US20080210553A1

US20080210553A1 - Hydrogen generator having a porous electrode plate

Info

Publication number: US20080210553A1
Application number: US12/010,239
Authority: US
Inventors: Jae Hyoung Gil; Hong Ryul Lee; Arunabha Kundu; Jae Hyuk Jang
Original assignee: Samsung Electro Mechanics Co Ltd
Current assignee: Samsung Electro Mechanics Co Ltd
Priority date: 2007-01-23
Filing date: 2008-01-23
Publication date: 2008-09-04
Also published as: JP2008179893A; KR100843404B1; JP5050248B2

Abstract

There is provided a hydrogen generator having a porous electrode plate. The hydrogen generator including: an electrolytic bath having an electrolyte of a predetermined amount filled therein; a cover hermetically covering an open top of the electrolytic bath and having at least one hydrogen outlet; an electrode part fixed to the cover and having a porous structure formed on a body portion thereof to allow the electrolyte of the electrolytic bath to pass freely there through, the body portion of the electrode part immersed in the electrolytic bath; and a power supply supplying current to the electrode part.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No. 2007-07209 filed on Jan. 23, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a hydrogen generator, and more particularly, to a hydrogen generator having a porous electrode plate in which an electrode plate in contact with an electrolyte is changed in structure to increase a contact area with the electrolyte, thereby generating a greater amount of hydrogen.
2. Description of the Related Art
Recent years have seen an increasing use of small-sized electronic devices such as mobile phones, personal digital assistants (PDAs), digital cameras and laptop computers. Particularly, with the start of digital multimedia broadcasting (DMB) for mobile phones, a small-sized mobile terminal is required to be improved in power capacity.
A lithium-ion secondary battery in current general use has a capacity enabling about two hours of DMB viewing and has been performing better. However, as a more fundamental solution, there has been a growing expectation for a micro fuel cell reduced in size and capable of providing high-capacity power.
In general, the micro fuel cell adopts hydrogen as the most appropriate fuel for realizing high performance. This has led to a need for a device for generating hydrogen supplied to the micro fuel cell.
There are two ways to produce this fuel cell. One is a direct methanol method in which a hydrocarbon fuel such as methanol is directly supplied to a fuel electrode. The other is a reformed hydrogen fuel cell (RHFC) method in which hydrogen is extracted from methanol to be injected to a fuel electrode.
The RHFC method utilizes hydrogen as a fuel in the same manner as a polymer electrode membrane (PEM) method. Thus, the RHFC has advantages of high-output, high power capacity attainable per unit volume, and no reactant present other than water. However, the RHFC method requires an additional reformer to be installed in a system, thus hindering miniaturization.
Also, the reformer includes a vaporizer vaporizing a hydrocarbon liquid fuel into a gas phase, a reforming unit converting methanol as a fuel into hydrogen through catalytic reaction at a temperature of 250° C. to 350° C., and a CO remover (or CO₂remover) removing a CO gas (or CO₂gas), i.e., the byproduct accompanying the reforming reaction.
However, the reforming reaction in the reforming unit is an endothermic reaction where a reaction temperature is maintained at 250° C. to 350° C. On the other hand, the reforming reaction in the CO remover is an exothermic reaction in which a reaction temperature is maintained at 170° C. to 200° C. Therefore, to attain good reaction efficiency, the RHFC method necessitates an intricate high-temperature system, thereby complicating a structure of an overall fuel cell device and impeding reduction in manufacturing costs thereof.
Moreover, the RHFC method inevitably entails an additional structure for removing the CO gas or CO₂gas, i.e., the byproduct generated during the reforming reaction. This hinders reduction in an overall volume of the device and in manufacturing costs.
Meanwhile, as a method for generating hydrogen by electrolysis, as shown in FIG. 1, an electrolyte such as sea water is filled in an electrolytic bath 1 of a predetermined size. In the electrolytic bath 1 are immersed an anode electrode 2 formed of magnesium (Mg) more ionizable than hydrogen and a cathode electrode 3 formed of iron (Fe). The anode electrode 2 and the cathode electrode 3 are fixed to the electrolytic bath 1 and a cover 4 having a hydrogen outlet is provided on the electrolytic bath 1.
Here, when current is supplied to the anode electrode 2 and the cathode electrode 3, respectively, magnesium reacts with water according to equations 1, 2 and 3. In turn, magnesium hydroxide is generated in the electrolytic bath 1 to generate hydrogen according to equation 4.
Mg→Mg⁺²+2e⁻ Equation 1
2H₂O→2OH⁻+2H⁺ Equation 2
2H⁺+2e⁻→H₂ Equation 3
Mg+2H₂O→Mg(OH)₂+H₂ Equation 4
Also, the magnesium hydroxide obtained by the equations above remain in the electrolytic bath 1, while the hydrogen is exhausted outward through the hydrogen outlet 5 of the cover 4 to be utilized as a fuel.
In FIG. 1, un unillustrated numeral 6 refers to a pump for replenishing the electrolyte bath 1 with the electrolyte. However, an amount of hydrogen generated in the electrolytic bath 1 is proportional to a contact area between the electrodes 2 and 3 immersed in the electrolytic bath 1 and the electrolyte of the electrolytic bath 1. Here, the anode electrode 2 and the cathode electrode 3 are formed of a square plate and a limited number of electrodes are disposed in the electrolytic bath 1, thereby limitedly increasing the amount of hydrogen generated in the electrolytic bath 1.

SUMMARY OF THE INVENTION

An aspect of the present invention provides a hydrogen generator having a porous electrode plate, in which a surface area of an electrode part in contact with an electrolyte within a limited space is increased to generate a greater amount of hydrogen.
According to an aspect of the present invention, there is provided a hydrogen generator having a porous electrode plate including: an electrolytic bath having an electrolyte of a predetermined amount filled therein; a cover hermetically covering an open top of the electrolytic bath and having at least one hydrogen outlet; an electrode part fixed to the cover and having a porous structure formed on a body portion thereof to allow the electrolyte of the electrolytic bath to pass freely therethrough, the body portion of the electrode part immersed in the electrolytic bath; and a power supply supplying current to the electrode part.
The electrode part may include an anode electrode plate and an anode electrode plate, wherein each of the anode and cathode electrode plates includes: first and second holders each provided on a surface thereof with a porous part through which the electrolyte passes freely; and a porous body fixedly disposed between the first and second holders.
The porous body may be formed of a conductive metal fiber.
The porous body may include at least two layers of conductive metal fiber having a porosity gradient different from each other.
The porous body may be electrically connected to the power supply.
A sealer may be provided between the electrolytic bath and the cover.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view illustrating a conventional hydrogen generator;

FIG. 2 is an exploded perspective view illustrating a hydrogen generator having a porous electrode plate according to an exemplary embodiment of the invention;

FIG. 3 is a view illustrating an electrode part employed in a hydrogen generator having a porous electrode plate according to an exemplary embodiment of the invention, in which A is an exploded perspective view and B is an overall configuration view; and

FIG. 4 is a cross-sectional view illustrating a hydrogen generator having a porous electrode plate according to an exemplary embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
FIG. 2 is an exploded perspective view illustrating a hydrogen generator having a porous electrode plate according to an exemplary embodiment of the invention. FIG. 3 is a view illustrating an electrode part employed in a hydrogen generator having a porous electrode plate according to an exemplary embodiment of the invention, in which A is an exploded perspective view and B is an overall configuration view. FIG. 4 is a cross-sectional view illustrating a hydrogen generator having a porous electrode plate according to an exemplary embodiment of the invention.
As shown in FIGS. 2 to 4, the hydrogen generator 100 of the first embodiment includes an electrolytic bath 110, a cover 120, an electrode part 130, and a power supply 140.
The electrolytic bath 110 is formed of a rectangular parallelepiped box having an inner space of a predetermined size to have an electrolyte of a predetermined amount filled therein.
Here, an electrolyte replenishing line (not shown) equipped with a pump may be installed on an outer surface of the electrolytic bath 110 to replenish the electrolyte.
The cover 120 is a plate-shaped structure attached on the electrolytic bath 110 to hermetically cover an open top of the electrolytic bath 110 where the electrolyte is filled.
A plurality of fixing holes 122 are formed in an outer surface of the cover 120 to fix the electrode part 130 including an anode electrode plate 131 and a cathode electrode plate 132.
Also, at least one hydrogen outlet 124 is formed in the outer surface of the cover 120 to exhaust hydrogen generated inside the electrolytic bath 110 outward.
A sealer 115 made of e.g., a rubber material is provided between an upper end of the electrolytic bath 110 and the cover 120 to prevent the electrolyte from leaking from the electrolytic bath 110.
The electrode part 130 is fixed to the cover 120 and has a body portion immersed in the electrolyte of the electrolytic bath 110. The electrode part 130 is provided on the body portion thereof with a porous structure through which the electrolyte of the electrolytic bath 110 passes freely to increase a contact area between the electrode part and the electrolyte. The electrode part 130 may be formed of a porous material.
The electrode part 130 includes the anode electrode plate 131 electrically connected to an anode terminal of the power supply 140 and a cathode electrode plate 132 electrically connected to a cathode terminal of the power supply 140.
Each of the anode and cathode electrode plates 131 and 132 includes first and second holders 130 a and 130 b each having a porous part 136 formed on a surface of the body portion immersed in the electrolyte of the electrolytic bath 110. This allows the electrolyte to pass through the porous part 136 freely. Each of the anode and cathode electrode plates 131 and 132 also includes a porous body 130 b disposed between the first and second holders 130 a and 130 b such that the electrolyte passed through the porous part 136 passes through the porous body 130 b freely to increase a contact area between the electrode part and the electrolyte.
The porous body 130 b may be fixed by compressing respective frames 135 of the first and second holders 130 a and 130 c against each other excluding the porous parts 136 thereof, or may be fixedly attached to the frames 135 of the first and second holders 130 a and 130 c.
Terminals are formed on the frames 135 to be electrically connected to the power supply 140.
Here, the porous body 130 b disposed between the first and second holders 130 a and 130 c may be formed of a conductive metal fiber.
The conductive metal fiber is made of at least one metal selected from stainless, copper, nickel and fecralloy. The metal selected is formed into a metal fiber having a thickness of 1 to 100 μm utilizing high-vacuum melting and ultra rapid cooling disk, which are known in the art. This metal fiber may be formed in a web shape to allow pores to be formed uniformly.
Alternatively, the porous body 130 b may be formed of at least two layers of web-shaped conductive metal fiber having a porosity gradient different from each other.
The power supply 140 is electrically connected to the anode electrode plate 131 and the cathode electrode plate 132 constituting the electrode part 130 to supply current to the anode and cathode electrode plates 131 and 132, respectively.
The power supply 140 may be electrically connected to the first and second holders 130 a and 130 c constituting the anode and cathode electrode plate 131 and 132, respectively, but not limited thereto. The power supply 140 may be electrically connected to the porous body 130 b disposed between the first and second holders 130 a and 130 c.
When the electrolyte such as sea water is filled in the electrolytic bath 110 of the hydrogen generator 100 configured as above, the electrode part 130 installed in the electrolytic bath 110 has most of the body portion immersed in the electrolyte.
Here, the cover 120 hermetically covers an open top of the electrolytic bath 110 and a sealer 115 is provided between an upper end of the electrolytic bath 110 and the cover 120 so as to prevent the electrolyte from being leaked to the outside.
In this state, when a switch (not shown) of the power supply 140 electrically connected to the electrode part 130 is turned “on”, current of a predetermined intensity is supplied to the anode electrode plate 131 and cathode electrode plate 132 of electrode part 130, respectively to electrolyze the electrolyte of the electrolytic bath 110, thereby generating hydrogen.
Here, each of the anode electrode plate 131 and cathode electrode plate 132 immersed in the electrolyte of the electrolytic bath 110 includes the first and second holders 130 a and 130 c each having the porous part 136 formed thereon, and the porous body 130 b disposed between the first and second holders 130 a and 130 c. Accordingly, the electrolyte freely passes through the porous body 130 b made of a metal fiber through the porous parts 136, thereby increasing its contact area with the electrode part over a case where the electrode plates are not configured as a porous structure. This as a result increases a contact area between the electrolyte and the electrode plates to generate a higher amount of hydrogen during electrolysis of the electrolyte.
That is, in a case where the anode electrode plate 131 is formed of magnesium (Mg) more ionizable than hydrogen, and the cathode electrode plate 132 is formed of iron (Fe), when current is supplied to the anode electrode plate 131 and the cathode electrode plate 132, respectively, the magnesium of the anode electrode plate 131 reacts with water in the electrolyte according to equations 1, 2 and 3, and then magnesium hydroxide is generated in the electrolytic bath 100 to generate hydrogen according to equation 4.
Then, the hydrogen generated inside the electrolytic bath 110 is exhausted outward through the hydrogen outlet 124 formed in the cover 120. The magnesium hydroxide remains in the electrolytic bath 110, and the hydrogen exhausted outward is supplied to a power generator of a fuel cell to generate electricity.
That is, the hydrogen is supplied to an anode through an anode separation plate provided in the power generator, and an air containing oxygen is supplied to a cathode through a cathode separation plate provided in the power generator.
As described above, the hydrogen and air supplied to the power generator flow, with a polyelectrolyte membrane interposed therebetween. In the anode, the hydrogen is electrochemically oxidized according to equation 5 below and in the cathode, the oxygen is electrochemically reduced according to equation 6 below.
Here, electricity is generated due to migration of electrons created. The generated electricity is collected on anode and cathode collection plates to be utilized as an energy source.
Anode electrode reaction: H₂->2H⁺+2e⁻ Equation 5
Cathode electrode reaction: (½)O₂+2H⁺+2e^−-->H ₂O Equation 6
As set forth above, according to exemplary embodiments of the invention, an anode electrode plate and a cathode electrode plate immersed in an electrolyte of an electrolytic bath are configured as a porous structure allowing the electrolyte to pass freely therethrough, thereby increasing a contact area between the electrode plates and the electrolyte. This increases a surface area of an electrode part in contact with the electrolyte within a limited space of the electrolytic bath to enable a higher amount of hydrogen to be generated, while precluding a need for enlarging an inner space of the electrolytic bath or augmenting the number of the electrode plates disposed inside the electrolytic bath.
In addition, the hydrogen generator is less bulky and more compact, and can be handled and used conveniently, thereby applicable to a fuel cell of e.g., a mobile terminal, an electronic notebook, a personal digital assistant (PDA), a portable multimedia player (PMP), an MPEG audio layer-III (MP3) player and a navigation.
While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A hydrogen generator having a porous electrode plate comprising:

an electrolytic bath having an electrolyte of a predetermined amount filled therein;

a cover hermetically covering an open top of the electrolytic bath and having at least one hydrogen outlet;

an electrode part fixed to the cover and having a porous structure formed on a body portion thereof to allow the electrolyte of the electrolytic bath to pass freely therethrough, the body portion of the electrode part immersed in the electrolytic bath; and

a power supply supplying current to the electrode part.

2. The hydrogen generator of claim 1, wherein the electrode part comprises an anode electrode plate and an anode electrode plate,

wherein each of the anode and cathode electrode plates comprises:

first and second holders each provided on a surface thereof with a porous part through which the electrolyte passes freely; and

a porous body fixedly disposed between the first and second holders.

3. The hydrogen generator of claim 2, wherein the porous body is formed of a conductive metal fiber.

4. The hydrogen generator of claim 2, wherein the porous body comprises at least two layers of conductive metal fiber having a porosity gradient different from each other.

5. The hydrogen generator of claim 2, wherein the porous body is electrically connected to the power supply.

6. The hydrogen generator of claim 1, wherein a sealer is provided between the electrolytic bath and the cover.