JP4972854B2 - Electrode and electrode manufacturing method - Google Patents

Description

The present invention relates to an electrode and a method for manufacturing the electrode .

In recent years, attempts have been made to mount capacitors (charge supply devices) having superior input / output characteristics of electric energy instead of batteries in devices such as electric vehicles and mobile phones. Of course, it is preferable for such a capacitor to have a large storage capacity of electric energy, and various techniques for increasing the storage capacity of the capacitor have been proposed.
As a means for increasing the volume capacity of the capacitor, it is conceivable to increase ions adsorbed on the current collector by increasing the specific surface area of the pair of current collectors immersed in the electrolytic solution. As an embodiment, there is a technique in which a carbon nanotube is used as a part of an electrode of a capacitor. In this technique, carbon nanotubes that have been broken short are fixed to a current collector plate made of a metal substance using a binder, and this is used as a current collector to increase the specific surface area of the current collector. In addition, a technique for directly depositing carbon nanotubes on a current collector plate has been proposed.
JP 2002-242026 A JP 2001-307951 A Special Table 2002-526913 JP 2000-510999 A JP 2002-29860 A JP 2001-233694 A JP 2000-1224079 A Japanese Patent Laid-Open No. 11-40767

  According to the technique described above, the storage capacity of the capacitor can be increased. However, it cannot be said that the accumulated dose is sufficient for mounting in an actual device because of problems such as time that can be used by one charge. For this reason, a technique for further increasing the storage capacity of the capacitor is required.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a current collector plate and a method of manufacturing the current collector plate that further improve the storage capacity of the charge supply device.

To achieve the above object, the present invention, as a first means according to the electrode, an electrode provided in the charge supply device, a porous current collector plate made of a conductive material, on the porous collector plate The structure which comprises the graphite fiber layer arrange | positioned in contact with respect is employ | adopted.

As a second means related to the electrode , a configuration is adopted in which, in the first means, the graphite fibrous layer is formed of carbon nanofibers, carbon nanotubes, or carbon nanowalls.

As a third means related to the electrode , in the second means, the porous current collector plate contains cobalt or nickel, and the graphite fibrous layer and the porous current collector plate are chemically bonded. The configuration is adopted.

As a fourth means related to the electrode , in any one of the first to third means, a configuration is adopted in which the charge supply device is a battery, and the charge supply device is a capacitor.

As a fifth means related to the electrode , in any one of the first to third means, a configuration is adopted in which the charge supply device is a battery.

As a sixth means related to the electrode , in any one of the first to third means, when the charge supply device is a nickel metal hydride battery, the porous collector plate is made of misch metal. To do.

As a first means related to an electrode manufacturing method, a method for manufacturing an electrode provided in a charge supply device, wherein a porous current collector plate is formed by rolling a powdery conductive material A configuration is adopted that includes a forming step and a graphite fibrous layer forming step for forming a graphite fibrous layer disposed in contact with the porous current collector plate.

As a second means related to the electrode manufacturing method, in the first means, in the graphite fibrous layer forming step, cobalt powder or nickel powder is disposed on the surface of the porous current collector plate, and the cobalt A configuration in which carbon nanofibers, carbon nanotubes, or carbon nanowalls are deposited using powder or nickel powder as a catalyst is employed.

As a third means related to the electrode manufacturing method, in the first means, in the porous current collector plate forming step, a conductive material containing cobalt powder or nickel powder is used as the powdered conductive material, and the graphite is used. In the fibrous layer forming step, a configuration is adopted in which carbon nanofibers, carbon nanotubes, or carbon nanowalls are deposited using the cobalt powder or nickel powder contained in the porous electrode as a catalyst.

As a fourth means related to the electrode manufacturing method, in the first means, when the charge supply device is a nickel metal hydride battery, a configuration is used in which Misch metal is used as the conductive material.

According to the electrode of the present invention, since the porous current collecting plate is used as the current collecting plate, the current collecting efficiency of the current collecting plate can be improved. Therefore, according to the current collector plate of the present invention, the storage capacity of the charge supply device can be further improved.
In addition, according to the electrode manufacturing method of the present invention, a porous current collector plate can be easily formed because a porous current collector plate is formed by rolling a powdered conductive material. Therefore, according to the manufacturing method of the electrode of the present invention, it is possible to manufacture an electrode easily provided with a porous current collector plate.

  Hereinafter, an embodiment of a current collector and a method for manufacturing the current collector according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member and each layer is appropriately changed in order to make each member and each layer recognizable.

(First embodiment)
FIG. 1 is a schematic diagram showing the overall configuration of a capacitor 1 (charge supply device). In this figure, reference numeral 2 is an electrode, 3 is a separator, 4 is a power source, 5 is a switch, and the capacitor 1 is constituted by these members.
The capacitor 1 is mounted on a device such as a mobile phone instead of a battery, and supplies electric charges to such a device, and is called a so-called super capacitor.

The capacitor 1 has a pair of electrodes 2. This electrode 2 constitutes a positive electrode and a negative electrode, respectively, and is disposed oppositely in a state of being immersed in an electrolytic solution 6 such as potassium hydroxide.
Each of such electrodes 2 is composed of a current collector plate 21 (porous current collector plate) and a graphite fiber layer 22. That is, in the capacitor 1 of the present embodiment, the current collector itself of the present invention is used as the electrode 2.
The current collecting plate 21 is a plate-like member (or a sheet-like member) made of a conductive material, and is configured as a porous body having many fine holes. Note that aluminum having high conductivity can be mainly used as the conductive material, but the current collector plate 21 in the capacitor 1 of the present embodiment is configured to include aluminum and cobalt.
The graphite fibrous layer 22 is formed of an aggregate of carbon nanofibers, carbon nanotubes, or carbon nanowalls, and is disposed in contact with the current collector plate 21. In the capacitor 1 of the present embodiment, the graphite fiber layer 22 and the current collector plate 21 are chemically bonded without using a binder.

The separator 3 is an insulating material that prevents the short circuit of the capacitor 1 caused by the electrodes 2 and 2 being in contact with each other by being disposed between the electrodes 2 and 2. The separator 3 is composed of a nonwoven fabric or a porous film through which the electrolytic solution 6 can pass.
Further, the current collector plates 21 and 21 are electrically connected to each other by a wiring 7 disposed outside the electrolyte solution 6. A power supply 4 and a switch 5 are arranged in the middle of the wiring 7.

In the capacitor 1 configured as described above, when the switch 5 is connected and voltage and current are applied to the electrode 2 from the power source 4, anions and cations in the electrolyte 6 are separated and adsorbed on the electrode 2. The
Here, in the capacitor 1 of the present embodiment, the current collector plate 21 is configured as a porous body. For this reason, the specific surface area of the current collecting plate 21 of the present embodiment is larger than that of the flat plate-shaped current collecting plate provided in the conventional capacitor. Therefore, the capacitor 1 and the electrode 2 of the present embodiment can adsorb more ions than the conventional capacitor and electrode, and the storage capacity of the capacitor 1 can be further improved.

Further, in the capacitor 1 according to the present embodiment, the graphite fibrous layer 22 is chemically bonded to the current collector plate 21. Therefore, the carbon nanofibers, the carbon nanotubes, or the carbon nanowalls are collected using a binder. The internal resistance can be reduced as compared with the case of being physically coupled to 21.
However, the present invention does not exclude a current collector in which carbon nanofibers, carbon nanotubes, or carbon nanowalls are physically bonded to the current collector plate 21 using a binder.

  The graphite fiber layer 22 described above is preferably subjected to an activation process such as sintering. As a result, the graphite fibrous layer 22 is oxidized, the surface becomes rough, and the specific surface area of the graphite fibrous layer 22 with respect to the electrolytic solution 6 can be increased.

  Next, a method for manufacturing such a capacitor 1 will be described.

FIG. 2 is a schematic diagram for explaining the current collector plate 21 forming step (porous current collector plate forming step).
The current collector plate 21 configured as a porous body is formed by rolling a powdered conductive material. Specifically, as shown in FIG. 2, the aluminum powder X <b> 1 and the cobalt powder X <b> 2 are supplied between a pair of rolls 41, 41 and cold-rolled between the rolls 41, 41. In addition, it is preferable to perform the sintering process on the current collector plate 21 thus formed in a temperature environment of about 400 °. By performing such a sintering process, the rigidity of the current collector plate 21 is improved. Further, by performing the sintering treatment, the cobalt powder X2 diffuses into the aluminum powder X1, and a part thereof is alloyed. As described above, by partially alloying, the heat resistance performance of the current collector plate 21 is improved, and damage to the current collector plate 21 in a sheet plasma CVD apparatus described later is suppressed.

Next, a graphite fiber layer 22 is formed which is arranged in contact with the current collector plate 21 formed as described above (graphite fiber layer forming step).
FIG. 3 is a schematic view of a sheet plasma CVD (Chemical Vapor Deposition) apparatus 30 for forming the graphite fibrous layer 22. In this figure, reference numeral 31 is a housing, 32 is a plasma gun, 33 is a positive electrode, 34 is a coil, 35 is a diffuser tube, 36 is a heater, and 37 is a substrate.

The casing 31 is a box-shaped member having a predetermined size, and the inside thereof is maintained in a vacuum atmosphere. On one side (left side in FIG. 3) of the casing 31, a plasma gun 32 is installed as shown.
The plasma gun 32 is installed at a substantially central portion in the height direction of the casing 31 (vertical direction in FIG. 3). A negative electrode 32a is disposed inside the plasma gun 32, and argon gas used as a carrier gas is supplied.
The positive electrode 33 is disposed in the vicinity of the side portion on the other side of the casing 31 so as to face the plasma gun 32 inside the casing 1.
A voltage P and a current are applied to the plasma gun 32 and the positive electrode 33, whereby plasma P using argon gas as a carrier gas is generated between the plasma gun 32 and the positive electrode 33.

  As shown in the drawing, a plurality of coils 34 are installed at appropriate positions on the outer surface of the housing 1, and the plasma P is formed in a horizontal sheet shape by a magnetic field generated by itself. The air diffuser 35 is disposed above the sheet-like plasma P in the housing 1 and ejects a predetermined gas supplied from the outside downward. As the predetermined gas, methane gas containing a carbon component or hydrogen gas is used.

In addition, the heater 36 and the substrate 37 are disposed below the sheet-like plasma P in the housing 1. The heater 36 heats the substrate 37 placed on the heater 36 and is supported by the housing 1 by a support member 38.
Therefore, the predetermined gas ejected from the air diffuser 35 is sprayed onto the substrate 37 via the plasma P.

The sheet plasma CVD apparatus 30 configured as described above deposits carbon nanofibers, carbon nanotubes, or carbon nanowalls on the surface of one side of the current collector plate 21.
Specifically, the current collector plate 21 made of a conductive material such as nickel is first placed on the substrate 37. In this state, a voltage and a current are applied to the negative electrode 32a and the positive electrode 33 of the plasma gun 32 to generate a sheet-like plasma P, and further, hydrogen gas from the diffuser tube 35 passes through the plasma P to the current collector plate 21. Is sprayed against. The hydrogen gas is ionized by being excited and decomposed by the plasma P and adheres to one surface of the current collector plate 21. As a result, the surface on one side of the current collector 21 is reduced.

  Subsequently, the current collector plate 21 is heated to 500 to 800 ° C. via the substrate 37 by the heater 36, and in this state, methane gas is sprayed from the diffuser tube 35 to the current collector plate 21 via the plasma P. This methane gas is also ionized by being excited and decomposed by the plasma P in the same manner as the hydrogen gas, and adheres to one surface of the current collector plate 21. In this way, when the methane gas is sprayed through the plasma P, a plurality of carbon nanofibers, carbon nanotubes, or carbon nanowalls are deposited on one surface of the current collector plate 21. These carbon nanofibers, carbon nanotubes, or carbon nanowalls are deposited using cobalt powder contained in the current collector plate 21 as a catalyst. The carbon nanofibers, carbon nanotubes, or carbon nanowalls deposited using cobalt powder as a catalyst in this way are chemically bonded to the current collector plate 21. Therefore, according to the capacitor manufacturing method of the present embodiment, it is possible to manufacture the electrode 2 (current collector) in which the current collector plate 21 and the graphite fibrous layer 22 are chemically bonded.

For example, carbon nanotubes can be deposited by setting the heating temperature of the current collector plate 21 to about 600 ° C., and carbon nanowalls can be deposited by setting the heating temperature of the current collector plate 21 to about 700 ° C. be able to. Note that the graphite fiber layer 22 in which carbon nanotubes and carbon nanowalls are mixed, for example, can also be formed by changing the temperature condition in the middle.
Further, as described above, carbon nanofibers, carbon nanotubes, or carbon nanowalls are deposited using cobalt powder as a catalyst. For this reason, it is preferable that the cobalt powder X2 has a smaller particle size than the aluminum powder X1. Thus, by making the particle diameter of cobalt powder X2 smaller than the particle diameter of aluminum powder X1, even when cobalt powder X2 and aluminum powder X1 are used at the same mass ratio, more cobalt powder X2 is present on the surface layer of the current collector plate 21. Therefore, more carbon nanofibers, carbon nanotubes, or carbon nanowalls can be deposited.

  And the electrode 2 of this embodiment, ie, the electrical power collector of this invention, is manufactured according to the above process. That is, the method for manufacturing a current collector of the present invention includes the above-described porous current collector forming step and graphite fiber layer forming step in the present embodiment.

  Two electrodes 2 are formed, a separator 3 is disposed between the electrodes 2 and 2, and the electrode 2 is stored in a capacitor housing (not shown) in which an electrolyte 6 is stored. 1 is connected to the outside of the electrolytic solution 6 by the wiring 7, and the power source 4 and the switch 5 are disposed in the middle portion of the wiring 7, thereby depositing on the current collecting plate 21 and the current collecting plate 21 as shown in FIG. The capacitor 1 according to the present embodiment using the graphite fiber layer 22 thus prepared as an electrode 2 is assembled and manufactured.

  As described above, when the activation process is performed on the graphite fiber layer 22, the graphite fiber layer 22 is oxidized by sintering or the like in a steam atmosphere before the capacitor 1 is assembled.

  According to the method for manufacturing a capacitor of this embodiment, since the current collector plate 21 is formed by rolling the powdered conductive materials X1 and X2, the porous current collector plate 21 is easily formed. can do. Therefore, it is possible to easily manufacture the electrode 2 in which the current collector plate is a porous body.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. In the description of the second embodiment, the description will be given with reference to FIG. 1, and the description of the same parts as those of the first embodiment will be omitted or simplified.

  In the capacitor 1 according to the second embodiment, the current collecting plate 21 is made of only aluminum, and cobalt powder (not shown in FIG. 1) is attached to the surface of the current collecting plate 21. The carbon nanofibers, carbon nanotubes, or carbon nanowalls of the graphite fibrous layer 22 are deposited using cobalt powder, which is attached to the surface of the current collector plate 21, as a catalyst.

Also in the capacitor 1 of the second embodiment having such a configuration, the current collector plate 21 is configured as a porous body. For this reason, the specific surface area of the current collecting plate 21 of the present embodiment is larger than that of the flat plate-shaped current collecting plate provided in the conventional capacitor. Therefore, the capacitor 1 and the electrode 2 of the second embodiment can adsorb more ions than the conventional capacitor and electrode, and the storage capacity of the capacitor 1 can be further improved.
In addition, since the current collecting plate 21 in the capacitor 1 of the second embodiment is formed only of aluminum, the electrode 2 is more than the capacitor 1 of the first embodiment having the electrode 2 containing cobalt and aluminum. The conductivity can be improved.

  In the case of manufacturing the capacitor 1 of the second embodiment, the current collector plate 21 is formed by cold-rolling only aluminum powder between the rolls 21 and 22, and the current collector plate 21 After applying a solvent containing cobalt powder (for example, cobalt acetic acid) on the surface, only the solvent component is evaporated to adhere and arrange the cobalt powder on the surface of the current collector plate 21. Thereafter, the graphite fiber layer 22 is formed by depositing carbon nanofibers, carbon nanotubes, or carbon nanowalls using cobalt powder adhered to the surface of the current collector plate 21 as a catalyst.

(Third embodiment)
FIG. 4 is a perspective view of a nickel-metal hydride battery 50 (charge supply device) on which an electrode E is loaded and is shaped into a cylinder. E1 is a negative electrode, E2 is a positive electrode, 51 is a separator, 52 is a battery case (negative electrode terminal), 53 is a positive electrode terminal, and 54 is a sealing plate.

  The negative electrode E1 and the positive electrode E2 are wound in a multiple manner with the separator 51 therebetween, and are housed in a cylindrical battery case (negative electrode terminal) 52, and the inside of the battery case 52 is filled with an electrolytic solution. An opening is formed at the upper end of the battery case 52, and the opening is sealed by a sealing plate 54 provided with a positive terminal 53 at the center and insulated from the battery case 52. The negative electrode E1 is connected to the battery case 52, the positive electrode E2 is connected to the positive terminal 53, and the negative electrode E1 and the positive electrode E2 constitute a series circuit via the electrolytic solution.

  The nickel metal hydride battery 50 according to the third embodiment includes, as a part of the electrode E, a current collector included in the capacitor 1 according to the first and second embodiments (the electrode 2 in the first and second embodiments). have. Specifically, the positive electrode E1 includes a current collector and nickel hydroxide powder (active material) that is pressure-bonded to the current collector, and the negative electrode E2 is pressure-bonded to the current collector and the current collector. And a hydrogen storage alloy powder (active material).

  Also in the nickel metal hydride battery 50 of the third embodiment having such a configuration, since the current collector plate provided in the current collector is configured as a porous body, the storage capacity is further improved over the conventional nickel metal hydride battery. It becomes possible to make it.

When the current collector of the present invention is applied to the negative electrode E2 of the nickel metal hydride battery 50, the current collector plate can be formed of misch metal . When the current collector plate is formed of misch metal in this way, the current collector plate can be made to function as a hydrogen storage alloy (active material), and therefore the current collector itself can be used as the negative electrode E2. Can do. The misch metal referred to here is a kind of hydrogen storage alloy containing a rare earth and nickel or cobalt, which is melted in a reduced state before refining an alloy lump collected at a mine or the like.
When the current collector plate is formed of such a misch metal , it can be formed by rolling the misch metal after making it into powder.

The rare earth contained in misch metal promotes the precipitation of carbon nanotubes or carbon nanowalls. Therefore, when the current collector is formed of misch metal , the precipitation of carbon nanofibers, carbon nanotubes, or carbon nanowalls is promoted. It becomes possible. Moreover, by mixing such rare earths with the conductive material used when forming the current collector plate 21 of the first and second embodiments, the carbon nanofibers, carbon nanotubes, or carbon in the first and second embodiments are used. It is also possible to promote the deposition of nanowalls.

  The preferred embodiments of the current collector and the method for manufacturing the current collector according to the present invention have been described above with reference to FIGS. 1 to 4. Needless to say, the present invention is not limited to the above-described embodiments. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above embodiment, cobalt is used as a catalyst for precipitating carbon nanofibers, carbon nanotubes, or carbon nanowalls, but the present invention is not limited to this, and the carbon nanofibers, carbon nanotubes or Nickel can also be used as a catalyst for depositing carbon nanowalls.
Moreover, the current collection plate which does not require a catalyst can also be formed by forming the current collection plate 21 with nickel. In this case, the current collector plate 21 need not contain cobalt.

It is the schematic which showed the whole structure of the capacitor of 1st Embodiment of this invention. It is a schematic diagram for demonstrating the formation process of a current collecting plate. It is the schematic of the sheet plasma CVD apparatus for forming a graphite fiber layer. It is a perspective view of the nickel metal hydride battery of 3rd Embodiment of this invention.

Explanation of symbols

1 …… Capacitor (Charge supply device)
2 ... Electrode (current collector)
21 …… Current collector (porous current collector)
22 ... Graphite fiber layer 50 ... Nickel metal hydride battery (charge supply device)

Claims (8)

A method of manufacturing an electrode provided in a charge supply device,
A porous current collector plate forming step of forming a porous current collector plate by rolling a conductive material containing powdered cobalt or powdered nickel and powdered aluminum ; and
Formation of a graphite fiber layer for forming a graphite fiber layer disposed in contact with the porous current collector plate using the powdered cobalt or the powdered nickel contained in the porous current collector as a catalyst A method for producing an electrode comprising the steps of: The method for producing an electrode according to claim 1, wherein the powdery cobalt or the powdery nickel has a particle size smaller than that of the powdery aluminum . 3. The method of manufacturing an electrode according to claim 1, wherein when the charge supply device is a nickel metal hydride battery, powdered misch metal is included as the conductive material. An electrode provided in a charge supply device,
A porous current collector plate made of a conductive material containing powdered cobalt or powdered nickel and aluminum;
An electrode comprising: a porous fibrous current collector plate; and a graphite fibrous layer disposed in a chemically bonded state.   The electrode according to claim 4, wherein the graphite fibrous layer is formed of carbon nanofibers, carbon nanotubes, or carbon nanowalls.   6. The electrode according to claim 4, wherein the charge supply device is a capacitor.   6. The electrode according to claim 4, wherein the charge supply device is a battery. 8. The electrode according to claim 7 , wherein when the charge supply device is a nickel metal hydride battery, the porous current collector plate includes powdered misch metal.

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