Positive electrode active material for all-solid-state batteries, positive electrode for all-solid-state batteries, and all-solid-state batteries containing the same

Abstract

This invention provides a positive electrode active material for all-solid-state batteries that can improve the interfacial resistance between the positive electrode active material layer and the solid electrolyte and suppress side reactions by forming a coating layer containing lithium carbon oxide and lithium titanium oxide on the positive electrode active material for all-solid-state batteries. [Solution] The present invention relates to a positive electrode active material for an all-solid-state battery comprising a coating layer formed on the surface of a core capable of reversible intercalation and release of lithium ions, comprising lithium carbon oxide represented by the following chemical formula 1 and lithium titanium oxide represented by the following chemical formula 2; a positive electrode for an all-solid-state battery comprising the positive electrode active material and a sulfide-based solid electrolyte; and 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. [Chemical formula 1] Li a CO b (a is 0 <a≦4、bは0<b≦4) [Chemical formula 2] Li x Ti y O4 (where x is 0.8 ≤ x ≤ 1.4 and y is 1.6 ≤ y ≤ 2.2)

Description

[Technical Field]

[0001] This application claims priority under Korean Patent Application No. 10-2022-0166647 dated 2 December 2022, and incorporates all the contents disclosed in the said Korean Patent Application as part of this Specification.

[0002] The present invention relates to a positive electrode active material for an all-solid-state battery, a positive electrode for an all-solid-state battery, and an all-solid-state battery containing the same. [Background technology]

[0003] Lithium-ion batteries have primarily been applied to small devices such as mobile devices and laptop computers, but recently, research in this area has expanded to medium and large-scale applications such as energy storage systems (ESS) and electric vehicles (EV).

[0004] Unlike smaller batteries, medium- and large-sized lithium-ion rechargeable batteries operate in harsh environments (e.g., temperature, shock) and require more batteries, thus needing to ensure safety along with superior performance and a reasonable price.

[0005] Currently, most commercially available lithium-ion batteries use an organic liquid electrolyte, which is a lithium salt dissolved in an organic solvent. This poses potential risks, including leakage, ignition, and explosion. As a result, using a solid electrolyte instead of the organic liquid electrolyte is attracting attention as an alternative to overcome these safety problems.

[0006] All-solid-state batteries consist of a positive electrode, a solid electrolyte, and a negative electrode. While sulfides and oxides can be used as the solid electrolyte in all-solid-state batteries, sulfide-based solid electrolytes are the most promising material from the viewpoint of lithium-ion conductivity.

[0007] However, when using sulfide-based solid electrolytes, due to the reaction between cobalt and sulfur, the positive electrode generally does not use a positive electrode active material coated with cobalt (Co).

[0008] Furthermore, during the charge-discharge cycle of all-solid-state batteries, reactions occur at the interface between the positive electrode active material and the sulfide-based solid electrolyte, and components such as Co, P, and S diffuse at the interface, reducing the lifespan characteristics. Therefore, improvements are needed to address this issue. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Korean Published Patent Publication No. 2010-0120153 [Patent Document 2] Korean Published Patent Publication No. 2018-0076132 [Overview of the project] [Problems that the invention aims to solve]

[0010] The object of the present invention is to provide a positive electrode active material for all-solid-state batteries that can improve the interfacial resistance between the positive electrode active material layer and the solid electrolyte and suppress side reactions by forming a coating layer containing lithium carbon oxide and lithium titanium oxide on the positive electrode active material for all-solid-state batteries.

[0011] Another object of the present invention is to provide a positive electrode for an all-solid-state battery comprising the positive electrode active material and sulfide-based solid electrolyte.

[0012] Another object of the present invention is to provide an all-solid-state battery in which the positive electrode active material for all-solid-state batteries is applied to the positive electrode, thereby improving electrochemical properties and lifespan characteristics. [Means for solving the problem]

[0013] One embodiment of the present invention provides a positive electrode active material for an all-solid-state battery, comprising a core capable of reversible intercalation and deintercalation of lithium ions and a coating layer formed on the surface of the core, wherein the coating layer comprises a lithium carbon oxide represented by the following chemical formula 1 and a lithium titanium oxide represented by the following chemical formula 2. [Chemical formula 1]

[0014] Li a CO b In the above chemical formula 1, a is 0 <a≦4、bは0<b≦4である; [Chemical formula 2]

[0015] Li x Ti y O4 In the aforementioned chemical formula 2, x is 0.8 ≤ x ≤ 1.4 and y is 1.6 ≤ y ≤ 2.2.

[0016] The coating layer comprises a first coating layer and a second coating layer extending from the center of the core toward the surface of the core, the first coating layer comprising lithium carbon oxide represented by chemical formula 1, and the second coating layer comprising lithium titanium oxide represented by chemical formula 2.

[0017] The coating layer may be included in an amount of 0.1 to 10 parts by weight, based on 100 parts by weight of the total positive electrode active material for the all-solid-state battery, which includes both the core and the coating layer.

[0018] The lithium carbon oxide represented by chemical formula 1 may be included in an amount of 0.1 to 1.6 parts by weight based on 100 parts by weight of the total positive electrode active material for the all-solid-state battery, including both the core and the coating layer.

[0019] The lithium titanium oxide represented by chemical formula 2 may be included in an amount of 0.1 to 1.5 parts by weight based on 100 parts by weight of the total positive electrode active material for the all-solid-state battery, including both the core and the coating layer.

[0020] The lithium carbonate oxide represented by Chemical Formula 1 and the lithium titanate oxide represented by Chemical Formula 2 contained in the coating layer can be contained in a weight ratio of 95:5 to 25:75.

[0021] The thickness ratio of the first coating layer to the second coating layer can be 20:80 to 80:20.

[0022] The thickness of the first coating layer is 0.001 to 0.02 μm, and the thickness of the second coating layer can be 0.001 to 0.02 μm.

[0023] The lithium carbonate oxide is Li2CO3, and the lithium titanate oxide can be Li4Ti5O 12 and so on.

[0024] Another embodiment of the present invention provides a positive electrode for an all-solid-state battery, which includes the positive electrode active material for an all-solid-state battery and a sulfide-based solid electrolyte.

[0025] The sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are positive numbers, and Z is any one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are positive numbers, and M is any one of P, Si, Ge, B, Al, Ga, or In), Li 7-x PS 6-x Cl x (where 0 ≦ x ≦ 2), Li 7-x PS 6-x Br [[ID=4I]] x (where 0 ≦ x ≦ 2) and Li7-x PS 6-x I x (However, it may be one or more selected from 0 ≤ x ≤ 2)

[0026] The sulfide-based solid electrolyte may be an argyrodite-type solid electrolyte containing one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0027] Another embodiment of the present invention provides 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 for the all-solid-state battery. [Effects of the Invention]

[0028] According to the present invention, by forming a coating layer on the positive electrode active material for an all-solid-state battery, and by having the coating layer simultaneously contain lithium carbon oxide and lithium titanium oxide, it is possible to improve the interfacial resistance between the positive electrode active material and the solid electrolyte in the positive electrode active material layer of the all-solid-state battery, thereby suppressing side reactions. Furthermore, by applying the positive electrode active material for an all-solid-state battery with the coating layer formed thereon to the positive electrode, the electrochemical properties and lifespan characteristics of the all-solid-state battery containing it can be improved. [Brief explanation of the drawing]

[0029] [Figure 1] This is a schematic diagram of a positive electrode active material for an all-solid-state battery according to one embodiment of the present invention. [Figure 2] This is a schematic diagram of a positive electrode active material for an all-solid-state battery according to one embodiment of the present invention. [Figure 3] This image shows the results of energy dispersive X-ray spectroscopy (EDAX) analysis of a positive electrode active material for an all-solid-state battery according to one embodiment of the present invention. [Modes for carrying out the invention]

[0030] Embodiments of the present invention will now be described in detail. Prior to this, terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, based on the principle that inventors may appropriately define the concepts of terms in order to best describe their invention. Therefore, it should be understood that the configurations described in the embodiments described herein represent only one of the most preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and that at the time of filing, there may be various equivalents and modifications that can substitute for them.

[0031] Whenever a part of this specification is said to "include" a certain component, unless otherwise stated, this means that it may include other components rather than excluding them.

[0032] Furthermore, explanations that specify or add components can be applied to all inventions unless otherwise specified, and are not limited to any particular invention.

[0033] Furthermore, throughout the description of the invention and the claims of this application, any singular reference includes plural references unless otherwise specified.

[0034] Furthermore, throughout the description of the invention and the claims of this application, "or" includes "and" unless otherwise specified. Therefore, "including A or B" means including A, including B, or including both A and B—all three of the aforementioned cases.

[0035] Furthermore, all numerical ranges include the values ​​at both ends and all intermediate values ​​between them, unless otherwise explicitly stated.

[0036] Throughout this specification, the average particle size may be, for example, the median diameter (D50) measured using a laser particle size analyzer.

[0037] The following describes a positive electrode active material for an all-solid-state battery according to one embodiment of the present invention.

[0038] The present invention relates to a positive electrode active material for all-solid-state batteries that can improve the electrochemical properties and lifespan characteristics of all-solid-state batteries by improving the interfacial resistance between the positive electrode active material and the solid electrolyte and suppressing side reactions.

[0039] Typically, in the case of all-solid-state batteries, unlike general lithium-ion secondary batteries, a liquid electrolyte is not used, so the positive electrode active material layer also contains a solid electrolyte in addition to the solid electrolyte layer.

[0040] At this time, in order to ensure stable ionic conductivity, the effective contact between the positive electrode active material and the solid electrolyte contained in the positive electrode active material layer to form a high effective contact area is an important factor in 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 approximately 500 MPa or more is applied during the manufacturing process of all-solid-state batteries. To solve problems such as side reactions between the positive electrode active material and the solid electrolyte caused by the pressurization process, there have been attempts to improve this by introducing a lithium oxide coating layer containing elements such as B, Al, Zr, Nb, and W into the positive electrode active material.

[0041] However, even if lithium oxide containing the aforementioned elements is introduced into the coating layer of the positive electrode active material, there is a problem in that the improvement in interfacial resistance between the positive electrode active material and the solid electrolyte, which is necessary to improve the output of all-solid-state batteries containing sulfide-based solid electrolytes and to ensure long lifespan, does not significantly improve.

[0042] In response to the above-mentioned problems, the present invention has been completed by forming a coating layer on the surface of the positive electrode active material for all-solid-state batteries, and by simultaneously containing lithium carbon oxide and lithium titanium oxide in the coating layer, thereby reducing the interfacial resistance between the positive electrode active material and the solid electrolyte, particularly sulfide-based solid electrolytes, in the positive electrode active material layer and suppressing side reactions.

[0043] Figure 1 is a schematic diagram showing a positive electrode active material for an all-solid-state battery according to one embodiment of the present invention.

[0044] Referring to Figure 1, a positive electrode active material for an all-solid-state battery according to one embodiment of the present invention includes a core capable of reversible intercalation and release of lithium ions and a coating layer formed on the surface of the core, wherein the coating layer includes a lithium carbon oxide represented by the following chemical formula 1 and a lithium titanium oxide represented by the following chemical formula 2. [Chemical formula 1] Li a CO b In the above chemical formula 1, a is 0 <a≦4、bは0<b≦4である; [Chemical formula 2] Li x Ti y O4 In the aforementioned chemical formula 2, x is 0.8 ≤ x ≤ 1.4 and y is 1.6 ≤ y ≤ 2.2.

[0045] The positive electrode active material for the all-solid-state battery, by including lithium carbon oxide represented by chemical formula 1 in the coating layer formed on its surface, can suppress the increase in electrochemical interface contact resistance caused by the contraction and expansion of the positive electrode active material during the charging and discharging process of the all-solid-state battery. Furthermore, by also including lithium titanium oxide represented by chemical formula 2, it is possible to prevent the formation of an excessively thick solid electrolyte interface film on the surface of the positive electrode active material and control thermal runaway factors, thereby improving the battery chemical properties and stability of the all-solid-state battery, allowing for smooth entry and exit of Li ions and providing the battery with rapid charge and discharge characteristics.

[0046] The lithium carbon oxide represented by chemical formula 1 and the lithium titanium oxide represented by chemical formula 2 are not limited to the aforementioned chemical formulas, and can also be represented in the form of multiples of the number of moles, within the range that satisfies the molar ratio of each atom.

[0047] For example, in the case of lithium titanium oxide represented by chemical formula 2, the number of moles of oxygen is fixed at 4, but chemical formula 2 is not limited to this and can be represented in the form of multiples that satisfy the molar ratio of each atom. If, for example, the number of moles of oxygen is 12, then chemical formula 2 is Li 3x Ti 3y O 12 It can also be shown as follows.

[0048] In one embodiment of the present invention, the lithium carbon oxide contained in the coating layer of the positive electrode active material for the all-solid-state battery may be, for example, Li2CO3, and the lithium titanium oxide may be Li4Ti5O 12 It is possible.

[0049] Referring to Figure 2, in one embodiment of the present invention, the coating layer may include a first coating layer and a second coating layer, respectively, extending from the center of the core toward the surface of the core, wherein the first coating layer contains lithium carbon oxide represented by chemical formula 1, and the second coating layer contains lithium titanium oxide represented by chemical formula 2.

[0050] In other words, the first coating layer near the surface of the positive electrode active material contains lithium carbon oxide represented by chemical formula 1, thereby solving the problem of increased interfacial resistance between the positive electrode active material and the solid electrolyte due to a decrease in the mechanical contact area. The second coating layer formed on the first coating layer and located at the outermost corner of the positive electrode active material contains lithium titanium oxide represented by chemical formula 2, thereby suppressing direct interfacial contact between the positive electrode active material and the solid electrolyte. + The movement of ions other than ions is restricted, and the problem of resistance increase due to electrochemical side reactions can be solved. However, if, unlike the above embodiment, the first coating layer contains lithium titanium oxide represented by chemical formula 2 and the second coating layer contains lithium carbon oxide represented by chemical formula 1, it becomes difficult for each coating layer to properly perform the role described above, which may lead to a problem of a significant increase in the interface resistance between the positive electrode active material and the solid electrolyte.

[0051] In one embodiment of the present invention, the coating layer is preferably included in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the total positive electrode active material for an all-solid-state battery, which includes both the core and the coating layer.

[0052] If the content of the coating layer is less than 0.1 parts by weight based on 100 parts by weight of the total positive electrode active material for all-solid-state batteries, problems may arise where a complete coating layer is not formed, such as the positive electrode active material not being partially coated. If it exceeds 10 parts by weight, problems arise where the gap between the positive electrode active material and the solid electrolyte widens, increasing the interfacial resistance.

[0053] In one embodiment of the present invention, the lithium carbon oxide represented by chemical formula 1 may be included in an amount of 0.1 to 1.6 parts by weight based on 100 parts by weight of the total positive electrode active material for the all-solid-state battery, including both the core and the coating layer. For example, it may be 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, or 0.9 parts by weight or more, and may be 1.6 parts by weight or less, 1.5 parts by weight or less, 1.4 parts by weight or less, 1.3 parts by weight or less, 1.2 parts by weight or less, or 1.1 parts by weight or less.

[0054] In one embodiment of the present invention, the coating layers formed on the surface of the positive electrode active material for the all-solid-state battery are formed as a first coating layer and a second coating layer, respectively, extending from the center of the core toward the surface of the positive electrode active material, and the lithium carbon oxide represented by chemical formula 1 is included in the first coating layer. In this case, the lithium carbon oxide represented by chemical formula 1 may be included in an amount of 0.1 to 1.6 parts by weight based on 100 parts by weight of the total positive electrode active material for the all-solid-state battery, which includes the core, the first coating layer and the second coating layer.

[0055] If the content of lithium carbon oxide represented by chemical formula 1 is less than 0.1 parts by weight, there may be problems such as partial coating of the surface of the positive electrode active material, resulting in the inability to form a complete coating layer. If it exceeds 1.6 parts by weight, there may be problems such as an increase in the gap between the positive electrode active material and the solid electrolyte, leading to increased interfacial resistance. Therefore, it is preferable that the lithium carbon oxide represented by chemical formula 1 is contained within the aforementioned range.

[0056] In one embodiment of the present invention, the lithium titanium oxide represented by chemical formula 2 may be included in an amount of 0.1 to 1.5 parts by weight based on 100 parts by weight of the total positive electrode active material for the all-solid-state battery, including both the core and the coating layer. For example, it may be 0.1 parts by weight or more, 0.2 parts by weight or more, 0.3 parts by weight or more, 0.4 parts by weight or more, 0.5 parts by weight or more, 0.6 parts by weight or more, 0.7 parts by weight or more, 0.8 parts by weight or more, or 0.9 parts by weight or more, and may be 1.5 parts by weight or less, 1.4 parts by weight or less, 1.3 parts by weight or less, 1.2 parts by weight or less, or 1.1 parts by weight or less.

[0057] In one embodiment of the present invention, the coating layers formed on the surface of the positive electrode active material for the all-solid-state battery are formed as a first coating layer and a second coating layer, respectively, extending from the center of the core toward the surface of the positive electrode active material, and the lithium titanium oxide represented by chemical formula 2 is included in the second coating layer. In this case, the lithium titanium oxide represented by chemical formula 2 may be included in an amount of 0.1 to 1.5 parts by weight based on 100 parts by weight of the total positive electrode active material for the all-solid-state battery, which includes the core, the first coating layer and the second coating layer.

[0058] If the content of lithium titanium oxide represented by chemical formula 2 is less than 0.1 parts by weight, there may be problems such as partial coating of the surface of the positive electrode active material, resulting in the inability to form a complete coating layer. If it exceeds 1.5 parts by weight, there may be problems such as an increase in the gap between the positive electrode active material and the solid electrolyte, leading to increased interfacial resistance. Therefore, it is preferable that the lithium titanium oxide represented by chemical formula 2 is contained within the aforementioned range.

[0059] Furthermore, in one embodiment of the present invention, the lithium carbon oxide represented by chemical formula 1 and the lithium titanium oxide represented by chemical formula 2 contained in the coating layer of the positive electrode active material for the all-solid-state battery may be present in a weight ratio of 95:5 to 25:75.

[0060] For example, the lithium carbon oxide represented by chemical formula 1 and the lithium titanium oxide represented by chemical formula 2 may be in a weight ratio of 95:5, 16:1, 90:10, 85:15, 5:1, 80:20, 75:25, 70:30, 65:35, 60:40, 55:45, 50:50, 45:55, 40:60, 35:65, 30:70, or 25:75.

[0061] In the positive electrode active material for all-solid-state batteries according to the present invention, if the content of lithium carbon oxide represented by chemical formula 1 is less than 25 parts by weight based on 100 parts by weight of the total of lithium carbon oxide represented by chemical formula 1 and lithium titanium oxide represented by chemical formula 2, there may be a problem in which the first coating layer containing lithium carbon oxide comes into direct contact with the solid electrolyte. If it exceeds 95 parts by weight, the lithium carbon oxide may be mixed into the second coating layer containing lithium titanium oxide, causing a side reaction, which may result in an increase in the interfacial resistance between the positive electrode active material and the solid electrolyte.

[0062] In the positive electrode active material for all-solid-state batteries according to the present invention, if the content of lithium titanium oxide represented by chemical formula 2 is less than 5 parts by weight, based on 100 parts by weight of the total of lithium carbon oxide represented by chemical formula 1 and lithium titanium oxide represented by chemical formula 2, there is a problem that lithium carbon oxide may be mixed into the second coating layer containing lithium titanium oxide, causing a side reaction and resulting in an increase in the interfacial resistance between the positive electrode active material and the solid electrolyte. If it exceeds 75 parts by weight, there is a problem that the first coating layer containing lithium carbon oxide may come into direct contact with the solid electrolyte.

[0063] In one embodiment of the present invention, the thickness ratio of the first coating layer to the second coating layer may be 20:80 to 80:20.

[0064] Furthermore, within the range that satisfies the aforementioned thickness ratio, the thickness of the first coating layer may be 0.001 to 0.02 μm, and the thickness of the second coating layer may be 0.001 to 0.02 μm.

[0065] In the positive electrode active material for an all-solid-state battery according to the present invention, when the first coating layer and the second coating layer formed on the surface have the aforementioned thickness ratio and thickness range, side reactions between the positive electrode active material and the sulfide-based solid electrolyte can be substantially reduced and / or effectively minimized or effectively blocked.

[0066] The core included in the positive electrode active material for the all-solid-state battery is not particularly limited as long as it is a lithium composite oxide system capable of reversible intercalation and release of lithium ions. For example, it may contain one or more composite oxides of metals such as cobalt, manganese, nickel, iron, or combinations thereof, and lithium.

[0067] As a more specific example, the positive electrode active material can be a compound represented by any one of the following chemical formulas: 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 and 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b R c D α(In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α ≤ 2); Li a Ni 1-b-c Co b R c O 2-α Z α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni 1-b-c Co b R c O 2-α Z2 (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni 1-b-c Mn b R c D α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α ≤ 2); Li a Ni 1-b-c Mn b R c O 2-α Z α (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni 1-b-c Mn b R c O 2-α Z2 (In the above formula, 0.90 ≤ a ≤ 1.8, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni b E c G d O2 (In the above formula, 0.90≦a≦1.8, 0≦b≦0.9, 0≦c≦0.5 and 0.001≦d≦0.1); Li a Ni b Co c Mn d G e O2(In the above formula, 0.90≦a≦1.8, 0≦b≦0.9, 0≦c≦0.5, 0≦d≦0.5 and 0≦e≦0.1);Li a NiG bO2 (where 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1 in the above formula); Li a CoG b O2 (where 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1 in the above formula); Li a MnG b O2 (where 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1 in the above formula); Li a Mn2G b O4 (where 0.90 ≤ a ≤ 1.8 and 0.001 ≤ b ≤ 0.1 in the above formula); 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.

[0068] In the above chemical formula, A is Ni, Co, Mn or a combination thereof; R is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements 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.

[0069] According to another aspect, a positive electrode for an all-solid-state battery including the positive electrode active material for an all-solid-state battery according to the above-described embodiment of the present invention is provided.

[0070] In one embodiment, the positive electrode for an all-solid-state battery may include the aforementioned positive electrode active material for an all-solid-state battery and a sulfide-based solid electrolyte.

[0071] At this time, since the positive electrode active material for the all-solid-state battery is the same as the content described above, hereinafter, regarding the positive electrode active material contained in the positive electrode for the all-solid-state battery according to the present invention, detailed description will be omitted hereinafter in this specification.

[0072] In one embodiment of the present invention, the sulfide-based solid electrolyte contained in the positive electrode for the all-solid-state battery may be represented by the following Chemical Formula 3. [Chemical Formula 3]

[0073] Li k M 2 l S m X 2 n In Chemical Formula 3, M 2 is Sn, Mg, Ba, B, Al, Ga, In, Si, Ge, Pb, N, P, As, Sb, Bi, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W, or La, and X 2 is F, Cl, Br, I, Se, Te, or O, and 0 < k ≦ 6, 0 < l ≦ 6, 0 < m ≦ 6, and 0 ≦ n ≦ 6.

[0074] For example, in Chemical Formula 3, M 2 may be B, Si, Ge, P, or N.

[0075] For example, in Chemical Formula 3, X 2 may be F, Cl, Br, I, or O.

[0076] For example, the sulfide-based solid electrolyte represented by Chemical Formula 3 is Li2S-P2S5, Li2S-P2S5-LiX, X is a halogen element, Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S nm and n are positive numbers, Z is one of Ge, Zn, or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q p and q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, In, Li 7-x PS 6-x Cl x , 0≦x≦2, Li 7-x PS 6-x Br x , 0≦x≦2, and Li 7-x PS 6-x I x , or one or more selected from 0 ≤ x ≤ 2.

[0077] Furthermore, preferably, the sulfide-based solid electrolyte may be an argyrodite-type solid electrolyte containing one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0078] In one embodiment of the present invention, the positive electrode for the all-solid-state battery may further include a conductive material and a binder.

[0079] The conductive material is not particularly limited as long as it does not induce a chemical change in the battery and is conductive. Examples include graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, and summer black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives. The conductive material may be included in an amount of about 0.01 to 10 parts by weight, or 0.01 to 5 parts by weight, or 0.01 to 3 parts by weight, based on 100 parts by weight of the total positive electrode.

[0080] The binder is an added component that takes into consideration the binding properties 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 art to which the present invention belongs can be used without any particular limitations.

[0081] 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), and of course, various other polymer binders can also be used. The binder may be included in an amount of approximately 0.01 to 10 parts by weight, 0.01 to 5 parts by weight, or 0.01 to 3 parts by weight based on 100 parts by weight of the total positive electrode.

[0082] A positive electrode for an all-solid-state battery according to one embodiment of the present invention may include a current collector and a positive electrode active material layer formed on at least one surface of the current collector, wherein the positive electrode active material layer may include the aforementioned positive electrode active material, a sulfide-based solid electrolyte, a conductive material, and a binder.

[0083] The positive electrode can be manufactured according to methods widely known in the art and is not limited to any particular manufacturing method, but for example, it can be manufactured by mixing the positive electrode active material, sulfide-based solid electrolyte, conductive material and binder, etc. in a solvent to produce a positive electrode mixture in the form of a slurry, and then applying this positive electrode mixture to a positive electrode current collector.

[0084] The positive electrode current collector is generally manufactured to a thickness of 3 to 500 μm. Such a positive electrode current collector is not particularly limited as long as it does not induce chemical changes in the battery and has high conductivity. For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with surface treatment of carbon, nickel, titanium, silver, etc., can be used. The current collector can also have fine irregularities formed on its surface to enhance the adhesion of the positive electrode active material, and can take various forms such as film, sheet, foil, net, porous material, foam, nonwoven fabric, etc.

[0085] In addition to the aforementioned positive electrode active material, sulfide-based solid electrolyte, conductive material, and binder, the positive electrode may further contain additives such as fillers, coating agents, dispersants, and ion conductivity enhancers. As the fillers, coating agents, dispersants, and ion conductivity enhancers, known materials commonly used in electrodes for all-solid-state secondary batteries can be used.

[0086] The thickness of the positive electrode may be, for example, 70 to 150 μm.

[0087] Another embodiment of the present invention provides 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 is the positive electrode for all-solid-state batteries described above.

[0088] As the positive electrode included in the all-solid-state battery has been explained in detail above, the negative electrode and solid electrolyte included in the all-solid-state battery will be explained in detail below.

[0089] The solid electrolyte layer disposed between the positive electrode and the negative electrode may 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 contained in the positive electrode.

[0090] For specific details regarding sulfide-based solid electrolytes, please refer to the positive electrode section described above.

[0091] The elastic modulus, or Young's modulus, of solid electrolytes is, for example, 35 GPa or less, 30 GPa or less, 27 GPa or less, 25 GPa or less, or 23 GPa or less. The elastic modulus, or Young's modulus, of solid electrolytes is, for example, 10-35 GPa, 15-35 GPa, 15-30 GPa, or 15-25 GPa. Having an elastic modulus in such a range makes pressurization and / or sintering of the solid electrolyte easier.

[0092] The solid electrolyte layer further includes, for example, a binder. Examples of binders included in the solid electrolyte layer include, but are not limited to, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene; any binder used in the relevant art is acceptable. 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.

[0093] Next, the negative electrode of the all-solid-state battery may include a negative electrode current collector and a negative electrode active material layer.

[0094] 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, lithium dendrites formed between the negative electrode active material layer and the negative electrode current collector will cause the negative electrode active material layer to disintegrate, making it difficult to improve the cycle characteristics of the all-solid-state battery. If the thickness of the negative electrode active material layer is excessively increased, the energy density of the all-solid-state battery decreases, the internal resistance of the all-solid-state battery due to the negative electrode active material layer increases, making it difficult to improve the cycle characteristics of the all-solid-state battery.

[0095] The negative electrode active material layer includes, for example, a negative electrode active material that forms an alloy or compound with lithium.

[0096] The negative electrode active material contained in the negative electrode active material layer has, for example, a particulate form. The average particle size 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 size of the negative electrode active material having a particulate form is, for example, 10 nm to 4 μm or less, 10 nm to 3 μm or less, 10 nm to 2 μm or less, 10 nm to 1 μm or less, or 10 nm to 900 nm or less. Having an average particle size in such a range of negative electrode active material may facilitate the reversible absorption and / or desorbing of lithium during charging and discharging. The average particle size of the negative electrode active material is, for example, the volume-reduced median diameter (D50) measured using a laser particle size analyzer.

[0097] The negative electrode active material contained in the negative electrode active material layer includes, for example, one or more selected from carbon-based negative electrode active materials and metallic or semimetallic negative electrode active materials.

[0098] Carbon-based negative electrode active materials are particularly amorphous carbon. Amorphous carbons include, for example, carbon black (CB), acetylene black (AB), furnace black (FB), Ketjen black (KB), and graphene, but are not necessarily limited to these; any material classified as amorphous carbon in the relevant technical field is acceptable. Amorphous carbon is carbon that does not have crystallinity or has very low crystallinity, and is classified as crystalline carbon or graphite-based carbon.

[0099] The metallic or metalloid anode active material includes, but is not limited to, 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). Any metallic or metalloid anode active material that forms an alloy or compound with lithium in the art is acceptable. For example, nickel (Ni) does not form an alloy with lithium and is therefore not a metallic anode active material.

[0100] The negative electrode active material layer contains one type of negative electrode active material from among these negative electrode active materials, or a mixture of multiple different negative electrode active materials. For example, the negative electrode active material layer contains only amorphous carbon, or 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). Alternatively, 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 amorphous carbon and silver (Ag) is, for example, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1 by weight, but is not necessarily limited to these ranges and is selected according to the required characteristics of the all-solid-state battery. Having such a composition in the negative electrode active material further improves the cycle characteristics of the all-solid-state battery.

[0101] The negative electrode active material layer contains, for example, a mixture of first particles made of amorphous carbon and second particles made of a metal or metalloid. Examples of metals or metalloids include gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Other metalloids include semiconductors. The content of the second particles is 8-60% by weight, 10-50% by weight, 15-40% by weight, or 20-30% by weight, based on the total weight of the mixture. Having a second particle content within this range further improves the cycle characteristics of, for example, all-solid-state batteries.

[0102] The negative electrode active material layer includes, for example, a binder. Examples of binders include styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, and polymethyl methacrylate, but are not necessarily limited to these; any binder used in the relevant art is acceptable. The binder can consist of one or more different binders.

[0103] The inclusion of a binder in the negative electrode active material layer stabilizes it on the negative electrode current collector. Furthermore, cracking of the negative electrode active material layer is suppressed despite volume changes and / or changes in relative position during the charge-discharge process. For example, if the negative electrode active material layer does not contain a binder, it can easily separate from the negative electrode current collector. In the portion where the negative electrode active material layer has detached from the negative electrode current collector, the negative electrode current collector is exposed and comes into contact with the solid electrolyte layer, increasing the likelihood of a short circuit. The negative electrode active material layer is manufactured, for example, by coating a slurry containing dispersed materials 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 is possible. For example, when coating the slurry onto the negative electrode current collector using a screen printing method, screen clogging (e.g., clogging by aggregates of negative electrode active material) can be suppressed.

[0104] The negative electrode current collector is composed of a material that does not react with lithium, i.e., does not form either an alloy or a compound. The materials constituting the negative electrode current collector include, but are not limited to, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), and any material used as an electrode current collector in the relevant art is acceptable. The negative electrode current collector can be composed of one of the aforementioned metals, or of an alloy or coating material of two or more metals. The negative electrode current collector may be in the form of a plate or foil, for example.

[0105] The negative electrode active material layer may further contain additives used in conventional all-solid-state batteries, such as fillers, dispersants, and ion conductive materials.

[0106] All-solid-state batteries can be manufactured, for example, by first manufacturing a positive electrode, a negative electrode, and a solid electrolyte layer, and then stacking these layers.

[0107] The present invention provides a battery module including the all-solid-state battery as a unit battery, a battery pack including the battery module, and a device including the battery pack as a power source.

[0108] Specific examples of the aforementioned devices include, but are not limited to, power tools powered by electric motors; electric vehicles including electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs); electric two-wheeled vehicles including electric bicycles (E-bikes) and electric scooters; electric golf carts; and power storage systems.

[0109] The following are specific embodiments of the present invention. However, the embodiments described below are merely for illustrative or explanatory purposes and do not limit the present invention. Furthermore, matters not described herein can be sufficiently inferred by technical analogy to those skilled in the art, and their explanations are omitted.

[0110] Manufacturing Example 1: Manufacturing of positive electrode active material for all-solid-state batteries (1) Li2CO3 and Ni 0.8 Co 0.1 Mn 0.1 (OH)2 was mixed in a mixer in a weight ratio of 1.1:1 to form a reaction mixture. This reaction mixture was then placed in a stainless steel crucible and subjected to primary heat treatment at 600°C in an air atmosphere for 6 hours to form a plastic mixture, after which it was cooled. After this, the mixture was crushed and sieved, and the crushed plastic mixture was placed in an aluminum crucible and subjected to secondary heat treatment at 800°C in an air atmosphere for 10 hours to produce the positive electrode active material.

[0111] (2) The positive electrode active material produced in (1) above was placed in a circular furnace (tube furnace) with an inner diameter of 50 mm and a length of 1,000 mm, and then heat-treated at 700°C to produce a positive electrode active material in which a first coating layer containing lithium carbon oxide Li2CO3 at an amount of 0.5 parts by weight relative to the total weight of the positive electrode active material was formed.

[0112] (3) Next, as precursors to lithium titanium oxide, titanium(IV) isopropoxide and lithium ethoxide are added in stoichiometric ratios and dissolved in ethanol to form Li4Ti5O 12 A solution is prepared. The positive electrode active material on which the first coating layer prepared in (2) is formed is prepared by the Li4Ti5O 12 A mixed solution is prepared by adding it to a solution. The mixed solution is mixed for 24 hours using a Lab Blender (Waring Inc.), then vacuum-dried to remove the solvent ethanol, and then placed in a circular furnace (tube furnace) with an inner diameter of 50 mm and a length of 1,000 mm, and heat-treated at 400°C for 4 hours to produce lithium titanium oxide (Li4Ti5O). 12 A positive electrode active material for an all-solid-state battery was manufactured, having a second coating layer formed on which the positive electrode active material was contained in an amount of 0.1 parts by weight relative to the total weight of the positive electrode active material.

[0113] Manufacturing Example 2: Manufacturing of positive electrode active material for all-solid-state batteries Lithium titanium oxide (Li4Ti5O) 12 A positive electrode active material for an all-solid-state battery was manufactured in the same manner as in Manufacturing Example 1, except that a second coating layer was formed containing 1.5 parts by weight of the positive electrode active material relative to the total weight of the positive electrode active material.

[0114] Manufacturing Example 3: Manufacturing of positive electrode active material for all-solid-state batteries A positive electrode active material for an all-solid-state battery was manufactured in the same manner as in Manufacturing Example 1, except that in step (1) above, a primary heat treatment was performed at 650°C to form a first coating layer containing 0.1 parts by weight of lithium carbon oxide, Li2CO3, relative to the total weight of the positive electrode active material.

[0115] Manufacturing Example 4: Manufacturing of positive electrode active material for all-solid-state batteries A positive electrode active material for an all-solid-state battery was manufactured in the same manner as in Manufacturing Example 1, except that in step (1) of Manufacturing Example 1, a primary heat treatment was performed at 700°C to form a first coating layer containing 1.6 parts by weight of lithium carbon oxide, Li2CO3, relative to the total weight of the positive electrode active material.

[0116] Comparative manufacturing example 1: Manufacturing of positive electrode active material for all-solid-state batteries (1) Li2CO3 and Ni 0.8 Co 0.1 Mn 0.1 (OH)2 was mixed in a mixer in a weight ratio of 1.1:1 to form a reaction mixture. This reaction mixture was then placed in a stainless steel crucible and subjected to primary heat treatment at 600°C in an air atmosphere for 5 hours to form a plastic mixture, after which it was cooled. After this, the mixture was crushed and sieved, and the crushed plastic mixture was placed in an aluminum crucible and subjected to secondary heat treatment at 800°C in an air atmosphere for 10 hours to produce the positive electrode active material. The produced positive electrode active material was charged into a circular furnace (tube furnace) with an inner diameter of 50 mm and a length of 1,000 mm, and then heat-treated at 700°C to completely remove the lithium carbon oxide, Li2CO3.

[0117] (2) Next, as precursors to lithium titanium oxide, titanium(IV) isopropoxide and lithium ethoxide are added in stoichiometric ratios and dissolved in ethanol to form Li4Ti5O 12 A solution is prepared. The positive electrode active material prepared in (1) above is prepared in Li4Ti5O 12 A mixed solution is prepared by adding it to a solution. The mixed solution is mixed for 24 hours using a Lab Blender (Waring Inc.), then vacuum-dried to remove the solvent ethanol, and then placed in a circular furnace (tube furnace) with an inner diameter of 50 mm and a length of 1,000 mm, and heat-treated at 400°C for 4 hours to produce lithium titanium oxide (Li4Ti5O). 12A positive electrode active material for all-solid-state batteries was manufactured in which only a coating layer containing 0.1 parts by weight of the positive electrode active material relative to the total weight of the positive electrode active material was formed.

[0118] Comparative manufacturing example 2: Manufacturing of positive electrode active material for all-solid-state batteries (1) Li2CO3 and Ni 0.8 Co 0.1 Mn 0.1 (OH)2 was mixed in a mixer in a weight ratio of 1.1:1 to form a reaction mixture. This reaction mixture was then placed in a stainless steel crucible and subjected to primary heat treatment at 600°C in an air atmosphere for 5 hours to form a plastic mixture, after which it was cooled. After this, the mixture was crushed and sieved, and the crushed plastic mixture was placed in an aluminum crucible and subjected to secondary heat treatment at 800°C in an air atmosphere for 10 hours to produce the positive electrode active material.

[0119] (2) The positive electrode active material produced in (1) above was placed in a circular furnace (tube furnace) with an inner diameter of 50 mm and a length of 1,000 mm, and then heat-treated at 700°C to produce a positive electrode active material for an all-solid-state battery in which only a coating layer containing Li2CO3, a lithium carbon oxide, at an amount of 0.5 parts by weight relative to the total weight of the positive electrode active material was formed.

[0120] Comparative manufacturing example 3: Manufacturing of positive electrode active material for all-solid-state batteries Lithium titanium oxide (Li4Ti5O) 12 A positive electrode active material for an all-solid-state battery was manufactured in the same manner as in Manufacturing Example 1, except that a second coating layer was formed containing 0.01 parts by weight of the positive electrode active material relative to the total weight of the positive electrode active material.

[0121] Comparative manufacturing example 4: Manufacturing of positive electrode active material for all-solid-state batteries Lithium titanium oxide (Li4Ti5O) 12 A positive electrode active material for an all-solid-state battery was manufactured in the same manner as in Manufacturing Example 1, except that a second coating layer was formed containing 2.0 parts by weight of the positive electrode active material relative to the total weight of the positive electrode active material.

[0122] Comparative manufacturing example 5: Manufacturing of positive electrode active material for all-solid-state batteries A positive electrode active material for an all-solid-state battery was manufactured in the same manner as in Manufacturing Example 1, except that a first coating layer containing 2.0 parts by weight of lithium carbon oxide, Li2CO3, relative to the total weight of the positive electrode active material was formed.

[0123] Comparative manufacturing example 6: Manufacturing of positive electrode active material for all-solid-state batteries (1) In the same manner as in Comparative Manufacturing Example 1, Li4Ti5O 12 A positive electrode active material for an all-solid-state battery was manufactured, having a first coating layer formed on which the positive electrode active material was contained in an amount of 0.1 parts by weight relative to the total weight of the positive electrode active material.

[0124] (2) Li2CO3 is added to ethanol to produce a Li2CO3 solution, and the positive electrode active material produced in (1) is added to the solution to produce a mixed solution. This is vacuum dried to remove the solvent ethanol, and a second coating layer containing 0.5 parts by weight of lithium carbon oxide Li2CO3 relative to the total weight of the positive electrode active material is formed to produce a positive electrode active material for an all-solid-state battery.

[0125] Example 1: Manufacturing of a positive electrode for an all-solid-state battery (1) 78 parts by weight of the positive electrode active material produced in Production Example 1, 19.5 parts by weight of Li6PS5Cl as a sulfide-based solid electrolyte, and vapor-grown carbon nanofibers (VGCF) as a conductive material. TM -H (Showa Denko Co.) 1.5 parts by weight and 1 part by weight of polytetrafluoroethylene (PTFE) as a binder were placed in a container and mixed for 1 minute at 5,000 rpm using a Lab Blender (Waring Co.) without using a separate solvent. Next, a shear force of 100 N was applied to the mixture and high-shear mixing (PBV-0.1 L, Irie Shokai Co.) was performed to produce a cathode slurry.

[0126] (2) A freestanding film was produced from the manufactured positive electrode slurry using a Two Roll Mill MR-3 (Inoue Corporation). The film was then placed on one surface of a 15 μm thick aluminum current collector and pressed to produce a positive electrode for an all-solid-state battery.

[0127] Examples 2-4: Manufacturing of positive electrodes for all-solid-state batteries Positive electrodes for all-solid-state batteries were manufactured according to Examples 2 to 4, in the same manner as in Example 1, except that the positive electrode active materials manufactured in Examples 2 to 4 were used instead of the positive electrode active material manufactured in Example 1.

[0128] Comparative Examples 1-6: Manufacturing of positive electrodes for all-solid-state batteries Positive electrodes for all-solid-state batteries were manufactured according to Comparative Examples 1 to 6, in the same manner as in Example 1, except that the positive electrode active materials manufactured in Comparative Examples 1 to 6 were used instead of the positive electrode active material manufactured in Manufacturing Example 1.

[0129] Experimental Example 1: EDX (Energy dispersive X-ray spectroscopy) analysis of positive electrode active material for all-solid-state batteries Energy dispersive X-ray spectroscopy (EDX) experiments were performed to measure the oxide components contained in the coating layer of the positive electrode active material for all-solid-state batteries manufactured according to Manufacturing Example 1, and the results are shown in Figure 3. The EDX measurement instrument used was the JSM7900F from JEOL.

[0130] As shown in Figure 3, in the case of the positive electrode active material for all-solid-state batteries manufactured by Manufacturing Example 1, it was found that the coating layer formed on the surface of the positive electrode active material simultaneously contained carbon and titanium elements.

[0131] Experimental Example 2: Evaluation of Initial Discharge Capacity and Lifetime Characteristics The initial discharge capacity and life characteristics of all-solid-state batteries including the positive electrode, based on Examples 1-4 and Comparative Examples 1-6, were evaluated.

[0132] The all-solid-state battery uses a 40 μm thick lithium metal negative electrode, and a 50 μm thick Li6PS5Cl solid electrolyte membrane is interposed between the positive electrode and the negative electrode manufactured in Examples 1-4 and Comparative Examples 1-6. This is then pressurized to a pressure of 500 MPa, and the battery has a driving pressure of 3 MPa and a power output of 5 mAh / cm². 2 We used products manufactured in a jig cell form with a defined capacity.

[0133] (1) Evaluation of the initial discharge capacity of all-solid-state batteries The charge-discharge characteristics of the all-solid-state batteries including the positive electrode according to Examples 1-4 and Comparative Examples 1-6 were evaluated by the following charge-discharge tests.

[0134] The battery was charged at a rate of 0.1C until the voltage reached 4.25V (vs. Li), and then cut off at a rate of 0.05C while maintaining the voltage at 4.25V (vs. Li). Subsequently, it was discharged at a rate of 0.1C until the voltage reached 3.0V (vs. Li). st (Cycle). The results are shown in Table 1 below.

[0135] Referring to Table 1, it was confirmed that the all-solid-state batteries according to Examples 1-4 exhibited higher reversible capacity and energy density compared to the all-solid-state batteries according to Comparative Examples 1-6. In particular, it can be seen that when the positive electrode active material does not contain the first coating layer (Comparative Example 1), or when the lithium carbon oxide content in the first coating layer exceeds a certain range (Comparative Example 5), the reversible capacity and energy density are significantly reduced compared to the all-solid-state batteries according to the examples.

[0136] (2) Evaluation of the life characteristics of all-solid-state batteries The lifespan characteristics of the all-solid-state batteries including the positive electrode according to Examples 1-4 and Comparative Examples 1-6 were evaluated by the following charge-discharge tests.

[0137] The battery was charged at a rate of 0.1C until the voltage reached 4.25V (vs. Li), and then cut off at a rate of 0.05C while maintaining the voltage at 4.25V (vs. Li). Subsequently, it was discharged at a rate of 0.1C until the voltage reached 3.0V (vs. Li). st The above charge-discharge test was repeated 50 times, and the capacity retention rate of the discharge capacity was measured. The results are shown in Table 1 below.

[0138] Referring to Table 1, it can be seen that the all-solid-state batteries containing the positive electrodes according to Examples 1-4 exhibited significantly improved lifespan characteristics compared to the all-solid-state batteries containing the positive electrodes according to Comparative Examples 1-6. This is presumed to be because the positive electrodes in the examples contain a positive electrode active material comprising a first coating layer containing lithium carbon oxide and a second coating layer containing lithium titanium oxide, which reduces the interfacial resistance between the sulfide-based solid electrolytes in the positive electrode active material layer and suppresses side reactions.

[0139] [Table 1]

[0140] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto. Various modifications and improvements by those skilled in the art, using the basic concepts of the present invention as defined in the following claims, also fall within the scope of the present invention. [Explanation of symbols]

[0141] 1: Positive electrode active material core 3: Positive electrode active material coating layer 5: First coating layer of positive electrode active material 7: Second coating layer of positive electrode active material 10: Positive electrode active material for all-solid-state batteries 20: Positive electrode active material for all-solid-state batteries

Claims

1. A core capable of reversible intercalation and deintercalation of lithium ions; and The coating layer formed on the surface of the core is included, The aforementioned coating layer contains lithium carbon oxide represented by the following chemical formula 1 and lithium titanium oxide represented by the following chemical formula 2. Cathode active material for all-solid-state batteries: [Chemical formula 1] Li ａ CO ｂ In the above chemical formula 1, a is 0 < a ≤ 4 and b is 0 < b ≤ 4; [Chemical formula 2] Li ｘ Ti ｙ O ４ In the above chemical formula 2, x is 0.8 ≤ x ≤ 1.4 and y is 1.6 ≤ y ≤ 2.

2.

2. The coating layer includes a first coating layer and a second coating layer, respectively, extending from the center of the core toward the surface of the core. The first coating layer contains a lithium carbon oxide represented by the chemical formula 1, The second coating layer contains lithium titanium oxide represented by the chemical formula 2, The positive electrode active material for an all-solid-state battery according to claim 1.

3. The coating layer is included in an amount of 0.1 to 10 parts by weight, based on 100 parts by weight of the total positive electrode active material for the all-solid-state battery, which includes both the core and the coating layer. The positive electrode active material for an all-solid-state battery according to claim 1.

4. The lithium carbon oxide represented by chemical formula 1 is included in an amount of 0.1 to 1.6 parts by weight based on 100 parts by weight of the total positive electrode active material for the all-solid-state battery, including both the core and the coating layer. The positive electrode active material for an all-solid-state battery according to claim 1.

5. The lithium titanium oxide represented by chemical formula 2 is included in an amount of 0.1 to 1.5 parts by weight based on 100 parts by weight of the total positive electrode active material for the all-solid-state battery, including both the core and the coating layer. The positive electrode active material for an all-solid-state battery according to claim 1.

6. The lithium carbon oxide represented by chemical formula 1 and the lithium titanium oxide represented by chemical formula 2 contained in the coating layer are present in a weight ratio of 95:5 to 25:

75. The positive electrode active material for an all-solid-state battery according to claim 1.

7. The thickness ratio of the first coating layer to the second coating layer is 20:80 to 80:

20. The positive electrode active material for an all-solid-state battery according to claim 2.

8. The thickness of the first coating layer is 0.001 to 0.02 μm. The thickness of the second coating layer is 0.001 to 0.02 μm. The positive electrode active material for an all-solid-state battery according to claim 2.

9. The lithium carbon oxide is Li ２ CO ３ And, The lithium titanate is Li ４ Ti ５ O １２ and is The positive electrode active material for an all-solid-state battery according to claim 1.

10. Positive electrode active material for all-solid-state batteries according to any one of claims 1 to 9; and Contains sulfide-based solid electrolytes, Positive electrode for all-solid-state batteries.

11. The sulfide-based solid electrolyte is Li ２ S-P ２ S ５ Li ２ S-P ２ S ５ -LiX (where X is a halogen element), Li ２ S-P ２ S ５ -Li ２ O, Li ２ S-P 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 S-B ２ S ３ Li ２ S-P ２ S ５ -Z ｍ S ｎ (where m and n are positive numbers, and Z is one of Ge, Zn, or Ga), Li ２ S-GeS ２ Li ２ S-SiS ２ -Li ３ PO ４ Li ２ S-SiS ２ -Li ｐ MO ｑ (where p and q are positive numbers, and M is one of P, Si, Ge, B, Al, Ga, or In), Li ７－ｘ PS ６－ｘ Cl ｘ (However, 0 ≤ x ≤ 2), Li ７－ｘ PS ６－ｘ Br ｘ (wherein 0 ≤ x ≤ 2) and Li ７－ｘ PS ６－ｘ I ｘ (where 0 ≤ x ≤ 2) is one or more selected from the above. Positive electrode for all-solid-state battery according to claim 10.

12. The aforementioned sulfide-based solid electrolyte is Li ６ PS ５ Cl, Li ６ PS ５ Br and Li ６ PS ５ An argyrodite-type solid electrolyte containing one or more selected from I, Positive electrode for all-solid-state battery according to claim 10.

13. positive electrode; Negative electrode; and It includes a solid electrolyte layer disposed between the positive electrode and the negative electrode, The positive electrode includes the positive electrode for a solid-state battery described in claim 10. All-solid-state battery.

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