Solid particle molding apparatus, punch for the solid particle molding apparatus, and method for measuring the electrical properties of solid particles

Abstract

This system efficiently performs compression molding of solid particles and measures the properties of the resulting molded products. [Solution] A solid particle molding apparatus for use when compressing solid particles 17, comprising a die 13 having a die hole that penetrates vertically and the inner wall surface of at least the die hole being insulating, and a conductive upper punch 10 and a conductive lower punch 11 inserted above and below the die hole, respectively, wherein at least one of the upper punch 10 and the lower punch 11 is slidable vertically within the die hole, and each of the upper punch 10 and the lower punch 11 has a connection terminal 12 at a location that does not hinder the insertion of the upper punch 10 and the lower punch 11 into the die 13 and the compression molding of the solid particles 17 in the die 13 by the upper punch 10, the lower punch 11 and the die 13, a solid particle molding apparatus.

Description

Technical Field

[0001] The present invention relates to a solid particle forming apparatus used when compressing and molding solid particles and a pestle for the solid particle forming apparatus. The present invention also relates to a method for measuring the electrical properties of solid particles.

Background Art

[0002] In recent years, all-solid-state batteries having excellent properties in terms of high capacity and safety have been actively studied as batteries used in automobiles such as electric vehicles and hybrid vehicles, and power generation devices such as solar cells and wind power generation.

[0003] All-solid-state batteries are composed of a solid electrolyte, a positive electrode, a negative electrode, etc. Many of these components are produced by compression molding a material in the form of solid particles. For example, Japanese Patent Application Laid-Open No. 2023-079115 (Patent Document 1) describes a procedure for producing an all-solid-state battery by compression molding a battery material using a general uniaxial press.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Measurement of the electrical properties of an all-solid-state battery by a conventional method as described in Patent Document 1 is performed on a cell produced by sandwiching a molded body of solid particles produced by compression molding in a solid particle forming apparatus between pestle-shaped current collectors, sandwiching the current collectors with a lid material and screwing them to maintain a constant compression state of the molded body. According to this procedure, it is necessary to produce a cell for each compression molding condition. Therefore, there has been a demand for a new measuring means capable of efficiently performing compression molding of solid particles and measurement of the electrical properties of solid particles.

Means for Solving the Problems

[0006] The present inventors conceived the idea that by using a pestle (at least its contact surface with the solid particles) used in a solid particle molding apparatus as a current collector, it would be possible to efficiently perform compression molding of solid particles and measure the electrical properties of solid particles, leading to the present invention.

[0007] The present invention [1] A solid particle molding apparatus for use in compression molding of solid particles, comprising a die having a die hole that penetrates vertically and the inner wall surface of at least the die hole being insulating, and a conductive upper punch and a conductive lower punch inserted above and below the die hole, respectively, wherein at least one of the upper punch and the lower punch is slidable vertically within the die hole, and each of the upper punch and the lower punch has a connecting terminal at a location that does not hinder the insertion of the upper punch and the lower punch into the die and the compression molding of the solid particles in the die by the upper punch, the lower punch and the die, the present invention provides a solid particle molding apparatus.

[0008] Furthermore, from a different perspective, the present invention is [2] A solid particle molding apparatus used for compression molding solid particles, comprising a die having a die hole that penetrates vertically and the inner wall surface of the die hole being insulating, and a conductive upper punch and a conductive lower punch inserted above and below the die hole, respectively, a step of placing the solid particles into the die hole, A step of compressing the solid particles by sliding at least one of the upper punch and the lower punch within the die cavity, The present invention provides a method that includes the step of measuring the electrical properties of the solid particles using measuring devices connected to the upper and lower punches while the compression is maintained.

[0009] Furthermore, the present invention is [3] A conductive punch for a solid particle molding apparatus used when compressing solid particles, The present invention provides a punch having a connection terminal on a surface different from the insertion tip surface of the punch and the surface opposite to it. [Effects of the Invention]

[0010] According to the present invention, compression molding of solid particles and measurement of the electrical properties of solid particles can be performed efficiently. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing a state in which a measuring device is connected to the connection terminals of the upper punch and the lower punch of a solid particle molding apparatus according to the first embodiment of the present invention. [Figure 2] This is a schematic diagram of a pair of pestle-type propellers in the first embodiment of the present invention. [Figure 3] This figure shows an upper punch equipped with a connection terminal of a different form than that of the first embodiment. [Figure 4A] This is a schematic diagram of a method for measuring the electrical properties of solid particles using a solid particle molding apparatus according to the first embodiment of the present invention. [Figure 4B] This is a schematic diagram of a conventional method for measuring the electrical properties of solid particles. [Figure 5] This figure shows the results of measuring ionic conductivity under different molding pressures / restraining pressures using a method employing the solid particle molding apparatus of the first embodiment of the present invention and a conventional method. [Figure 6] This figure shows the results of measuring ionic conductivity under different molding pressures using a method employing the solid particle molding apparatus of the first embodiment of the present invention. [Figure 7] This figure shows a schematic diagram of a battery configured in a solid particle molding apparatus according to the first embodiment of the present invention. [Figure 8A] This figure shows the results of measuring the charge and discharge capacity of a battery configured in a solid particle molding apparatus according to the first embodiment of the present invention. [Figure 8B] This figure shows the results of measuring the solid electrolyte resistance and charge transfer resistance of a battery configured in a solid particle molding apparatus according to the first embodiment of the present invention. [Figure 9A] This figure shows the results of measuring the charge and discharge capacity of a battery configured under different molding pressures than those shown in Figure 8A within a solid particle molding apparatus according to the first embodiment of the present invention. [Figure 9B]The figure shows the results of measuring the solid electrolyte resistance and charge transfer resistance of a battery configured under a forming pressure different from that in FIG. 8A in the solid particle forming apparatus according to the first embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the present invention will be described in more detail with reference to the drawings. Note that the following description is illustrative in all respects and should not be construed as limiting the present invention.

[0013] (First Embodiment) (Regarding the Configuration of the Solid Particle Forming Apparatus) FIG. 1 is a schematic view showing a state in which a measuring device 101 is connected to connection terminals 12 of an upper punch 10 and connection terminals 12 of a lower punch 11 of a solid particle forming apparatus 1 according to the first embodiment of the present invention. This solid particle forming apparatus 1 is an apparatus used when compressing solid particles to produce a formed body of the solid particles, and includes a cylindrical mortar 13, a lower punch 11 fitted into the mortar hole of the mortar 13 from below the hole, an upper punch 10 fitted into the mortar hole of the mortar 13 from above the hole, a punch holding portion 15 that holds the upper punch 10, a hydraulic cylinder as a pressurizing portion 14 connected to the punch holding portion 15, a fixing portion 16 that fixes the lower punch 11 and the pressurizing portion 14, and a sealed container 100 that houses these components. In the solid particle forming apparatus 1, connection terminals 12 are provided on the upper peripheral surface of the upper punch 10, connection terminals 12 are provided on the lower peripheral surface of the lower punch 11, and a displacement meter 105 is connected to the punch holding portion 15. The connection terminals 12 of the upper punch 10 and the connection terminals 12 of the lower punch 11 are electrically connected to the measuring device 101 via wiring 102, and the pressurizing portion 14 is connected to a hydraulic portion 104 via a connection hose 106, a valve 103, and a pressure gauge 107. In the case of this embodiment, the hydraulic portion 104 is configured to generate hydraulic pressure by stepping on a pedal, but it may be configured to generate hydraulic pressure with an electric pump.

[0014] The die 13 used in the solid particle molding apparatus 1 has a die hole that penetrates vertically, into which an upper punch 10 and a lower punch 11 (details of this pair of punches will be described later) can be inserted. The shape and size of the die hole can be appropriately selected to match the shape and size of the upper punch 10 and the lower punch 11. For example, the cross-section perpendicular to the hole axis of the die hole may be circular, elliptical, square, etc. At least one of the upper punch 10 and the lower punch 11 is slidable vertically within the die hole. The die 13 may be placed on top of the lower punch 11 and fixed in place, in which case the upper punch 10 is slidable vertically within the die hole. To measure the electrical properties of the solid particles 17 using a measuring device 101 connected to the connection terminals 12 of the upper punch 10 and the lower punch 11, electrical insulation is ensured between the upper punch 10 and the mortar 13, and between the lower punch 11 and the mortar 13, so that when current is applied between the connection terminals 12, current does not flow through the mortar 13. The material of the insulating surface is not particularly limited as long as it is an electrically insulating substance under the measurement conditions of the electrical properties of the solid particles 17. Preferably, at least the inner wall surface of the mortar cavity of the mortar 13 is electrically insulating. The mortar 13 may be a metal mortar whose inner wall surface of the mortar cavity is covered with an electrically insulating substance.

[0015] It is preferable that the upper punch 10 and lower punch 11 of the solid particle molding apparatus 1 are electrically conductive through the solid particles 17 in the die cavity. The upper punch 10 may be integrated with the punch holder 15 or may be detachable from the punch holder 15. The lower punch 11 may be integrated with the fixing part 16 or may be detachable from the fixing part 16. In addition, the solid particle molding apparatus 1 may be provided as one set of the upper punch 10, lower punch 11 and die 13, or as multiple sets of different shapes and / or sizes.

[0016] The measuring device 101 measures the electrical properties (including electrochemical properties) of the solid particles 17 present between the upper punch 10 and the lower punch 11 in the solid particle molding apparatus 1. Examples of the measuring device 101 include a potentiostat, impedance analyzer, galvanostat, and charge / discharge tester. The measuring device 101 is connected to the respective connection terminals 12 of the upper punch 10 and lower punch 11 of the solid particle molding apparatus 1, thereby forming an electrical circuit that energizes the solid particles 17. In this case, the upper punch 10 and lower punch 11 act as punches for compression molding of the solid particles 17 and also function as current collectors. Therefore, the electrical properties of the solid particles 17 during and / or after compression molding can be measured in the solid particle molding apparatus 1. In addition, / or, the electrical properties of the compression-molded solid particles 17 can be measured under different pressurized and constrained pressures after unloading.

[0017] The pressurizing unit 14 is not limited to a hydraulic cylinder, and any pressurizing or compression device can be used as long as it can pressurize the solid particles 17 placed in the die cavity of the die 13 with a desired pressure via the upper punch 10 and / or lower punch 11. In this embodiment, the pressure applied to the solid particles 17 is measured by a pressure gauge 107, but it can also be measured by any pressure sensor provided between the hydraulic unit 104 and the pressurizing unit 14, between the pressurizing unit 14 and the upper punch 10 or lower punch 11, or between the upper punch 10 and the lower punch 11. Other types of pressurizing or compressing devices besides hydraulic ones include, for example, pneumatic and electric types. In pneumatic pressurizing or compressing devices, a compressor is used instead of the hydraulic unit 104. In electric types, the hydraulic unit 104, valve 103 and connecting hose 106 are omitted, and a reciprocating actuator such as a ball screw mechanism is used. The pressurizing unit 14 may be integrated with the upper punch 10 or the lower punch 11. When the pressurizing unit 14 is integrated with the lower punch 11, the pressurizing unit 14 causes the lower punch 11 (and optionally the mortar 13) to move up and down relative to the upper punch 10.

[0018] The pestle holder 15 may, for example, detachably hold the upper pestle 10 using a clamping mechanism, or it may be integrated with the upper pestle 10.

[0019] In this embodiment, the fixing section 16 comprises a base capable of positioning and fixing the lower punch 11, a plurality of support columns erected on the base, and a top plate connecting the upper ends of the plurality of support columns, with the pressurizing section 14 fixed to the top plate. The material of the fixing section 16 is not particularly limited, but metal is common. The fixing section 16 may consist only of a frame as in this embodiment, or it may have the shape of a container and also serve as a sealed container as described later.

[0020] The displacement meter 105 can measure the relative amount of movement in the compression direction between the upper punch 10 and the lower punch 11 during pressurization. By measuring the amount of movement of the punches during compression molding and / or during pressurization and restraint after unloading, data such as the thickness and porosity of the solid particles 17 during the compression molding process and / or pressurization and restraint process can be obtained. As a result, the electrical properties of the molded body of solid particles 17 during the compression molding process and / or during pressurization and restraint at different restraint pressures can be measured with higher accuracy. The displacement sensor may be, for example, a contact-type displacement sensor, or a non-contact type displacement sensor using a laser, optical, ultrasonic, or overcurrent. Furthermore, if the pressurizing unit 14 is configured to control the pressure with high precision, this displacement sensor can be omitted.

[0021] The sealed container 100 can house at least a mortar, an upper punch, and a lower punch. The solid particles 17 compressed by the solid particle molding apparatus 1 of the first embodiment of the present invention may contain substances that react with oxygen and moisture in the air under atmospheric conditions. Therefore, by controlling the atmosphere inside the sealed container 100 (for example, by filling the sealed container 100 with an inert gas such as argon gas), even if the solid particles 17 contain substances that are reactive under atmospheric conditions, it is possible to perform compression molding of the solid particles 17 and / or measure their electrical properties while avoiding the denaturation of such substances due to reactions and / or the generation of undesirable substances. The sealed container 100 may further include a valve for replacing the air inside the sealed container 100, a pressure reducing pump for discharging air, and fasteners for fixing the mortar, upper punch, and lower punch.

[0022] (Regarding the pestle pair) Figure 2 is a schematic diagram of a pestle pair 2 (a pestle pair consisting of an upper pestle 10 and a lower pestle 11) in the first embodiment. The upper pestle 10 has a projection-shaped insertion portion 10b having an insertion tip surface 10a and an outer flange portion 10d having a surface 10c opposite to the insertion tip surface 10a, and a connection terminal 12 is provided on the circumferential surface of the outer flange portion 10d. The lower pestle 11 has a projection-shaped insertion portion 11b having an insertion tip surface 11a and an outer flange portion 11d having a surface 11c opposite to the insertion tip surface 11a, and a connection terminal 12 is provided on the circumferential surface of the outer flange portion 11d. It is preferable that the opposing insertion tip surfaces 10a, 11a and their opposing surfaces 10c, 11c are parallel. In this embodiment, the connection terminal 12 of the upper punch 10 extends in a direction parallel to the opposing surface 10c, but the direction of protrusion of the connection terminal 12 is not limited, and as shown in Figure 3, it may protrude diagonally toward the opposing surface 10c.

[0023] The upper punch 10 and the lower punch 11 are electrically connected between their respective connection terminals 12 and insertion tip surfaces 10a and 11a that can come into contact with the solid particles 17. Therefore, in the solid particle molding apparatus 1 of this embodiment, by energizing the connection terminal 12 of the upper punch 10 and the connection terminal 12 of the lower punch 11, the electrical properties of the solid particles 17 between the upper punch 10 and the lower punch 11 can be measured under different pressurized and constrained pressures during and / or after compression molding and / or after unloading. The conductive insertion tip surfaces 10a and 11a can function as current collectors when measuring electrical properties.

[0024] The upper punch 10 and lower punch 11 may be composed entirely of a conductive material, or their surfaces may be coated with a conductive material. The conductive material is not particularly limited as long as it is conductive under the measurement conditions of the electrical properties of the solid particles 17, but examples of high-hardness materials include iron, chromium, titanium, cobalt, nickel, tungsten, molybdenum, carbon, silicon, manganese, copper, alloys thereof, and SUS containing these elements. The material constituting the punch is preferably a material that does not deform even when pressed at a pressure of 10 MPa or more, more preferably 50 MPa, more preferably 100 MPa, more preferably 150 MPa, and more preferably 200 MPa. Here, SUS refers to stainless steel with iron as the main component and elements such as chromium, carbon, and nickel added.

[0025] The shapes of the insertion portions 10b and 11b of the upper pestle 10 and lower pestle 11 can be appropriately selected according to the desired shape of the molded body. The length of the insertion portions 10b and 11b is not particularly limited, as long as a molded body of solid particles 17 of the desired thickness can be produced within the die cavity of the die 13. The upper pestle 10 and lower pestle 11 may be interchangeable. The shapes of the outer flange portions 10d and 11d of the upper pestle 10 and lower pestle 11 are also not particularly limited, and may be disc-shaped, or may be provided with fasteners for fixing to the pressurizing portion 14 (see Figure 1). The shape, size, and material of the upper pestle 10 and the lower pestle 11 may be different or the same, as long as the insertion parts 10b and 11b can be inserted into the mortar hole of the mortar 13. However, from the viewpoint of more accurately measuring the electrical properties of solid particles, it is preferable that the material of the insertion tip surfaces 10a and 11a be the same. The insertion parts 10b and 11b may be interchangeable.

[0026] In the upper punch 10, the shape and position of the connecting terminal 12 are not particularly limited, as long as it is provided in a location that does not hinder the insertion of the upper punch 10 into the mortar 13 and the compression molding of the solid particles 17 in the mortar 13 by the upper punch 10 and the lower punch 11. The connecting terminal 12 may be in the shape of a general electrical terminal, may be one of an electrical connector pair, may be in the shape of a terminal to which an electric wire can be connected, or may be integrated with an electric wire. In this embodiment, there is one connecting terminal 12, but multiple terminals may be provided. The connecting terminal 12 does not have to be provided on the circumferential surface of the outer flange portion 10d, and may be provided in a location other than the insertion portions 10b, 11b and the opposing surfaces 10c, 11c, including the insertion tip surfaces 10a, 11a, in a manner that does not hinder the insertion of the insertion portions 10b, 11b into the mortar cavity and the compression molding of the solid particles 17. The same applies to the lower punch 11.

[0027] (Regarding solid particles) The solid particles 17 are not particularly limited as long as they can be compressed by the solid particle molding apparatus 1 equipped with the punch pair 2 and die 13 of this embodiment. The solid particles 17 may consist of a single or a plurality of substances, or they may be a combination of particles of different substances. When a combination of different particles is used, they may be compressed and molded to form layers for each particle. Examples of solid particles 17 include particles containing one or more of the following: iron, chromium, titanium, cobalt, nickel, tungsten, molybdenum, lithium, manganese, silicon, alloys thereof, carbon materials, solid electrolytes, electrode active materials (positive electrode active materials, negative electrode active materials), drugs, and excipients. Particles containing at least one of a solid electrolyte and an electrode active material are preferred. Furthermore, it is preferable that the compressed molded body exhibits conductivity. Here, conductivity means that the compressed molded body is conductive to the extent that its electrical properties can be measured. Solid particles 17 as a solid electrolyte can be used, for example, in all-solid-state batteries, and solid particles 17 as an electrode active material can be used, for example, in liquid lithium-ion batteries and liquid potassium-ion batteries.

[0028] (Method for measuring the electrical properties of solid particles) Figure 4A is a schematic diagram of a method for measuring the electrical properties of solid particles using a solid particle molding apparatus 1 according to the first embodiment of the present invention. Figure 4B is a schematic diagram of a conventional method for compression molding of solid particles and a method for measuring the electrical properties of a molded solid particle body. Unlike the conventional upper punch 10 and lower punch 11 of the first embodiment of the present invention, the conventional upper punch 110 and lower punch 111 shown in Figure 4B do not have connection terminals that enable connection to a measuring device 101. In the conventional method, the connection terminal 112 is provided on the opposite side of the surface of the solid particle 17 that contacts the molded body, in a pair of current collectors 118 provided in the measuring cell 108. The shape, size, and material of the upper pestle 110 and the lower pestle 111 may be different or the same, but the upper pestle 110, the lower pestle 111, and the mortar 113 are made of a material that does not deform when solid particles 17 are pressed at a predetermined pressure to produce a molded body of solid particles 17. For comparative experiments, the upper pestle 110, the lower pestle 111, and the mortar 113 have the same dimensions as the upper pestle 10, the lower pestle 11, and the mortar 13 of the solid particle molding apparatus 1 of the first embodiment of the present invention. The following describes the method for measuring the electrical properties of the solid particles 17, comparing this embodiment with the prior art, with reference to Figures 4A and 4B.

[0029] As shown in Figures 1 and 4A, in this embodiment, first, solid particles 17 are placed into the die holes of the die 13 of the solid particle molding apparatus 1 described above. Next, the hydraulic unit 104 is driven to operate the pressurizing unit 14, and the upper punch 10 is lowered to pressurize the solid particles 17 in the die holes of the die 13. The compression conditions at this time can be set according to the molded body to be obtained. As an example when obtaining a solid electrolyte (molded body) for an all-solid-state battery, the compression conditions are preferably 10 MPa or higher, more preferably 50 MPa or higher, more preferably 100 MPa or higher, more preferably 150 MPa or higher, and more preferably 200 MPa or higher.

[0030] Next, in the solid particle molding apparatus 1, the electrical properties of the solid particles 17 located between the upper punch 10 and the lower punch 11 while compression is maintained are measured by a measuring device 101 connected to the respective connection terminals 12 of the upper punch 10 and the lower punch 11. In this embodiment, the molded body of the solid particles 17 is electrically connected to the connection terminals 12 via the conductive upper punch 10 and the lower punch 11, while the upper punch 10, the lower punch 11, and the solid particles 17 are electrically insulated from the die 13 by the inner wall surface of the die hole. Therefore, it is possible to measure the electrical properties of the solid particles 17 sandwiched between the upper punch 10 and the lower punch 11 using the measuring device 101 connected to the two connection terminals 12. By determining the thickness of the solid particles 17 based on the relative movement of the upper punch 10 and the lower punch 11 measured by the displacement meter 105, it becomes possible to measure the electrical properties with higher accuracy. The electrical characteristics to be measured may include, for example, at least one of the following: ionic conductivity, AC impedance, charge / discharge curve, solid electrolyte resistance, charge transfer resistance, electron conductivity, rate characteristics, cycle characteristics, etc. In this embodiment, since the solid particles 17 are still sandwiched between the upper punch 10 and lower punch 11 of the solid particle molding apparatus 1, it is possible to further increase the compression pressure and measure the electrical properties of the solid particles 17 (i.e., measurements at multiple points in time during the compression molding process). It is also possible to unload the solid particles 17 and then pressurize them again to measure the electrical properties of the molded body (i.e., measurements at multiple points in time during the pressurization process), and therefore the present invention is useful for easily and / or quickly determining the optimal pressurization conditions.

[0031] On the other hand, in the conventional technology, as shown in Figure 4B, solid particles 17 are pressed in the die cavity of the die 113 by a pressurizing unit 14 via the upper punch 110 and the lower punch 111 to form a molded body. After unloading, the molded body of solid particles 17 is removed from between the upper punch 110 and the lower punch 111, and the molded body of solid particles 17 is placed in the measuring cell 108. The measuring cell 108 includes a sample guide 119 for housing a molded body of solid particles 17, a pair of current collectors 118 that sandwich the molded body of solid particles 17 in the sample guide 119 from above and below, a pair of connection terminals 112 provided on the protruding parts of each of the pair of current collectors 118, and a fixing part 116 for fixing the pair of current collectors 118. Each connection terminal 112 can be electrically connected to the measuring device 101 via wiring 102. Examples of measuring devices include an impedance analyzer (frequency response analyzer), a potentiostat, a galvanostat, a resistance meter, etc. In this prior art, the fixing part 116 is capable of positioning and fixing the lower current collector 118 and comprises a base with a through hole formed therein for insertion into the protruding part of the lower current collector 118, a plurality of support columns erected on the base, a top plate (pressing member) with a through hole formed therein for insertion into the plurality of support columns and the protruding part of the upper current collector 118, and a plurality of tightening nuts that are inserted and screwed onto the plurality of support columns to press and support the top plate from above. The molded body of solid particles 17, removed from the die hole of the die 113, is placed in the sample guide 119 and sandwiched between a pair of current collectors 118. It is then positioned between the base and top plate of the fixing part 116, and the upper current collector 118 is pressed down by screwing a nut onto the support column, thereby pressurizing and restraining it. The electrical properties of the molded body of solid particles 17, thus pressurized and restrained, are measured by a measuring device 101 connected to connection terminals 112 provided on the protrusions of each of the pair of current collectors 118.

[0032] Thus, in the conventional technology, in order to measure the electrical properties, it is necessary to remove the molded body of solid particles 17 from the die hole of the die 113, and therefore it is not possible to measure the electrical properties of the compression molding process of the solid particles 17. Furthermore, since the pressure applied to the molded body of solid particles 17 by the pair of current collectors 118 is due to the pressure exerted by the tightening nuts, there is a risk that the molded body of solid particles 17 may not be uniformly pressurized, and the thickness may not be uniform, so large variations may occur in the electrical properties measured by the conventional method. In contrast, according to this embodiment, since the upper punch 10 and lower punch 11 are used as current collectors, there is no need to remove the molded solid particles 17 from the die hole of the die 13 in order to measure the electrical properties. Therefore, (i) the electrical properties of the molded solid particles 17 can be easily (or quickly) measured, (ii) the electrical properties of the solid particles 17 during the compression molding process can be measured, and (iii) after unloading, it is also possible to pressurize again and measure the electrical properties of the molded solid particles 17 during the pressurized and constrained process. Furthermore, in this embodiment, the connection terminal 12 is provided in locations other than the insertion portions 10b, 11b and opposing surfaces 10c, 11c of the upper punch 10 and lower punch 11. This allows the entire opposing surfaces 10c, 11c to be pressed with a uniform force, enabling uniform pressure to be applied to the molded body of solid particles 17 during molding and after molding. Furthermore, according to this embodiment, for example, during the compression molding process of an all-solid-state battery, by stacking and compressing positive electrode active material particles, solid electrolyte particles, and negative electrode active material particles within the die holes of the die 13, it becomes possible to easily perform charge-discharge tests under high pressure, which could not be easily done with conventional methods.

[0033] (Modification 1 of the first embodiment) The solid particle molding apparatus 1 of the first embodiment may not have a sealed container 100. If the solid particles 17 do not contain substances that react with oxygen and moisture in the air, compression molding and measurement of electrical properties can be performed under atmospheric conditions.

[0034] (Modification 2 of the first embodiment) The solid particle molding apparatus 1 of the first embodiment may comprise a die with an open top (non-through hole) and at least the inner wall surface of the die is insulating and the inner bottom surface is conductive, and a conductive upper punch inserted into the die from above. In other words, it does not have a lower punch. In this modified example 2, the upper punch is slidable up and down within the die and has a connecting terminal on the circumferential surface of the outer flange, similar to the first embodiment. On the other hand, in a die where at least the inner wall surface of the die is insulating, the inner bottom surface of the die is conductive, and the connecting terminal is electrically connected to the inner bottom surface. In the modified example 2, the molded body is removed from the die by, for example, inverting the die upside down through the top opening.

[0035] (Second Embodiment) The solid particle molding apparatus of the second embodiment is generally the same as the first embodiment, except that the positions of the connection terminals 12 of the upper punch 10 and lower punch 11 have been changed. The solid particle molding apparatus of the second embodiment will be described below with reference to Figures 1 to 4A. In the case of the solid particle molding apparatus of the second embodiment, for example, at least a part of the outer flange portion 10d of the upper punch 10 protrudes to a position that extends horizontally beyond the pressurizing portion 14. Therefore, the opposing surface 10c of the protruding portion of the outer flange portion 10d is not in contact with the pressurizing portion 14 and is exposed to the outside, and the connection terminal 12 is provided vertically on the externally exposed portion of the opposing surface 10c. This point is also the same for the upper punch 11 in the modified example 2 of the first embodiment. In addition, in the case of the second embodiment, for example, a part of the outer flange portion 11d of the lower punch 11 protrudes to a position that extends horizontally beyond the support base that supports the lower punch 11 in the fixing portion 16. Therefore, the opposing surface 11c of the protruding portion of the outer flange 11d is not in contact with the support base and is exposed to the outside, and the connection terminal 12 is provided vertically on the externally exposed portion of the opposing surface 11c. [Examples]

[0036] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. The following experiments used battery materials as experimental materials. The battery materials used in each experiment are described below.

[0037] (Battery materials) As the positive electrode active material, LiNi 0.5 Co 0.2 Mn 0.3 LiNbO3-coated LiNi (LiNbO3 coated O2 (hereinafter also referred to as NCM523: manufactured by Sumitomo Metal Mining Co., Ltd.) is coated with LiNbO3) 0.5 Co 0.2 Mn 0.3 O2 (hereinafter also referred to as LiNbO3-NCM523) was used. LiNbO3-NCM523 was prepared as follows.

[0038] 1) To obtain a coating-forming solution, 0.0352 g of ethoxylithium and 0.2180 g of pentaethoxyniobium were added to 2.1843 g of ethanol solvent so that lithium ethoxide and niobium(V) ethoxide were each contained in ethanol at a concentration of 0.2445 mol / L. 2) NCM523 was placed in a rolling fluid coating apparatus (MP-01, manufactured by Powrec Co., Ltd.), and dry air heated to approximately 80°C was introduced as the fluid gas. The positive electrode active material was circulated inside the rolling fluid coating apparatus by being stirred up by the dry air, while the prepared coating solution was sprayed from a spray nozzle. By operating the rolling fluid coating apparatus for 8 hours, NCM523 coated with the solution was obtained. LiNbO3-NCM523 was obtained by heat-treating NCM523 coated with a solution in an electric furnace.

[0039] Li3PS4 (75Li2S-25P2S5: manufactured by Admatex Corporation) was used as the solid electrolyte. When using the positive electrode active material as an all-solid-state secondary battery, a mixture of LiNbO3-NCM523 and Li3PS4 was used. The mixture was prepared by mixing LiNbO3-NCM523 and Li3PS4 in a mortar and pestle for 10 minutes, with a mass ratio of LiNbO3-NCM523:Li3PS4 = 7:3. For the negative electrode, a lithium-indium alloy foil (0.65 mm thick) manufactured by Furuuchi Chemical Co., Ltd. was used.

[0040] (Measurement of ionic conductivity under different confinement pressures) Using a solid particle molding apparatus 1 equipped with a die 13 and a pair of punches 2, the ionic conductivity was measured while applying different pressures to a solid electrolyte sample.

[0041] (Preparing the pestle) A pair of pestles 2 was prepared, consisting of an upper pestle 10 and a lower pestle 11, each equipped with a connecting terminal 12 on its side surface, as shown in Figure 2. The insertion parts of the upper pestle 10 and lower pestle 11 are cylindrical with a diameter of 1 cm (therefore, the insertion tip surface is circular with a diameter of 1 cm), and the material of the pestles is SKD (die steel).

[0042] (Formation of a solid particle molding apparatus) The lower punch 11 of the punch pair 2 described above was inserted into the die hole (1 cm in diameter) of a die 13 for powder molding made of Macol (registered trademark). This was then fixed to a uniaxial compression testing machine (Mini Press Set CDM-5 manufactured by Riken Kiki Co., Ltd.). Next, the upper punch 10 of the punch pair 2 described above was held by the punch holder 15 of this uniaxial compression testing machine to form the solid particle molding apparatus 1. The solid particle molding apparatus 1 is shown in Figure 1. The uniaxial compression testing machine that constitutes the solid particle molding apparatus 1 consists of the pressurizing section 14, the punch holder 15, and the fixing section 16.

[0043] (Ion conductivity measurement using a solid particle molding device 1: Ion conductivity measurement under different confinement pressures) An experiment was conducted to measure the ionic conductivity of a sample using the solid particle molding apparatus 1 described above. For molded bodies made using Li3PS4 solid electrolyte particles at a constant molding pressure (360 MPa), the ionic conductivity of molded bodies pressurized and constrained at different constraining pressures was measured. The test procedure was as follows.

[0044] 1. A hydraulic press (hydraulic section 104) was connected to the pressurizing section 14 of the solid particle molding apparatus 1. 2. Potentiostats SI-1287 (manufactured by Bio-Logic Sciences Instruments) were connected as measuring devices 101 to the connection terminals 12 of the upper punch 10 and the lower punch 11. 3. A displacement sensor 105 (high-precision contact-type digital sensor GT2-S1 manufactured by Keyence Corporation) is connected to the pestle holding section 15 to measure the amount of movement of the pestle. 4. After inserting the lower punch 11 into the die cavity of the die 13 equipped with the solid particle molding apparatus 1, 60 mg of Li3PS4 particles were placed in from the upper opening, and the upper punch 10 was inserted into the die cavity of the die 13. 5. The hydraulic unit 104 was activated, and a molding pressure of 360 MPa was applied to the particles via the upper punch 10 to produce a molded body (pellet). 6. After unloading, a pressure of 20 MPa (restraining pressure) was applied again to the molded body, and the ionic conductivity was measured using a potentiostat SI-1287 under those conditions. 7. The ionic conductivity was measured in the same manner as in 6. above, with the confinement pressure changed to 40 MPa, 75 MPa, and 120 MPa.

[0045] The above steps 4-7 were also performed on two other lots of Li3PS4 samples, resulting in a total of three tests. All of these procedures were carried out in a glove box (sealed container 100) under an argon atmosphere. A schematic of the above measurement method is shown in Figure 4A.

[0046] The results are shown in Figure 5. In Figure 5, the horizontal axis represents the constraining pressure applied after molding, and the vertical axis represents the ionic conductivity. For comparison, Figure 5 also includes the results measured by the conventional method. The conventional method was performed as follows (see Figure 4B).

[0047] 1. A hydraulic press (hydraulic section 104 in Figure 1) was connected to the pressurizing section 14 of a uniaxial compression testing machine (Mini Press Set CDM-5 manufactured by Riken Kiki Co., Ltd.). 2. In order to ensure that the manufacturing conditions for the molded body are the same, a lower punch 111, which has the same dimensions as the lower punch 11, was inserted into the die hole of a die 113, which has the same dimensions as the die 13, and this die 113 and lower punch 111 were placed in a uniaxial compression testing machine. 3. 60 mg of Li3PS4 particles were placed in the die cavity of die 113, which was placed in a uniaxial compression testing machine. 4. In order to ensure that the conditions for manufacturing the molded body are the same, an upper punch 110 with the same dimensions as the upper punch 10 was inserted into the die cavity. 5. The hydraulic unit 104 (see Figure 1) was activated, and a molding pressure of 360 MPa was applied to the particles via the upper punch 110 to produce a molded body (pellet). 6. After unloading, the molded body (pellets) was removed from the die cavity. 7. The molded body was placed in the sample guide 119, sandwiched between a pair of SUS current collectors 118, positioned on the fixing part 116 of the measuring cell 108, and secured with a restraining pressure of 10 MPa by screwing in a nut. 8. Ionic conductivity was measured using a potentiostat SI-1287, which served as a measuring device 101, connected to each connection terminal 112 of the current collector 118.

[0048] The ionic conductivity of molded bodies was measured for those produced by changing the pressure (restraining pressure) applied in step 7 above to 30 MPa and 40 MPa. The data indicated by black circles in Figure 5 are data obtained using the solid particle molding apparatus 1 of the embodiment of the present invention (data from three molded bodies), and the data indicated by the × marks are data obtained by the conventional method (data from one molded body). From Figure 5, it can be seen that there is no significant difference between the ionic conductivity measured using the solid particle molding apparatus 1 of the embodiment of the present invention and the ionic conductivity measured by the conventional method. From this, it can be seen that the ionic conductivity of a compressed solid particle molded body can be easily (or quickly) measured by using the solid particle molding apparatus 1 of the embodiment of the present invention.

[0049] (Ion conductivity measurement using a solid particle molding device 2: Measurement of ion conductivity of compression molded bodies produced at different molding pressures) In the measurement of ionic conductivity using the solid particle molding apparatus 1 described above, the experiment was conducted in the same manner as in steps 1 to 4 and step 6, except that the molding pressure applied in step 5 was changed to 120 MPa, 240 MPa, 320 MPa, 440 MPa, and 560 MPa. The test was performed on three molded bodies (molded bodies produced using the solid particle molding apparatus 1 of the embodiment of the present invention) produced at each molding pressure. The measurement results are shown in Figure 6. In Figure 6, the horizontal axis represents the molding pressure and the vertical axis represents the ionic conductivity. From Figure 6, it can be seen that the ionic conductivity of the molded body improves with increasing molding pressure up to approximately 320 MPa, but becomes almost constant when the molding pressure exceeds 350 MPa. Here, the data obtained when a pressure of 300 MPa or more was applied roughly matches the results obtained by conventional methods for the same material in prior literature (Atsushi Sakuda et al. Sulfide Solid Electrolyte with Favorable Mechanical Property for All-Solid-State Lithium Battery Sci. Rep. (2013)). From this, it can be seen that the ionic conductivity of a compression molded body can be measured in the solid particle molding apparatus 1 of the embodiment of the present invention, and as a result, the ionic conductivity of a solid particle molded body can be easily (or quickly) measured using the solid particle molding apparatus 1 of the embodiment of the present invention.

[0050] (Charge-discharge test 1, simulating a compression molding process using a solid particle molding device) A solid-state battery was constructed and a charge-discharge test was performed within the solid particle molding apparatus 1 described above. The battery was configured as follows: 1. The operations from steps 1 to 3 of the ion conductivity measurement 1 using the solid particle molding apparatus 1 described above were performed. 2. A lithium-indium alloy film (manufactured by Furuuchi Chemical Co., Ltd.) with a thickness of 0.65 mm was placed as the negative electrode on the insertion tip surface 11b of the lower punch 11 inserted into the die hole of the die 13. 3. 80 mg of Li3PS4 particles were placed on top of the lithium-indium alloy film as a solid electrolyte, and the surface was flattened by tapping. 4. 10 mg of a mixed particle of the above-mentioned LiNbO3-NCM523 and Li3PS4 was placed on the Li3PS4 particle layer as the positive electrode active material, the surface was flattened by tapping, and the upper punch 10 was inserted into the die hole of the die 13. 5. The hydraulic unit 104 was activated, and a molding pressure of 185 MPa was applied to the stacked particles via the upper punch 10 to produce a stacked molded body (pellet). A schematic diagram of the configured battery is shown in Figure 7. In Figure 7, 20 represents the positive electrode, 21 represents the solid electrolyte layer, and 22 represents the negative electrode. 6. The above-mentioned batteries were subjected to charge-discharge tests under the conditions described in Table 1 below, while maintaining the molding pressure, and their battery performance was measured.

[0051] [Table 1]

[0052] Next, the molding pressure was increased to 256 MPa, and the battery performance was measured by performing a charge-discharge test in the same manner as in step 6 above. Furthermore, the molding pressure was increased to 333 MPa, and step 6 was repeated.

[0053] The measurement results are shown in Figure 8A for the charge-discharge curves measured under each pressure, and in Figure 8B for the solid electrolyte resistance and charge transfer resistance. In Figure 8A, the horizontal axis represents capacity and the vertical axis represents voltage. In Figure 8B, the horizontal axis represents molding pressure and the vertical axis represents resistance. In Figure 8A, the upward-sloping graphs from around 3.8(V) to around 4.2(V) represent the charging curves under each pressure condition (185MPa, 256MPa, 333MPa), while the downward-sloping graphs from around 4.0(V) to around 3.0(V) represent the discharge curves under each pressure condition (185MPa, 256MPa, 333MPa). Figure 8A shows that charge-discharge curves can be formed under each pressure condition. Focusing on the discharge results, the horizontal axis becomes larger as the pressure increases, indicating an increase in battery capacity. For example, the voltage at a capacity of 40 mAg / h increases with increasing pressure, indicating a decrease in overvoltage during discharge. From these findings, it can be seen that the solid particle molding apparatus 1 of the embodiment of the present invention makes it possible to easily (or quickly) measure the electrical characteristics of solid particles during the compression molding process (in other words, under high pressure conditions), which could not be measured by conventional methods. In other words, conventionally, a total of six tests are required to perform charge and discharge tests at each pressure condition (185 MPa, 256 MPa, 333 MPa) during the compression molding process of solid particles. However, using the solid particle molding apparatus 1 of the embodiment of the present invention, charge and discharge test data can be efficiently obtained in a single experiment, even under different pressure conditions (185 MPa, 256 MPa, 333 MPa).

[0054] (Charge-discharge test 2, assuming a pressurized and constrained process using a solid particle molding apparatus) For the battery used in the above charge / discharge test 1, after unloading, the charge / discharge test was repeated at each pressure while sequentially re-pressurizing it to 185 MPa, 256 MPa, and 333 MPa, which correspond to the confinement pressure. The measurement results are shown in Figure 9A for the charge-discharge curves measured under each pressure, and in Figure 9B for the solid electrolyte resistance and charge transfer resistance. In Figure 9A, the horizontal axis represents capacity and the vertical axis represents voltage. In Figure 9B, the horizontal axis represents confinement pressure and the vertical axis represents resistance. In Figure 9A, the upward-sloping graphs from around 3.8(V) to around 4.2(V) are the charge curves under each pressure condition (185MPa, 256MPA, 333MPa), and the downward-sloping graphs from around 4.0(V) to around 3.0(V) are the discharge curves under each pressure condition (185MPa, 256MPA, 333MPa). Figure 9A shows that charge-discharge curves can be formed under each pressure condition. Focusing on the discharge results, for example, the voltage at a capacity of 40 mAg / h is approximately constant regardless of pressure, but as the pressure increases, the final value on the horizontal axis becomes smaller, indicating that the total amount of Li ions used in the battery reaction decreases. From this, it can be seen that the electrical characteristics of solid particles during the pressurized confinement process can be easily (or quickly) measured using the solid particle molding apparatus 1 of the embodiment of the present invention. In other words, conventionally, a total of six tests are required to perform charge and discharge tests at each pressure condition (185 MPa, 256 MPa, 333 MPa) during the pressurized confinement process of solid particles, but by using the solid particle molding apparatus 1 of the embodiment of the present invention, charge and discharge test data can be efficiently obtained in a single experiment even under different pressure conditions (185 MPa, 256 MPa, 333 MPa). [Explanation of symbols]

[0055] 1: Solid particle forming equipment 2: Pestle 3: Upper pestle 10: Upper punch, 10a: Insertion tip surface, 10b: Insertion part, 10c: Opposing surface, 10d: Outer flange 11: Lower punch, 11a: Insertion tip surface, 11b: Insertion part, 11c: Opposing surface, 11d: Outer flange 12: Connection terminals on the pestle 13: Mortar 14: Pressurized section (hydraulic cylinder) 15: Pestle holding part 16: Fixed part 17: Solid particles 20: Positive electrode 21: Solid electrolyte sample 22: Negative electrode 100: Airtight container (glove box) 101: Measuring device 102: Wiring 103: Valve 104: Hydraulic section 105: Displacement meter 106: Connection hose 107: Pressure Gauge 108: Measuring cell

Claims

1. A solid particle molding apparatus used when compressing solid particles, It comprises a die having a die hole that penetrates vertically and at least the inner wall surface of the die hole being insulating, and a conductive upper punch and a conductive lower punch inserted above and below the die hole, respectively. At least one of the upper punch and the lower punch is capable of sliding up and down within the die cavity. A solid particle molding apparatus wherein each of the upper punch and the lower punch has a connecting terminal at a location that does not hinder the insertion of the upper punch and the lower punch into the mortar and the compression molding of the solid particles in the mortar by the upper punch, the lower punch and the mortar.

2. The solid particle molding apparatus according to claim 1, wherein each of the upper punch and the lower punch has a connecting terminal on a surface different from the insertion tip surface of the punch and the surface opposite it.

3. The solid particle molding apparatus according to claim 1, wherein the upper punch and the lower punch are capable of conducting electricity through the solid particles in the die cavity.

4. The solid particle molding apparatus according to claim 1, wherein the connection terminal is capable of connecting a measuring device for measuring the electrical properties of the solid particles.

5. The solid particle molding apparatus according to claim 1, further comprising a compression device capable of compressing the solid particles via at least one of the upper punch and the lower punch.

6. The solid particle molding apparatus according to claim 1, further comprising a device capable of measuring the amount of movement in the compression direction by at least one of the upper punch and the lower punch.

7. The solid particle molding apparatus according to claim 1, further comprising a device capable of measuring compression pressure.

8. The solid particle molding apparatus according to claim 1, wherein the mortar, the upper pestle, and the lower pestle are stored in a sealed container.

9. The solid particle molding apparatus according to claim 1, wherein the solid particles include at least one of a solid electrolyte and an electrode active material.

10. A solid particle molding apparatus used when compressing solid particles, The device comprises a die having a die cavity with an open top, the inner wall surface of which is insulating and the inner bottom surface of which is conductive, and a conductive upper punch inserted into the upper part of the die cavity. The upper punch is capable of sliding up and down within the die cavity, A solid particle molding apparatus wherein the upper punch and the mortar have connecting terminals at locations that do not hinder the insertion of the upper punch into the mortar and the compression molding of the solid particles in the mortar by the upper punch and the mortar.

11. The upper punch has the connection terminal on a surface different from the insertion tip surface of the punch and the surface opposite to it. The solid particle molding apparatus according to claim 10, wherein the mortar has the connection terminal connected to the inner bottom surface of the mortar cavity.

12. A solid particle molding apparatus according to any one of claims 1 to 9, wherein the solid particles can be compressed at a pressure of 10 MPa or more via the upper punch and the lower punch, or a solid particle molding apparatus according to claim 10 or 11, wherein the solid particles can be compressed at a pressure of 10 MPa or more via the upper punch and the mortar.

13. A solid particle molding apparatus used for compression molding solid particles, comprising a die having a die hole that penetrates vertically and the inner wall surface of the die hole being insulating, and a conductive upper punch and a conductive lower punch inserted above and below the die hole, respectively; a step of placing the solid particles into the die hole; A step of compressing the solid particles by sliding at least one of the upper punch and the lower punch within the die cavity, A method comprising the step of measuring the electrical properties of the solid particles using measuring devices electrically connected to the upper punch and the lower punch while compression is maintained.

14. The method according to claim 13, further comprising the step of connecting the measuring device to a connecting terminal provided in the upper punch and the lower punch in the mortar, in a location that does not interfere with the insertion of the upper punch and the lower punch into the mortar and the compression molding of the solid particles in the mortar by the upper punch, the lower punch and the mortar.

15. A solid particle molding apparatus used for compression molding solid particles, comprising a die having an open top and at least the inner wall surface of the die being insulating and the inner bottom surface of the die being conductive, and a conductive upper punch inserted into the top of the die, a step of placing the solid particles into the die cavity, A step of compressing the solid particles by sliding the upper punch within the die cavity, A method comprising the step of measuring the electrical properties of the solid particles using a measuring device electrically connected to the upper punch and the inner bottom surface of the die cavity while compression is maintained.

16. The method according to claim 15, further comprising the step of connecting the measuring device to a connecting terminal provided in the upper punch and the lower punch at a location that does not hinder the insertion of the upper punch into the mortar and the compression molding of the solid particles in the mortar by the upper punch and the mortar.

17. The method according to claim 13 or 15, wherein the measurement step is performed multiple times by varying the compression conditions for the solid particles in the die cavity.

18. The method according to claim 13 or 15, wherein the measurement step is performed by compressing the solid particles at a pressure of 10 MPa or more.

19. A conductive punch for a solid particle molding apparatus used when compressing solid particles, A punch having a connection terminal on a surface different from the insertion tip surface of the punch and the surface opposite to it.

20. A pair of punches comprising two punches according to claim 16, wherein electricity can be conducted through the solid particles.

Images