at almost the same level as the all-solid-state battery according to Comparative Example 1, and a higher reversible capacity and energy density than the all-solid-state batteries according to Comparative Examples 2 and 3.

[0128] Evaluation Example 4: High-rate characteristic analysis For each of the all-solid-state batteries of Example 1, Comparative Example 1 to Comparative Example 3, after charging and discharging in the region of 3.0 to 4.25 V at 0.1 C, 0.2 C, 0.3 C, and 0.5 C, the change in discharge capacity according to each c-rate is shown in Figure 6.

[0129] Referring to Figure 6, in the case of the all-solid-state battery according to Example 1, it can be seen that the high-rate characteristics are improved due to the improvement of the ionic conductivity and the interfacial characteristics between the active material and the solid electrolyte compared to the all-solid-state batteries of Comparative Example 1 to Comparative Example 3.

[0130] In particular, a second sulfide-based solid electrolyte containing no bromine element is formed in the coating layer of the positive electrode active material, and a first sulfide-based solid electrolyte containing a bromine element is formed in a region other than the positive electrode active material coating layer. That is, as a result of applying by swapping the configurations of the first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte compared with Example 1, it was confirmed that the high-rate characteristics of the all-solid-state battery were significantly reduced. Thereby, it can be seen that when applying a sulfide-based solid electrolyte containing a bromine element to the positive electrode active material coating layer, the high-rate characteristics of the all-solid-state battery are improved.

[0131] As described above, the preferred embodiments of the present invention have been described in detail. However, the scope of the rights of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also belong to the scope of the rights of the present invention.

Claims

1. A positive electrode for an all-solid-state battery, comprising a positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a binder, wherein the sulfide-based solid electrolyte includes a first sulfide-based solid electrolyte containing a bromine (Br) element and a second sulfide-based solid electrolyte not containing a bromine (Br) element, the positive electrode active material includes a core capable of reversibly occluding and releasing lithium ions; and a coating layer formed on the surface of the core, the coating layer includes the first sulfide-based solid electrolyte, a positive electrode for an all-solid-state battery.

2. The positive electrode for an all-solid-state battery according to claim 1, wherein the first sulfide-based solid electrolyte is represented by the following chemical formula 1. [Chemical formula 1] Li ａ M １ ｂ S ｃ X １ ｄ Br ｅ In the formula 1, M １ is Sn, Mg, Ba, B, Al, Ga, In, In, Si, Ge, Pb, N, P, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W, or La, and X １ is F, Cl, Br, I, Se, Te, or O, 0 < a ≤ 6, 0 < b ≤ 6, 0 < c ≤ 6, 0 ≤ d ≤ 6, and 0 < e ≤ 6.

3. The positive electrode for an all-solid-state battery according to claim 1, wherein the second sulfide-based solid electrolyte is represented by the following chemical formula 2. [Chemical formula 2] Li ｋ M ２ ｌ S ｍ X ２ ｎ In the formula 2, M ２ is Sn, Mg, Ba, B, Al, Ga, In, In, Si, Ge, Pb, N, P, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W, or La, and X ２ is F, Cl, I, Se, Te, or O, 0 < k ≤ 6, 0 < l ≤ 6, 0 < m ≤ 6, and 0 ≤ n ≤ 6.

4. The positive electrode for an all-solid-state battery according to claim 1, wherein the sulfide-based solid electrolyte has an argyrodite-type crystal structure.

5. The positive electrode for an all-solid-state battery according to claim 1, wherein the first sulfide-based solid electrolyte is contained in an amount of 5 to 25 parts by weight based on 100 parts by weight of the total of the first sulfide-based solid electrolyte and the second sulfide-based solid electrolyte.

6. The positive electrode for an all-solid-state battery according to claim 1, wherein the positive electrode active material is contained in an amount of 50 to 95 parts by weight based on 100 parts by weight of the entire positive electrode.

7. The positive electrode for an all-solid-state battery according to claim 1, wherein the sulfide-based solid electrolyte is contained in an amount of 5 to 49 parts by weight based on 100 parts by weight of the entire positive electrode.

8. The positive electrode for an all-solid-state battery according to claim 1, wherein the positive electrode active material is coated with 1 to 20 parts by weight of the first sulfide-based solid electrolyte based on 100 parts by weight of the entire positive electrode active material including the core and the coating layer.

9. The positive electrode for an all-solid-state battery according to claim 1, wherein the average particle size of the first sulfide-based solid electrolyte is 0.1 μm to 5 μm.

10. The positive electrode for an all-solid-state battery according to claim 1, wherein the average particle size of the second sulfide-based solid electrolyte is 0.1 μm to 5 μm.

11. The positive electrode for an all-solid-state battery according to claim 1, wherein the thickness of the coating layer of the positive electrode active material is 0.05 μm to 0.2 μm.

12. An all-solid-state battery, comprising a positive electrode; a negative electrode; and a solid electrolyte layer disposed between the positive electrode and the negative electrode, wherein the positive electrode includes the positive electrode according to any one of claims 1 to 11.

Images