JP2011082059A - Electrode drying device and electrode drying method - Google Patents

Abstract

An electrode drying apparatus capable of preventing a condensed solvent from re-adhering to a dried electrode film and producing a uniformly dried electrode film.
An electrode drying apparatus for drying an electrode foil by induction heating, the induction heating means for heating the electrode foil by induction heating, and a solvent vapor evaporated from the electrode foil by the induction heating means. The cooling means 41 (42) to be recovered, the recovery means 43 to recover the solvent condensed by the cooling means 41 (42), the induction heating means 3, the cooling means 41 (42), and the electrode drying chamber 2 storing the recovery means 43 And comprising.
[Selection] Figure 1

Description

The present invention relates to a technique for drying an electrode coated with an active material by induction heating.

  Conventionally, in the production of an electrode film for a battery such as a lithium battery, an induction heating method is known in which the electrode film is dried by induction heating in order to dry the electrode film (see, for example, Patent Document 1). According to the technique described in Patent Document 1, the current collector can be heated by concentrating the magnetic flux of the induction heating coil on the current collector by the magnetic core. Thereby, the active material applied to the surface of the current collector can be dried.

JP 2004-327203 A JP-A-9-283123

  In the conventional induction heating method using the induction heating coil (and magnetic core) described in Patent Document 1 described above, for example, a cooling water channel provided inside the induction heating coil in order to prevent a temperature rise of the induction heating coil. The induction heating coil itself is cooled by supplying a cooling liquid to. For this reason, the generated solvent vapor may condense in the drying furnace. As a result, the solvent condensed around the ceiling of the drying furnace or around the induction heating coil may fall, and the dropped solvent may be reattached to the dried electrode film.

  That is, the technique described in Patent Document 1 does not consider the treatment of the solvent condensed in the drying furnace, and has a problem that it is difficult to produce a uniformly dried electrode film.

  The present invention has been made in view of the above-mentioned problems, and the generated solvent vapor is actively condensed by cooling, preventing the condensed solvent from reattaching to the dried electrode film, and uniformly drying the electrode. An object is to provide a technique capable of manufacturing a film.

  The present invention is an electrode drying apparatus for drying an electrode foil by induction heating. The electrode drying apparatus includes an induction heating unit that heats the electrode foil by induction heating, a cooling unit that condenses the solvent vapor evaporated from the electrode foil by the induction heating unit, and a recovery that collects the solvent condensed by the cooling unit. And an electrode drying chamber for storing the induction heating means, the cooling means, and the recovery means.

  Further, the electrode drying method is for drying an electrode foil coated with an active material in an electrode drying chamber. This electrode drying method is characterized in that the electrode foil is heated by induction heating, the solvent vapor evaporated from the heated electrode foil is cooled to condense, and the condensed solvent is recovered.

  According to the present invention, the solvent vapor evaporated from the electrode foil is cooled and condensed, and the condensed solvent is recovered. Therefore, the condensed solvent can be prevented from reattaching to the electrode.

It is explanatory drawing which shows the structure of the electrode drying apparatus of the 1st Embodiment of this invention. It is explanatory drawing which shows the structure of the cooling device of the 1st Embodiment of this invention. It is explanatory drawing which shows the example of arrangement | positioning of the induction heating apparatus of the 1st Embodiment of this invention. It is explanatory drawing which shows the example of arrangement | positioning of the cooling device of the 1st Embodiment of this invention. It is explanatory drawing which shows the example of arrangement | positioning of the cooling device of the 2nd Embodiment of this invention. It is explanatory drawing which shows the structure of the cooling device of the 3rd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1]
FIG. 1 is an explanatory diagram showing the configuration of the electrode drying apparatus according to the first embodiment of the present invention.

  The electrode drying apparatus of the present embodiment is an apparatus for drying the current collector 7 coated with the electrode active material by induction heating in the electrode manufacturing apparatus. The induction heating apparatus 3, the cooling apparatus 4, and the induction heating apparatus. 3 and the induction heating drying furnace 2 which stores the cooling device 4 is provided.

  In addition, an electrode manufacturing apparatus is provided with the coating machine 1 and the transfer apparatus 8 other than an electrode drying apparatus, for example.

  The coating machine 1 applies the active material to the strip-shaped current collector 7. Since the coating machine is a well-known technique, a detailed description thereof will be omitted.

The active material is prepared by dispersing the positive or negative electrode active material, the conductive material, and the binder in an organic solvent. The active material is appropriately selected according to the type of battery. For example, an active material used for a positive electrode of a lithium battery includes a composite oxide of lithium and a transition metal such as LiMn ₂ O ₄ . Further, for example, active materials used for the negative electrode of a lithium battery include metal materials such as graphite, metallic lithium, lithium alloy, and tin compounds, conductive polymers, and the like.

  Further, the conductive agent is a substance used for ensuring the conductivity of the positive electrode, such as carbon black and acetylene black. In addition, the binder is a compound having an action of holding active material particles together, and examples thereof include polyvinylidene fluoride (PVDF), polyvinylidene chloride, and polytetrafluoroethylene (PTFE).

  The current collector 7 is a strip-shaped electrode foil that is appropriately selected according to the type of battery. In the case of the positive electrode, for example, aluminum and stainless steel are used, and in the case of the negative electrode, copper, nickel, and the like are used.

  The induction heating device 3 heats the current collector 7 coated with the active material by induction heating. The configuration of the induction heating device 3 will be described later with reference to FIG.

  The cooling device 4 condenses the solvent vapor by cooling the solvent vapor evaporated by induction heating, and collects the condensed solvent. Details of the configuration of the cooling device 4 will be described later with reference to FIG.

  The transfer device 8 holds the current collector 7 in a substantially horizontal state, and continuously sends the held current collector 7 to the induction heating drying furnace 2.

  FIG. 2 is an explanatory diagram showing the configuration of the cooling device 4 according to the first embodiment of the present invention.

  The cooling device 4 includes a cooling plate 41, a recovery rod 43, a duct 44 and a fan 45. The configuration of the cooling plate 41 is not particularly limited. For example, the cooling plate 41 is composed of an ingot formed by forging or rolling copper, a copper alloy, or the like, and has a passage for cooling water (cooling medium) inside, and is connected to supply or discharge the cooling water (cooling medium). Connected to the tube.

  The solvent vapor is sucked from the suction port 46 of the duct 44 by the fan 45 and cooled by the cooling plate 41. The solvent vapor condenses when cooled, and the condensed solvent adheres to the inner wall of the cooling plate 41.

  Then, the adhering solvent falls along the inner wall of the cooling plate 41 and is recovered by the recovery rod 43. Further, the solvent vapor becomes dry air when passing through the cooling plate 41 and is discharged from the duct 44 by the fan 45.

  In the induction heating method, it is not necessary to recirculate hot air into the induction heating drying furnace 2. Moreover, the boiling point of the organic solvent is generally low (for example, 30 ° C to 45 ° C). For this reason, the cooling device 4 can remove the solvent from the solvent vapor only by cooling the solvent vapor to a temperature slightly higher than room temperature. Therefore, the electrode drying apparatus of this embodiment can reduce the cost of operating the cooling device 4.

  Drawing 3 is an explanatory view showing an example of arrangement of induction heating device 3 of a 1st embodiment of the present invention.

  The induction heating device 3 includes, for example, a power supply 33 that supplies electric power, a resonance frequency automatic regulator 34 that generates an induction current, a transformer 35 that controls the induction current, an induction heating coil 31, and a magnetic core 32 that concentrates magnetic flux.

  The induction heating coil 31 is, for example, a substantially rectangular single or multiple flat coil having a straight portion 36. The substantially rectangular straight portion 36 is arranged along the width direction of the belt-like current collector 7. The induction heating coil 31 generates a magnetic flux by an induced current.

  The magnetic core 32 is, for example, a ferrite in the shape of a recess, and accommodates the linear portion 36 of the induction heating coil 31 disposed along the width direction of the belt-like current collector 7. The magnetic core 32 concentrates the magnetic flux generated by the induction heating coil 31. The magnetic flux concentrated by the magnetic core passes through the current collector 7. The current collector 7 generates heat due to this magnetic flux.

  The power source 33 is a device that supplies an input alternating current as a direct current. The automatic resonance frequency adjuster 34 converts the direct current supplied from the power supply 33 into an alternating current, and generates an induced current by controlling the frequency of the converted alternating current. The transformer 35 controls the magnitude of the induction current supplied to the induction heating coil 31 by increasing or decreasing the voltage. In addition, since the induction heating apparatus 3 is a well-known technique, detailed description of each structure is abbreviate | omitted.

  FIG. 4 is an explanatory diagram showing an example of the arrangement of the cooling device 4 according to the first embodiment of the present invention.

  In FIG. 4, a set of induction heating devices 3 and a cooling device 4 are shown.

  A part surrounded by a dotted line shown in FIG. 4 is a part of the induction heating device 3 shown in FIG. 3, and a set of induction heating coils 31 and magnetic cores 32 arranged above and below the current collector 7 are It is the cross section (cross section of AA of FIG. 3) cut out along the length direction of a collector.

  The induction heating coil 31 and the magnetic core 32 are spaced apart from the upper and lower surfaces of the current collector 7 so as not to interfere with the air flow.

  The cooling device 4 includes a cooling plate 41 on the outer wall near the suction port 46 of the duct 44. The suction port 46 of the duct 44 is disposed above the opening provided in the center of the induction heating coil 31 of the set of induction heating devices 3. The cooling device 4 may include a cooling plate 41 on the inner wall near the suction port 46 of the duct 44.

  When the current collector 7 coated with the active material passes between a pair of upper and lower induction heating coils 31, it is heated by induction heating. For this reason, solvent vapor is generated from the active material of the current collector 7.

  Then, the cooling device 4 recovers the generated solvent vapor from the suction port 46 of the duct 44. In this case, since the surrounding air flows from the gap between the current collector 7 and the induction heating coil 31, the cooling device 4 can efficiently suck the solvent vapor.

  As described with reference to FIG. 2, when the sucked solvent vapor is cooled by the cooling plate 41, the condensed solvent is recovered in the recovery tank 43.

  The cooling device 4 may be connected to an organic solvent recovery device (not shown) provided outside. In this case, the solvent recovered by the recovery tank 43 is pumped to the organic solvent recovery device via, for example, a pipe and a pump (not shown).

  Further, it is desirable that the entire duct 44 of the cooling device 4 is disposed inside the induction heating drying furnace 2. Thus, the dry air from which the solvent vapor has been removed is refluxed inside the induction heating drying furnace 2.

  As described above, according to the present embodiment, by cooling the vicinity of the suction port of the duct disposed immediately above the induction heating coil, the solvent vapor is actively condensed and the condensed solvent is recovered. It is possible to prevent the solvent from reattaching to the electrode film. As a result, a uniformly dried electrode film can be produced.

[Embodiment 2]
FIG. 5 is an explanatory diagram showing an example of the arrangement of the cooling device 4 according to the second embodiment of the present invention.

  The cooling device 4 of the present embodiment includes cooling fins 42 on the inner wall of the upper portion of the suction port 46 of the duct 44 instead of the cooling plate 41 shown in FIG. The cooling fin 42 is, for example, a heat exchanger such as a condenser having a large number of cooling fins. The cooling device 4 may cool the entire duct 44 by a device other than the cooling plate and the cooling fin.

  The duct 44 may include at least two fans 45 and at least two exhaust ports. In this case, one of the two exhaust ports may be disposed inside the induction heating drying furnace 2, and the other may be connected to an exhaust concentrator (not shown) provided outside.

  A part of the gas containing the organic solvent is supplied to the exhaust concentrator, and the other remaining gas is returned to the inside of the induction heating drying furnace 2. That is, since all the gas is not exhausted from the induction heating drying furnace 2, the electrode drying apparatus of this embodiment can reduce the load of the exhaust concentration apparatus provided outside.

  The exhaust concentrator separates the gas exhausted from the induction heating drying furnace 2 into a gas containing a concentrated organic solvent and a gas not containing an organic solvent, and then the gas not containing the organic solvent is taken out of the system. It may be discharged. Further, the exhaust concentration device may be connected to an organic solvent recovery device (not shown) and supply the concentrated gas to the connected organic solvent recovery device.

  As described above, according to the present embodiment, by cooling the inside of the duct arranged directly above the induction heating coil or the duct itself, the solvent vapor is actively condensed, and the condensed solvent is recovered. It is possible to prevent the condensed solvent from reattaching to the electrode film. As a result, a uniformly dried electrode film can be produced.

  In addition, since at least part of the exhaust gas that has passed through the cooling device and from which the solvent vapor has been removed is recirculated to the induction heating drying furnace, the load on the exhaust concentrating device disposed outside the induction heating drying furnace is reduced. Can do.

[Embodiment 3]
FIG. 6 is an explanatory diagram illustrating a configuration of the cooling device 4 according to the third embodiment.

  In the cooling device 4 of the third embodiment, a cooling plate 60 for cooling the induction superheater 3 is provided at a position adjacent to the induction superheater 3. The cooling plate 60 is configured by an ingot formed by forging or rolling copper, a copper alloy, or the like, similar to the cooling plate 41, and has a cooling water (cooling medium) passage therein, and includes cooling water (cooling medium). It is good also as a structure connected to the connecting pipe for supplying or discharging | emitting, and it is good also as a structure different from the cooling plate 41. FIG. Further, the position where the cooling plate 60 is arranged is not limited to the position shown in FIG.

  The solvent vapor evaporated by the induction heating is sucked from the suction port 46 of the duct 44 by the fan 45. At this time, the temperature of the cooling plate 60 is set so that the solvent vapor is cooled and not condensed by the cooling plate 60. That is, the temperature of the cooling plate 60 is higher than the temperature of the cooling plate 41.

  As described above, according to the third embodiment, since the cooling plate 60 for cooling the induction overheating device 3 is provided, the induction heating device 3 can be cooled. Further, by setting the temperature of the cooling plate 60 higher than the temperature of the cooling plate 41, the solvent vapor evaporated by induction heating is prevented from condensing by the cooling plate 60, and the condensed solvent is re-applied to the electrode film. It can be prevented from adhering. That is, the solvent vapor is cooled and condensed by the cooling plate 41 and is recovered by the recovery bar 43 as in the first embodiment.

  6 shows a configuration in which the cooling plate 60 is added to the configuration of the cooling device 4 of the first embodiment shown in FIG. 4, the cooling device 4 of the second embodiment shown in FIG. A cooling plate 60 for cooling the induction superheater 3 can be added to the configuration.

  Moreover, although the cooling plate 60 was mentioned as an example and demonstrated as a means to cool the induction heating apparatus 3, it is not limited to a cooling plate.

1 Coating machine 2 Induction heating drying furnace (electrode drying room)
3 Induction heating device (induction heating means)
4 Cooling device 7 Current collector (electrode foil)
8 Transfer device 31 Induction heating coil 41 Cooling plate (cooling means, first cooling means)
42 Cooling fins (cooling means, first cooling means)
43 Collection dredging (collection means)
44 Duct 45 Fan 46 Suction port 60 Cooling plate (second cooling means)

Claims (8)

An electrode drying apparatus for drying an electrode foil coated with an active material,
Induction heating means for heating the electrode foil by induction heating;
A cooling means for condensing solvent vapor evaporated from the electrode foil by the induction heating means;
Recovery means for recovering the solvent condensed by the cooling means;
An electrode drying chamber for storing the induction heating means, the cooling means, and the recovery means;
An electrode drying apparatus comprising: The cooling means is disposed in the vicinity of the induction heating means,
The electrode drying apparatus according to claim 1, wherein the recovery unit is disposed vertically below the cooling unit. The electrode drying apparatus further includes a duct for sucking the evaporated solvent vapor,
The cooling means is disposed inside the duct;
The electrode drying apparatus according to claim 1, wherein the recovery unit is disposed vertically below the duct. The electrode drying apparatus further includes a duct for sucking the evaporated solvent vapor,
The cooling means is arranged to cool the outer wall of the duct;
The electrode drying apparatus according to claim 1, wherein the recovery unit is disposed vertically below the duct.   5. The electrode drying apparatus according to claim 1, wherein part or all of the air that has passed through the cooling device is returned to the electrode drying chamber. The induction heating means includes a substantially rectangular induction heating coil,
The electrode drying apparatus according to claim 3, wherein the duct is disposed on a central upper surface of the substantially rectangular induction heating coil. An electrode drying apparatus for drying an electrode foil coated with an active material,
Induction heating means for heating the electrode foil by induction heating;
First cooling means for condensing solvent vapor evaporated from the electrode foil by the induction heating means;
A recovery means for recovering the solvent condensed by the first cooling means;
A second cooling means for cooling the induction superheating means;
An electrode drying chamber for storing the induction heating means, the first cooling means, the second cooling means, and the recovery means;
With
The electrode drying apparatus characterized in that the first cooling means has a temperature lower than that of the second cooling means. An electrode drying method for drying an electrode foil coated with an active material in an electrode drying chamber,
Heating the electrode foil by induction heating,
Condensing by cooling the solvent vapor evaporated from the heated electrode foil;
An electrode drying method, wherein the condensed solvent is recovered.

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