Dry Powder Bed

Abstract

To provide a high-performance and low environmental impact dry powder layer and the like with an increased contact area between a dry powder layer and an adjacent layer due to the increase in surface area which is caused by an uneven surface formed on the surface of the dry powder layer carved into a sinusoidal standing wave pattern.SOLUTION: The dry powder layer includes at least a solid electrolyte in which the concentration of a solvent contained in the dry powder layer is 50 ppm or less, and the surface of the dry powder layer has an uneven surface scraped off by a squeegee vibrated by a sinusoidal standing wave.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to dry powder Layer Regarding. [Background technology]

[0002] In recent years, dry coating methods, which directly apply powder, have been attracting attention as a method that can form powder layers with high performance and low environmental impact compared to wet coating methods, which disperse powder in a solvent and then apply the coating. This is because dry coating methods can produce powder layers that are less susceptible to material damage caused by solvents, maintain high performance, and do not require drying the solvent, resulting in significantly reduced energy consumption. Furthermore, because dry coating methods do not require drying, coating can be done inexpensively, leading to lower costs for powder layers.

[0003] As a method for dry coating of powder, a technique has been known in the past in which powder is coated onto the surface of a member such as a metal foil while the member is being conveyed by a conveying device.

[0004] For example, Patent Document 1 discloses a technique for applying powder by electrostatic screen coating.

[0005] Patent Document 1 describes a method in which powder is supplied onto the surface of a metal foil, and then a powder layer is formed by a solvent-free dry coating method. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-179673 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in Patent Document 1, the surface of the powder layer is flat, so there is room for improvement if further performance improvement is required, such as increasing the surface area of ​​the powder layer and increasing the contact area with adjacent layers.

[0008] Therefore, the present disclosure table Dry powder with increased surface area Layer The purpose is to provide. [Means for solving the problem]

[0009] A dry powder layer according to one embodiment of the present disclosure is a dry powder layer containing at least a solid electrolyte, wherein the concentration of a solvent contained in the dry powder layer is 50 ppm or less, and the surface of the dry powder layer has an uneven surface scraped off by a squeegee vibrated with a sinusoidal standing wave. [Effects of the Invention]

[0010] According to the present disclosure, a high-performance, low-environmental-load dry powder layer or the like can be provided in which the surface of the dry powder layer is scraped in a sinusoidal standing wave pattern to form an uneven surface, thereby increasing the surface area and increasing the contact area between the dry powder layer and an adjacent layer. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating a portion of a powder coating apparatus and a powder alignment step according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a schematic diagram showing a portion of a powder coating apparatus and a powder bed according to one embodiment of the present disclosure. [Figure 3] FIG. 3 is a schematic diagram illustrating a portion of a powder coating apparatus and a powder alignment step according to an embodiment of the present disclosure. [Figure 4] FIG. 4 is a schematic diagram showing a portion of a powder coating apparatus and a powder bed according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not described in the independent claims are described as optional components.

[0013] In addition, each drawing is a schematic diagram and is not necessarily an exact illustration. In addition, the same components are denoted by the same reference numerals in each drawing.

[0014] (overview) Dry coating is a method for applying powder to a substrate. This method is expected to produce a high-performance, low-cost, and environmentally friendly dry powder layer (hereinafter simply referred to as a powder layer). When forming a powder layer using this method, a squeegee vibrated at high frequency (2 kHz to 300 kHz) can align the powder particles in the powder layer. Because the squeegee is vibrated at high frequency, the vibrations are transmitted to the powder in the powder layer, imparting fluidity to the powder, resulting in a powder layer with aligned powder particles without powder clogging. Furthermore, when the squeegee is vibrated at high frequency, the squeegee vibrates in a sinusoidal standing wave due to its natural vibration. As a result, the surface of the powder layer that passes under the squeegee becomes an uneven surface scraped in the shape of a sinusoidal standing wave. In other words, the surface area of ​​the powder layer increases due to the uneven surface. This increases the contact area between the powder layer and adjacent layers, further improving the performance of the powder layer.

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0016] (Embodiment) Hereinafter, the embodiment will be described with reference to FIGS.

[0017] FIGS. 1 and 3 are schematic diagrams illustrating a portion of a powder coating apparatus 1 according to an embodiment of the present disclosure and a powder alignment step. FIGS. 2 and 4 are schematic diagrams illustrating a portion of a powder coating apparatus 1 according to an embodiment of the present disclosure and a powder layer. FIG. 2(a) is a diagram illustrating a case in which the squeegee 6 vibrates naturally with a sinusoidal standing wave when viewed from above. FIG. 2(b) is a diagram illustrating a powder layer 5 coated on a sheet 4 when viewed from the front. FIG. 4(a) is a diagram illustrating a case in which the first-stage squeegee 11 and the second-stage squeegee 12 vibrate naturally with a sinusoidal standing wave when viewed from above. FIG. 4(b) is a diagram illustrating a powder layer 5 coated on a sheet 4 when viewed from the front. The first-stage squeegee 11 is an example of a first squeegee. The second-stage squeegee 12 is an example of a second squeegee.

[0018] [Powder layer, coating film (compressed powder layer), and powder coating equipment] An overview of the powder layer 5, the coating film (compressed powder layer), and the powder coating device 1 in one embodiment of the present disclosure will be described.

[0019] Powder layer 5 of an energy device according to one embodiment of the present disclosure has a film thickness of 30 μm or more formed on a current collector, which is sheet 4. Powder layer 5 contains powder composed of at least one type of particulate material. The concentration of the solvent contained in powder layer 5 is 50 ppm or less. The surface of powder layer 5 has an uneven surface scraped in the form of a sinusoidal standing wave.

[0020] This suppresses deterioration of the solvent contained in the powder layer 5, and allows the formation of a high-performance powder layer 5 with a large surface area. Furthermore, since drying of the solvent is not required, the energy consumed for drying the solvent can be reduced, thereby suppressing the environmental impact and preventing an increase in manufacturing costs. Therefore, by using such a powder layer 5 in an energy device, it is possible to improve the performance of the energy device, reduce the environmental impact, and achieve low costs.

[0021] The powder layer 5 of this embodiment can be used in, for example, an all-solid-state battery.

[0022] The powder coating apparatus 1 of this embodiment will be described in detail below.

[0023] 1, powder layer 5 is produced by powder coating apparatus 1. Powder coating apparatus 1 includes a conveying device (not shown) that serves as a driving means, a powder supplying means (not shown), and a squeegee 6 that vibrates at high frequency.

[0024] The powder coating apparatus 1 transports a sheet-like member (hereinafter also referred to as sheet 4) in the traveling direction using a transport device. The powder coating apparatus 1 continuously supplies powder 3 to the surface of the transported sheet 4 using a powder supplying means. The powder coating apparatus 1 then adjusts the film thickness and packing rate of the powder 3 supplied to the surface of the sheet 4 using a squeegee 6, thereby making the powder layer 5 have a desired basis weight. Here, the basis weight is a value expressed in weight of powder per unit area, and the unit of basis weight is, for example, g / cm. 2 It is shown as follows.

[0025] The conveying device is not particularly limited and may be any device that can convey the sheet 4. For example, the conveying device may be a conveying device that can continuously pay out the sheet 4 wound in a roll shape, or a conveying device that can intermittently pay out the sheet 4.

[0026] In addition, on the conveyance path of the sheet 4, a guide roller that rotates in accordance with the movement of the sheet 4, a control device that corrects meandering of the sheet 4, and the like may be provided.

[0027] In this embodiment, the sheet 4 is a long, strip-shaped thin plate that is wound up. However, the sheet 4 is not limited to a long, strip-shaped thin plate. For example, a sheet 4 of a desired shape may be unwound from a conveying device, and after coating of the powder 3 onto the sheet 4 is completed, a new sheet 4 may be unwound from the conveying device. The sheet 4 does not have to be wound into a roll. In other words, the sheet 4 may have any shape that allows powder to be coated using the powder coating device 1. Therefore, the shape of the sheet 4 is not particularly limited. In this embodiment, the sheet 4 is a current collector including a metal foil, but the material of the member is not particularly limited. In other words, the sheet 4 may be any member that allows powder to be coated using the powder coating device 1.

[0028] The powder 3 may be any powdery substance. That is, there are no particular limitations on the raw material of the powder 3, the composition of the powder 3, and the particle shape of the powder 3. In this embodiment, the powder 3 is a particle group containing a solid electrolyte.

[0029] The average particle diameter (D50) of the powder 3 is preferably 0.005 μm or more and 30 μm or less. In this case, the fluidity of the powder 3 tends to decrease, but the vibration of the squeegee 6 prevents the powder 3 from accumulating and agglomerating, allowing a powder layer 5 with little variation in basis weight to be formed on the surface of the sheet 4. Here, the average particle diameter (D50) is the volume-based median diameter calculated from particle size distribution measurements obtained by laser diffraction and scattering. This average particle diameter (D50) can be measured using a commercially available laser analysis and scattering particle size distribution analyzer.

[0030] Furthermore, the powder 3 may contain only one type of powder, or may contain two or more types of powder.

[0031] In this embodiment, a hopper is used as the powder supplying means. The hopper can store powder 3 therein and supplies the powder 3 to the surface of the sheet 4. The hopper is disposed upstream of the squeegee 6 in the traveling direction of the sheet 4. The powder 3 supplied to the surface of the sheet 4 reaches the squeegee 6 as the sheet 4 moves. Note that, although a hopper is used as the powder supplying means in this embodiment, the present invention is not limited to this, and any device capable of supplying powder 3 to the surface of the sheet 4 may be used as the powder supplying means.

[0032] The squeegee 6 is positioned so as to form a predetermined gap (hereinafter also referred to as a gap) between it and the sheet 4. The powder 3 supplied to the surface of the sheet 4 passes through this gap. When the powder 3 passes through the gap, the squeegee 6 adjusts the film thickness and packing rate of the powder 3 supplied to the surface of the sheet 4, thereby reducing variation in the coating weight of the powder layer 5.

[0033] (High frequency near the ultrasonic band) The squeegee 6 vibrates at a frequency of 2 kHz to 300 kHz. That is, the squeegee 6 vibrates at a high frequency close to the ultrasonic band. Specifically, when the powder 3 supplied to the surface of the sheet 4 passes through the gap between the squeegee 6 and the sheet 4, the squeegee 6 is vibrated at a high frequency close to the ultrasonic band, thereby increasing the fluidity of the powder 3 in the powder layer 5. This prevents the powder from clogging.

[0034] The fluidity of the powder 3 tends to increase as the vibration frequency of the squeegee 6 increases. Therefore, by vibrating the squeegee 6 at a frequency of 2 kHz or higher, which is in the high-frequency range near the ultrasonic band, the fluidity of the powder 3 can be sufficiently increased. However, if the frequency is too high, high frequencies near the ultrasonic band are easily attenuated, making it difficult for the vibration of the squeegee 6 to be transmitted to the powder 3. Furthermore, if the frequency is 300 kHz or lower, the fluidity of the powder 3 can be sufficiently increased. By vibrating the squeegee 6 at a high frequency near the ultrasonic band, the powder 3 in contact with the squeegee 6 is less susceptible to frictional resistance due to powder pressure, increasing the fluidity and suppressing retention and aggregation of the powder 3.

[0035] Furthermore, the vibration effect of the squeegee 6 reduces the frictional force between powder particles of the powder 3 located near the squeegee 6, increasing the flowability and suppressing aggregation of the powder 3.

[0036] As a result, even if powder 3 with a particle size of 30 μm or less and low fluidity is used, the vibrating squeegee 6 allows the powder 3 to pass through the gap without accumulating or agglomerating.

[0037] When the squeegee 6 is vibrated at a high frequency near the ultrasonic band, the squeegee 6 undergoes natural vibration (vibration in a resonant state) and oscillates in a sinusoidal standing wave as shown by the dashed line in Figure 2(a). The amplitude of the sinusoidal standing wave of the squeegee 6 is large at the antinodes compared to the nodes, where the amplitude is almost zero. Therefore, when passing through the gap between the squeegee 6 and the sheet 4, more of the powder layer 5 corresponding to the antinodes is scraped off than the powder layer 5 corresponding to the nodes. The squeegee 6 scrapes off the surface of the powder layer 5 to form a sinusoidal standing wave, thereby coating the powder layer 5. Therefore, the surface of the powder layer 5 becomes uneven along the shape of the sinusoidal standing wave, and the surface area is larger than when the powder layer has a flat surface. The increased surface area of ​​the powder layer 5 increases the contact area between the surface of the powder layer 5 and another layer adjacent to the powder layer 5 compared to when the powder layer has a flat surface. This allows for a powder layer 5 with high performance and low environmental impact.

[0038] For example, the period of the uneven surface formed on the surface of powder layer 5 scraped off by squeegee 6 vibrated with a sine standing wave is preferably 5 mm to 100 mm.

[0039] To make the period of the uneven surface less than 5 mm, the length of the squeegee 6 must be shortened. In this case, coating becomes difficult on a wide powder layer 5. For this reason, the period of the uneven surface is preferably 5 mm or more. To make the period of the uneven surface greater than 100 mm, the vibration frequency of the squeegee 6 must be low. In this case, the vibration effect applied to the powder 3 decreases, reducing fluidity and making it difficult to form the powder layer 5. For this reason, the period of the uneven surface is preferably 100 mm or less.

[0040] For example, the difference in thickness between the irregularities formed on the surface of powder layer 5 scraped off by squeegee 6 vibrated with a sine standing wave is preferably 5 μm to 300 μm.

[0041] If the difference in the thickness direction of the uneven surface is less than 5 μm, the effect of increasing the contact area between the surface of the powder layer 5 and another layer adjacent to the powder layer 5 is reduced compared to when the powder layer has a flat surface. Furthermore, in order to reduce the difference (amplitude) between the maximum and minimum points on the uneven surface, it is necessary to reduce the vibration power applied to the squeegee 6. In this case, the vibration effect applied to the powder 3 decreases, reducing the fluidity of the powder 3 and making it difficult to form the powder layer 5. For this reason, the difference in the thickness direction of the uneven surface, which is the surface of the powder layer 5, is preferably 5 μm or more. Furthermore, if the difference in the thickness direction of the uneven surface is more than 300 μm, the vibration power applied to the squeegee 6 becomes too large, causing the powder 3 constituting the powder layer 5 to scatter, making it difficult to form the powder layer 5. For this reason, the difference in the thickness direction of the uneven surface, which is the surface of the powder layer 5, is preferably 300 μm or less.

[0042] (Surface shape of powder layer 5 when first stage squeegee 11 and second stage squeegee 12 are used) In the following description, the surface of powder layer 5 has an uneven surface scraped off by first-stage squeegee 11 and second-stage squeegee 12 vibrating with two sinusoidal standing waves that are shifted by a quarter wavelength from each other. This makes it possible to both increase the surface area of ​​powder layer 5 and suppress variations in basis weight. Although the above description has been given of a case where one squeegee is used, two squeegees may also be used.

[0043] The two squeegees used are a first-stage squeegee 11 and a second-stage squeegee 12. Hereinafter, the first-stage squeegee 11 and the second-stage squeegee 12 will also be collectively referred to as squeegees.

[0044] Powder layer 5 is formed by powder coating apparatus 1 shown in Fig. 3. What differs from Fig. 1 is that it includes first-stage squeegee 11 that vibrates at high frequency, and second-stage squeegee 12 that is positioned further in the direction of travel than first-stage squeegee 11 and also vibrates at high frequency.

[0045] Powder coating apparatus 1 conveys sheet 4 using a conveying device. Powder coating apparatus 1 continuously supplies powder 3 to the surface of the conveyed sheet 4 using powder supply means. Powder coating apparatus 1 then uses first-stage squeegee 11 and second-stage squeegee 12 to adjust the film thickness and filling rate of powder 3 supplied to the surface of sheet 4, thereby achieving a desired basis weight in powder layer 5 and reducing variation in basis weight.

[0046] The powder 3 supplied to the surface of the sheet 4 is first smoothed by a first-stage squeegee 11 to form a powder layer 5 , and then the surface of the powder layer 5 is further smoothed by a second-stage squeegee 12 .

[0047] The first-stage squeegee 11 and the second-stage squeegee 12 are vibrated at a high frequency near the ultrasonic band. As shown in (a) of Figure 4, the first-stage squeegee 11 and the second-stage squeegee 12 undergo natural vibration (resonant state) and oscillate with a sine standing wave.

[0048] 4(a), the first-stage squeegee 11 and the second-stage squeegee 12 are arranged so that the antinode portion of the sine standing wave of the first-stage squeegee 11 corresponds to the node portion of the sine standing wave of the second-stage squeegee 12. In other words, the first-stage squeegee 11 and the second-stage squeegee 12 are arranged so that the node portion of the sine standing wave of the first-stage squeegee 11 corresponds to the antinode portion of the sine standing wave of the second-stage squeegee 12.

[0049] Specifically, a first-stage squeegee 11 and a second-stage squeegee 12 having the same shape are prepared, and the first-stage squeegee 11 and the second-stage squeegee 12 are vibrated in a state of the same natural vibration. Here, the state of the same natural vibration means a state in which the antinodes and nodes correspond to each other at the same positions. For example, this state can be achieved by vibrating the first-stage squeegee 11 and the second-stage squeegee 12 at the same frequency. Specifically, this state can be achieved by arranging the first-stage squeegee 11 and the second-stage squeegee 12 in this order along the direction of travel of the powder layer 5, and displacing the second-stage squeegee 12 relative to the first-stage squeegee 11 by a quarter wavelength of a sinusoidal standing wave.

[0050] 4(b), the surface area of ​​the powder layer 5 is increased compared to when the powder layer has a flat surface, and coating can be performed with less variation in the powder weight of the powder layer 5. As a result, a high-performance, high-quality powder layer 5 can be formed.

[0051] This is because first-stage squeegee 11 first scrapes away the surface of powder layer 5 in accordance with the shape of a sine standing wave, and then coats it. Compared to node portions where the amplitude of the sine standing wave of first-stage squeegee 11 is almost zero, antinode portions have large amplitudes. For this reason, more of the powder 3 corresponding to the antinode portions is scraped away as it passes through the gap between squeegee 6 and sheet 4 than more of the powder 3 corresponding to the node portions.

[0052] Next, the second stage squeegee 12 scrapes off the part of the powder layer 5 where the first stage squeegee 11 had a high powder weight, i.e., the part of the powder layer 5 that passed through the node part of the first stage squeegee 11 (hereinafter also referred to as the peak part), and the surface of the scraped off powder layer 5 complements the part where the first stage squeegee 11 had a low powder weight, i.e., the belly part of the second stage squeegee 12 (hereinafter also referred to as the valley part).

[0053] Furthermore, it is preferable that the magnitude of the amplitude of the first-stage squeegee 11 and the second-stage squeegee 12 satisfy the relationship first-stage squeegee 11≧second-stage squeegee 12. This is because, by making the amplitude of the second-stage squeegee 12 the same as that of the first-stage squeegee 11 or by making the amplitude of the second-stage squeegee 12 smaller than that of the first-stage squeegee 11, the coating results of the first-stage squeegee 11 are not completely reset. In this way, the effects of both the first-stage squeegee 11 and the second-stage squeegee 12 can reduce the amount of variation in basis weight of the powder layer 5.

[0054] Furthermore, the amplitude of the second-stage squeegee 12 is preferably one-quarter to three-quarters of the amplitude of the first-stage squeegee 11. By setting the amplitude of the second-stage squeegee 12 to one-quarter to three-quarters of that of the first-stage squeegee 11, the second-stage squeegee 12 scrapes off the peaks of the powder layer 5 left by the first-stage squeegee 11, and the powder 3 scraped off from the peaks is replenished in the valleys of the powder layer 5. This improves the balance between the peaks after scraping and the valleys after replenishment. As a result, the variation in basis weight of the powder layer 5 can be further reduced.

[0055] The gap between the first stage squeegee 11 and the second stage squeegee 12 and the sheet 4 will be described below.

[0056] If the first gap between the first-stage squeegee 11 and the sheet 4 is h1 and the second gap between the second-stage squeegee 12 and the sheet 4 is h2, it is preferable that the relationship h1≦h2 be satisfied. This is because by making the second gap of the second-stage squeegee 12 the same as the first gap of the first-stage squeegee 11 or by making the second gap of the second-stage squeegee 12 wider than the first gap of the first-stage squeegee 11, the coating results of the first-stage squeegee 11 are not completely reset. In this way, the effects of both the first-stage squeegee 11 and the second-stage squeegee 12 can reduce the amount of variation in basis weight in the powder layer 5.

[0057] Furthermore, when the amplitudes of the sine standing waves of the first-stage squeegee 11 and the second-stage squeegee 12 are the same, it is preferable that the second gap of the second-stage squeegee 12 be one-quarter to three-quarters wider than the first gap of the first-stage squeegee 11. By making the amplitude of the second-stage squeegee 12 one-quarter to three-quarters wider than that of the first-stage squeegee 11, the second-stage squeegee 12 scrapes off the peaks of the powder layer 5 left by the first-stage squeegee 11, and the powder 3 scraped off from the peaks is replenished in the valleys of the powder layer 5. This improves the balance between the peaks after scraping and the valleys after replenishment. As a result, the variation in basis weight of the powder layer 5 can be further reduced.

[0058] (Details of the powder layer) The powder layer 5 is formed on a current collector, which is a sheet 4. The powder layer 5 and the current collector are used, for example, as an electrode of an energy device or in an all-solid-state battery. The current collector may further include another layer located between the current collector and the powder layer 5. The other layer is, for example, a connection layer made of a conductive carbon material or the like.

[0059] The powder layer 5 has a film thickness of 30 μm or more. There is no particular upper limit to the film thickness of the powder layer 5, but it is, for example, 2000 μm or less.

[0060] The powder layer 5 also contains powder 3 made of at least one type of particulate material.

[0061] The concentration of the solvent contained in the powder layer 5 is 50 ppm or less. In other words, the powder layer 5 does not substantially contain any solvent. Here, "substantially not containing" means that the powder layer 5 does not contain any solvent at all, or that the powder layer 5 unavoidably contains the solvent at 50 ppm or less as an impurity or the like. The solvent concentration is a concentration based on weight.

[0062] The size of powder layer 5 in plan view is, for example, 30 mm×30 mm or more. There is no particular upper limit to the size of powder layer 5 in plan view, but it is, for example, 300 mm×500 mm or less.

[0063] The powder layer 5 is formed by applying high-frequency vibrations to the powder 3 supplied to the surface of the sheet 4, thereby imparting fluidity to the powder 3 and aligning the powder 3 in the powder layer 5. This makes it possible to produce a high-quality powder layer 5 having a size of 30 mm x 30 mm or more and a thickness of 30 μm or more. This allows the powder layer 5 to be used in large, high-capacity energy devices.

[0064] Furthermore, the powder layer 5 is produced, for example, through a coating process that is substantially free of solvent. Therefore, a powder layer 5 that is substantially free of solvent can be formed. This prevents damage to the powder layer 5 from solvents. Furthermore, the powder layer 5 has an uneven surface that is scraped in a sinusoidal standing wave pattern in the width direction of the powder layer 5. This increases the surface area of ​​the powder layer 5. Therefore, deterioration of the powder layer 5 is suppressed, and the large surface area of ​​the powder layer 5 improves the ion conduction path between the powder layer 5 and adjacent layers. As a result, a powder layer 5 for a large-capacity energy device with high output and excellent quality can be formed. The width direction of the powder layer 5 is perpendicular to the traveling direction.

[0065] Furthermore, the powder layer 5 can be used, for example, as a positive electrode, a negative electrode, or a solid electrolyte layer of an energy device such as an all-solid-state battery.

[0066] When the powder layer 5 is used for a positive electrode, for example, the sheet 4 is a positive electrode current collector, and the powder layer 5 containing the powder 3 is a positive electrode mixture layer. That is, the positive electrode mixture layer is formed on the positive electrode current collector. The powder 3 in the positive electrode mixture layer contains, as at least one type of particulate material, a positive electrode active material and an ion-conductive solid electrolyte.

[0067] When the powder layer 5 is used for a negative electrode, for example, the sheet 4 is a negative electrode current collector, and the powder layer 5 containing the powder 3 is a negative electrode mixture layer. That is, the negative electrode mixture layer is formed on the negative electrode current collector. The powder 3 in the negative electrode mixture layer contains, as at least one type of particulate material, a negative electrode active material and an ion-conductive solid electrolyte.

[0068] When the powder layer 5 is used for a solid electrolyte layer, for example, the powder layer 5 containing the powder 3 is a solid electrolyte layer. The solid electrolyte layer is formed on the surface of the powder layer 5 in the positive electrode or the surface of the powder layer 5 in the negative electrode. The powder 3 in the solid electrolyte layer contains an ion-conductive solid electrolyte as at least one kind of particulate material.

[0069] The concentrations of solvents contained in the positive electrode mixture layer, the negative electrode mixture layer, and the solid electrolyte layer are 50 ppm or less. That is, the positive electrode mixture layer, the negative electrode mixture layer, and the solid electrolyte layer are substantially free of solvent. Here, "substantially free of solvent" means that these layers are completely free of solvent and that these layers unavoidably contain 50 ppm or less of solvent as impurities or the like.

[0070] The solvent is, for example, an organic solvent. The method for measuring the solvent is not particularly limited, and can be measured using, for example, gas chromatography, mass variation analysis, etc. Examples of organic solvents include nonpolar organic solvents such as heptane, xylene, and toluene, polar organic solvents such as tertiary amine solvents, ether solvents, thiol solvents, and ester solvents, and combinations thereof. Examples of tertiary amine solvents include triethylamine, tributylamine, and triamylamine. Examples of ether solvents include tetrahydrofuran and cyclopentyl methyl ether. Examples of thiol solvents include ethane mercaptan. Examples of ester solvents include butyl butyrate, ethyl acetate, and butyl acetate.

[0071] Next, the materials used in the positive electrode mixture layer, the negative electrode mixture layer, and the solid electrolyte layer will be described in detail.

[0072] The positive electrode active material is a substance in which metal ions such as lithium (Li) are inserted into or extracted from the crystal structure at a higher potential than the negative electrode, and oxidation or reduction occurs along with the insertion or extraction of the metal ions such as lithium. The type of positive electrode active material is appropriately selected depending on the type of all-solid-state battery, and examples thereof include oxide active materials and sulfide active materials.

[0073] In this embodiment, for example, an oxide active material (lithium-containing transition metal oxide) is used as the positive electrode active material. Examples of oxide active materials include LiCoO2, LiNiO2, LiMn2O4, LiCoPO4, LiNiPO4, LiFePO4, LiMnPO4, and compounds obtained by substituting one or two different elements for the transition metals in these compounds. Examples of compounds obtained by substituting one or two different elements for the transition metals in the above compounds include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.8 Co 0.15 Al 0.05 O2, LiNi 0.5 Mn 1.5Known materials such as O2 can be used. The positive electrode active material may be used alone or in combination of two or more.

[0074] Examples of the shape of the positive electrode active material include particles and thin films. When the positive electrode active material is particulate, the particle diameter of the positive electrode active material is, for example, in the range of 50 nm to 30 μm, and may be in the range of 1 μm to 15 μm. If the particle diameter of the positive electrode active material is 50 nm or more, handling tends to be improved. On the other hand, if the particle diameter is 30 μm or less, using an active material with a small particle size increases the surface area, making it easier to obtain a high-capacity positive electrode. Note that the particle diameter of the material contained in the positive electrode mixture layer or the negative electrode mixture layer in this specification is, for example, the above-mentioned D50.

[0075] The content of the positive electrode active material in the positive electrode mixture layer is not particularly limited, but may be, for example, in the range of 40% by weight to 99% by weight, or 70% by weight to 95% by weight.

[0076] The surface of the positive electrode active material may be coated with a coating layer. This is because it is possible to suppress the reaction between the positive electrode active material (e.g., oxide active material) and the solid electrolyte (e.g., sulfide-based solid electrolyte). Examples of materials for the coating layer include Li-ion conductive oxides such as LiNbO3, Li3PO4, and LiPON. The average thickness of the coating layer is, for example, in the range of 1 nm to 20 nm, and may be in the range of 1 nm to 10 nm.

[0077] The ratio of the positive electrode active material to the solid electrolyte contained in the positive electrode mixture layer, expressed as a weight ratio of positive electrode active material / solid electrolyte, may be within a range of 1 to 19, or may be within a range of 2.3 to 19. When the weight ratio is within this range, both the lithium ion conduction path and the electron conduction path are likely to be secured in the positive electrode mixture layer.

[0078] The negative electrode active material is a substance in which metal ions such as lithium are inserted into or extracted from the crystal structure at a lower potential than the positive electrode, and which undergoes oxidation or reduction as the metal ions such as lithium are inserted or extracted.

[0079] Examples of the negative electrode active material in this embodiment include metals that are easily alloyed with lithium, such as lithium, indium, tin, and silicon, carbon materials such as hard carbon and graphite, and Li4Ti5O 12 , SiO x Known materials such as oxide active materials, etc., can be used. Furthermore, as the negative electrode active material, a composite in which the above-mentioned negative electrode active materials are appropriately mixed can also be used.

[0080] The particle size of the negative electrode active material is, for example, 30 μm or less. By using an active material with a small particle size, the surface area becomes large, and a high capacity can be achieved.

[0081] The ratio of the negative electrode active material to the solid electrolyte contained in the negative electrode mixture layer, calculated as a weight ratio of negative electrode active material / solid electrolyte, may be, for example, in the range of 0.6 to 19, or in the range of 1 to 5.7. When the weight ratio is within this range, both the lithium ion conduction path and the electron conduction path are likely to be secured in the negative electrode mixture layer.

[0082] The solid electrolyte may be appropriately selected depending on the type of conductive ion (for example, lithium ions), and can be broadly divided into sulfide-based solid electrolytes, oxide-based solid electrolytes, and halide-based solid electrolytes, for example.

[0083] The type of sulfide-based solid electrolyte in this embodiment is not particularly limited. Examples of sulfide-based solid electrolytes include Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, and Li2S-P2S5. In particular, from the viewpoint of excellent lithium ion conductivity, the sulfide-based solid electrolyte may contain Li, P, and S. The sulfide-based solid electrolyte may be used alone or in combination of two or more. Furthermore, the sulfide-based solid electrolyte may be crystalline, amorphous, or glass ceramic. Note that the above description "Li2S-P2S5" refers to a sulfide-based solid electrolyte formed using a raw material composition containing Li2S and P2S5, and the same applies to other descriptions.

[0084] In the present embodiment, one form of the sulfide-based solid electrolyte is a sulfide glass ceramic containing Li2S and P2S5, and the ratio of Li2S and P2S5, when expressed in terms of moles as Li2S / P2S5=molar ratio, is, for example, in the range of 2.3 to 4, and may be in the range of 3 to 4. By keeping the molar ratio within this range, it is possible to obtain a crystal structure with high ion conductivity while maintaining the lithium concentration that affects the battery characteristics.

[0085] The shape of the sulfide-based solid electrolyte in this embodiment may be, for example, a particulate shape such as a spherical shape or an oval spherical shape, or a thin film shape. When the sulfide-based solid electrolyte material is particulate, the particle diameter of the sulfide-based solid electrolyte is not particularly limited, but may be 30 μm or less, 20 μm or less, or 10 μm or less, since this facilitates improving the filling rate in the positive electrode or negative electrode. On the other hand, the particle diameter of the sulfide-based solid electrolyte may be 0.001 μm or more, or 0.01 μm or more.

[0086] Next, the oxide-based solid electrolyte in this embodiment will be described. The type of oxide-based solid electrolyte is not particularly limited, but examples thereof include LiPON, Li3PO4, Li2SiO2, Li2SiO4, and Li 0.5 La0.5 TiO3, Li 1.3 Al 0.3 Ti 0.7 (PO4)3, La 0.51 Li 0.34 TiO 0.74 , Li 1.5 Al 0.5 Ge 1.5 (PO4)3, etc. The oxide-based solid electrolyte may be used alone or in combination of two or more.

[0087] Next, the positive electrode current collector and the negative electrode current collector will be described in detail.

[0088] The positive electrode in this embodiment includes a positive electrode current collector made of, for example, a metal foil, etc. The positive electrode current collector may be, for example, a foil, plate, mesh, or the like made of aluminum, gold, platinum, zinc, copper, SUS, nickel, tin, titanium, or an alloy of two or more of these metals.

[0089] The thickness and shape of the positive electrode current collector may be appropriately selected depending on the application of the positive electrode.

[0090] The negative electrode in this embodiment includes a negative electrode current collector made of, for example, a metal foil, etc. The negative electrode current collector may be, for example, a foil, plate, mesh, or the like made of SUS, gold, platinum, zinc, copper, nickel, titanium, tin, or an alloy of two or more of these metals.

[0091] The thickness and shape of the negative electrode current collector may be appropriately selected depending on the application of the negative electrode.

[0092] (Compressed powder layer) The powder layer 5 may be a compressed powder layer or a dry-coated film obtained by pressing the powder layer 5. The dry-coated film can be used, for example, for the positive electrode, negative electrode, or solid electrolyte layer of an energy device such as an all-solid-state battery. When the powder layer 5 is a compressed powder layer or a dry-coated film, the powder 3 can be fixed on the sheet 4, which has the advantage of facilitating transportation of the powder 3.

[0093] (Details of the direction and magnitude of high-frequency vibrations near the ultrasonic band, and the shape of the squeegee) The direction of high-frequency vibration of the squeegee near the ultrasonic band includes at least one of a vertical component and a horizontal component. That is, the squeegee vibrates in at least one of the vertical and horizontal directions. Note that the term "squeegee" here collectively refers to the squeegee 6, first-stage squeegee 11, and second-stage squeegee 12 described above.

[0094] The vertical direction is a direction perpendicular to the main surface of the squeegee. Vibrations in the vertical direction tend to propagate longitudinal waves (waves in the vibration direction in which the squeegee approaches and moves away from the powder 3) to the powder 3.

[0095] The vertical component has a large effect on reducing the frictional resistance between the powder particles 3. This is because the vertical vibration is a vibration direction in which the squeegee approaches and moves away from the powder 3, causing repeated collisions between the powder particles 3 and making it easier for the vibration to be transmitted to the powder 3. High frequencies in the vicinity of the ultrasonic band are high, so there is a risk that the vibration will not be easily transmitted between the powder particles 3, but vertical vibration makes it particularly easy for the vibration to be transmitted to the powder 3.

[0096] Here, the horizontal direction is a direction parallel to the main surface of the squeegee and parallel to the axis of the squeegee. Vibrations in the horizontal direction tend to transmit transverse waves (waves in the direction in which the squeegee vibrates as it rubs against the powder 3) to the powder 3. Here, the axis of the squeegee refers to an axis parallel to the width direction of the sheet 4. The axis of the squeegee may also be parallel to the longitudinal direction of the squeegee.

[0097] The horizontal component of the squeegee's high-frequency vibration near the ultrasonic band not only reduces the frictional resistance between the powder particles 3, but also significantly reduces the frictional force between the squeegee and the powder 3. If the vertical vibration component is too large, the vibration may be transmitted to the powder 3 too much, causing the powder 3 to vibrate significantly and resulting in greater film thickness variation. However, the horizontal vibration component can also reduce the frictional force between the squeegee and the powder 3, thereby particularly improving the fluidity of the powder 3. Note that horizontal vibration of the squeegee can be achieved by attaching a high-frequency transducer in the axial direction of the squeegee and supporting the end of the squeegee with bearings, which allows for a simpler device structure than vibration in the planar direction.

[0098] The direction of the high-frequency vibration of the squeegee near the ultrasonic band may be either only vertical or only horizontal. However, if high-frequency vibration near the ultrasonic band in both the vertical and horizontal directions is used in combination, the fluidity of the powder 3 can be further improved. For example, when focusing on one particle of powder 3, the vibration direction of the powder 3 becomes random and vibration is applied to the entire surface of the powder 3, so there are no surfaces where the vibration is not transmitted and frictional resistance is high, and the fluidity of the powder 3 is improved.

[0099] When the squeegee vibrates vertically and horizontally at a high frequency near the ultrasonic band, the magnitude of the horizontal vibration of the squeegee is preferably greater than the magnitude of the vertical vibration of the squeegee. That is, the magnitude of the vibration of the shear wave component of the powder 3 (the direction in which the squeegee vibrates as it rubs against the powder 3) is preferably greater than the magnitude of the longitudinal wave component of the powder 3 (the direction in which the squeegee vibrates toward and away from the powder 3). In this case, the horizontal vibration of the squeegee can reduce the frictional resistance at the interface between the squeegee and the powder 3, where frictional resistance is particularly likely to be high, and can also reduce the frictional resistance between the powder particles 3. This can further improve the fluidity of the powder 3.

[0100] The magnitude of the vertical vibration of the squeegee is preferably 2 μm or more. That is, the vertical amplitude of the squeegee is preferably 2 μm or more. In this case, the frictional resistance between the powder particles 3 can be sufficiently reduced, and the fluidity of the powder 3 can be further improved. In this case, the vertical amplitude of the squeegee is preferably, for example, 20 μm or less. This prevents the powder 3 from vibrating too strongly, causing the powder 3 to turn into dust and scatter, thereby contaminating the surrounding area.

[0101] The magnitude of the horizontal vibration of the squeegee is preferably 4 μm or more. That is, the horizontal amplitude of the squeegee is preferably 4 μm or more. In this case, the frictional resistance at the interface between the squeegee and the powder 3 can be sufficiently reduced, and the fluidity of the powder 3 can be further improved. In this case, the horizontal amplitude of the squeegee is preferably, for example, 40 μm or less. This prevents the powder 3 from vibrating too strongly, causing the powder 3 to turn into dust and scatter, thereby contaminating the surrounding area.

[0102] The squeegee is, for example, cylindrical, and is arranged so that the axial direction of the cylinder (the height direction of the cylinder) is parallel to the upper surface of the sheet 4 and intersects (for example, perpendicular to) the direction of movement of the sheet 4. The cylindrical squeegee is arranged with both ends of the axial direction of the squeegee fixed to supports with bearings so that it can slide horizontally. The amount of horizontal sliding can be adjusted by providing a stopper or the like on the squeegee. In addition, the axis of the squeegee can be shaped to fit into the diameter of a circular bearing, and the amount of vertical vibration can be adjusted by adjusting the difference between the squeegee diameter and the bearing diameter. This makes it possible to create a relationship in which the horizontal amplitude is greater than the vertical amplitude.

[0103] [Powder bed manufacturing method] The following describes a method for producing powder layer 5. By using powder coating apparatus 1, powder layer 5 can be produced.

[0104] The method for manufacturing the powder layer 5 includes supplying powder 3 onto the surface of a sheet 4 such as a current collector while moving the sheet 4 in a predetermined direction (powder supplying step), and adjusting the thickness and basis weight of the powder 3 supplied onto the surface of the sheet 4 using at least one squeegee (powder alignment step).

[0105] First, the powder 3 is prepared. The raw material of the powder 3 is not particularly limited, but for example, a particle group containing an active material may be used. The active material and binder are mixed with an appropriate additive (for example, a conductive material) to prepare the powder 3. Examples of the mixing method include mixing using a mortar, a ball mill, a mixer, etc. A method of mixing the powder 3 without using a solvent, etc., is particularly preferred as it does not cause material deterioration.

[0106] In the powder supplying step, powder 3 is supplied onto the surface of the sheet 4 using a powder supplying means such as a hopper while the sheet 4 is being moved in a predetermined direction. The sheet 4 may have a shape other than a sheet, such as a plate or block shape. In this case, the plate or block may be intermittently flowed.

[0107] The powder alignment process is a process of aligning the powder 3 on the surface of the sheet 4 using the first-stage squeegee 11 and the second-stage squeegee 12 of the powder coating device 1. That is, in the powder alignment process, the thickness and basis weight of the powder 3 supplied to the surface of the sheet 4 are adjusted using the first-stage squeegee 11 and the second-stage squeegee 12. At this time, the first-stage squeegee 11 and the second-stage squeegee 12 vibrate at a frequency of 2 kHz or more and 300 kHz or less. The first-stage squeegee 11 and the second-stage squeegee 12 are respectively positioned so as to be shifted by a quarter wavelength of a sinusoidal standing wave in the coating width direction. Furthermore, at this time, the first-stage squeegee 11 and the second-stage squeegee 12 scrape off the surface of the powder layer 5 along the shape of the sinusoidal standing wave, which is the vibration of the first-stage squeegee 11 and the second-stage squeegee 12, resulting in a shape with a large surface area.

[0108] The method for producing powder layer 5 may further include a powder sheeting step. The powder sheeting step is a step of compressing the aligned powder 3 onto sheet 4 using a roll press of powder coating device 1. As a result, a compressed powder layer is formed on the surface of sheet 4 by compressing powder layer 5.

[0109] As described above, in the method for producing the powder layer 5, the powder supplying step and the powder aligning step are performed in this order, thereby forming the powder layer 5 made of the powder 3 on the surface of the sheet 4. Such a laminate of the sheet 4 and the powder layer 5 can be used in an energy device. For example, when a current collector is used as the sheet 4 and an active material is used as the powder 3, a positive electrode and a negative electrode for an energy device can be produced. When a solid electrolyte is used as the powder 3, a solid electrolyte layer for an energy device such as an all-solid-state battery can be produced.

[0110] An energy device produced using the powder coating apparatus 1 can have a powder layer 5 with a large surface area by imparting fluidity to the powder 3 and directly coating it. Therefore, according to the method for producing the powder layer 5, the powder 3 is dispersed in a solvent or the like, coated, and then directly coated without using a drying process, which prevents material deterioration due to the solvent and suppresses cost increases. Furthermore, because the surface area of ​​the powder layer 5 is large, its performance as an electrode in the energy device can be improved, and high-performance, high-quality energy devices can be produced at low cost.

[0111] (Other variations) Although the dry powder layer and the like according to the present disclosure have been described above based on the embodiments, the present disclosure is not limited to the above-described embodiments.

[0112] In addition, the present disclosure also includes forms obtained by applying various modifications to the above embodiments that a person skilled in the art would conceive, and forms realized by arbitrarily combining the components and functions of the above embodiments within the scope of the present disclosure. [Industrial Applicability]

[0113] The dry powder layer, dry coated film, and all-solid-state battery of the present disclosure can be applied to applications such as a mixture layer of a high-performance, low-cost, and low-environmental-impact all-solid-state battery by forming a powder layer with a large surface area without using a solvent. [Explanation of symbols]

[0114] 1 Powder coating equipment 3 Powder 4 seats 5 Powder layer (dry powder layer) 6 Squeegee 11 First stage squeegee (first squeegee) 12 Second stage squeegee (second squeegee)

Claims

1. A dry powder layer including at least a solid electrolyte, The concentration of the solvent contained in the dry powder layer is 50 ppm or less; The surface of the dry powder layer has an uneven surface scraped off by a squeegee vibrated with a sinusoidal standing wave. Dry powder bed.

2. The period of the uneven surface scraped off by the squeegee vibrated with the sine standing wave is 5 mm to 100 mm. The dry powder bed of claim 1 .

3. The difference in thickness of the uneven surface scraped off by the squeegee vibrated with the sinusoidal standing wave is 5 μm to 300 μm. The dry powder bed according to claim 1 or 2.

4. The squeegee includes a first squeegee and a second squeegee, The surface of the dry powder layer has an uneven surface scraped off by the first squeegee and the second squeegee vibrated with two sinusoidal standing waves that are shifted by a quarter wavelength. The dry powder layer according to any one of claims 1 to 3.

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