Coated active material and method for manufacturing coated active material

Abstract

To provide a coated active material that can suppress an increase in battery resistance.SOLUTION: A coated active material includes an electrode active material and a coating layer that coats the electrode active material, and the coating layer contains an oxide solid electrolyte that includes Li, P, and O elements, and the particle diameter (D50) of the coated active material is 5.5 μm or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a coated active material and a method for manufacturing the coated active material. [Background technology]

[0002] In recent years, the development of batteries has been actively pursued. For example, in the automotive industry, development of batteries for use in electric vehicles (BEVs), plug-in hybrid vehicles (PHEVs), and hybrid electric vehicles (HEVs) is underway. It is also known to coat the surface of the electrode active material used in batteries with a coating layer.

[0003] For example, Patent Document 1 discloses composite particles including positive electrode active material particles and a coating film containing a phosphorus compound, which coats at least a portion of the surface of the positive electrode active material particles. Patent Document 1 also discloses a method for producing composite particles by mixing positive electrode active material particles with an aqueous coating liquid containing phosphorus (aqueous coating liquid) and drying the mixture. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-136763 Summary of the Invention [Problem to be solved by the invention]

[0005] From the viewpoint of chemical stability and ionic conductivity of the coating film (coating layer), the use of phosphorus (P) in the coating layer has been considered. However, compounds used as phosphorus sources, such as phosphoric acid, have high viscosity, which can cause aggregation during the formation of the coating layer, potentially increasing the particle size of the coated active material. An increase in the particle size of the coated active material can increase the battery resistance.

[0006] The present disclosure has been made in view of the above circumstances, and has as its main object to provide a coated active material that can suppress an increase in battery resistance. [Means for solving the problem]

[0007] [1] A coated active material having an electrode active material and a coating layer that coats the electrode active material, the coating layer contains an oxide solid electrolyte containing Li, P, and O elements; The particle diameter of the coated active material (D 50 ) is 5.5 μm or less.

[0008] [2] The particle diameter (D 50 ) is 1.0 μm or more.

[0009] [3] The coated active material according to [1] or [2], wherein the oxide solid electrolyte further contains a B element or a La element.

[0010] [4] A method for producing a coated active material according to any one of [1] to [3], a slurry preparation step of preparing a slurry containing the electrode active material, the oxide solid electrolyte, and a solvent for dissolving the oxide solid electrolyte; and a coating layer forming step of forming the coating layer by a spray drying method in which the slurry is sprayed together with atomized air and dried, The gas-liquid ratio in the spray drying method is 5.0 x 10 -3 The following is a method for producing a coated active material.

[0011] [5] The method for producing a coated active material according to [4], wherein the flow rate of the atomized air is 60 L / min or more. [Effects of the Invention]

[0012] The present disclosure has an effect of providing a coated active material that can suppress an increase in battery resistance. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic cross-sectional view illustrating a coated active material according to the present disclosure. [Figure 2] FIG. 1 is a schematic cross-sectional view illustrating a battery according to the present disclosure. [Figure 3] 1 is a flowchart illustrating a method for producing a coated active material according to the present disclosure. [Figure 4] 1 is a graph showing the relationship between the gas-liquid ratio and particle size in Examples and Comparative Examples. [Figure 5] 1 is an SEM image of the coated active material produced in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0014] The coated active material and the method for producing the coated active material according to the present disclosure will be described in detail below.

[0015] A. Coated active material The coated active material according to the present disclosure has an electrode active material and a coating layer that coats the electrode active material. The coating layer contains an oxide solid electrolyte containing Li, P, and O elements. In particular, the coated active material according to the present disclosure has a particle diameter (D 50 ) is 5.5 μm or less.

[0016] The coated active material in the present disclosure has a particle diameter (D 50 ) is 5.5 μm or less, so that when used in a battery, an increase in battery resistance can be suppressed.

[0017] From the viewpoint of suppressing battery resistance, it is preferable that the particle size of the coated active material is small. This is because an increase in the specific surface area of ​​the coated active material allows for a larger contact area with the electrolyte. Also, this is because the diffusion distance of carrier ions within the coated particles can be reduced. On the other hand, as mentioned above, if the coating layer contains phosphorus (P), the active material may be granulated, which may increase the particle size of the coated active material, posing a problem in suppressing battery resistance by reducing the particle size of the coated active material. In this regard, the present inventors have conducted extensive research into the conditions for producing coated active materials using the so-called spray drying method, and as a result, have found that the gas-liquid ratio in the spray drying method should be set to 5.0 × 10 -3 By setting the particle diameter (D 50 ) can be reduced. Generally, when the gas-liquid ratio is reduced, the flow rate of atomized air becomes relatively larger. It is thought that when the flow rate of atomized air is high, the coating liquid can be sufficiently atomized to coat the active material, resulting in the formation of a uniform and thin coating layer. If the coating layer is thick, the phosphorus contained in the coating layer is likely to cause aggregation and granulation between the coated particles, resulting in an increase in the particle size of the coated active material; however, it is thought that if the coating layer is thin, such aggregation can be suppressed.

[0018] Furthermore, in the manufacture of a battery, it is expected that the electrode layer will be pressed. In this regard, if the particle size of the coated active material increases due to granulation, the coated active material is likely to be deformed by the pressing, and the deformation of the coated active material may cause cracks in the electrode layer, which may be a factor in increasing battery resistance. On the other hand, since the coated active material in the present disclosure has a small particle size, that is, aggregation is suppressed, it is also possible to suppress an increase in battery resistance due to cracks in the electrode layer.

[0019] The coated active material in the present disclosure has a particle diameter (D 50 ) is 5.5 μm or less. D 50 may be 5.0 μm or less, 4.5 μm or less, or 4.0 μm or less. 50is, for example, 1.0 μm or more, may be 2.0 μm or more, or may be 3.0 μm or more. 10 ) is not particularly limited, but is, for example, 0.5 μm or more and 3.0 μm or less. 90 ) is not particularly limited, but is, for example, 3.0 μm or more and 15.0 μm or less. 10 , particle diameter D 50 and particle diameter D 90 correspond to particle sizes corresponding to 10% cumulative volume, 50% cumulative volume, and 90% cumulative volume, respectively, as measured using a laser diffraction particle size distribution analyzer.

[0020] Furthermore, it is preferable that the variation in particle size of the coated active material is small. 50 ) / (particle diameter D 90 -Particle size D 10 The variation in particle size is, for example, 0.4 or more and 1.1 or less.

[0021] 1.Coating layer The coating layer is a layer that coats the electrode active material and contains an oxide solid electrolyte containing Li, P, and O elements.

[0022] The proportion of Li element in the oxide solid electrolyte is not particularly limited, but is, for example, 20 mol% or more and 50 mol% or less. The proportion of P element in the oxide solid electrolyte is not particularly limited, but is, for example, 5 mol% or more and 20 mol% or less. The proportion of each element can be calculated, for example, by ICP (inductively coupled plasma) analysis.

[0023] The proportion of O element can be determined as oxygen concentration by, for example, a thermal fusion method. The oxygen concentration of the oxide solid electrolyte according to the present disclosure determined by the thermal fusion method is, for example, 45% by weight or more and 60% by weight or less. The molar ratio of O element in the oxide solid electrolyte is not particularly limited, but is, for example, 30 mol% or more and 60 mol% or less.

[0024] The oxide solid electrolyte may further contain B or La. The molar ratio of B to P (B / P) is not particularly limited, but is, for example, 0.5 or more and 2.0 or less. The molar ratio of Li to the total of P and B (Li / (P+B)) is not particularly limited, but is, for example, 0.3 or more and 1.2 or less. The molar ratio of La to P (La / P) is, for example, 0.005 or more and 0.15 or less.

[0025] The coverage of the coating layer with respect to the electrode active material is not particularly limited, but may be, for example, 75% or more, or 80% or more. If the coverage is too low, it may be impossible to sufficiently suppress the increase in resistance caused by a high-resistance layer resulting from the reaction between the electrode active material and the electrolyte. On the other hand, the coverage may be 100% or less. The coverage in the present disclosure is determined by calculating the element ratio from the intensity ratio of each major element based on X-ray photoelectron spectroscopy (XPS) measurement, and expressing the ratio of the elements contained in the coating layer to the total of the elements contained in the electrode active material and the elements contained in the coating layer.

[0026] The thickness of the coating layer is not particularly limited, but may be, for example, 1 nm to 100 nm, or may be 5 nm to 50 nm, or may be 10 nm to 30 nm. The thickness of the coating layer is determined as the average thickness of multiple samples (e.g., 100 or more samples) observed by, for example, a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0027] The coating layer may directly coat the electrode active material. Alternatively, the coating layer may indirectly coat the electrode active material. "Indirectly coating" refers to a case where a layer not containing the oxide solid electrolyte of the present disclosure is disposed between the electrode active material and the coating layer. Even if a layer not containing the oxide solid electrolyte is disposed between a part of the coated active material and the electrode active material and the coating layer, the coating layer can be considered to directly coat the electrode active material if there is a portion where the electrode active material and the coating layer are in direct contact with each other.

[0028] 2. Electrode active material The electrode active material according to the present disclosure contains, for example, Li, M, and O. M is a metal (including metalloids) other than Li, and preferably contains at least Ni. M other than Ni may be a transition metal or a metal (including metalloids) belonging to Groups 13 to 16 of the periodic table. Furthermore, M other than Ni may be one type of metal or two or more types of metals. In particular, M other than Ni is preferably at least one of Co, Mn, Al, V, and Fe.

[0029] The molar ratio of Ni to M (Ni / M) is, for example, 80% or more, or may be 85% or more, or may be 90% or more, while Ni / M may be 100% or less than 100%.

[0030] The electrode active material may contain a nonmetallic element such as P in addition to Li, M, and O. The crystalline structure of the electrode active material is not particularly limited, and examples thereof include a rock salt layer structure, a spinel structure, and an olivine structure.

[0031] An example of the composition of the electrode active material is LiNi x Co y Al z O2(0.80≦x, 0≦y, 0≦z, x+y+z=1), and LiNi a Co b Mn c Examples include O2 (0.80≦a, 0≦b, 0≦c, a+b+c=1).

[0032] The electrode active material is usually in the form of particles. 50 is, for example, 100 nm or more, and may be 1 μm or more. 50 is, for example, 10 μm or less, and may be 5 μm or less.

[0033] 3.Coated active material The coated active material of the present disclosure is typically used in a battery, and may be used as either a positive electrode active material or a negative electrode active material in the battery, with the former being preferred.

[0034] Fig. 2 is a schematic cross-sectional view illustrating a battery using the coated active material of the present disclosure. The battery 20 shown in Fig. 2 has a positive electrode active material layer 11, a negative electrode active material layer 12, an electrolyte layer 13 disposed between the positive electrode active material layer 11 and the negative electrode active material layer 12, a positive electrode current collector 14 that collects current from the positive electrode active material layer 11, and a negative electrode current collector 15 that collects current from the negative electrode active material layer 12. In the battery 20, the positive electrode active material layer 11 preferably contains the coated active material described above.

[0035] The positive electrode active material layer contains at least a positive electrode active material, and may contain at least one of a conductive additive, a binder, and an electrolyte, as necessary. The positive electrode active material is preferably the coated active material described above. Examples of the conductive additive, binder, and electrolyte include materials commonly used in batteries. The electrolyte may be a liquid electrolyte (electrolytic solution) or a solid electrolyte, with the latter being preferred. Examples of solid electrolytes include inorganic solid electrolytes such as sulfide solid electrolytes and oxide solid electrolytes.

[0036] The negative electrode active material layer contains at least a negative electrode active material, and may contain at least one of a conductive additive, a binder, and an electrolyte as needed. The conductive additive, binder, and electrolyte are as described above. Examples of the negative electrode active material include metal active materials such as Li and Sn, Si-based active materials, carbon active materials such as graphite, and Li4Ti5O12 Examples of oxide active materials include:

[0037] The electrolyte layer contains at least an electrolyte and may contain a binder as needed. The binder and electrolyte are as described above. Here, a battery in which the electrolyte layer contains a solid electrolyte (e.g., an inorganic solid electrolyte) is generally referred to as a solid-state battery. The solid-state battery may be a semi-solid-state battery or an all-solid-state battery.

[0038] The positive electrode current collector and the negative electrode current collector can be materials commonly used in batteries. Examples of materials for the positive electrode current collector include SUS, aluminum, nickel, iron, titanium, and carbon. Examples of materials for the negative electrode current collector include SUS, copper, nickel, and carbon.

[0039] The method for producing the coated active material is not particularly limited, but the method described in "B. Method for producing the coated active material" is preferred.

[0040] B. Method for manufacturing coated active material Fig. 3 is a flow chart illustrating a method for producing a coated active material according to the present disclosure. In the production method shown in Fig. 3, a slurry containing an electrode active material, the oxide solid electrolyte, and a solvent for dissolving the oxide solid electrolyte is prepared (slurry preparation step). Next, the coating layer is formed by a spray drying method in which the slurry is sprayed together with atomized air and dried (coating layer formation step). In the present disclosure, the coating conditions are adjusted so that the coated active material described above in "A. Coated active material" is obtained. In particular, in the spray drying method in the coating layer formation step, the gas-liquid ratio is adjusted to 5.0 x 10 -3 Adjust as follows:

[0041] According to the present disclosure, the gas-liquid ratio is 5.0 × 10 -3 By adjusting the particle diameter (D 50 ) can be produced as a coated active material having a thickness of 5.5 μm or less.

[0042] 1. Slurry preparation process The slurry preparation step is a step of preparing a slurry containing an electrode active material, the oxide solid electrolyte, and a solvent for dissolving the oxide solid electrolyte. The electrode active material and the oxide solid electrolyte are the same as those described in "A. Coated active material."

[0043] The solvent is not particularly limited as long as it can dissolve the oxide solid electrolyte, and an example of the solvent is water.

[0044] The slurry can be prepared, for example, by preparing a coating solution by dissolving raw materials for the oxide solid electrolyte (e.g., a Li source, a B source, a P source, a La source, and an O source) in water, and then adding and mixing the electrode active material to the coating solution.

[0045] The Li source is not particularly limited as long as it is a simple substance or compound containing the Li element, and examples thereof include lithium hydroxide (LiOH). The B source is not particularly limited as long as it is a simple substance or compound containing the B element, and examples thereof include boric acid (H3BO3). The P source is not particularly limited as long as it is a simple substance or compound containing the P element, and examples thereof include orthophosphoric acid (H3PO4) and metaphosphoric acid (HPO3). The La source is not particularly limited as long as it is a simple substance or compound containing the La element, and examples thereof include lanthanum oxide (La2O3). The O source is, for example, the O element contained in the above-mentioned element sources.

[0046] The solid content of the slurry is not particularly limited, and is preferably adjusted appropriately so as to obtain the gas-liquid ratio described below. The solid content of the slurry is, for example, 50% by weight or more and 70% by weight or less.

[0047] 2.Coating layer formation process The coating layer forming step is a step of forming a coating layer by a spray drying method. More specifically, the coating layer is formed by spraying the slurry together with atomized air and drying it. In particular, in the coating layer forming step of the present disclosure, the gas-liquid ratio is set to 5.0 × 10-3 The adjustment is as follows: The coating layer forming step in the present disclosure corresponds to so-called wet coating.

[0048] The gas-liquid ratio is 3.0 x 10 -3 may be less than or equal to 1.0 x 10 -3 may be less than 5.0 x 10 -4 On the other hand, the gas-liquid ratio may be, for example, 1.0×10 -4 The gas-liquid ratio can be calculated as the ratio of the amount of water supplied (L / min) to the flow rate of atomized air (L / min).

[0049] The flow rate of the atomized air is not particularly limited as long as the above gas-liquid ratio is obtained, but may be, for example, 60 L / min or more, 100 L / min or more, 300 L / min or more, or 1000 L / min or more. On the other hand, the flow rate of the atomized air may be, for example, 2500 L / min or less, or 2000 L / min or less.

[0050] The water supply rate (L / min) can be calculated, for example, by the following formula. Water supply rate = [Slurry supply rate (L / min)] × [1 - (solid concentration (%) / 100)] The water supply rate is not particularly limited as long as the above gas-liquid ratio is obtained, but may be, for example, 0.10 L / min or more, 0.50 L / min or more, or 1.0 L / min or more, while the water supply rate may be, for example, 10 L / min or less, 5.0 L / min or less, or 3.0 L / min or less.

[0051] The powder obtained through the coating layer forming step may be calcined. This is because the crystallinity of the oxide solid electrolyte in the coating layer can be increased. The calcination temperature is not particularly limited, but is, for example, 500°C or higher and 1000°C or lower. The calcination time is not particularly limited, but is, for example, 30 minutes or higher and 20 hours or lower.

[0052] 3.Coated active material The coated active material produced through the above-described steps is the same as that described in "A. Coated active material."

[0053] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure. [Example]

[0054] [Example 1] (Preparation of coating liquid) A coating solution for the coating layer, which contained an oxide solid electrolyte containing Li, P, B and O elements, was prepared as follows. First, 4.52 g of metaphosphoric acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in 191.8 g of ion-exchanged water. Next, boric acid (manufactured by Nacalai Tesque, Ltd.) was added and dissolved so that the molar ratio (B / P) was 1.0. Furthermore, lithium hydroxide monohydrate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added so that the molar ratio (Li / (P+B)) was 1.00, and the mixture was stirred.

[0055] (Preparation of coated active material) The coating solution described above is coated with an active material (NCA: LiNi 0.81 Co 0.15 Al 0.04 O2; particle size D 50 A slurry was obtained by dispersing particles (size: 2.9 μm) in the slurry. The solid content of the slurry was adjusted by further diluting it with ion-exchanged water. The obtained slurry was dried using a spray dryer to obtain a solid component. The spray drying conditions were an inlet air temperature of 200°C, an atomized air flow rate (air flow rate), and a water supply rate as shown in Table 1. The water supply rate was calculated using the above-mentioned formula. The obtained solid component was then heat-treated at 200°C for 5 hours in an air atmosphere. This resulted in a coated active material.

[0056] [Examples 2 to 8 and Comparative Example 1] A coated active material was obtained in the same manner as in Example 1, except that the particle size of the active material and the coating layer formation conditions (spray drying conditions) were changed as shown in Table 1. The amount of water supplied was adjusted by changing the solid content concentration of the slurry.

[0057] [Table 1]

[0058] [evaluation] (particle size) The particle size distribution of each coated active material was measured using a Microtrac-Bell product called "Aerotrac II." 10 (particle size at which the cumulative total becomes 10%), D 50 (particle size at which the cumulative value reaches 50%) and D 90 The particle size (particle size at which the cumulative total is 90%) was calculated. The results are shown in Table 2. Furthermore, from the obtained values, the ratio of particle sizes before and after coating layer formation and the variation in particle size of the coated active material were calculated. The results are shown in Table 2. Note that the smaller the ratio of particle sizes before and after coating layer formation, the more the aggregation of the coated particles can be suppressed. Furthermore, regarding the variation in particle size, the closer the value is to 1.0, the smaller the variation.

[0059] In addition, the gas-liquid ratio and the D of the coated active material 50 The relationship between the gas-liquid ratio and the particle size ratio before and after the formation of the coating layer is shown in FIG. 4(a), and the relationship between the gas-liquid ratio and the particle size ratio before and after the formation of the coating layer is shown in FIG. 4(b).

[0060] (coverage rate) The coverage of each coated active material was measured by X-ray photoelectron spectroscopy (XPS). Specifically, surface elemental analysis of the coated active material was performed using an X-ray photoelectron spectrometer (ULVAC-PHI, PHI X-tool). Narrow scan analysis was performed with a pass energy of 224 eV. Subsequently, the element ratios were calculated from the intensity values ​​of the detected Li1s, Ni2p3, Co2p3, Al1p, and B1s using analysis software (ULVAC-PHI, MultiPak). The coverage was calculated as the value (P + B) / (P + B + Ni + Co + Al) [%]. The results are shown in Table 2.

[0061] (Microscopic observation) An image of the coated active material prepared in Example 1 was taken with a scanning electron microscope (SEM), as shown in FIG.

[0062] (battery resistance) Using each of the coated active materials of Comparative Example 1 and Examples 1 to 8, a test battery (all-solid-state battery) having a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer was fabricated as follows. A positive electrode slurry was prepared by mixing the coated active material (positive electrode active material), sulfide solid electrolyte (10LiI-15LiBr-75Li3PS4), conductive material (VGCF), binder (SBR), and dispersion medium (heptane) using an ultrasonic homogenizer. The ratio of the positive electrode active material to the sulfide solid electrolyte was 6 / 4 (volume ratio). The conductive material and binder were each 3 parts by mass per 100 parts by mass of the positive electrode active material. The positive electrode slurry was applied to the surface of a positive electrode current collector (Al foil) and dried at 100°C for 30 minutes on a hot plate. This resulted in a positive electrode with a positive electrode active material layer and a positive electrode current collector. An all-solid-state battery was fabricated using this positive electrode. Graphite was used as the negative electrode active material, and the solid electrolyte in the negative electrode active material layer and solid electrolyte was the same sulfide solid electrolyte as in the positive electrode active material layer.

[0063] The open circuit voltage (OCV) of each test battery was adjusted to 2.03 V. Constant current discharge was then performed, and the voltage drop over 5 seconds was divided by the current to measure the battery resistance. The discharge current rate was set to 2.5 C. Evaluation was performed relative to Comparative Example 1 (1.00). The results are shown in Table 2.

[0064] [Table 2]

[0065] As shown in Tables 1 and 2 and Figures 4(a) and (b), the gas-liquid ratio was set to 5.0 × 10 -3 By setting the temperature below 100°C, aggregation can be suppressed and D 50 It was possible to produce a coated active material with a small particle size. It was also confirmed that the use of this coated active material significantly reduced battery resistance. In addition, the particle size variation and coverage rate were both good in the comparative example and the example, with no significant differences observed. In particular, as shown in Figure 5, it was confirmed that the coated active material of Example 1 produced particles with a more uniform size.

[0066] [Reference example 1] A coating solution containing an oxide solid electrolyte containing Li, Nb, and O elements was prepared as follows. 870.4 g of 30% by mass hydrogen peroxide solution was placed in a container, followed by 987.4 g of ion-exchanged water and 44.2 g of niobic acid (Nb2O5·3H2O (Nb2O5 water content 72%)). Next, 87.9 g of 28% by mass ammonia water was added to the container. After adding the ammonia water and stirring, a clear solution was obtained. 10.1 g of lithium hydroxide monohydrate (LiOH·H2O) was added to the resulting clear solution. This produced a complex solution containing a niobium peroxo complex and lithium ions as a coating solution.

[0067] A coated active material was obtained in the same manner as in Example 1, except that this coating solution was used and the conditions for forming the coating layer were changed as shown in Table 3.

[0068] [Reference examples 2~7] Active material particle diameter (D 50 ) and the gas-liquid ratio were changed as shown in Table 3, and the same procedure as in Example 1 was carried out to prepare coated active materials.

[0069] The particle size and coverage of each coated active material obtained in the Reference Examples were measured in the same manner as above. The results are shown in Table 4 together with those of Example 1.

[0070] [Table 3]

[0071] [Table 4]

[0072] As shown in Tables 3 and 4, in Reference Example 1, in which the oxide solid electrolyte did not contain P, granulation of the active material was suppressed even when the gas-liquid ratio was increased. Thus, it was confirmed that granulation of the active material is a problem specific to when the coating layer contains P. Furthermore, in Reference Examples 2 to 8, the particle size ratio was as low as in the Examples, and it was confirmed that granulation itself was suppressed even when the particle size of the active material was increased. Furthermore, D 50 Even when using an active material with a relatively large solubility, the gas-liquid ratio is 5.0 × 10 -3 By setting the following, the D of the coated active material 50 It was confirmed that the thickness could be reduced. It is presumed that this is because a thin coating layer could be formed by reducing the gas-liquid ratio. [Explanation of symbols]

[0073] 1...electrode active material 2...Covering layer 10...Coated active material 11...Cathode active material layer 12...Negative electrode active material layer 13...electrolyte layer 14...Positive electrode current collector 15...Negative electrode current collector 20...battery

Claims

1. A coated active material having an electrode active material and a coating layer that coats the electrode active material, the coating layer contains an oxide solid electrolyte containing Li, P, and O elements; The particle diameter (D ５０ ) is 5.5 μm or less.

2. The particle diameter (D ５０ 2. The coated active material according to claim 1, wherein the thickness of the coated active material is 1.0 μm or more.

3. The coated active material according to claim 1 , wherein the oxide solid electrolyte further contains a B element or a La element.

4. A method for producing a coated active material according to any one of claims 1 to 3, comprising: a slurry preparation step of preparing a slurry containing the electrode active material, the oxide solid electrolyte, and a solvent for dissolving the oxide solid electrolyte; and a coating layer forming step of forming the coating layer by a spray drying method in which the slurry is sprayed together with atomized air and dried, The gas-liquid ratio in the spray drying method is 5.0 × 10 －３ The following is a method for producing a coated active material.

5. The method for producing a coated active material according to claim 4, wherein a flow rate of the atomized air is 60 L / min or more.

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