Method for manufacturing a positive electrode material and a positive electrode containing the positive electrode material manufactured thereby.

Abstract

To provide a manufacturing method of a positive electrode material and a positive electrode material produced by the method of substituting a more economical solvent for an organic solvent used in a surface modification process of coating the surface of lithium oxide particles with a lithium ion conductor.SOLUTION: A manufacturing method of a positive electrode material includes a step of adding, mixing, and dissolving a coating material raw material containing lithium (Li) and niobium (Nb) to a solvent containing water to produce a coating liquid, a step of injecting the coating liquid onto the surface of lithium oxide particles to form a coating layer, and a step of heat-treating the coating layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a positive electrode material and a positive electrode including the positive electrode material manufactured thereby. More specifically, the present invention is characterized by providing a manufacturing method that improves the efficiency of the process while improving the positive electrode performance in view of the practical application of all-solid-state batteries when manufacturing a positive electrode for an all-solid-state battery.

Background Art

[0002] The positive electrode material for an all-solid-state battery is used after undergoing a surface modification process in which a lithium ion conductor such as LiNbO3, Li4Ti5O 12 is uniformly coated to a thickness of several nanometers on the surface of Li(Ni / Co / Mn)O2 lithium oxide powder having a layered crystal structure. In particular, the LiNbO3 surface coating layer significantly reduces the migration resistance of lithium ions by the "space charge layer mechanism" to improve the battery capacity and output performance, or suppresses the chemical reaction between different materials between the oxide (positive electrode) and sulfide (electrolyte) in the positive electrode composite layer to maintain the life (K. Takada, "LiNbO3-coated LiCoO2 as cathode material for all solid-state lithium secondary batteries"). However, the current positive electrode surface coating technology has problems that the interfacial resistance between the positive electrode and the electrolyte occupies 70% or more in the resistance components of the entire all-solid-state battery cell, and the current "positive electrode surface coating" cost (coating raw material price / coating process cost) is at the level of 20 to 40% of the current price composition of all-solid-state batteries.

Summary of the Invention

Problems to be Solved by the Invention

[0003] According to the present invention, an object is to provide a method for substituting an organic solvent used during a surface modification process of coating a lithium ion conductor on the surface of existing lithium oxide-based particles contained in a positive electrode material with a more economical solvent.

[0004] The present invention aims to improve the uniformity of the coating layer when coating the surface of lithium oxide particles with a lithium ion conductor using a water-based solvent.

[0005] The objectives of the present invention are not limited to those described above. The objectives of the present invention will become clearer from the following description and will be realized by the means and combinations described in the claims. [Means for solving the problem]

[0006] The present invention provides a method for producing a positive electrode material, comprising the steps of: preparing a coating solution by adding, mixing, and dissolving coating material raw materials containing lithium (Li) and niobium (Nb) in a solvent containing water (H2O); forming a coating layer by spraying the coating solution onto the surface of lithium oxide particles; and heat-treating the coating layer.

[0007] An auxiliary agent may be further added to the solvent, and the auxiliary agent may contain at least one of ammonia (NH3) and a surfactant.

[0008] The aforementioned auxiliary agent may be present in an amount of 0.001 to 0.30 parts by weight based on 100 parts by weight of the solvent.

[0009] The surfactant may include at least one of an anionic surfactant and a nonionic surfactant.

[0010] The coating solution may contain lithium at a concentration of 1 M to 10 M and niobium at a concentration of 1 M to 10 M.

[0011] The molar ratio of lithium and niobium contained in the coating solution may be Li / Nb = 0.9 to 1.2.

[0012] The steps for manufacturing the coating solution may include an input step of adding coating material raw materials to a solvent containing water, a dissolution step of dissolving the coating material raw materials in the solvent, and a neutralization step of adding hydroxide to the solvent to carry out a neutralization reaction.

[0013] In the input step, hydrogen peroxide (H2O2) is added along with the coating material raw materials to create a weakly acidic environment, and in the dissolution step, ammonia (NH3) is added to the solvent to create a strongly alkaline environment, in which case the coating material raw materials dissolve in the solvent.

[0014] The coating material raw materials introduced may have varying solubility depending on the hydrogen ion concentration of the solvent, and the hydrogen ion concentration of the solvent may be adjusted using the introduced hydrogen peroxide, ammonia, and hydroxide.

[0015] The hydrogen ion concentration in the input step may be pH 3 or less, the hydrogen ion concentration in the dissolution step may be pH 3 to pH 12, and the hydrogen ion concentration in the neutralization step may be pH 6 to pH 8.

[0016] In the step of forming the coating layer, the coating liquid may be sprayed onto the surface of lithium oxide particles by a spray coating method and adhered to them.

[0017] In the heat treatment step, the heat treatment may be carried out at a temperature of 300°C to 450°C.

[0018] The present invention provides a positive electrode characterized by comprising a positive electrode material containing lithium oxide-based particles manufactured by the manufacturing method described in claim 1 and having a coating layer formed on its surface, and at least one additive of a solid electrolyte, a conductive material, and a binder.

[0019] The thickness of the coating layer included in the positive electrode material may be 3 nm to 50 nm.

[0020] The positive electrode material may contain lithium and at least two or more elements of nickel (Ni), cobalt (Co), manganese (Mn), and aluminum (Al).

[0021] According to the present invention, there is provided an all-solid-state battery including the positive electrode, a negative electrode containing carbon, and a solid electrolyte interposed between the positive electrode and the negative electrode.

Effects of the Invention

[0022] According to the present invention, it is possible to provide a method for replacing an organic solvent used during a surface modification process of coating a surface of existing lithium oxide-based particles contained in a positive electrode material with a more economical solvent.

[0023] According to the present invention, when coating a lithium ion conductor on the surface of lithium oxide-based particles using a water-based solvent, the uniformity of the coating layer can be improved.

[0024] The effects of the present invention are not limited to the effects described above. It should be understood that the effects of the present invention include all effects that can be inferred in the following description.

Brief Description of the Drawings

[0025] [Figure 1] It is a diagram briefly showing a process of manufacturing the positive electrode material of the present invention. [Figure 2] It is a diagram showing a flowchart regarding a manufacturing method of the positive electrode material of the present invention. [Figure 3] It is a diagram obtained by observing the surface of the positive electrode material manufactured in Example 1 by Auger electron spectroscopy (AES).

Embodiments for Carrying Out the Invention

[0026] The above-described objects, other objects, features, and advantages of the present invention will be readily apparent through the following preferred embodiments relating to the attached drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in many other forms. Rather, the embodiments presented herein are provided to ensure that the disclosed content is thorough and complete, and that the idea of ​​the present invention is fully conveyed to the ordinary person in the art.

[0027] In describing each drawing, similar reference numerals were used for similar components. In the attached drawings, the dimensions of the structures are shown enlarged for clarity of the invention. Terms such as "first," "second," etc., are used to describe various components, but the components should not be limited by such terms. The terms are used solely for the purpose of distinguishing one component from another. For example, without departing the scope of the invention, the first component may be named the second component, and similarly, the second component may be named the first component. Singular expressions include plural expressions unless the context clearly indicates otherwise.

[0028] In this specification, terms such as “includes” or “have” are intended to indicate the presence of features, figures, stages, actions, components, parts, or combinations thereof described in the specification, and should be understood not to preemptively exclude the possibility of the presence or addition of one or more other features, figures, stages, actions, components, parts, or combinations thereof. Furthermore, when a part such as a layer, film, region, or plate is said to be “on top” of another part, this includes not only when it is “directly on top” of the other part, but also when there are other parts in between. Conversely, when a part such as a layer, film, region, or plate is said to be “below” another part, this includes not only when it is “directly below” the other part, but also when there are other parts in between.

[0029] Unless otherwise explicitly stated, all numbers, values, and / or expressions used herein to describe the quantities of components, reaction conditions, polymer compositions, and formulations should be understood to be approximate in all cases, as they reflect the various uncertainties of measurement that arise in obtaining these values ​​among essentially different numbers. Furthermore, where numerical ranges are disclosed herein, such ranges are continuous and, unless otherwise noted, include all values ​​from the minimum to the maximum value within such range. Additionally, where such ranges refer to integers, unless otherwise noted, include all integers from the minimum to the maximum value within such range.

[0030] In this specification, when a range is described for a variable, it will be understood that the variable includes all values ​​within the described range, including the described endpoint of the range. For example, the range "5 to 10" will be understood to include not only the values ​​5, 6, 7, 8, 9, and 10, but also any sub-ranges such as 6 to 10, 7 to 10, 6 to 9, 7 to 9, and any values ​​between integers that are appropriate within the range, such as 5.5, 6.5, 7.5, 5.5 to 8.5, and 6.5 to 9. Similarly, the range "10% to 30%" will be understood to include not only all integers up to 30% and values ​​such as 10%, 11%, 12%, 13%, and any sub-ranges such as 10% to 15%, 12% to 18%, and 20% to 30%, but also any values ​​between integers that are appropriate within the range, such as 10.5%, 15.5%, and 25.5%.

[0031] This invention relates to a method for manufacturing a positive electrode material and a positive electrode containing the positive electrode material manufactured thereby. The method for manufacturing a positive electrode material according to the present invention will be described below with reference to Figures 1 and 2, and then a positive electrode containing the positive electrode material manufactured by the above method will be described.

[0032] Manufacturing method for positive electrode material The present invention is characterized by comprising the steps of: preparing a coating solution by adding, mixing, and dissolving coating material raw materials containing lithium (Li) and niobium (Nb) in a solvent containing water (H2O); forming a coating layer by spraying the coating solution onto the surface of lithium oxide particles; and heat-treating the coating layer.

[0033] The following steps will be explained with reference to Figures 1 and 2.

[0034] Coating liquid manufacturing step S1 This step involves adding, mixing, and dissolving coating material raw materials containing lithium (Li) and niobium (Nb) in a solvent containing water (H2O) to produce a coating solution.

[0035] The solvent preferably consists only of pure water (H2O).

[0036] The present invention aims to reduce the process cost of all-solid-state batteries by using only water as the solvent for the coating solution. Therefore, its ultimate goal is to improve the problems associated with using water as a solvent and, as a result, provide a method for manufacturing a superior performing cathode.

[0037] The coating material raw material contains a substance that reduces the resistance of lithium ion movement, and contains lithium (Li) and niobium (Nb), preferably lithium hydroxide (LiOH) and niobium acid (Nb2O2·3H2O).

[0038] The aforementioned coating material raw material is highly soluble in organic solvents but insoluble in water. Therefore, an auxiliary agent is further added to the solvent to ensure the smooth dissolution of the coating material raw material.

[0039] The auxiliary agent comprises at least one of ammonia (NH3) and a surfactant, preferably both ammonia and a surfactant. In this case, the auxiliary agent is preferably present in an amount of 0.001 to 0.3 parts by weight, and more preferably 0.01 to 0.1 parts by weight, based on 100 parts by weight of the solvent.

[0040] The surfactant is used to suppress a decrease in coating uniformity when coating lithium oxide particles 10 with a coating solution using water as the solvent. This coating non-uniformity is a fundamental limitation that arises from using water as a solvent, which has a higher surface tension compared to organic solvents such as ethanol. In this invention, it is essential to introduce an optimal surfactant to overcome this limitation.

[0041] The surfactant preferably includes at least one of an anionic surfactant and a nonionic surfactant. In this case, it is preferable to exclude cationic surfactants, because cationic surfactants can change their charge properties depending on the hydrogen ion concentration (pH) environment, or it may be difficult to sensitively adjust the surface tension of the solvent. In particular, if the range of change in charge properties is large, they may react with the material that modifies the physical properties of the positive electrode material surface or generate residues, so the type of surfactant must be selected taking these points into consideration.

[0042] The aforementioned anionic surfactant may contain anionic groups such as sulfates, sulfonates, phosphates, and carboxylates in its hydrophilic molecular ring. Typical examples of sulfates include ammonium lauryl sulfate, sodium lauryl sulfate, alkyl polyoxyethylene sulfate, alkylnaphthalene sulfate, and alkyl ether sulfate, while examples of phosphates may include phosphate phosphate, ethanolamine phosphate, phosphate chloride, and sphingomyelin.

[0043] The aforementioned nonionic surfactant has a structural form in which there is no charge within the hydrophilic ring, but generally contains oxygen within the hydrophilic group through hydrogen bonding. Typical examples include polysorbate-based, sorbitan-based, phenyl ether-based, and polyethylene glycol-based surfactants, and as an example, polyoxyethylene distyrenated polyethylene can be used, but is not limited to these.

[0044] In the present invention, it is preferable to use a nonionic surfactant. This is because the change in surface charge is minimized even when the surfactant is adsorbed onto the surface of the lithium oxide particles 10 or the coating layer 20. This suppresses side reactions such as the diffusion of transition metals on the surface of the positive electrode material, and also reduces the possibility of inhibiting crystal growth due to valence deformation during the crystallization process after the lithium niobium oxide (LiNbO3) is dissolved in the coating solution and formed on the coating layer 20.

[0045] The surfactant most preferably used is a phenyl ether-based nonionic surfactant.

[0046] The mixing is preferably carried out at a temperature of 50°C to 70°C for a period of time from 0.5 hours to 4 hours.

[0047] The coating liquid manufacturing step S1 of the present invention is further divided into an input step S1-1 in which coating material raw materials are added to a solvent containing water, a dissolution step S1-2 in which the coating material raw materials are dissolved in the solvent, and a neutralization step S1-3 in which hydroxide is added to the solvent to cause a neutralization reaction.

[0048] The hydrogen ion concentration of the solvent can be changed by the influence of the auxiliary agents or reactions introduced in each of the aforementioned steps.

[0049] The present invention is characterized by optimally adjusting the hydrogen ion concentration at each of the steps described above, and by finely controlling variables such as reaction time and reaction temperature.

[0050] Input step S1-1 This step involves adding coating material raw materials to a solvent containing water.

[0051] The solvent may contain hydrogen peroxide (H2O2), and preferably, the solvent has a weakly acidic environment. In this case, the hydrogen ion concentration of the solvent is pH 3 or less.

[0052] The coating material raw materials used are those containing lithium and niobium that are completely soluble in water, preferably lithium hydroxide and niobium acid. The amount of raw materials added is preferably 0.05 M to 0.3 M each of lithium and niobium, based on the molar concentration (M), which represents the molar ratio of elements per liter, and is more preferably manufactured at a solution concentration of 0.1 M to 0.2 M.

[0053] Dissolution step S1-2 This is a dissolution step in which the coating material raw materials are dissolved in a solvent.

[0054] In this invention, ammonia (NH3) is added to the solvent to create a strongly alkaline environment in order to smoothly dissolve the coating material raw materials in the solvent. The reason for adjusting the solvent environment to a strongly alkaline environment as described above is that the solvent of this invention is essentially water-based, and it is difficult to dissolve the coating material raw materials containing niobium acid in water without any additional processing.

[0055] The hydrogen ion concentration of the solvent is preferably adjusted to a pH of 3 to 12, and more preferably to a pH of 8 to 11. Only when the hydrogen ion concentration of the solvent is adjusted to a strongly alkaline environment, as described above, can the coating material raw materials dissolve smoothly in the solvent.

[0056] However, even if the coating material raw materials dissolve in the solvent, if fine adjustments to the hydrogen ion concentration and reaction temperature are not made, a localized reprecipitation reaction occurs, generating niobium oxide (Nb2O5) precipitate.

[0057] Since the precipitate is a very stable substance and can act as a resistor at the interface between the positive electrode and the solid electrolyte, the hydrogen ion concentration, reaction temperature, and reaction time must be adjusted to a preferred range at each step of the process.

[0058] Neutralization Step S1-3 This step involves adding hydroxide to the solvent to carry out a neutralization reaction.

[0059] The addition of the hydroxide preferably adjusts the hydrogen ion concentration of the solvent to pH 6 to pH 8. The hydroxide preferably contains lithium hydroxide, which not only plays a role in slowly neutralizing the solvent environment so that it does not become acidic, but also provides a direct raw material for the coating layer 20 that is later formed.

[0060] After the neutralization reaction is completely carried out, a coating solution can be obtained in which the coating material raw materials are completely dissolved in the solvent.

[0061] The coating solution contains lithium at a concentration of 1 M to 10 M and niobium at a concentration of 1 M to 10 M.

[0062] The molar ratio of lithium to niobium contained in the coating liquid is preferably Li / Nb = 0.9 to 1.2. More preferably, the molar ratio is Li / Nb = 1.0 to 1.1.

[0063] Coating layer 20 formation step S2 This step involves spraying a coating liquid onto the surface of lithium oxide particles 10 to form a coating layer 20.

[0064] In the present invention, the spraying of the coating liquid, the formation of the coating layer 20, and the drying of the coating layer 20 are performed simultaneously. That is, in the step of forming the coating layer 20, the spraying of the coating liquid and the formation of the coating layer 20 must occur simultaneously with the rapid evaporation of the solvent by drying to enable the formation of a uniform coating layer 20 by thermal hydrolysis.

[0065] Referring to Figure 1, it can be seen that a coating layer 20 is formed on the surface of the lithium oxide particles 10.

[0066] The lithium oxide-based particles 10 may include, but are not limited to, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium cobalt oxide, lithium manganese oxide, and any lithium oxide-based material applicable to the positive electrode in the field of all-solid-state battery technology.

[0067] Preferably, the coating liquid is sprayed onto the surface of the lithium oxide particles 10 by a spray coating method in which the spraying, coating, and drying of the coating liquid are performed simultaneously.

[0068] In the present invention, the environment in the coating layer 20 formation step, in which coating and drying are performed, is 60°C to 150°C and 0.20 m 3 / min~0.60m 3 It is preferable that the airflow is at a rate of / min. Furthermore, it is preferable that the injection is carried out at a speed of 2g / min to 20g / min. This corresponds to a specific gravity of 1.0g / cm³. 3 This takes into account the properties of water, which has a boiling point of 100°C and a latent heat of vaporization of 500 cal / g or more, and can be changed depending on the type of process.

[0069] Heat treatment step S3 This step involves heat-treating the coating layer 20 formed on the surface of lithium oxide particles 10 to promote crystallization of the coating layer 20 as shown in Figure 1, thereby obtaining a crystalline coating layer 21. The heat treatment is preferably carried out at a temperature of 300°C to 450°C.

[0070] Cathode material The present invention makes it possible to obtain a positive electrode material by the manufacturing method described above.

[0071] The positive electrode material is characterized by having a core-shell configuration in which lithium oxide-based particles 10 are contained in the core and a coating layer 20 is formed on the shell. In this case, the thickness of the coating layer contained in the positive electrode material is preferably 5 nm to 50 nm.

[0072] The positive electrode material of the present invention is characterized by containing lithium and at least two elements of nickel (Ni), cobalt (Co), manganese (Mn), and aluminum (Al).

[0073] positive electrode The positive electrode of the present invention comprises the positive electrode material and additives of the present invention.

[0074] The additive may, but is not limited to, include at least one of a solid electrolyte, a conductive material, and a binder.

[0075] all solid state battery The all-solid-state battery of the present invention is characterized by comprising a positive electrode, a negative electrode containing carbon, and a solid electrolyte interposed between the positive electrode and the negative electrode.

[0076] In the present invention, there are no particular limitations on the type of solid electrolyte; any material that is fully usable in the field of all-solid-state battery technology is sufficient.

[0077] The negative electrode may further include, but is not limited to, a solid electrolyte, a conductive material, and a binder.

[0078] The present invention will be described in more detail below through specific examples. However, these examples are for illustrative purposes only, and the scope of the present invention is not limited thereto.

[0079] Example 1 Using 100 parts by weight of water containing hydrogen peroxide as a base, 40 parts by weight of niobium acid was added, and ammonia was added and mixed until the hydrogen ion concentration reached pH 10. Subsequently, lithium hydroxide was added to allow the neutralization reaction to proceed, and the reaction was terminated. A coating solution containing lithium and niobium in a molar ratio of 1:1 was then prepared.

[0080] The manufactured coating liquid was sprayed into a rolling fluidized bed spray coater (Powrex MP-01) containing lithium oxide particles. At this time, the temperature was 140°C and 0.40 m 3 While circulating lithium oxide particles at an airflow rate of / min, the coating liquid was sprayed at a rate of 4g / min to a thickness of 5nm.

[0081] Subsequently, the coated cathode material is heat-treated at 350°C to crystallize the coating layer. The cathode material containing the coating layer is then placed in a solvent together with the conductive material and binder and mixed, resulting in a concentration of 15 mg / cm³. 2 A thin-film cathode with a certain level of loading capacity was manufactured. At this time, the cathode material on which the coating layer was formed was observed by Auger electron spectroscopy (AES) as shown in Figure 3, and it was confirmed that the coating was performed uniformly.

[0082] Furthermore, graphite active material, solid electrolyte, and binder were added to a solvent, mixed, and coated to produce a negative electrode. Subsequently, the negative and positive electrodes were punched out into 13 mm diameter discs, and solid electrolyte powder was placed between the electrodes to assemble an all-solid-state battery evaluation cell.

[0083] Example 2 A cathode material was manufactured using the same process as in Example 1, except that 0.125 parts by weight of a nonionic surfactant (polyoxyethylene distyrenated polyethylene) was added along with niobic acid and ammonia, based on 100 parts by weight of water as in Example 1, and an all-solid-state battery evaluation cell was assembled.

[0084] Example 3 A cathode material was manufactured using the same process as in Example 1, except that 0.125 parts by weight of a nonionic surfactant (polyoxyethylene alkyl ether type) was added along with niobic acid and ammonia, based on 100 parts by weight of water as in Example 1, and an all-solid-state battery evaluation cell was assembled.

[0085] Example 4 A cathode material was manufactured using the same process as in Example 1, except that 0.125 parts by weight of an anionic surfactant (sodium alkylnaphthalene sulfate) was added along with niobic acid and ammonia, based on 100 parts by weight of water as in Example 1, and an all-solid-state battery evaluation cell was assembled.

[0086] Example 5 A cathode material was manufactured using the same process as in Example 1, except that 0.125 parts by weight of an anionic surfactant (alkyl polyoxyethylene sulfate) was added along with niobic acid and ammonia, based on 100 parts by weight of water as in Example 1, and an all-solid-state battery evaluation cell was assembled.

[0087] Comparative Example 1 An all-solid-state battery evaluation cell was assembled using the same process as in Example 1, except that no other coating solution was applied to the lithium oxide particles.

[0088] Comparative Example 2 The all-solid-state battery evaluation cell was assembled using the same process as in Example 1, except that ethanol was used as the solvent instead of water.

[0089] Comparative Example 3 A cathode material was manufactured using the same process as in Example 1, except that 0.125 parts by weight of a cationic surfactant (alkylbenzylmethylammonium salt) was added along with niobic acid and ammonia, based on 100 parts by weight of water as in Example 1, and an all-solid-state battery evaluation cell was assembled.

[0090] Comparative Example 4 A cathode material was manufactured using the same process as in Example 1, except that 0.125 parts by weight of an amphoteric surfactant (alkyl carboxybetaine) was added along with niobic acid and ammonia, based on 100 parts by weight of water as in Example 1, and an all-solid-state battery evaluation cell was assembled.

[0091] Experimental example (DC-IR) The discharge capacity and DC-IR values ​​were measured for the all-solid-state battery evaluation cells of Examples 1 to 6 and Comparative Examples 1 to 4, and the results are shown in Table 1 below. [Table 1]

[0092] The results in Table 2 show that Example 1, which uses water as the solvent, has superior discharge capacity compared to Comparative Example 2, which uses ethanol as the solvent.

[0093] A solid-state battery evaluation cell (Comparative Example 1) manufactured using lithium oxide particles as the cathode material without applying the coating solution of the present invention exhibits low discharge capacity and very high resistance.

[0094] Furthermore, it has been found that when coating solutions containing anionic and nonionic surfactants are used, they exhibit superior discharge capacity and lower resistance compared to when other surfactants are used. In particular, it can be confirmed that the lowest resistance value is observed when nonionic surfactants are applied to the coating solution. [Explanation of Symbols]

[0095] 10: Lithium oxide particles 20: Coating layer 21: Crystalline coating layer

Claims

1. Water (H ２ A step of preparing a coating solution by adding, mixing, and dissolving coating material raw materials containing lithium (Li) and niobium (Nb) to a solvent containing O), The steps include: spraying the coating liquid onto the surface of lithium oxide particles to form a coating layer; The step includes heat-treating the coating layer, Further additives are added to the aforementioned solvent. The aforementioned auxiliary agent contains a surfactant, A method for producing a cathode material, characterized in that the surfactant comprises at least one of an anionic surfactant and a nonionic surfactant.

2. The method for producing a positive electrode material according to claim 1, wherein the auxiliary agent is contained in an amount of 0.001 to 0.30 parts by weight based on 100 parts by weight of the solvent.

3. The coating solution contains lithium at a concentration of 1 M to 10 M. A method for producing a cathode material according to claim 1, comprising niobium at a concentration of 1 M to 10 M.

4. The method for producing a positive electrode material according to claim 1, wherein the molar ratio of lithium and niobium contained in the coating liquid is Li / Nb = 0.9 to 1.

2.

5. The steps for manufacturing the coating solution include an input step in which coating material raw materials are added to a solvent containing water, A dissolution step in which coating material raw materials are dissolved in the solvent, A method for producing a cathode material according to claim 1, comprising a neutralization step of adding a hydroxide to the solvent and causing a neutralization reaction.

6. In the input step, hydrogen peroxide (H) is added along with the coating material raw materials. ２ O ２ ) is added, creating a slightly acidic environment. In the dissolution step, ammonia (NH) is added to the solvent. ３ ) is added to create a strongly alkaline environment, The method for producing a cathode material according to claim 5, wherein the coating material raw material dissolves in the solvent in the strongly alkaline environment.

7. The coating material raw materials introduced change in solubility depending on the environment of the hydrogen ion concentration of the solvent. The method for producing a cathode material according to claim 5, wherein the hydrogen ion concentration of the solvent is adjusted using the hydrogen peroxide, ammonia, and hydroxide introduced.

8. The hydrogen ion concentration in the input step is pH 3 or less. The hydrogen ion concentration during the dissolution step is pH 3 to pH 12. The method for producing a cathode material according to claim 5, wherein the hydrogen ion concentration in the neutralization step is pH 6 to pH 8.

9. The method for manufacturing a positive electrode material according to claim 1, wherein in the step of forming a coating layer, the coating liquid is sprayed onto the surface of lithium oxide particles by a spray coating method and adheres to them.

10. The method for manufacturing a cathode material according to claim 1, wherein in the heat treatment step, the heat treatment is performed at a temperature of 300°C to 450°C.

11. A step of preparing a positive electrode material by the manufacturing method described in Claim 1, A method for manufacturing a positive electrode, comprising the steps of: manufacturing a positive electrode comprising the positive electrode material, lithium oxide-based particles having a coating layer formed on their surface, and at least one additive of a solid electrolyte, a conductive material, and a binder.

12. The method for manufacturing a positive electrode according to claim 11, wherein the thickness of the coating layer contained in the positive electrode material is 3 nm to 50 nm.

13. The method for producing a positive electrode according to claim 11, wherein the positive electrode material comprises lithium and at least two elements: nickel (Ni), cobalt (Co), manganese (Mn), and aluminum (Al).

14. A step of preparing a positive electrode by the method described in Claim 11, A method for manufacturing an all-solid-state battery, comprising the steps of manufacturing an all-solid-state battery comprising a positive electrode, a negative electrode containing carbon, and a solid electrolyte interposed between the positive electrode and the negative electrode.

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