JP2014182971A - Method and apparatus for coating electrode of lithium ion secondary battery - Google Patents

Abstract

The electrical properties of an active material layer obtained by drying an electrode slurry are obtained by drying the electrode slurry while keeping the active material in a homogeneous state in the electrode slurry applied to the electrode foil. Keep good.
An electrode coating apparatus 10 for a lithium ion secondary battery applies an electrode slurry 13 in which an active material and a conductive auxiliary agent are dispersed to the electrode foil 11 while the electrode foil 11 is pulled out by a winding roll 12. And a drying device 16 for drying the electrode slurry 13 applied to the electrode foil 11 in this order. Further, between the coating device 14 and the drying device 16, a vibration device 21 that applies vibration to the electrode slurry 13 is provided.
[Selection] Figure 1

Description

  The present invention relates to a method and an apparatus for applying an electrode slurry containing an active material, a conductive additive, a binder and a solvent to an electrode foil of a lithium ion secondary battery.

  Conventionally, it has a slurry replenishing tank and a slurry bath, and slurry in which carbonyl nickel powder is dispersed in an aqueous solution such as carboxymethyl cellulose or methyl cellulose is stored in this slurry bath, and passes through a band-shaped porous metal core in the slurry bath. An apparatus for manufacturing a sintered substrate for an alkaline battery, which is configured to apply a slurry, is disclosed (for example, see Patent Document 1). In this apparatus for manufacturing a sintered substrate for an alkaline battery, an electrical or mechanical vibrator is provided in a slurry replenishing tank in which slurry is stored, and the viscosity of the slurry is adjusted by the vibration of the vibrator to replenish the slurry bath. Configured as follows. Further, the thickness of the coating film is adjusted by passing the band-shaped porous metal core material coated with the slurry through the slurry bath through a slit for adjusting the thickness of a predetermined gap, and the temperature is increased to 130 ° C. by an infrared lamp. It is configured to remove moisture by drying in a set atmosphere.

  In the apparatus for manufacturing a sintered substrate for an alkaline battery configured as described above, in the step of continuously applying the slurry to the band-shaped porous metal core material, the viscosity of the slurry supplied to the slurry bath is adjusted to the viscosity of the slurry in the slurry bath. By making it the same as the viscosity, it is possible to obtain a sintered substrate with little variation in coating film thickness. Further, it is possible to manufacture a sintered substrate with little variation in coating thickness without always adjusting the gap of the thickness adjusting slit.

Japanese Examined Patent Publication No. 3-45865 (Claim 1, third column, first line to same column, sixth line, third column, 32nd line to fourth column, first line, FIG. 1)

  However, in the apparatus for producing a sintered substrate for an alkaline battery shown in the above-mentioned conventional patent document 1, even if vibration is applied to the slurry in the slurry replenisher and the viscosity of the slurry is adjusted, the specific gravity in the slurry is The high carbonyl nickel powder settles under the influence of gravity in the slurry bath, and further settles in the slurry after being applied to the porous metal core and before being dried. There was a problem that the powder could not be kept homogeneous. For this reason, the film obtained after drying of the slurry becomes inhomogeneous, and there is a possibility that the electrical characteristics of the film are deteriorated.

  The object of the present invention is to dry the electrode slurry while keeping the active material, etc. in a homogeneous state in the electrode slurry applied to the electrode foil. An object of the present invention is to provide an electrode coating method and apparatus for a lithium ion secondary battery that can maintain good mechanical properties. In the present invention, when the electrode slurry is in a liquid state after being applied to the electrode foil, an ultrasonic vibration is applied to the liquid electrode slurry to vibrate an active material having a high specific gravity in the electrode slurry, thereby Thus, the electrode slurry can be dried while maintaining a homogeneous composition in the slurry without being affected by the above. That is, since the liquid electrode slurry is always subjected to slight vibrations either before or during drying, or while the liquid electrode slurry is being dried, a relatively large active material having a high specific gravity as in the past is used in the electrode foil. No settling near.

  A first aspect of the present invention is an electrode coating method for a lithium ion secondary battery in which an electrode slurry in which an active material and a conductive additive are dispersed is applied to the electrode foil and dried while the electrode foil is drawn out by a winding roll. The electrode slurry is characterized by applying vibration to the electrode slurry before or during drying of the electrode slurry applied to the electrode foil.

  A second aspect of the present invention is an invention based on the first aspect, and further receives a surface on the opposite side of the electrode slurry application surface from both surfaces of the electrode foil in the application portion of the electrode slurry to the electrode foil. A coating roll is rotatably provided, and vibration is applied to the electrode slurry through the electrode foil by vibrating the coating roll.

  A third aspect of the present invention is an invention based on the second aspect, and further vibrates a coating roll holding device that rotatably holds the coating roll, via the coating roll and the electrode foil. It is characterized by applying vibration to the electrode slurry.

  A fourth aspect of the present invention is the invention based on the first aspect, and further includes an application surface of the electrode slurry on both surfaces of the electrode foil between the application portion of the electrode slurry on the electrode foil and the winding roll. Is provided with a vibration roll for receiving the opposite surface, and the vibration is applied to the electrode slurry via the electrode foil by vibrating the vibration roll.

  A fifth aspect of the present invention is an invention based on the first aspect, and further by vibrating a guide roll that guides the electrode foil after drying the coated electrode slurry to a winding roll, Vibration is applied to the electrode slurry through the electrode foil.

  According to a sixth aspect of the present invention, there is provided a coating apparatus for applying an electrode slurry, in which an active material and a conductive additive are dispersed, to the electrode foil while the electrode foil is drawn out by a winding roll, and drying the electrode slurry applied to the electrode foil. In the electrode coating apparatus of a lithium ion secondary battery provided with a drying apparatus in this order, a vibration apparatus for applying vibration to the electrode slurry between the coating apparatus and the drying apparatus or between the drying apparatus and the take-up roll Is provided.

  7th viewpoint of this invention is invention based on 6th viewpoint, Comprising: The surface on the opposite side to the application surface of electrode slurry among the both surfaces of electrode foil in the application part to electrode foil of electrode slurry is received. The coating roll is rotatably provided, and the vibration exciter is configured to vibrate the electrode slurry through the electrode foil by vibrating the coating roll.

  An eighth aspect of the present invention is the invention based on the seventh aspect, and further, the vibrating device vibrates the coating roll holding device that rotatably holds the coating roll, whereby the coating roll and the electrode are provided. The electrode slurry is configured to be vibrated through a foil.

  A ninth aspect of the present invention is the invention based on the sixth aspect, and further includes an application surface of the electrode slurry among both surfaces of the electrode foil between the application portion of the electrode slurry on the electrode foil and the winding roll. Is provided with a vibrating roll that receives the opposite surface, and the vibrating device is configured to vibrate the electrode slurry through the electrode foil by vibrating the vibrating roll.

  A tenth aspect of the present invention is an invention based on the sixth aspect, wherein the electrode foil after the applied electrode slurry is dried is further wound between the drying device and the winding roll. A guide roll for guiding is provided, and the vibration exciter is configured to vibrate the electrode slurry through the electrode foil by vibrating the guide roll.

  In the electrode coating method according to the first to fifth aspects of the present invention, vibration is applied to the electrode slurry before or during drying of the electrode slurry applied to the electrode foil. The electrode slurry can be dried while the active material and the like are kept in a homogeneous state in the applied electrode slurry. As a result, the electrical characteristics of the active material layer obtained by drying the electrode slurry can be kept good.

  In the electrode coating apparatus according to the sixth to tenth aspects of the present invention, a vibrating device for applying vibration to the electrode slurry is provided between the coating device and the drying device or between the drying device and the winding roll. Therefore, the active material and the like are kept in a homogeneous state in the electrode slurry applied to the electrode foil by applying vibration to the electrode slurry with a vibration device before or during the drying of the electrode slurry. The electrode slurry can be dried as it is. As a result, the electrical characteristics of the active material layer obtained by drying the electrode slurry can be kept good.

It is a principal part block diagram which shows the electrode coating apparatus of the lithium ion secondary battery of 1st Embodiment of this invention. It is a principal part block diagram which shows the electrode coating apparatus of the lithium ion secondary battery of 2nd Embodiment of this invention. It is a principal part block diagram which shows the electrode coating apparatus of the lithium ion secondary battery of 3rd Embodiment of this invention.

  Next, an embodiment for carrying out the present invention will be described with reference to the drawings.

<First Embodiment>
As shown in FIG. 1, an electrode coating apparatus 10 for a lithium ion secondary battery applies an electrode slurry 13 in which an active material or the like is dispersed while pulling out an electrode foil 11 by a take-up roll 12. And a drying device 16 for drying the electrode slurry 13 applied to the electrode foil 11 in this order. Examples of the electrode foil 11 include an aluminum foil for a positive electrode, a copper foil for a negative electrode, a stainless steel foil, an aluminum foil, and the like. The electrode slurry 13 includes a positive electrode active material or a negative electrode active material, a conductive additive, a binder (binder), and a solvent. Examples of the positive electrode active material include powders such as LiCoO ₂ [LCO], Li (Ni _1/3 Mn _1/3 Co _1/3 ) O ₂ [NMC], LiMn ₂ O ₄ [LMO], LiFePO ₄ [LFP]. Examples of the negative electrode active material include a mixture of graphite (carbon powder such as natural graphite or artificial graphite) and SiO (inorganic powder), powders of Li ₄ Ti ₅ O ₁₂ [LTO], Sn, SnCo, and the like. . Examples of the conductive aid include powders such as acetylene black [AB], carbon nanotube [CNT], ketjen black [KB], and flake graphite. Furthermore, examples of the binder (binder) include polyvinylidene fluoride [PVDF] using an organic solvent as a solvent, and styrene butadiene rubber [SBR] using water as a solvent. When the binder (binder) is PVDF, an organic solvent such as N-methylpyrrolidone [NMP] is used as a solvent, and when the binder (binder) is SBR, carboxymethyl cellulose [CMC] as a thickener. Is added.

  On the other hand, the electrode foil 11 to which the electrode slurry 13 is not yet applied is wound around the feeding roll 17, the electrode slurry 13 is applied by the application device 14, and the electrode slurry 13 is applied by the drying device 16. The dried electrode foil 11 is taken up by the take-up roll 12. A driving device (not shown) for pulling out the electrode foil 11 wound around the feeding roll 17 is connected to the winding roll 12, and a brake mechanism for adjusting the drawing speed of the electrode foil 11 is connected to the feeding roll 17. (Not shown) is provided. The coating device 14 is provided between the feeding roll 17 and the winding roll 12, and is provided to receive the electrode foil 11 fed from the feeding roll 17 and apply the electrode slurry 13 on the electrode foil 11. The coating roll 14a and the plate 14b provided close to the upper outer peripheral surface of the coating roll 14a obliquely from above. The coating roll 14 a is configured to receive a surface on the opposite side of the application surface of the electrode slurry 13 from both surfaces of the electrode foil 11 in the application portion of the electrode slurry 13 to the electrode foil 11. A predetermined gap is formed between the lower end of the plate 14b and the outer peripheral surface of the coating roll 14a. Although the predetermined gap can be slidably inserted through the electrode foil 11, the predetermined gap is set so that the electrode slurry 13 cannot pass through the lower end of the plate 14b when the electrode foil 11 is inserted.

  Further, a comma roll coater 14c is provided above the coating roll 14a so as not to rotate at a predetermined interval. The comma roll coater 14c has a cross section cut out by a vertical plane extending vertically downward from the coater shaft 14d holding the comma roll coater 14c and a horizontal plane extending horizontally from the coater shaft 14d toward the drying device 16 side. A substantially fan-shaped notch 14e is formed, and has a function of scraping off a portion exceeding the target thickness of the coating film of the electrode slurry 13 applied on the electrode foil 11. A receiving portion 14f is formed by the upper surface of the plate 14b, the upper outer peripheral surface of the coating roll 14a, and the lower outer peripheral surface of the comma roll coater 14c, and the electrode slurry 13 is stored in the receiving portion 14f. Further, the coating roll 14 a and the comma roll coater 14 c are held by the coating roll holding device 18. The coating roll holding device 18 includes a base 18a and a pair of support columns 18b provided upright on the base 18a. A pair of struts 18b is rotatably mounted with a coating roll shaft 14g inserted through the center of the coating roll 14a, and the coater shaft 14d inserted through the center of the comma roll coater 14c cannot rotate. It will be erected. The coater shaft 14d is configured to be finely adjustable in the vertical direction, whereby a predetermined distance between the coating roll 14a and the comma roll coater 14c, that is, the coating film of the electrode slurry 13 applied on the electrode foil 11 is formed. The thickness can be adjusted.

  On the other hand, the drying device 16 is provided between the coating roll 14 a and the winding roll 12. The drying device 16 includes a housing 16a in which a flat through hole (not shown) through which the electrode foil 11 coated with the electrode slurry 13 can pass is formed, and the housing 16a accommodated on the electrode foil 11 A far infrared heater (not shown) for heating the electrode slurry 13. In addition, the code | symbol 19 in FIG. 1 is the guide roll provided between the drying apparatus 16 and the winding roll 12. FIG. The guide roll 19 is configured to guide the electrode foil 11 after the applied electrode slurry 13 is dried to the take-up roll 12.

  On the other hand, a vibration device 21 that vibrates the electrode slurry 13 is provided between the coating device 14 and the drying device 16. In this embodiment, the vibration device 21 is an ultrasonic vibration device that applies vibration to the coating roll 14 a of the coating device 14. The ultrasonic vibration device 21 controls the ultrasonic oscillator 22 and the ultrasonic oscillator 22 that oscillates the ultrasonic wave on the coating roll shaft 14g to vibrate the coating roll shaft 14g at a predetermined frequency. And a control device 23. The ultrasonic oscillator 22 is attached to each of the pair of support columns so as to be in contact with the outer peripheral surfaces at both ends of the coating roll shaft 14g. The control device 23 also includes an oscillator (not shown) that oscillates ultrasonic waves of a predetermined frequency, and a drive amplifier (not shown) that amplifies the ultrasonic waves oscillated by the oscillators and sends them to the ultrasonic oscillator 22. It consists of. The ultrasonic vibration device 21 is configured to vibrate the electrode slurry 13 via the electrode foil 11 by vibrating the coating roll 14a via the coating roll shaft 14g. The frequency of vibration generated by the ultrasonic oscillator 22 is preferably in the range of 10 kHz to 5000 kHz, and more preferably in the range of 50 kHz to 200 kHz. Furthermore, the output of vibration generated by the ultrasonic oscillator 22 is preferably in the range of 10 W to 1000 W, and more preferably in the range of 50 W to 500 W. Here, the frequency of vibration generated by the ultrasonic oscillator 22 is limited to the range of 10 kHz to 5000 kHz. If the frequency is less than 10 kHz, the period (time required for one cycle) is too long, and the active material does not vibrate. This is because if the frequency exceeds 5000 kHz, the vibration becomes too small, that is, the cycle is too short, and the active material does not move greatly in the electrode slurry. The reason why the output of the vibration generated by the ultrasonic oscillator 22 is limited to the range of 10 W to 1000 W is that the vibration force decreases when the power is less than 10 W, and excessive vibration is generated when the power exceeds 1000 W. Because it ends up. By appropriately adjusting the frequency and output of the vibration oscillated by the ultrasonic vibrator 22 within the above range according to the specific gravity and particle size of the active material and the conductive aid, or according to the viscosity of the electrode slurry 13. Even if the specific gravity and particle size of the active material and the conductive additive are different, or the viscosity of the electrode slurry 13 is different, the active material and the like can be uniformly dispersed in the electrode slurry 13.

  A method of applying and drying the electrode slurry 13 on the electrode foil 11 using the electrode coating apparatus 10 of the lithium ion secondary battery configured as described above will be described. The electrode foil 11 wound around the feeding roll 17 is drawn out by the winding roll 12, passes through the coating device 14 and the drying device 16, and further passes through the guide roll 19 and is wound up on the winding roll 12. The electrode slurry 13 is applied to the electrode foil 11 on the coating roll 14a of the coating device 14, and then the electrode slurry 13 applied to the electrode foil 11 is dried by the drying device 16. Since the ultrasonic vibrator 22 of the ultrasonic vibration device 21 vibrates the coating roll 14a through the coating roll shaft 14g from the coating process to the drying process, this vibration is applied to the electrode through the electrode foil 11. Added to slurry 13. That is, since vibration is applied to the electrode slurry 13 before and during the drying of the electrode slurry 13 applied to the electrode foil 11, the specific gravity of the active material, the conductive auxiliary agent, etc. in the electrode slurry 13 applied to the electrode foil 11 Even if is larger than the solvent, the electrode slurry 13 can be dried while maintaining the active material, the conductive additive and the like in a homogeneous state. As a result, the electrical characteristics of the active material layer 24 obtained by drying the electrode slurry 13 can be kept good. Even if vibration is applied to the electrode slurry 13 during the drying of the electrode slurry 13, by setting the frequency and output of the vibration to appropriate values, the active force by the binder can be increased by the force acting on the electrode slurry 13 by vibration. Since the binding force of the substance and the conductive auxiliary agent is greater, the dried active material layer 24 is not separated and scattered. Further, by reducing the output of the vibration oscillated by the ultrasonic vibrator 22, the vibration applied to the electrode slurry 13 is applied only before the electrode slurry 13 is dried, not before and during the drying of the electrode slurry 13. be able to.

<Second Embodiment>
FIG. 2 shows a second embodiment of the present invention. 2, the same reference numerals as those in FIG. 1 denote the same components. In this embodiment, the electrode slurry 13 is vibrated via the coating roll 14 a and the electrode foil 11 by vibrating the coating roll holding device 18 that rotatably holds the coating roll 14 a. That is, the ultrasonic vibration device 51 is configured to vibrate the electrode slurry 13 through the coating roll 14 a and the electrode foil 11 by vibrating the coating roll holding device 18. The upper surface of the ultrasonic vibration device 51 is formed in substantially the same shape as the lower surface of the base 18 a of the coating roll holding device 18, and the base 18 a can be placed on the ultrasonic vibration device 51. In this embodiment, an ultrasonic vibration device 51 in which an ultrasonic oscillator and a control device are provided integrally is used. Then, by controlling the frequency and output of the ultrasonic vibration device 51, the active material and the conductive auxiliary agent in the electrode slurry 13 in which the specific gravity and particle size of the active material and the conductive auxiliary agent are different or the viscosity of the electrode slurry 13 is different. Etc. can be uniformly dispersed. The configuration other than the above is the same as that of the first embodiment.

  In the electrode coating apparatus 50 of the lithium ion secondary battery configured as described above, the machining for attaching the ultrasonic oscillator to the support column of the coating roll holding apparatus as in the first embodiment is not performed. Since only the coating roll holding device 18 needs to be placed on the ultrasonic vibration device 51, the number of assembling steps of the ultrasonic vibration device 51 can be reduced as compared with the first embodiment. In the method of applying the electrode slurry 13 to the electrode foil 11 and drying using the electrode coating apparatus 50, the ultrasonic vibration device 51 vibrates the coating roll holding device 18, whereby the coating roll 14 a and the electrode are vibrated. Except for applying vibration to the electrode slurry 13 via the foil 11, it is substantially the same as in the first embodiment, and therefore, repeated description is omitted.

<Third Embodiment>
FIG. 3 shows a third embodiment of the present invention. 3, the same reference numerals as those in FIG. 1 denote the same components. In this embodiment, vibration is applied to the electrode slurry 13 via the electrode foil 11 by vibrating a vibration roll 81 provided separately from the coating roll 14 a. Specifically, a vibrating roll 81 that receives a surface of the electrode foil 11 opposite to the surface to which the electrode slurry 13 is applied between both sides of the electrode foil 11 between the application portion of the electrode slurry 13 on the electrode foil 11 and the winding roll 12. Is provided. That is, the vibration roll 81 is provided so as to be in contact with the lower surface of the electrode foil 11 between the coating roll 14 a and the drying device 16. The ultrasonic vibration device 91 is configured to apply vibration to the electrode slurry 13 via the electrode foil 11 by vibrating the vibration roll 81. The vibration roll 81 is held by a vibration roll holding device 82. Further, the upper surface of the ultrasonic vibration device 91 is formed in substantially the same shape as the lower surface of the vibration roll holding device 82, and the vibration roll holding device 82 can be placed on the ultrasonic vibration device 91. Further, as the ultrasonic vibration device 91, a device in which an ultrasonic oscillator and a control device are integrally provided is used. Then, by controlling the frequency and output of the ultrasonic vibration device 91, the active material and the conductive auxiliary agent in the electrode slurry 13 in which the specific gravity and particle size of the active material and the conductive auxiliary agent are different or the viscosity of the electrode slurry 13 is different. Etc. can be uniformly dispersed. The configuration other than the above is the same as that of the first embodiment.

  In the electrode coating device 80 of the lithium ion secondary battery configured as described above, since the vibration roll 81 can be brought closer to the drying device 16, during the drying of the electrode slurry 13 more reliably than in the first embodiment. Vibration can be applied to the electrode slurry 13. In the method of applying the electrode slurry 13 to the electrode foil 11 and drying using the electrode coating device 80, the ultrasonic vibration device 91 vibrates the vibration roll 81 via the vibration roll holding device 82. Except for applying vibration to the electrode slurry 13 via the electrode foil 11, it is substantially the same as that of the first embodiment, so that repeated description is omitted.

  In the first embodiment, the coating roll is vibrated to vibrate the electrode slurry via the electrode foil. In the second embodiment, the coating roll holding device is vibrated. In the third embodiment, vibration is applied to the electrode slurry via the coating foil and the electrode foil, and in the third embodiment, the vibration is applied to the electrode slurry via the electrode foil. May be vibrated to the electrode slurry via the electrode foil by vibrating with an ultrasonic vibration device. In the first to third embodiments, the application device using the comma roll coater is used to apply the electrode slurry to the electrode foil. However, an application device using a slot die or a transfer roll is used. The electrode slurry may be applied to the electrode foil using a conventional coating apparatus. Here, when a slot die is used as a coating device, a coating roll is not necessary. Therefore, as in the third embodiment, the vibrating slurry is vibrated by the vibrating device, so that the electrode slurry is vibrated. It is preferable to add. Moreover, in the said 1st-3rd embodiment, although the ultrasonic vibration apparatus was mentioned as a vibration apparatus, you may use an electromagnetic adsorption apparatus as a vibration apparatus. This electromagnetic adsorption device has an electromagnetic coil in which a coil is wound around a magnetic core. The electromagnetic coil is provided close to a coating roll shaft made of a magnetic material, and an alternating current having a predetermined frequency is passed through the coil. Thus, the coating roll or the like is configured to vibrate by electromagnetic force through the coating roll shaft or the like. Further, in the first to third embodiments, the drying apparatus having the far infrared heater is described. However, a drying apparatus having an electric heater, a gas heater, or the like may be used.

  Next, examples of the present invention will be described in detail together with comparative examples.

<Example 1>
As shown in FIG. 3, an electrode coating apparatus 80 provided with a feeding roll 17, a coating apparatus 14, a drying apparatus 16, a guide roll 19 and a winding roll 12 was prepared. A vibration roll 81 is provided so as to be in contact with the lower surface of the electrode foil 11 between the coating roll 14 a of the coating device 14 and the drying device 16, and an electrode is passed through the vibration roll 81 and the electrode foil 11 by the ultrasonic vibration device 91. A predetermined frequency and output vibration were applied to the slurry 13. Further, an electrode slurry 13 was prepared by mixing a positive electrode active material, a conductive additive and a binder in a solvent. Here, LiCoO ₂ [LCO] having an average particle diameter of 10 μm is used as the positive electrode active material, acetylene black [AB] (manufactured by Denki Kagaku Kogyo Co., Ltd .: HS100) is used as the conductive auxiliary agent, and polyfluoride is used as the binder. Vinylidene [PVDF] (Kureha Battery Materials Japan: # 7200) was used. The mixing ratio of LCO, AB and PVDF was 94: 3: 3 by mass ratio. Further, N-methylpyrrolidone [NMP] was used as a solvent, and the viscosity of the electrode slurry 13 was adjusted to about 5 Pa · s with the amount of NMP added.

On the other hand, an aluminum foil having a width and a thickness of 30 cm and 15 μm, respectively, was used as the electrode foil 11, and the winding speed of the aluminum foil by the winding roll 12 was set to 1 m / min. Moreover, the diameter of the coating roll 14a and the winding roll 12 was 150 mm. Moreover, the frequency and output of the vibration applied to the electrode slurry 13 via the vibration roll 81 and the electrode foil 11 by the ultrasonic vibration device 91 are set to 200 kHz and 100 W, respectively, and the lower end (knife part) of the comma roll coater 14c The distance (gap) from the electrode foil 11 was set to 120 μm, and the battery capacity of the active material applied to the electrode foil 11 was adjusted to 2.0 mAh / cm ² .

The electrode slurry 13 was applied to the electrode foil 11 using the electrode coating apparatus 80 and dried to obtain a positive electrode sheet. This positive electrode sheet was punched with a cut punch so that the length and width were 3 cm and 4 cm, respectively. Moreover, metallic lithium was punched out to the same size as the positive electrode sheet to produce a negative electrode sheet. The polyethylene fine porous separator was sandwiched between the positive electrode sheet and the negative electrode sheet, and inserted into an aluminum laminate pack. Next, after injecting an electrolyte solution containing 1 mol of LiPF ₆ in a solvent in which ethylene carbonate [EC] and diethyl carbonate [DEC] are mixed at a mass ratio of 1: 1, into the aluminum laminate pack, vacuum packing is performed, A laminate cell was produced. This laminate cell was referred to as Example 1. In addition, in this specification, the average particle diameter of an active material etc. is a particle diameter measured using the particle size distribution measuring apparatus (Horiba LA-950), and is a volume reference average particle diameter.

<Example 2>
As shown in FIG. 1, an ultrasonic oscillator 22 of an ultrasonic vibration device 21 is provided in contact with a coating roll shaft 14 g of a coating apparatus 14, and the coating roll shaft 14 g and a coating roll are provided by the ultrasonic vibration device 21. A laminate pack was produced in the same manner as in Example 1 except that the electrode slurry 13 was subjected to vibration at a predetermined frequency and output via 14a and the electrode foil 11. This laminate cell was referred to as Example 2.

<Example 3>
Example 1 except that the ultrasonic oscillator of the ultrasonic vibration device is provided in contact with the guide roll, and vibration of a predetermined frequency and output is applied to the electrode slurry through the guide roll and the electrode foil by the ultrasonic vibration device. A laminate pack was produced in the same manner as described above. This laminate cell was referred to as Example 3.

<Example 4>
Li (Ni _1/3 Mn _1/3 Co _1/3 ) O ₂ [NMC] having an average particle diameter of 11 μm is used as the positive electrode active material, and is added to the electrode slurry through the vibration roll and the electrode foil by an ultrasonic vibration device. A laminate pack was produced in the same manner as in Example 1 except that the frequency and output of the vibration were set to 50 kHz and 150 W. This laminate cell was referred to as Example 4.

<Example 5>
LiMn ₂ O ₄ [LMO] having an average particle diameter of 15 μm is used as the positive electrode active material, and the frequency and output of vibration applied to the electrode slurry by the ultrasonic vibration device through the vibrating roll and the electrode foil are 10 kHz and 150 W, respectively. A laminate pack was produced in the same manner as in Example 1 except that it was set. This laminate cell was referred to as Example 5.

<Example 6>
LiFePO ₄ [LFP] having an average particle diameter of 1.5 μm was used as the positive electrode active material, the mixing ratio of LFP, AB, and PVDF was 92: 5: 3 by mass ratio, and the vibrating roll and the electrode foil were attached by an ultrasonic vibration device. A laminate pack was produced in the same manner as in Example 1 except that the frequency and output of vibration applied to the electrode slurry were set to 5000 kHz (5 MHz) and 1000 W, respectively. This laminate cell was referred to as Example 6. The mixing ratio of LFP was slightly less than 92% by mass and the mixing ratio of LCO in Example 1 (94% by mass), and the mixing ratio of PVDF was 5% by mass and the mixing ratio of PVDF in Example 1 (3% by mass). The reason why the average particle size of LFP is smaller than that of LCO, NMC, and LMO and a large amount of PVDF is required.

<Example 7>
A negative electrode active material was used as the active material. And the negative electrode active material, the conductive support agent, the binder, and the thickener were mixed with the solvent, and the electrode slurry was prepared. Here, natural graphite having an average particle diameter of 15 μm and SiO having an average particle diameter of 3 μm are used as the negative electrode active material, and a carbon nanotube [CNT] having an average diameter (outer diameter) and an average length of 20 nm and 1 μm, respectively, as the conductive assistant. , Styrene butadiene rubber [SBR] was used as a binder, and carboxymethyl cellulose [CMC] was used as a thickener. The mixing ratio of natural graphite, SiO, CNT, SBR, and CMC was 87: 10: 1: 1: 1 in terms of mass ratio. In addition, in this specification, the average diameter (outer diameter) and average length of a conductive support agent are the diameter and length which were measured using the particle size distribution measuring apparatus (Horiba LA-950), and are based on volume. Average diameter and average length.

  Specifically, first, natural graphite and SiO were put into an aqueous solution in which the CMC was dissolved in water, and stirred using a rotation and revolution hybrid mixer to prepare a slurry. Next, after adding CNT to this slurry and stirring again using a rotation / revolution hybrid mixer, a liquid in which SBR was dispersed was added to this slurry, and stirring was again performed using the rotation / revolution hybrid mixer to prepare an electrode slurry. Furthermore, the viscosity of the electrode slurry was adjusted to about 500 mPa · s by adding some water to the electrode slurry and sufficiently stirring.

A copper foil having a width and a thickness of 30 cm and 15 μm, respectively, was used as the electrode foil, and the winding speed of the copper foil by a winding roll was set to 5 m / min. Moreover, the diameter of the coating roll and the winding roll was 150 mm. Similarly to Example 1, a vibrating roll is provided so as to be in contact with the lower surface of the electrode foil between the coating roll and the drying apparatus of the coating apparatus, and the electrode slurry is passed through the vibrating roll and the electrode foil by an ultrasonic vibration apparatus. A vibration with a predetermined frequency and output was applied. However, the frequency and output at the time of vibration of the vibrating roll by the ultrasonic vibration device are set to 500 kHz and 100 W, respectively, and the interval (gap) between the lower end (knife portion) of the comma roll coater and the electrode foil is set to 90 μm, The battery capacity of the active material applied to the electrode foil was adjusted to 2.0 mAh / cm ² .

An electrode slurry was applied to the electrode foil using the electrode coating apparatus and dried to obtain a negative electrode sheet. This negative electrode sheet was punched with a cut punch so that the length and width were 3 cm and 4 cm, respectively. Further, metallic lithium was punched out to the same size as the above negative electrode sheet to produce a positive electrode sheet. A polyethylene microporous separator was sandwiched between the negative electrode sheet and the positive electrode sheet, and inserted into an aluminum laminate pack. Next, after injecting an electrolyte solution containing 1 mol of LiPF ₆ in a solvent in which ethylene carbonate [EC] and diethyl carbonate [DEC] are mixed at a mass ratio of 1: 1, into the aluminum laminate pack, vacuum packing is performed, A laminate cell was produced. This laminate cell was referred to as Example 7.

<Example 8>
Li ₄ Ti ₅ O ₁₂ [LTO] with an average particle diameter of 2 μm is used as the negative electrode active material, acetylene black [AB] with an average particle diameter of 50 μm is used as the conductive auxiliary agent, and the mixing ratio of LTO, AB, SBR, and CMC is mass The ratio was set to 95: 3: 1: 1, and the frequency and output of the vibration applied to the electrode slurry through the vibrating roll and the electrode foil by the ultrasonic vibration device were set to 10 kHz and 100 W, respectively. A laminate pack was produced in the same manner as in Example 7. This laminate cell was referred to as Example 8.

<Comparative Example 1>
The laminate pack was prepared in the same manner as in Example 1 except that the vibration roll and the ultrasonic vibration device were not used, that is, the electrode slurry was not vibrated through the vibration roll and the electrode foil by the ultrasonic vibration device. Produced. This laminate cell was designated as Comparative Example 1.

<Comparative example 2>
A laminate pack was prepared in the same manner as in Example 4 except that the vibration roll and the ultrasonic vibration device were not used, that is, the electrode slurry was not vibrated through the vibration roll and the electrode foil by the ultrasonic vibration device. Produced. This laminate cell was designated as Comparative Example 2.

<Comparative Example 3>
A laminate pack was prepared in the same manner as in Example 5 except that the vibration roll and the ultrasonic vibration device were not used, that is, the electrode slurry was not vibrated through the vibration roll and the electrode foil by the ultrasonic vibration device. Produced. This laminate cell was designated as Comparative Example 3.

<Comparative example 4>
A laminate pack was prepared in the same manner as in Example 6 except that the vibration roll and the ultrasonic vibration device were not used, that is, the electrode slurry was not vibrated through the vibration roll and the electrode foil by the ultrasonic vibration device. Produced. This laminate cell was designated as Comparative Example 4.

<Comparative Example 5>
A laminate pack was prepared in the same manner as in Example 7 except that the vibration roll and the ultrasonic vibration device were not used, that is, the electrode slurry was not vibrated through the vibration roll and the electrode foil by the ultrasonic vibration device. Produced. This laminate cell was designated as Comparative Example 5.

<Comparative Example 6>
A laminate pack was prepared in the same manner as in Example 8 except that the vibration roll and the ultrasonic vibration device were not used, that is, the electrode slurry was not vibrated through the vibration roll and the electrode foil by the ultrasonic vibration device. Produced. This laminate cell was designated as Comparative Example 6.

<Comparative test 1 and evaluation>
The discharge capacities of the laminate cells of Examples 1 to 8 and Comparative Examples 1 to 6 were measured. Specifically, in the laminated cells of Examples 1 to 5 and Comparative Examples 1 to 3, charging is performed by the CC-CV method (constant current-constant voltage method) under the condition of a constant 0.2 C rate and a voltage of 4.2 V. The discharge was performed by the CC method (constant current method) at a constant 0.2 C rate, and the discharge capacity after 3 cycles was measured. The measurement temperature was constant at 25 ° C. Further, the cut-off voltage at the time of discharge was fixed at 3.0 V, and when the voltage dropped to this potential, the measurement was stopped without waiting for a predetermined time of the C rate. Here, the “C rate” means a charge / discharge rate, and a current amount sufficient to discharge the entire capacity of the battery in one hour is referred to as 1C rate charge / discharge. This is called rate charge / discharge.

  In the laminated cells of Example 6 and Comparative Example 4, charging was performed by the CC-CV method (constant current-constant voltage method) under the condition of a constant 0.2 C rate and a voltage of 3.6 V, and discharging was performed at a 0.2 C rate. It was carried out by a constant CC method (constant current method), and the discharge capacity after 3 cycles was measured. The measurement temperature was constant at 25 ° C. Further, the cut-off voltage at the time of discharge was kept constant at 2.5 V, and when the voltage dropped to this potential, the measurement was stopped without waiting for a predetermined time of the C rate.

  In the laminated cells of Example 7 and Comparative Example 5, charging was performed by the CC-CV method (constant current-constant voltage method) under the condition of a constant 0.2 C rate and a voltage of 0.02 V, and discharging was performed at a 0.2 C rate. It was carried out by a constant CC method (constant current method), and the discharge capacity after 3 cycles was measured. The measurement temperature was constant at 25 ° C. Further, the cut-off voltage at the time of discharge was fixed at 1.0 V, and when the voltage dropped to this potential, the measurement was stopped without waiting for a predetermined time of the C rate.

  In the laminated cells of Example 8 and Comparative Example 6, charging was performed by the CC-CV method (constant current-constant voltage method) under the condition of a constant 0.2 C rate and a voltage of 1.2 V, and discharging was performed at a 0.2 C rate. It was carried out by a constant CC method (constant current method), and the discharge capacity after 3 cycles was measured. The measurement temperature was constant at 25 ° C. Further, the cut-off voltage at the time of discharge was fixed at 2.0 V, and when the voltage dropped to this potential, the measurement was stopped without waiting for a predetermined time of the C rate. Table 1 shows the discharge capacity after 3 cycles. Table 1 shows the types and content ratios of the respective components of the electrode slurry, the members to which vibration was applied by the ultrasonic vibration device, and the vibration frequency.

  As is apparent from Table 1, when LCO was used as the positive electrode active material, the discharge capacity was low at 86 mAh / g in Comparative Example 1 where no vibration was applied to the vibration roll, whereas the vibration roll or guide roll In Examples 1 to 3 in which vibration was applied to the discharge capacity, the discharge capacity increased to 125 to 131 mAh / g. Further, when NMC was used as the positive electrode active material, the discharge capacity was low at 71 mAh / g in Comparative Example 2 in which vibration was not applied to the vibrating roll, whereas in Example 4 in which vibration was applied to the vibrating roll. The discharge capacity increased to 125 mAh / g. Further, when LMO was used as the positive electrode active material, the discharge capacity was low at 54 mAh / g in Comparative Example 3 in which vibration was not applied to the vibrating roll, whereas in Example 5 in which vibration was applied to the vibrating roll. The discharge capacity increased to 98 mAh / g.

  In addition, when LFP was used as the positive electrode active material, the discharge capacity was low at 90 mAh / g in Comparative Example 4 in which vibration was not applied to the vibrating roll, whereas in Example 6 in which vibration was applied to the vibrating roll. The discharge capacity increased to 133 mAh / g. Moreover, when natural graphite and SiO were used as the negative electrode active material, the discharge capacity was low at 71 mAh / g in Comparative Example 5 in which vibration was not applied to the vibration roll, whereas vibration was applied to the vibration roll. In Example 7, the discharge capacity increased to 125 mAh / g. Furthermore, when LTO was used as the negative electrode active material, the discharge capacity was low at 95 mAh / g in Comparative Example 6 in which vibration was not applied to the vibrating roll, whereas in Example 8 in which vibration was applied to the vibrating roll. The discharge capacity increased to 129 mAh / g. From the above, the active material layer obtained by drying the electrode slurry by applying vibrations of a predetermined frequency and output to the electrode slurry before or during drying of the electrode slurry, or before and during drying. It has been found that the discharge capacity of the laminate cell (lithium ion secondary battery) is increased. This is considered to be because the electrode slurry could be dried while keeping the active material and the like in a homogeneous state in the electrode slurry applied to the electrode foil.

DESCRIPTION OF SYMBOLS 10, 50, 80 Electrode coating apparatus 11 Electrode foil 12 Winding roll 13 Electrode slurry 14 Coating apparatus 14a Coating roll 16 Drying apparatus 18 Coating roll holding apparatus 19 Guide roll 21, 51, 91 Ultrasonic vibration apparatus (vibration) apparatus)
81 Excitation roll

Claims (10)

In the electrode coating method for a lithium ion secondary battery, the electrode foil in which the active material and the conductive additive are dispersed is applied to the electrode foil and dried while the electrode foil is drawn out by a winding roll.
An electrode coating method for a lithium ion secondary battery, wherein vibration is applied to the electrode slurry before or during drying of the electrode slurry applied to the electrode foil.   A coating roll that receives a surface opposite to the coating surface of the electrode slurry among both surfaces of the electrode foil in a coating portion of the electrode slurry to the electrode foil is rotatably provided to vibrate the coating roll. The electrode coating method of a lithium ion secondary battery according to claim 1, wherein vibration is applied to the electrode slurry through the electrode foil.   3. The lithium ion secondary battery according to claim 2, wherein vibration is applied to the electrode slurry through the coating roll and the electrode foil by vibrating a coating roll holding device that rotatably holds the coating roll. Electrode coating method.   An excitation roll is provided between the application portion of the electrode slurry to the electrode foil and the take-up roll, and receives a surface of the electrode foil opposite to the electrode slurry application surface. The electrode coating method for a lithium ion secondary battery according to claim 1, wherein vibration is applied to the electrode slurry through the electrode foil by vibrating a vibrating roll.   2. The lithium according to claim 1, wherein a vibration is applied to the electrode slurry through the electrode foil by vibrating a guide roll that guides the electrode foil after drying the applied electrode slurry to the winding roll. An electrode coating method for an ion secondary battery. An application device for applying an electrode slurry, in which an active material and a conductive additive are dispersed, to the electrode foil while the electrode foil is drawn out by a winding roll, and a drying device for drying the electrode slurry applied to the electrode foil in this order. In the lithium ion secondary battery electrode coating apparatus provided,
A lithium ion secondary battery comprising a vibration device for applying vibration to the electrode slurry between the coating device and the drying device or between the drying device and the winding roll. Electrode coating device.   A coating roll that receives a surface of the electrode foil on the opposite side of the electrode slurry from the both sides of the electrode foil in the electrode foil coating portion is rotatably provided, and the vibration exciter is the coating device. The electrode coating apparatus for a lithium ion secondary battery according to claim 6, configured to apply vibration to the electrode slurry through the electrode foil by vibrating a work roll.   The vibrator is configured to vibrate the electrode slurry through the coating roll and the electrode foil by vibrating a coating roll holding device that rotatably holds the coating roll. Item 8. An electrode coating apparatus for a lithium ion secondary battery according to Item 7.   An excitation roll is provided between the application portion of the electrode slurry to the electrode foil and the take-up roll, and receives a surface of the electrode foil opposite to the electrode slurry application surface. The electrode coating apparatus for a lithium ion secondary battery according to claim 6, wherein a vibration device vibrates the vibration roll to apply vibration to the electrode slurry via the electrode foil.   A guide roll for guiding the electrode foil after drying the applied electrode slurry to the take-up roll is provided between the drying device and the take-up roll, and the vibration exciter is the guide roll. The electrode coating apparatus for a lithium ion secondary battery according to claim 6, wherein vibration is applied to the electrode slurry via the electrode foil.

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