JP2006261399A - Accumulation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an accumulation device such as en electric double layer capacitor using a polarizable electrode, which controls the carbon concentration distribution of a polarizable electrode by using carbon nano thin film materials for controlling film thickness, specific surface density, bulk density and orientational property, improves a thin hole use rate, and also controls the absorptivity of electrolytic medium ion and electrolyte. <P>SOLUTION: This accumulation device is configured by arranging at least a pair of polarizable electrodes with or without a separator, a space between the pair of polarizable electrodes is filled with electolyte, and the structure of a polarizable electrode where carbon nano thin film materials are grown on a conductive substrate with surface density and bulk density whose level is almost identical and different is provided. Inorganic system gel elecrolyte, for example, inorganic system phosphoric acid glass gel electroyte such as alkali glass, is used as the electrolyte. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electricity storage device, and more particularly to an electricity storage device using a polarizable electrode, such as an electric double layer capacitor.

  2. Description of the Related Art Conventionally, power storage devices such as Li-ion batteries, organic radical batteries, nanogate redox capacitors, and electric double layer capacitors have been developed as power sources mounted on wearable devices such as watches and hearing aids, or devices in the ubiquitous field. In these fields, as well as miniaturization, weight reduction, thinning, long life, high reliability, energy density, power density and current capacity are high, internal resistance and leakage current are small, There is a strong demand for the development of an electricity storage device that satisfies the electrical characteristics capable of rapid charging.

  In order to obtain such an electricity storage device, the electrolyte has a high charge density, mobility and dissociation, and has a large number of carriers such as ions and protons. High surface area and bulk density) are demanded.

  Conventionally, as a polarizable electrode used for an electric storage device such as an electric double layer capacitor, an organic, inorganic, polymer material or the like has been used. As a typical example, a refined nano-sized carbon (carbon nanomaterial) )It has been known. This carbon nanomaterial has advantages such as high pore utilization rate and high electrical conductivity, and is manufactured by various production methods.

  For example, as an example of a method for producing a carbon nanomaterial and electrode formation using the carbon nanomaterial, carbon is produced at a high temperature by a reaction between a hydrocarbon polymer material and hydrogen, followed by steps such as sintering and pulverization. A method of forming an electrode by a physical method such as a spray method or a doctor blade method using a solvent that generates carbon is known. In addition, research on a method for forming a nanomaterial by a chemical method such as a reactive plasma method is also in progress.

JP 2000-1224079 A JP 2004-87213 A Japanese Patent Laid-Open No. 2004-289421

  However, conventional polarizable electrodes using carbon nanomaterials require the use of solvents, binders, etc. when fixing the carbon nanomaterial film onto the electrode, which generates gas and increases chemical stability. There was a problem that the film of the carbon nanomaterial was missing from the electrode. In addition, the conventional polarizable electrode has a problem that it is difficult to control the carbon concentration distribution of the carbon nanomaterial when the electrode film is formed.

  In general, when the carbon density is increased, the ion absorption concentration distribution of the electrolyte in the electrode is increased. However, the densification conversely reduces the voids and impedes the permeation of ions, and as a result, the electrolyte required for charging and discharging As a result, the cycle time and charge / discharge characteristics are lowered, and the energy density is lowered.

  On the other hand, when the carbon density is reduced to a rough state, the electrolytic solution is easily absorbed and the permeation of ions is facilitated, but the energy density is reduced.

  In this way, taking into consideration cycleability and charge / discharge characteristics, controlling the carbon concentration distribution of the polarizable electrode to achieve a high energy density is a major problem with power storage devices using polarizable electrodes. It has become.

  The present invention uses a carbon nano-thin film material with controlled film thickness, specific surface density, bulk density, orientation, etc. in an electricity storage device using a polarizable electrode, and can control the carbon concentration distribution of the polarizable electrode and use pores. It is an object of the present invention to provide an electricity storage device capable of improving the rate and controlling the absorption of electrolyte medium ions and electrolyte.

  Therefore, the present invention provides an electricity storage device in which at least a pair of polarizable electrodes are arranged with or without a separator and an electrolyte is filled between the pair of polarizable electrodes. At least one of the polarizable electrodes is formed by growing a carbon nano thin film material on a conductive substrate.

  According to a second aspect of the present invention, in the electric storage device according to the first aspect, a graphite substrate is used as the conductive substrate.

  According to a third aspect of the present invention, in the electricity storage device according to the first or second aspect, an inorganic gel electrolyte is used as the electrolytic solution.

  According to a fourth aspect of the present invention, in the electricity storage device according to any one of the first, second, or third aspect, a metal atom is supported in the carbon nano thin film material.

  According to this invention, since at least one of the pair of polarizable electrodes is formed by growing the carbon nano thin film material on the conductive substrate, the polarizable electrode has a film thickness, specific surface density, bulk density, orientation, etc. Carbon nano-thin film material can be used, so that the pore utilization rate (specific surface area, bulk density) of the polarizable electrode can be improved, and a small-sized and high electric storage device can be provided. it can.

  In addition, since the surface density and bulk density of the polarizable electrode can be controlled and the carbon concentration distribution can be controlled, it is possible to provide an electricity storage device suitable for the positive and negative ion sizes of the electrolyte.

  Furthermore, because a carbon nano thin film material is grown on a conductive substrate to form a polarizable electrode, for example, the heat retention effect due to the retained resistance value of graphite contributes to the stabilization of the mobility of electrolyte ions and is an excellent power storage device Can be provided.

  Furthermore, to form a polarizable electrode by growing a carbon nano thin film material on a conductive substrate, for example, a graphite film is formed on the back surface of a current collector, and a carbon nanotube is grown thereon, or Since carbon nanotubes are grown on a graphite substrate and the graphite substrate is brought into contact with a current collector, the adhesion process at the time of electrode formation, which has been conventionally required, can be eliminated.

  According to the invention of claim 3, since the inorganic gel electrolyte is used as the electrolytic solution, there is no shape restriction as in the case of using a solid electrolyte, and the penetration into the polarizable electrode is reduced. Excellent storage device without causing temperature rise, gas generation, or liquid leakage due to reaction during use, as in the case of using a liquid electrolyte Can be provided.

  According to the fourth aspect of the present invention, since metal atoms are supported in the carbon nano thin film material, the electrical conductivity of the carbon nano thin film material is increased, and an electricity storage device having a low internal resistance can be formed.

The best mode for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing an internal configuration of an electricity storage device using an example separator according to the present invention. FIG. 2 is a perspective view showing the external shape of the electricity storage device, and a partial longitudinal sectional view is shown in part.

  In the electricity storage device 1 of the present invention, at least a pair of polarizable electrodes 2 and 3 are arranged via a separator 4, and an electrolyte solution 5 is filled between the pair of polarizable electrodes 2 and 3. A carbon nano thin film material is grown on at least one of the polarizable electrodes 2 and 3 on a conductive substrate.

  For example, in the pair of polarizable electrodes 2 and 3, first, conductive graphite thin films (graphite film-like substrates) 21 and 31 are formed on the back surfaces of the pair of current collectors 6 and 7, and the graphite thin films are formed. The carbon nanotubes 22 and 32 are formed on the 21 and 31 by growing the carbon nanotubes 22 and 32 while controlling the crystal growth direction by using, for example, a plasma vapor phase growth method or the like.

  The separator 4 is arranged between the pair of polarizable electrodes 2 and 3 formed in this way. The separator 4 is appropriately selected so that ions in the electrolyte can pass therethrough and electrons can move and pass through. Between the pair of polarizable electrodes 2 and 3, an inorganic phosphate glass gel electrolyte such as alkali glass is filled as the electrolytic solution 5.

  When a voltage that does not cause electrolysis is applied between the polarities of the polarizable electrodes 2 and 3, ions are adsorbed on the electrodes, positive and negative electricity are accumulated, and function as a power storage device. It becomes.

  3 and 4 are scanning electron microscope (SEM) photographs showing crystal growth of carbon nanotubes formed on a conductive substrate (graphite substrate) used as a polarizable electrode in the present invention. FIG. 4 shows a case where the magnification is 20000, and FIG. 4 shows a case where the magnification is 4000.

  3 and 4, this carbon nanotube is excellent in pore utilization rate, and thus it can be seen that an electricity storage device with high carrier generation in the electrolyte and a large electric capacity can be formed.

  Moreover, a metal atom can also be carried in the carbon nano thin film material. A polarizable electrode carrying metal atoms in a carbon nano thin film material can increase the electrical conductivity of the carbon nano thin film material, accelerate the reaction speed, and form an electricity storage device with a small internal resistance and an increased electric capacity. it can.

  FIGS. 5 and 6 respectively show a case where a carbon nanotube polarizable electrode is brought into contact with a positive and negative gold current collector, and an electrolytic solution using an inorganic phosphate glass gel electrolyte such as alkali glass is sandwiched between both electrodes (FIG. 5). ) And a case where a gold electrode is used as a positive and negative current collector and an electrolyte is sandwiched between both electrodes (in the case of FIG. 6), the applied voltages: 1 Vpp and −1 Vpp, It is a figure which shows the relationship between charge amount change (coulomb) and time (second) measured by giving a repetition pulse of application time (cycle): 30 seconds and cycle number: 5 times.

  From FIG. 5 and FIG. 6, when the polarizable electrode of the present invention is used, the charge amount is about 2000 times as compared with the case where the polarizable electrode is not used. It can be seen that an electricity storage device having a high electric capacity can be obtained.

  In the above-described embodiments, the carbon nano thin film material used for the polarizable electrodes 2 and 3 may be carbon nano fibers in addition to the carbon nanotubes.

  In the above-described embodiment, an alkaline glass gel electrolyte such as phosphate glass was used as the electrolytic solution 5, but other than that, an inorganic, organic, or polymer gel electrolyte, or an organic, inorganic, A polymer electrolyte or electrolyte may be used.

  In the above-described embodiment, a low temperature plasma vapor deposition method using an ion, a laser source, or the like was adopted as a method for forming the carbon nano thin film material on the graphite substrate.

  In the above-described embodiment, the graphite substrate is used when forming the polarizable electrode. However, other conductive substrates can be used. In the above-described embodiments, a graphite thin film (graphite film-like substrate) is used as the graphite substrate, but a graphite crystalline substrate can also be used.

  In the above-described embodiment, the carbon nano thin film material having the same surface density and bulk density is grown on the conductive substrate of each of the pair of polarizable electrodes. It is also possible to grow carbon nano thin film materials having different surface densities and bulk densities on a conductive substrate.

  In the electricity storage device, graphite thin films (conductive substrates) 21 and 31 are formed on the metal back surfaces of the current collectors 6 and 7, and then carbon nanotubes (carbon nano thin film material) are formed on the graphite thin films (conductive substrates) 21 and 31. ) After the electrodes 22 and 32 are grown to form the polarizable electrodes 2 and 3, the periphery is covered with an insulator 8, but the formation of the polarizable electrodes and the configuration of the electricity storage device are not limited to this. The polarizable electrodes 2 and 3 formed by generating the carbon nanotubes (carbon nano thin film material) 22 and 32 on the conductive substrates 21 and 31 in advance are brought into contact with and sandwiched between the current collectors 6 and 7, and then the surroundings are insulated. The power storage device can also be configured by covering with the body 8.

  In the above-described embodiments, the shape of the electricity storage device is shown as a disk-like configuration as shown in FIG. Can do. Furthermore, it can also be set as the structure which laminated | stacked the electrolyte and the polarizable electrode.

It is a longitudinal cross-sectional view which shows the internal structure of the electrical storage device using the separator of an example by this invention. It is a perspective view which shows the external appearance shape of the electrical storage device, and is a figure which also shows a partial longitudinal cross-sectional view in part. It is a scanning electron microscope (SEM) photograph (magnification 20000 times) which shows the crystal growth of the carbon nanotube formed on the conductive substrate (graphite substrate). It is a scanning electron microscope (SEM) photograph (magnification 4000 times) which shows crystal growth of a carbon nanotube formed on a conductive substrate (graphite substrate). It is a figure which shows the relationship between the charge amount change measured by giving a repetitive pulse and time when using a polarizable electrode. It is a figure which shows the relationship between the charge amount change measured by giving a repetitive pulse, and time when not using a polarizable electrode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric storage device 2.3 Polarized electrode 4 Separator 5 Electrolyte 6-7 Current collector 8 Insulator 21/31 Graphite thin film (conductive substrate)
22.32 Carbon nanotube (carbon nano thin film material)

Claims (4)

  In an electricity storage device in which at least a pair of polarizable electrodes is disposed with or without a separator and an electrolyte is filled between the pair of polarizable electrodes, the pair of polarizable electrodes An electricity storage device, at least one of which is obtained by growing a carbon nano thin film material on a conductive substrate.   The electricity storage device according to claim 1, wherein a graphite substrate is used as the conductive substrate.   The electricity storage device according to claim 1 or 2, wherein an inorganic gel electrolyte is used as the electrolytic solution. The electrical storage device in any one of Claims 1, 2, or 3 made to carry | support a metal atom in the said carbon nano thin film material.

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