JP2012169131A - Coating device and method of active material for battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for finishing a process in a proper coating state and a coating device therefor, when coating an active material for a battery.SOLUTION: A coating device 100 includes a processing chamber 110 for coating granular materials by spraying a coating liquid to the granular materials while floating and circulating the granular materials serving as the active material for the battery by a gas, a spray nozzle 120 for spraying the coating liquid, and an inlet 130 for the gas, an outlet 140 for the gas, and a filter 150 for separating the granular materials from the gas. The coating device is also equipped with a green compact resistance measuring part 170 including a collecting mechanism for the granular materials, a mechanism for forming a green compact by pressurizing the granular materials, and a resistance measuring mechanism for measuring the electric resistivity or the electric resistance of the green compact, and a control device 240 for adjusting the coating conditions of the granular materials by feeding back the measured electric resistivity or the electric resistance.

Description

  The present invention relates to an apparatus and a coating method for coating a battery active material.

  One of the powder coating apparatuses is a fluidized bed apparatus. Generally, a fluidized bed apparatus floats and flows particles in a fluidized bed container with a gas (fluidized gas) introduced from the bottom of the fluidized bed container. Granulation, coating, drying and the like are performed while forming a fluidized bed. This type of fluidized bed apparatus includes those that involve rolling, jetting, stirring, etc. of powder particles, and representative examples thereof include a rolling flow in which a rotating body is disposed at the bottom of a fluidized bed container. Examples thereof include a Werster fluidized bed apparatus in which a draft tube (inner tower) is installed inside a bed apparatus and a fluidized bed container (Patent Document 1).

  Further, in a lithium ion secondary battery including a positive electrode layer and a negative electrode layer, and an electrolyte disposed between them, a nonflammable solid electrolyte may be used as an electrolyte in place of a generally flammable electrolyte. Proposed. Since the solid electrolyte does not easily penetrate into the voids formed by the positive electrode active material, the interface between the positive electrode active material and the electrolyte is likely to be reduced, and when the lithium ions move through the interface between the positive electrode active material and the solid electrolyte. Resistance (also referred to as interfacial resistance) tends to increase, which is problematic because it affects battery performance. In order to cope with this problem, it is disclosed that a positive electrode active material is coated with a solid electrolyte using a fluidized bed apparatus (Patent Document 2).

JP 2007-307448 A JP 2009-193940 A

  However, when another substance is coated on the surface of the granular material by the fluidized bed apparatus, there is a problem that the coating amount often tends to vary. In particular, when coating the surface of an active material for a battery using a fluidized bed apparatus, if insufficient coating or excessive coating occurs, battery performance may vary and insufficient performance is undesirable.

  In a fluidized bed apparatus, in order to make the coating quality on the surface of the granular material constant, it is important to keep the flow state of the granular material constant. It is affected by numerous factors such as amount, temperature, and humidity, coating fluid spray amount and temperature, and particle size distribution of the powder.

  In particular, the active material powder of a battery generally has an average particle size of 10 μm or less, and when coating is performed by a fluidized bed apparatus, it is very difficult to stabilize the flow. Depending on the condition, the coating quality is greatly affected.

  However, in existing fluidized bed equipment, the coating process is managed by time, so there may be insufficient coating or overcoating due to variations in the flow state of battery active material powder or variations between lots. When using as an active material for a battery, it has been a problem.

  Then, an object of this invention is to provide the coating apparatus for the method of ending a process in a suitable coating state in coating of the active material for batteries.

  The present inventors pay attention to the fact that the powder resistance of the active material powder changes when the surface of the active material powder is coated with another material, and during the coating, the powder resistivity or dust resistance of the active material is changed. And a method for terminating the coating process in an appropriate coating state and an apparatus therefor were found by feeding back the measured powder resistivity or dust resistance to the coating conditions.

The present invention provides a treatment chamber for performing a coating treatment of the granular material for spraying a coating liquid on the granular material while the powdery active material for a battery is suspended and flowing with a gas, A coating apparatus comprising a spray nozzle for spraying a coating liquid, an inlet for the gas, an exhaust port for the gas, and a filter for separating the granular material and the gas;
Powder resistance including a collecting mechanism for the powder, a mechanism for forming a green compact by pressurizing the collected powder, and a resistance measuring mechanism for measuring the electrical resistivity or the electric resistance of the green compact A measurement unit, and a control device that adjusts the coating conditions of the granular material by feeding back the measured electrical resistivity or electrical resistance,
It is a coating device.

The present invention is also a method for coating a battery active material, in which a coating liquid is sprayed on the powder while the powder of the battery active material is suspended and flowed with a gas.
It is a coating method including the process of measuring the electrical resistivity or electrical resistance of the granular material, and feeding back the measured electrical resistivity or electrical resistance to adjust the coating condition of the granular material.

  According to the method and the coating apparatus for coating the battery active material of the present invention, the battery active material can be manufactured without being affected by the flow state of the active material granules or the variation between production lots of the active material granules. It is possible to stabilize the coating quality and obtain a desired coating thickness.

It is a cross-sectional schematic diagram of the coating apparatus in one embodiment of this invention. It is an upper surface schematic diagram of the dust resistance measurement part in one embodiment of the present invention. It is a schematic diagram of the electrode component which comprises the dust resistance measurement part in one embodiment of this invention. It is a schematic diagram of the electrode components which serve as the dust compaction mechanism which comprises the dust resistance measurement part in one embodiment of this invention. It is a schematic diagram of the guide component which comprises the dust resistance measurement part in one embodiment of this invention. It is a cross-sectional schematic diagram of the dust resistance measurement part provided with the 4-terminal electrode in the other embodiment of this invention. It is a schematic diagram of the guide component which attached the piezo terminal in the other embodiment of this invention. It is a cross-sectional schematic diagram of the coating apparatus in the other embodiment of this invention.

  Hereinafter, the coating apparatus which concerns on 1st embodiment of this invention is demonstrated, referring drawings.

  FIG. 1 is a schematic cross-sectional view of a coating apparatus according to the first embodiment of the present invention. The coating apparatus 100 includes a processing chamber 110 for coating powder particles, a spray nozzle 120 for spraying a coating liquid, a flowing gas inlet 130 for floating and flowing the particles, a flowing gas exhaust port 140, and the particles and gas. A filter 150, a gas dispersion plate 160, a dust resistance measurement unit 170, and a feedback control device 240 are provided. A wavy line 180 schematically represents a flow path of powder particles in the coating apparatus, and the flow is continuously repeated in the processing chamber 110 through a path as indicated by the wavy line 180. A wavy line 190 schematically represents the flow path of the flowing gas from the flowing gas inlet 130. The wavy line 200 schematically represents the flow path of the flowing gas to the flowing gas exhaust port 140. Further, if desired, a blade rotor 210 and a motor 220 for rotating the blade rotor 210 may be provided.

  In the present invention, the granular material of the battery active material is wound up by the flowing gas introduced from the flowing gas inlet 130, and the coating liquid is sprayed from the spray nozzle 120 to perform the coating process. The coated powder particles are dried while flowing as indicated by the dotted line 180, flow from the upper part of the apparatus to the lower part, and sprayed with the coating liquid while being wound up with a flowing gas again, and the coating process is repeatedly performed. Coating and drying are performed sequentially until the desired coating thickness is obtained. The gas that is introduced into the processing chamber 110 and floats and flows the granular material is separated from the granular material by the filter 150 and is exhausted from the fluid gas exhaust port 140 to the outside of the coating apparatus.

  The gas dispersion plate 160 is disposed near the flowing gas inlet 130. In FIG. 1, a metal plate having a gas flow path at the center is shown as the gas dispersion plate 160, but the gas dispersion plate 160 is a porous plate such as a punching metal instead of or in addition to the metal plate, Alternatively, it can be constituted by a mesh-like wire mesh or the like.

  FIG. 2 is a schematic top view of the dust resistance measurement unit 170 in the first embodiment of the present invention. The dust resistance measuring unit 170 includes a component 171 serving as an electrode, a component 172 serving as an electrode also serving as a dust compaction mechanism, and a component 173 serving as a guide.

  The electrode component 171 shown in FIG. 3 is disposed on the end surface 174A of the groove 174 of the guide component 173 shown in FIG. 5, and the component 171 is placed so that the electrode surface 171A matches the surface position of the end surface 174A as shown in FIG. Can be arranged. The outer shape of the electrode surface 171A can be the same as the shape of the end surface 174A. Alternatively, the outer shape of the electrode surface 171A may be smaller than the end surface 174A, but in this case, the electrode surface 171A is disposed so that the surface position of the electrode surface 171A matches the surface position of the end surface 174A. The component 172 can have a configuration that slides in a groove 174 provided in the component 173. Although the outer shape of the end face of the component 172 facing the 174A can also be an arbitrary shape, in this embodiment, it is the same shape as the 174A.

  The material constituting the component 171 and the component 172 is not particularly limited as long as it can pressurize the powder and can function as an electrode. For example, SUS304 or the like can be used.

  The material constituting the component 173 functions as a guide for pressurizing the powder and is not particularly limited as long as it is an insulator. For example, the material which is made by abrading aluminum and insulating the surface by anodizing may be used. In addition, a surface processed with Teflon (registered trademark) can be used.

  The dust resistance measuring unit 170 includes a powder collecting unit 175 between a component 171 and a component 172 formed by pulling a predetermined amount of the component 172 in the groove 174 of the component 173.

  Although not shown, the electrode component 172 is connected to a hydraulic pump and has a dusting mechanism. The component 172 can also be connected to the displacement meter 240 and have a green compact thickness measuring mechanism.

  Although not shown, the guide component 173 is connected to a rotation mechanism and can rotate around the longitudinal axis.

  As shown in FIG. 3, the component 171 includes a terminal portion 171B to which a voltage line and a current line can be connected. The voltage line is connected to a voltmeter, the current line is connected to a DC power source, and the DC power source is It may be a constant current source. Similarly, the component 172 includes terminal portions 172B and 172C to which a voltage line and a current line can be connected. The voltage line is connected to a voltmeter, the current line is connected to a DC power source, and the DC power source is fixed. It may be a current source.

  The coated and dried powder particles descend from the upper part of the coating apparatus to the powder collecting unit 175 and are collected. After a predetermined time has passed while collecting the granular material in the powder collecting part or after the mass of the collected powder reaches a predetermined value, the part 172 is pushed in at a predetermined pressure by a hydraulic press, and the granular material is Press to form a green compact.

  After forming the green compact, a voltage is measured by applying a current between the electrodes of the component 171 and the component 172, and at the same time, the thickness of the green compact is measured by a displacement meter connected to the component 172.

In this case, in the present invention, the resistivity ρ of the green compact is calculated by the following equation.
ρ = (V ₁ × A ₁ ) ÷ (I ₁ × L ₁ ) (Ω · m)
In the formula, V ₁ is the measurement voltage, A ₁ is the area of the electrode surface 171A, I ₁ is the applied current value, and L ₁ is the thickness of the green compact.

  In another method, instead of the electrode component 171, as shown as the electrode component 271 in FIG. 6, four terminals including two current terminals and two voltage terminals are used, and the front end surface of each terminal is formed as a groove portion of the component 173. It can also be fixed and arranged in accordance with the end face 174A of 174. In this case, it is not necessary to measure the thickness of the green compact, and it is not necessary to consider the influence of the contact resistance, so that the voltage of the green compact can be measured more stably. The electrode component 171 or 271 can be selected according to the resistance of the green compact sample. The material of the component 271 is not particularly limited as long as the terminal is not deformed when the powder is pressed and can function as an electrode. For example, SUS304 or the like can be used.

When this four-terminal method is used, the voltage measurement of the green compact is performed between the voltage terminals installed on the end face 174A, and therefore the resistance of the green compact can be measured without measuring the thickness of the green compact. . The resistance of the green compact is calculated by the following equation.
R = V ₂ ÷ I ₂ (Ω)
In the formula, V ₂ is a measurement voltage and I ₂ is an applied current value.

  Regardless of the two-terminal method or the four-terminal method described above, the pressing force for forming the green compact by pressing the component 172 is not particularly limited as long as the measured voltage value falls within the measurable range, but if the pressing force is too low, the voltage is reduced. If the green compact is returned to the inside of the coating system of the coating apparatus after voltage measurement, the green compact may be difficult to disintegrate if the applied pressure is too high. A pressing force in the range of 5-30 MPa can be used.

  The applied current value for measuring the voltage is not particularly limited, but can be adjusted so that the measured voltage value falls within the measurable range of the voltmeter. For example, a current value in the range of 500 μA to 500 mA may be used. it can.

  The electrical resistivity or electrical resistance value of the dust is measured, and a signal is sent to the feedback controller 240, and the powder coating time, fluid gas temperature, fluid gas flow rate, coating fluid amount, and coating fluid amount At least one of the temperatures can be adjusted.

  As for the coating time of the granular material, the electrical resistivity or electrical resistance value of the compact is measured, and when it is confirmed that the powder has increased or decreased to a specified value, a signal is sent to the feedback control device 240, The coating process time can be determined or the coating process can be terminated immediately.

  Regarding the temperature of the flowing gas, the flow rate of the flowing gas, the amount of the coating liquid, and the temperature of the coating liquid, the electrical resistivity or electrical resistance value of the dust is measured, and it is confirmed that it has increased or decreased to the specified value. Then, a signal is sent to the feedback controller 240 to increase or decrease the temperature of the flowing gas, the flow rate of the flowing gas, the amount of the coating liquid, and the temperature of the coating liquid.

  The coating time, the temperature of the flowing gas, the flow rate of the flowing gas, the amount of the coating liquid, and the temperature of the coating liquid may be adjusted independently depending on the powder to be coated, the coating material, the coating thickness, etc., or They may be combined or adjusted.

  Preferably, the electrical resistivity or electrical resistance value of the dust is measured, and if it is confirmed that the electrical resistivity or electrical resistance value has increased or decreased to a specified value, a signal is sent to the feedback controller 240 to terminate the coating process. Can do.

  The time for collecting the granular material in the powder collecting unit is such that the green compact completely covers the electrode surface 171A of the component 171 when the green compact is formed by pressurization. Can be sufficient time to fill the powder collecting unit 175. If the dust resistance measuring unit 170 is equipped with a mechanism for measuring the collected powder mass, the collected powder mass can be measured instead of the collection time. The mass is such that when the green compact is formed by pressurization, the powder collector 175 is filled with the granular material so that the green compact completely covers at least the electrode surface 171A of the component 171. A sufficient powder mass can be obtained.

  The part 173 can have a tapping mechanism. The tapping mechanism vibrates the component 173 to help stabilize the packing density of the powder and particulates collected in the powder collection unit 175 and / or to discharge the green compact from the powder collection unit. For example, as shown in FIG. 7, the piezo element 230 can be attached to the component 173 to vibrate the component 173.

  After measuring the voltage, the hydraulic pressure is released and the green compact is discharged from the powder collection unit 175. The green compact can be discharged into the coating system or discharged out of the coating system. When discharging into the coating system, the utilization efficiency of the granular material can be improved. When the amount of green compact discharged is small or when it is difficult to crush the green compact after discharge, it is also effective to discharge the green compact outside the coating system.

  The component 173 can have a rotation mechanism that rotates about the longitudinal axis, and rotates the dust resistance measurement unit 170 to collect the powder particles falling with the powder collection unit 175 facing upward. be able to. After the voltage measurement, the dust resistance measuring unit 170 can be rotated so that the powder collecting unit 175 faces downward and the green compact can be dropped and discharged.

  Alternatively, or in addition, shutters that can be opened and closed are provided on the upper and lower surfaces of the powder collecting unit 175 to serve as a powder collection port and a green compact discharge port. By opening the shutter on the upper surface, the falling powder particles can be collected. After the voltage measurement, the green compact can be dropped and discharged by opening the shutter on the lower surface.

  Whether the part 173 has a rotation mechanism and / or a shutter mechanism, the tapping mechanism is used to vibrate the part 173 to stabilize the packing density of the green compact; It is possible to improve the discharge performance.

  In place of or in addition to the rotation mechanism and / or the shutter mechanism, gas may be blown to the powder collecting section to discharge the green compact.

  As shown in FIG. 1, a blade rotor 210 may be disposed inside the coating apparatus. When the green compact whose voltage has been measured is discharged into the coating system, the blade rotor 210 can accelerate the crushing of the discharged green compact. The blade rotor can also serve to stir the powder particles. The blade rotor can be arranged at an arbitrary position, but is preferably installed below the dust resistance measuring unit, and when the green compact is dropped and discharged from the powder collecting unit 175 of the dust resistance measuring unit 170 Furthermore, the crushing of the green compact that has fallen can be promoted with a blade rotor.

  Prior to the start of the coating process, a predetermined amount of powder particles can be placed at any position where it is wound up by the flowing gas to be introduced, for example, on the gas dispersion plate 160, on the blade rotor 210, etc. Can do. If desired, a powder nozzle may be added continuously or intermittently while a coating nozzle is provided and a coating process is performed.

  A series of processes of collecting powder, pressurizing, measuring voltage, and discharging can be repeated. The series of processes can be performed automatically, can be performed any number of times or at regular time intervals, and the coating process can be terminated as soon as the target resistivity or resistance value is reached. Alternatively, the coating process can be terminated by estimating the time to reach the target resistivity or resistance value from the measured voltage before reaching the target resistivity or resistance value.

The battery active material used in the present invention is not particularly limited as long as it is a powder that can be used in the coating method and coating apparatus of the present invention. For example, LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ , LiNi _{1 / 3} CO _1/3 Mn _1/3 O ₂ , LiFePO ₄ , MnO ₂ , Zn, CuO, Ni (OH) ₂ etc. are used as the main component. Preferably, the powder which can be used as a positive electrode active material of a lithium ion secondary battery can be used.

The coating material used in the present invention is not particularly limited as long as it is a sprayable liquid substance that can be used in the coating method and coating apparatus of the present invention. For example, the coating material is applied to an organic solvent or an aqueous solution. A solution obtained by dissolving a solid electrolyte such as LiOC ₂ H ₅ or Nb (OC ₂ H ₅ ) ₅ in ethanol or the like can be used.

  The flowing gas is not particularly limited as long as it is a gas that can flow the granular material, but is preferably a gas not containing moisture, and for example, dry air or the like can be used. Further, the temperature of the fluid gas to be introduced is not particularly limited, but is preferably a temperature at which the coating that has been sprayed and wetted on the granular material is easily dried during the flow of the granular material, for example, 50 to 120 ° C. A gas at a temperature of 5 mm can be used.

  The filter 150 is not particularly limited as long as it separates the flowing gas and the granular material. For example, a woven fabric filter called a bag filter, a breathable resin sheet subjected to pleating, and the like are formed into a cylindrical shape. A cartridge type filter held by a retainer can be used. In addition, the filter can be provided with a shaking operation, jet air injection, a cleaning mechanism, and the like for removing powder particles adhering to the filter.

  Although not shown, the coating apparatus of the present invention can also include a heating unit and / or an electromagnetic wave irradiation unit for drying the coating of the granular material. The heating unit and / or the electromagnetic wave irradiation unit may be arranged at an arbitrary position, but it is preferable to arrange the heating unit and / or the electromagnetic wave irradiation unit around the processing chamber 110 and above the spray nozzle so as to dry the powder after spraying the coating liquid. I can help.

  The heating unit can be composed of a heater such as a high frequency coil. In the case of using a high frequency coil, the temperature and temperature gradient in the processing chamber can be adjusted by adjusting the number and interval of the high frequency coils, the positional relationship between the high frequency coil and the processing chamber 110, and the output of the high frequency coil.

  The electromagnetic wave irradiation unit is an apparatus that emits an electromagnetic wave that can promote solvent drying, and it is preferable to use a wavelength that is easily absorbed by the solvent of the coating solution. If the solvent of the coating liquid is an aqueous solvent, an apparatus having a light source capable of irradiating microwaves is preferable. For example, a microwave drying apparatus having a wavelength of 12.3 cm can be mentioned. If the solvent of the coating liquid is an ethanol solvent, An apparatus having a light source capable of irradiating ultraviolet rays is preferable, and examples thereof include an excimer lamp having a wavelength of 220 nm.

  Specific examples of the coating method and coating apparatus of the present invention will be described below.

Example 1
A coating solution was prepared by dissolving 0.6 mol of LiOC ₂ H ₅ and Nb (OC ₂ H ₅ ) ₅ in 1 l of ethanol, respectively.

The coating liquid is spray-coated and dried on the powder of LiCoO ₂ active material according to the following processes i) to vi) using the fluidized coating apparatus having the dust resistance measuring unit shown in FIG. 1 and FIG. Thus, an active material coated to a desired thickness was obtained.

i) Introducing 0.2 m ³ / min of dry air at 60 ° C. into the coating apparatus 100 to flow 1 kg of the LiCoO ₂ active material powder particles, the prepared coating solution was applied from the spray nozzle 120 at 5 g / min. The LiCoO ₂ active material powder was wetted with the coating liquid by spraying. Process i) was continued during the following processes ii) -vi).

  ii) The powder resistance measuring unit 170 is rotated so that the powder collecting unit 175 faces upward, and the piezo element (AE0505D16F manufactured by NEC TOKIN) attached to the component 173 is vibrated and tapped for 1 minute. The body was collected.

  iii) A part 172 connected to a hydraulic press and a cantilever type digital displacement meter (CE-5, manufactured by Tokyo Sokki Kenkyujo) was slid by the hydraulic press, and the collected granular material was pressurized at 5 MPa.

iv) A voltage of 50 μA was applied between the components 171 and 172 to measure the voltage, and at the same time, the thickness of the green compact was measured. Then, the resistivity was calculated from the electrode area of 171A. The resistivity at the start of coating was 3.9 × 10 ² Ω · cm.

  v) The powder resistance measuring unit 170 is rotated so that the powder collecting unit faces downward, and the piezoelectric element attached to the component 173 is vibrated and tapped while releasing the hydraulic pressure to collect the powder. It discharged from part 175.

vi) While continuing the process i), repeat the processes ii) to v) once every 10 minutes. When the target resistivity of 1.8 × 10 ³ Ω · cm is reached, spray the coating liquid. Ended. The operating time of the coating apparatus was 5.5 hours. According to observation with a transmission electron microscope (TEM), the coating thickness at this time was 10 nm, and a desired coating thickness could be obtained.

(Example 2)
Using the fluidized coating apparatus provided with the dust resistance measuring unit having the four-terminal method shown in FIG. 6, according to the following processes i) to vi), the LiCoO ₂ active material powder is coated in the same manner as in Example 1. The liquid was spray coated and dried to obtain an active material coated to a desired thickness.

i) Introducing 0.2 m ³ / min of dry air at 60 ° C. into the coating apparatus 100 to flow 1 kg of the LiCoO ₂ active material powder particles, the prepared coating solution was applied from the spray nozzle 120 at 5 g / min. The LiCoO ₂ active material powder was wetted with the coating liquid by spraying. Process i) was continued during the following processes ii) -vi).

  ii) Rotate the dust resistance measurement unit 270 so that the powder collection unit faces upward, and the piezoelectric element (AE0505D16F manufactured by NEC TOKIN) attached to the component 273 is vibrated and tapped for 1 minute. Was collected.

  iii) The part 272 connected to the hydraulic press was slid by the hydraulic press, and the collected powder was pressurized at 5 MPa.

  iv) A direct current of 50 μA was applied between the current terminals of the component 271, and the voltage between the voltage terminals of the component 271 was measured. The resistance value was 1.1 kΩ.

  v) Rotating the dust resistance measurement unit 270 so that the powder collection unit faces downward, and the piezoelectric element attached to the component 273 is vibrated and tapped while releasing the hydraulic pressure to collect the powder. Discharged from the department.

  vi) While continuing the process i), the processes ii) to v) were repeated once every 10 minutes, and when the target resistance value of 5.1 kΩ was reached, the spraying of the coating liquid was terminated. The operating time of the coating apparatus was 5.6 hours, and the coating thickness at this time was 10 nm, and a desired coating thickness could be obtained.

(Example 3)
As shown in FIG. 8, the coating process was performed using the coating apparatus provided with the dust resistance measurement part which has the upper shutter and lower shutter which were arrange | positioned at the lower part of the gas dispersion plate 160. FIG. An opening was provided at a location corresponding to the upper shutter of the gas dispersion plate 160 so that the powder particles could be collected when the upper shutter was opened. The other conditions were the same as in Example 2. According to the following processes i) to vi), the LiCoO ₂ active material powder was spray coated and dried, and the active material was coated to a desired thickness. Got.

i) Introducing 0.2 m ³ / min of dry air at 60 ° C. into the coating apparatus 100 to flow 1 kg of the LiCoO ₂ active material powder particles, the prepared coating solution was applied from the spray nozzle 120 at 5 g / min. The LiCoO ₂ active material powder was wetted with the coating liquid by spraying. Process i) was continued during the following processes ii) -vi).

  ii) The upper shutter of the dust resistance measurement unit was opened, and the powder particles were collected for 1 minute while vibrating and tapping the piezo element (AE0505D16F manufactured by NEC TOKIN).

  iii) The part 272 was slid by a hydraulic press, and the collected powder was pressurized at 5 MPa.

  iv) A direct current of 50 μA was applied between the current terminals of the component 271, and the voltage between the voltage terminals of the component 271 was measured. The resistance value was 1.2 kΩ.

  v) The lower shutter of the dust resistance measurement unit was opened, the piezoelectric element was vibrated and tapped, the hydraulic pressure was released, and the green compact was discharged from the powder collection unit.

  vi) While continuing the process i), the processes ii) to v) were repeated once every 10 minutes, and when the target resistance value of 5.1 kΩ was reached, the spraying of the coating liquid was terminated. The operating time of the coating apparatus was 5.4 hours, and the coating thickness at this time was 10 nm, and a desired coating thickness could be obtained.

DESCRIPTION OF SYMBOLS 100 Coating apparatus 110 Processing chamber 120 Spray nozzle 130 Fluid gas introduction port 140 Fluid gas exhaust port 150 Filter 160 Gas dispersion | distribution board 170 Powder resistance measurement part 171 Electrode part of dust resistance measurement part 171A Electrode surface 171B Electrode part 171B Electrode part 171 Voltage / current terminal part 172 Electrode part also serving as dust mechanism of dust resistance measuring part 172B Voltage terminal part of electrode part 172 172C Current terminal part of electrode part 172 173 Guide part of dust resistance measuring part 174 Guide part Groove 174A End surface 175 of guide part groove 175 Powder collecting part 180 Flow path of granular material 190 Flow path of fluid gas from fluid gas inlet 130 200 Flow path of fluid gas to fluid gas outlet 140 210 Blade rotor 220 Motor 230 Piezo element 24 Feedback controller 270 electrode part 273 powder resistance measuring unit of the guide part also serves as a dust resistance measuring unit 271 4 powder mechanism terminal 272 powder resistance measuring unit equipped with a 4-terminal method

Claims (19)

A processing chamber for coating the granular material for spraying a coating liquid onto the granular material while the powdered active material powder is suspended and flowing with a gas, and spraying the coating liquid A coating apparatus comprising a spray nozzle, a gas inlet, a gas outlet, and a filter that separates the granular material from the gas,
Powder resistance including a collecting mechanism for the powder, a mechanism for forming a green compact by pressurizing the collected powder, and a resistance measuring mechanism for measuring the electrical resistivity or the electric resistance of the green compact A measurement unit, and a control device that adjusts the coating conditions of the granular material by feeding back the measured electrical resistivity or electrical resistance,
Coating equipment.   Adjusting the coating conditions includes adjusting at least one of the coating time of the granular material, the temperature of the gas, the flow rate of the gas, the amount of the coating liquid, and the temperature of the coating liquid. The coating apparatus according to claim 1, comprising:   The coating apparatus according to claim 1, wherein adjusting the coating conditions includes determining a coating end time of the granular material.   The coating apparatus according to claim 1, wherein the coating process is terminated when the measured electrical resistivity or electrical resistance rises to a specified value.   The coating apparatus according to claim 1, wherein the coating process is terminated when the measured electrical resistivity or electrical resistance falls to a specified value.   The coating apparatus according to claim 1, wherein the battery active material powder is a positive electrode active material powder for a lithium ion secondary battery.   The coating apparatus according to claim 1, wherein the coating liquid is a solution obtained by dissolving a solid electrolyte in an organic solvent or an aqueous solution.   The coating apparatus according to claim 1, wherein the dust resistance measurement unit includes a tapping mechanism.   The coating apparatus according to claim 1, wherein the dust resistance measurement unit includes a mechanism for discharging the dust compact into the coating system.   The coating apparatus according to claim 1, wherein the dust resistance measurement unit includes a mechanism for discharging the powder particles out of the coating system.   The coating apparatus according to claim 1, wherein the dust resistance measurement unit includes a mechanism for measuring the mass of the collected powder particles.   The coating apparatus according to claim 1, further comprising a blade rotor below the dust resistance measurement unit. A battery active material coating method in which a coating liquid is sprayed onto a granular material while the powdered active material powder is suspended and flowed with a gas.
A coating method comprising a process of measuring the electrical resistivity or electrical resistance of the granular material, and feeding back the measured electrical resistivity or electrical resistance to adjust the coating conditions of the granular material.   Adjusting the coating conditions includes adjusting at least one of the coating time of the granular material, the temperature of the gas, the flow rate of the gas, the amount of the coating liquid, and the temperature of the coating liquid. The coating method according to claim 13, comprising:   The coating method according to claim 13, wherein adjusting the coating conditions includes determining a coating end time of the granular material.   The coating method according to claim 13, wherein the coating process is terminated when the measured electrical resistivity or electrical resistance rises to a specified value.   The coating method according to claim 13, wherein the coating process is terminated when the measured electrical resistivity or electrical resistance falls to a specified value.   The coating method according to claim 13, wherein the powder of the battery active material is a powder of a positive electrode active material for a lithium ion secondary battery.   The coating method according to claim 13, wherein the coating liquid is a solution obtained by dissolving a solid electrolyte in an organic solvent or an aqueous solution.

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