HIGH RATE ELECTROCHEMICAL DEVICES
A device and system useful for highly efficient chemical and electrochemical reactions is described. The device comprises a preferably porous electrode and a plurality of suspended nanoparticles diffused within the void volume of the electrode when used within an electrolyte. The device is suitable within a system having a first and second chamber preferably positioned vertically or in other special arrangements with respect to each other, and each chamber containing an electrode and electrolyte with suspended nanoparticles therein. When reactive metal particles are diffused into the electrode structure and suspended in electrolyte by gasses, a fluidized bed is established. The reaction efficiency is increased and products can be produced at a higher rate. When an electrolysis device can be operated such that incoming reactants and outgoing products enter and exit from opposite faces of an electrode, reaction rate and efficiency are improved. Ideally, this device and system can be used to rapidly produce significant quantities of high purity hydrogen gas with minimal electricity cost.
This application is a continuation-in-part of application Ser. No. 11/716,375, filed on Mar. 9, 2007.
BACKGROUND OF THE INVENTION1. Technical Field
The inventions disclosed herein generally relate to improved electrochemical systems and their use and, in particular, to water electrolysis devices for the production of high purity hydrogen and oxygen, and catalysts for these devices which promote increased electrical and cost efficiency, and methods of using such devices and for the production of hydrogen and oxygen.
2. Related Art
Hydrogen is a renewable fuel that produces zero emissions when used in a fuel cell. In 2005, the Department of Energy (DoE) developed a new hydrogen cost goal and methodology, namely to achieve $2.00-3.00/gasoline U.S. gallon equivalent (gge, delivered, untaxed, by 2015), independent of the pathway used to produce and deliver hydrogen. The principal method to produce hydrogen is by stream reformation. Nearly 95% of the hydrogen currently being produced is made by steam reformation, where natural gas is reacted on metallic catalyst at high temperature and pressure. While this process has the lowest cost, four pounds of the greenhouse gasses carbon monoxide (CO) and carbon dioxide (CO2) are produced for every one pound of hydrogen. Without further costly purification to remove CO and CO2, the hydrogen fuel cell cannot operate efficiently.
Alternatively, 5% of hydrogen production is from water electrolysis. This reaction is the direct splitting of water molecules to produce hydrogen and oxygen. Note that greenhouse gasses are not produced in these reactions. In this process, electrodes composed of catalyst particles are submersed in water and energy is applied to them. Using this energy, the electrodes split water molecules into hydrogen and oxygen. Hydrogen is produced at the cathode electrode which accepts electrons and oxygen is produced at the anode electrode which liberates electrons. The amount of hydrogen and oxygen produced by an electrode is dictated by the current supplied to the electrodes. The efficiency depends upon the voltage between the two electrodes, and is proportional to the reciprocal of that voltage. That is to say; efficiency increases as the voltage decreases. A more catalytic system will have a lower voltage for any one current, and therefore be more efficient in producing hydrogen and oxygen. If the catalyst is highly efficient, there will be minimal energy input to achieve a maximum hydrogen output. Unfortunately, this process is currently too expensive to compete with steam reformation due low efficiency and the use of expensive catalysts in the electrodes.
Devices that are configured to electrochemically convert reactants into products when energy is applied are generally known as electrolyzers. For an electrolyzer to operate with high efficiency, the amount of product produced during reaction should be maximized relative to the amount of energy input. In many conventional devices, low catalyst utilization in the electrodes, cell resistance, inefficient movement of electrolyte, and inefficient collection of reaction products from the electrolyte stream contribute to significant efficiency loss. In many cases, low efficiency is compensated for by operating the cell at a low rate (current). This strategy does increase efficiency, however, it also lowers the amount of products that can be produced at a given time. The electrolyzer described in the preferred embodiments can operate both at high rates and efficiencies.
Fluidized bed reactors (FBRs) have been designed to carry out chemical reactions that take place between materials of the same or different phases (solids, liquids and/or gasses). In an FBR that contains catalyst particles, a gas or liquid is passed upwardly through the FBR with enough flow rate to cause suspension of the catalyst particles. While FBRs have been used in the chemical industry because of their positive heat and mass transfer characteristics, use of FBRs remain unexplored in conjunction with electrochemical cells.
SUMMARY OF THE INVENTIONIn one aspect of the invention, there is provided a device suitable for use in an electrochemical and/or catalytic application, the device comprising a metal component, preferably having substantial void volume, a reaction medium to which the metal component is at least partially exposed during use, and a plurality of reactive metal nanoparticles suspended in the reaction medium when the device is in use and diffused into the metal component when the metal component preferably has said substantial void volume and when the device is in use. The reaction medium is preferably an electrolyte, with metal components comprising an anode and a cathode to form an electrochemical cell.
The invention thereby provides a high-surface area electrode. In one embodiment, the electrode comprises a porous or reticulate metal plate combined with catalytic metal particles, preferably at the nanoscale. The plate preferably includes some void volume to allow infusion of a plurality of metal nanoparticles. More preferably, the plates are porous, such as sintered or reticulate, and most preferably they comprise metal foams.
When immersed within an electrolyte, the metal particles can float freely and can substantially infuse into the porous/reticulate metal plate to create an electrode with extremely high surface area.
The electrodes in this invention can be applied to a variety of devices, including a hydrogen generation electrode in a water electrolyzer system. In such an embodiment, the electrode can function as a fluidized bed. At least one advantage is that the electrode can be operated at currents (rates) exceeding 1 A/cm2 and efficiencies in excess of 65% (measured by voltammetric or galvanometric electrochemical testing.), which in turn means that large amounts of hydrogen can be produced using less electricity. Typical electrodes have a far lower surface area and thus cannot operate at rates significant enough to produce large quantities of hydrogen. Other advantages may include, depending upon the configuration, circumstances, and environment, the ability to scale the electrode to a wide variety of sizes, a high rate of hydrogen production, and the ability to minimize agglomeration by using nano-sized particles. The fluidized bed reactor of the invention preferably produces from about 0.1 to about 3, more preferably from about 1 to about 3 gge/hr/m2 of hydrogen. A gge is a “U.S. gallon of gasoline equivalent”
One embodiment of the invention provides an electrochemical system, comprising: a first chamber and a second chamber, the first chamber being separated or partitioned from the second chamber by a separator, such as a membrane, the first chamber comprising an electrode, electrolyte, and metal catalyst particles arranged such that, when in operation, a fluidized bed may be established and gaseous products may be removed from the first chamber, such as from an upper portion thereof, the second outer chamber comprising an electrode, electrolyte, and metal catalyst particles arranged such that, when in operation, a fluidized bed may be established, and gaseous products may be removed from the second chamber, such as from an upper portion thereof.
The chambers can be arranged in a variety of ways, such as one at least partially above the other; one at least partially surrounding the other; one laterally displaced with respect to the other and one coiled at least partially around the other.
The reaction efficiency may be enhanced depending on the metal nanoparticles chosen. Efficiencies of at least 75%, preferably at least 85% may be achieved. Preferably, the plurality of reactive metal particles have an oxide shell. The reactive particles preferably comprise a metal selected from the group consisting of metals from groups 3-16, lanthanides, combinations thereof, and alloys thereof, and most preferably the metal nanoparticles are nickel, iron, combinations thereof, and alloys thereof.
The anode and cathode chambers may be filled with electrolyte that preferably contains a plurality of reactive and conductive metal nanoparticles. Preferably, the metal nanoparticles are on average less than 100 nm in diameter Average particle size is typically measured by TEM microscopy and GAA analysis, and is more preferably less than 50 nm in diameter, such as from 10-30 nm. The reaction efficiency may be enhanced depending on the metal nanoparticles chosen. Nickel or iron is preferred.)
Preferably, the generated anode and cathode gasses flow through the container in a manner that suspends the nanoparticles within the fluid, creating a fluidized bed. Most preferably, the bed is fluidized by the reaction products. At least some advantages of this configuration include, (i) elimination of pumps via direct extraction of gasses from the container, such as via upper vents, and the self propagating nature of the fluidized bed, (ii) ease of keeping hydrogen and oxygen gasses separated, (iii) ease of controlling temperature and pressure, (iv) simple design, and (v) less expensive per unit of hydrogen produced, to name a few.
The invention also provides a method of operating an electrochemical cell, which cell comprises an anode chamber containing electrolyte and an anode, a cathode chamber containing electrolyte and a cathode, which method comprises suspending reactive metal particles, preferably nanoparticles, in the anode chamber and/or the cathode chamber electrolyte, applying electric current to the anode and the cathode. Preferably, the suspension of reactive nanoparticles is provided in at least the cathode chamber, more preferably in both chambers, and the chambers are configured so that, in use, the suspension(s) act in the nature of a fluidized bed to transport gases from the chamber(s). Thus, the invention provides a method of generating hydrogen from water by electrolysis, comprising suspending reactive metal nanoparticles in a chamber containing a cathode and electrolyte, applying electric current to the cathode and to an anode in a chamber containing the anode and electrolyte, producing hydrogen in the cathode chamber and forming in that chamber from the hydrogen, electrolyte and particles a system akin to a fluidized bed whereby the hydrogen bubbles upwardly through the electrolyte, the method further comprising collecting the hydrogen so produced. These methods are applicable to the devices, systems, compositions and components described herein in connection with other embodiments of the invention.
In another aspect of the invention, a new electrochemical device is provided, preferably a water electrolysis device. Unlike traditional electrolyzers, such as that shown in
In yet another aspect of the invention, a fluidized bed electrolyzer may be provided that comprises a corrosion resistant container that houses a cylindrical separator. In one embodiment, porous anode and cathode electrodes may be disposed on the outer and/or inner circumference of the separator.
In the preferred embodiments, the individual anode or cathode electrodes in the cell may be fluidized, or both may be fluidized. Preferably, both electrodes are fluidized. A number of electrolyzer cells may be interconnected to function as an electrolyzer stack, and preferably they are electrically connected in a vertical orientation.
The features mentioned above in the summary of the invention, along with other features of the inventions disclosed herein, are described below with reference to the drawings of some preferred embodiments. The illustrated embodiments in the figures listed below are intended to illustrate, but not to limit the inventions.
DETAILED DESCRIPTION OF SOME PREFERRED EMBODIMENTSReferring to
When electricity is applied to electrode 209 via electrical contact 212, oxygen is produced pursuant to the following general reaction: 2OH—→H2O+½O2+2e−. Oxygen is eliminated from the electrolyte stream before the electrolyte is returned to the cell. To ensure that all oxygen is being eliminated from the upper surfaces of the lower chamber, angled deflector 213 is placed proximal to port 211 to ensure that deoxygenated electrolyte is washing the separator 207. For some system measurements, a side chamber containing separator mat 214 is filled with electrolyte 201, and reference electrode 215 is placed to measure electrochemical potential versus the upper chamber. Additionally, working reference electrode 216 is placed in contact with electrode 204.
The system configuration illustrated in
The cathode electrode in the upper chamber has increased efficiency relative to a conventional electrode, in that reacting hydroxyl ions leave from the bottom of the electrode and resulting gas leaves from the top of the electrode. This minimizes ionic resistance in the device, as gas bubbles do not block catalyst sites on the electrode to outgoing hydroxyl ions or incoming water molecules.
In the lower chamber of the device, an angled deflector is placed proximal to the electrolyte inlet port. Because the electrolyte flows in a parallel fashion to the electrode surface and product gas rises, it is possible for gas bubbles to become lodged on the upper surface of the chamber proximal to the separator membrane, which can impede both water and ionic transport. By deflecting electrolyte to the upper surface of the chamber, the increased flow force of the electrolyte on that surface prevents gas bubbles from lodging and results in improved system efficiency.
In some of the preferred embodiments, the upper chamber features both an inlet and outlet port. One of the ports allows the removal of hydrogen gas from the system, and the other allows for direct injection of new electrolyte, compensatory water, or new catalyst. This feature allows for both simple cleaning and replenishment or replacement if catalyst and reactants.
Some of the preferred embodiments detail an increased available reaction surface through the use of porous electrodes. The electrodes can be prepared of networking metal particles, for example reticulate nickel or nickel foam. In other embodiments, the electrodes may be sintered metal plates, prepared such that the electrode is highly porous with a relatively large void volume. The electrodes are preferably prepared from metals, preferably selected from the group of metals from groups 3-16, the lanthanide series and combinations thereof and alloys thereof. More preferably, the metals are transition metals, mixtures thereof, and alloys thereof and their respective oxides. Most preferably, the metal or metals are selected from the group consisting of nickel, iron, manganese, cobalt, tin, and silver, or combinations, alloys, and oxides thereof.
An aspect of at least some of the embodiments in this invention includes the realization that a reticulate or porous electrode's surface area can be increased significantly through the use of free moving reactive metal particles within the electrolyte. The electrolyte serves as both an ionic conductor and medium for the particles. Because of the reticulate or porous nature of the electrode, reactive metal particles can infuse into the electrode surface and become diffuse throughout the void volumes in the electrode. Preferably, the particles are less than one micron in effective diameter, and more preferably less than 100 nanometers in diameter. Most preferably, the reactive metal particles are less than 50 nm in diameter such that substantial portion can infuse into the electrode. Larger particles tend to agglomerate to the extent that the void volume within the electrode can no longer accommodate their size. This results in a significant loss in efficiency.
Referring to
The system configuration illustrated in
Referring to
An electrode with infused nanoparticles has a larger reaction surface than the electrode alone. To illustrate the concept, a catalytic nanoparticle 502 touches the surface of electrode 501 and collects electrons 508, splitting two surrounding water molecules within the interior of the electrolyte 504 into an H2 molecule 505 and two hydroxyl ions 507. The gas lifts the nanoparticle off the surface of the electrode 501, while a sister particle 511 replaces it to repeat the reaction. When the system is running at it's optimum, a fluidized bed is desirably established between the electrolyte, nano-catalysts and the tiny hydrogen gas bubbles. At least one aspect of the preferred embodiments includes the realization that gas or liquid does not necessarily need to be flowed into the bottom of the chamber once a fluidized bed has been established. In the described embodiments, gasses released from electrochemical reaction establish fluidization in-situ. A significant energy savings is inherent by eliminating the need for continuous pumping.
Unlike a traditional electrolyzer, whose efficiency decreases as current increases, a fluidized bed electrolyzer described in the preferred embodiments will increase in efficiency as current is increased, until a limiting current is reached in which further gas generation disrupts fluidization and the percolation pathway, ultimately lowering efficiency. Nevertheless, this limiting current at maximum efficiency is significantly higher in the devices described in the preferred embodiments compared to a traditional electrolysis system.
Additionally, reactive surface area is increased by order of magnitude by operation with catalytic nanoparticles in the fluidized bed. In addition to the surface area of the porous or reticulate electrode, and nanoparticles infused into the electrode, the system capitalizes on the additional surface area of the fluidized catalytic nanoparticles. The increased catalytic behavior of the reactive metal nanoparticles, compared to the surface of the metal substrate alone, is high due to the very large number of atoms on the surface of the nanoparticles, as shown in
The reactive metal particles can be formed through any known manufacturing technique, including, for example, but without limitation, ball milling, precipitation, plasma torch synthesis, combustion flame, exploding wires, spark erosion, ion collision, laser ablation, electron beam evaporation, and vaporization-quenching techniques such as joule heating.
Another possible technique includes feeding a material onto a heater element so as to vaporize the material in a well-controlled dynamic environment. Such technique desirably includes allowing the material vapor to flow upwardly from the heater element in a substantially laminar manner under free convection, injecting a flow of cooling gas upwardly from a position below the heater element, preferably parallel to and into contact with the upward flow of the vaporized material and at the same velocity as the vaporized material, allowing the cooling gas and vaporized material to rise and mix sufficiently long enough to allow nano-scale particles of the material to condense out of the vapor, and drawing the mixed flow of cooling gas and nano-scale particles with a vacuum into a storage chamber. Such a process is described more fully in U.S. patent Ser. No. 10/840,109, filed May 6, 2004, the entire contents of which is hereby expressly incorporated by reference.
The chemical kinetics of catalysts generally depend on the reaction of surface atoms. Having more surface atoms available will increase the rate of many chemical reactions such as combustion, electrochemical oxidation and reduction reactions, and adsorption. Extremely short electron diffusion paths, (for example, 6 atoms from the particle center to the edge in 3 nanometer particles) allow for fast transport of electrons through and into the particles for other processes. These properties give nanoparticles unique characteristics that are unlike those of corresponding conventional (micron and larger) materials. The high percentage of surface atoms enhances galvanic events such as the splitting of water molecules into its composite gasses of hydrogen and oxygen.
The reactive metal particles referenced herein are preferably selected from the group of metals from groups 3-16, and the lanthanide series. More preferably, the metals are transition metals, mixtures thereof, and alloys thereof and their respective oxides. Most preferably, the metal or metals are selected from the group consisting of nickel, iron, manganese, cobalt, tin, and silver, or combinations, alloys, and oxides thereof. The nanoparticles may be the same as, substantially the same, or entirely different materials from those chosen for the electrode. Additionally, the nanoparticles may comprise a metal core and an oxide shell having a thickness in the range from 5 to 100% of the total particle composition, wherein the metal core may be an alloy.
In other preferred embodiments, new fluidized bed electrolyzer designs are shown. These designs improve performance by enhancing reaction efficiency and reducing size. In some designs, reaction efficiency may be maximized when ionic resistance losses are reduced by minimizing the distance between the separator membrane and electrode. In other designs, the electrodes may be formed into a smaller area allowing for a smaller footprint.
Irrespective of design, a significant aspect of the preferred embodiments is adequate composition of the membrane separator. The separator should be able to operate at temperatures up to 130° C., permit an ion flux exceeding 5 A/cm2, maintain stability in strongly alkaline solutions such as high concentration potassium or sodium hydroxide, and prevent product gas bubbles from permeating between cell chambers. The membrane may be micro porous, such that electrolyte is permitted to move between reaction chambers, or may be nonporous but ionically conductive.
A spiral orientation of the fluidized bed reactor is illustrated in
In another aspect of the preferred embodiments, a fluidized bed reactor may be established wherein the current collector is in a horizontal configuration and the separator membrane is in a vertical orientation. Referring to
Referring to
Additionally, the electrodes and separator may be oriented vertically. Referring to
The foregoing description is that of preferred embodiments having certain features, aspects, and advantages in accordance with the present inventions. Various changes and modifications also may be made to the above-described embodiments without departing from the spirit and scope of the inventions.
Example 1 Effect of Nanoparticle Addition to Upper (Cathode) ChamberThe water electrolysis device shown in
Claims
1. A device suitable for use in an electrochemical and/or catalytic application, the device comprising a first component and a second component, said first component being at least partially exposed to a reaction medium during use, the second component comprising a plurality of reactive metal nanoparticles suspended in the reaction medium and diffused into the first component when the device is in use.
2. The device of claim 1, wherein the first component comprising a metal having a substantial void volume.
3. The device of claim 1, wherein at least a substantial portion of the plurality of reactive metal particles comprises particles have an average diameter of less than about 100 nm.
4. The device of claim 1, wherein at least a portion of the reactive metal particles comprise nanoparticles having an oxide shell.
5. The device of claim 1, wherein the plurality of reactive metal particles comprise one or more of the metals from groups 3-16, lanthanides, combinations thereof, and alloys thereof.
6. The device of claim 2, wherein the first component is a sintered porous metal plate.
7. The device of claim 2, wherein the first component is a reticulate metal plate.
8. The device of claim 1, wherein the first component comprises one or more of the metals from groups 3-16, lanthanides, combinations thereof, and alloys thereof.
9. The device of claim 1, wherein the device comprises an electrolysis cell whereby reaction products are produced when energy is applied.
10. The device of claim 9, wherein the device is configured to generate hydrogen from water.
11. An electrochemical system, comprising: a first chamber comprising an electrode, electrolyte, and metal catalyst particles arranged such that, when in operation, a zone in the nature of a fluidized bed may be established in the electrolyte and gaseous products produced by the supply of electricity to the system may be removed from the first chamber;
12. The electrochemical system of claim 11, further comprising: a second chamber, the first chamber being partitioned from the second chamber by a separator, the second chamber comprising an electrode, electrolyte, and metal catalyst particles arranged such that, when in operation, a fluidized bed may be established, and gaseous products are removed from the second chamber.
13. The electrochemical system of claim 12, wherein the first and second chambers are arranged with the first chamber at least partially above the second chamber, at least partially around the second chamber, at least partially displaced laterally with respect to the second chamber, or at least partially coiled around the second chamber.
14. The electrochemical system of claim 13, wherein the first chamber is positioned at least partially above the second chamber, the second chamber having an inlet and an outlet and being configured such that electrolyte circulated through the second chamber when in use may flow from the inlet past the second chamber electrode to the outlet in a generally transverse direction and, when in use, reactants may flux in the first chamber and gases generated in the first chamber may move upwardly for collection.
15. The electrochemical system of claim 14, further comprising a pump to circulate at least a portion of the electrolyte in the second chamber.
16. The electrochemical system of claim 13, wherein the system is configured and adapted to permit useful operation while being oriented such that the first chamber is positioned at least partially horizontally displaced from the second chamber.
17. The electrochemical system of claim 11, wherein the electrolyte in the first chamber is generally confined to that space.
18. The electrochemical system of claim 14, further comprising a plurality of reactive metal particles in the upper chamber suitably sized to permit particle diffusion into voids within one or both of the electrodes.
19. The system of claim 11, wherein at least a substantial portion of the reactive metal particles have an average diameter of less than one micrometer.
20. The system of claim 19, wherein the nanoparticles have an average diameter of less than about 100 nm.
21. The system of claim 11, wherein the plurality of reactive metal particles comprises a metal selected from the group consisting of metals from groups 3-16, lanthanides, combinations thereof, and alloys thereof.
22. The system of claim 3, wherein the separator comprises a membrane formed from an ionically conductive material.
23. The system of claim 22, wherein the separator membrane comprises multiple layers of ionically conductive material to increase mechanical, chemical, and electrochemical durability.
24. The system of claim 22, wherein the separator membrane is capable of at least 5 A/cm2 flux.
25. The system of claim 14, wherein the electrolyte flow channel of the second chamber contains a deflector to aid in transport to the separator surface.
26. The system of claim 3, wherein the first chamber electrode is configured to generate hydrogen from water and the second chamber electrode is configured to generate oxygen from water.
27. An electrochemical system, comprising: a first chamber and a second chamber, the first chamber being disposed within the second chamber when the system is oriented such that it can be used in at least one useful purpose, the first chamber comprising an electrode, electrolyte, and metal catalyst particles arranged such that, when in operation, a fluidized bed may be established, and gaseous products may be removed from the upper portion of the first chamber; the second outer chamber comprising an electrode, electrolyte, and metal catalyst particles arranged such that, when in operation, a fluidized bed may be established, and gaseous products are removed from the upper portion of the second chamber.
28. The system of claim 27, further comprising a separator membrane disposed between the first and second chambers.
29. The system of claim 27, further comprising electrical contacts on the first and second electrodes to permit the flow of electricity therebetween.
30. The system of claim 27, wherein the electrolyte in the first chamber is generally confined to that space.
31. The system of claim 27, wherein the electrolyte in the second chamber is generally confined to that space.
32. The system of claim 27, wherein at least a substantial portion of the reactive metal particles have an effective diameter of less than one micrometer.
33. The system of claim 27, wherein the particles have a diameter of less than about 100 nm.
34. The system of claim 27, wherein the plurality of reactive metal particles comprises a metal selected from the group consisting of metals from groups 3-16, lanthanides, combinations thereof, and alloys thereof.
35. The system of claim 28, wherein the separator membrane comprises an ionically conductive material.
36. The system of claim 35, wherein the separator membrane comprises multiple layers of ionically conductive material to increase mechanical, chemical, and electrochemical durability.
37. The system of claim 27, wherein the first chamber electrode is configured to generate hydrogen from water and the second chamber electrode is configured to generate oxygen from water.
38. The system of claim 27, wherein a multiple of first inner chambers are placed within a single outer chamber, and where each inner chamber is electrically connected in a circuit with the outer chamber.
39. The system of claim 38, wherein the first chamber electrode is configured to generate hydrogen from water and the second chamber electrode is configured to generate oxygen from water.
40. An electrochemical system, comprising: a first chamber and a second chamber, the first chamber being separated from the second chamber by a separator membrane when the system is oriented such that it can be used in at least one useful purpose, the first chamber comprising a current collector, electrolyte, and metal catalyst particles arranged such that, when in operation, a fluidized bed may be established, and gaseous products may be removed from the upper portion of the first chamber; the second outer chamber comprising an electrode, electrolyte, and metal catalyst particles arranged such that, when in operation, a fluidized bed may be established, and gaseous products are removed from the upper portion of the second chamber.
41. The system of claim 40, further comprising electrical contacts on the first and second electrodes to permit the flow of electricity therebetween.
42. The system of claim 40, wherein the current collector and separator is wound into a spiral.
43. The system of claim 40, wherein the electrolyte in the first chamber is generally confined to that space.
44. The system of claim 40, wherein the electrolyte in the second chamber is generally confined to that space.
45. The system of claim 40, wherein the separator is microporous.
46. The system of claim 40, wherein the separator is nonporous and ion-conducting.
47. The system of claim 40, wherein the separator membrane comprises multiple layers of ionically conductive material to increase mechanical, chemical, and electrochemical durability.
48. The system of claim 40, wherein the separator is capable of permitting the transport of at least 5 A/cm2 current flux.
49. The system of claim 40, wherein the current collector is generally horizontal and the separator is generally vertical.
50. The system of claim 40, wherein the current collector and separator are generally vertical.
51. The system of claim 40, wherein the current collector and separator are conical.
52. The system of claim 40, further comprising an insulating sheet.
53. The system of claim 40, wherein the current collector is porous or reticulate.
54. The system of claim 40, wherein the current collector protrudes into the fluidized bed.
55. The system of claim 40, wherein at least a substantial portion of the reactive metal particles have an average diameter of less than one micrometer.
56. The system of claim 40, wherein the particles have an average diameter of less than about 100 nm.
57. The system of claim 40, wherein the plurality of reactive metal particles comprises a metal selected from the group consisting of metals from groups 3-16, lanthanides, combinations thereof, and alloys thereof.
58. The system of claim 40, wherein the first chamber electrode is configured to generate hydrogen from water and the second chamber electrode is configured to generate oxygen from water.
59. A method of operating an electrochemical cell, which cell comprises an anode chamber containing electrolyte and an anode, a cathode chamber containing electrolyte and a cathode, which method comprises suspending reactive metal particles in the anode chamber and/or the cathode chamber electrolyte, and applying electricity such that a circuit is formed.
60. A method of claim 59, comprising suspending reactive nanoparticles in at least the cathode chamber and forming in the electrolyte in the cathode chamber a reaction zone in the nature of a fluidized bed to increase the effective area of the cathode and transport gas produced by the reaction from the chamber.
61. A method of claim 59, comprising also suspending reactive nanoparticles in the anode chamber and forming therein a reaction zone in the nature of a fluidized bed to transport gas formed in the anode chamber from the chamber.
62. A method of claim 60, wherein the electrolyte comprises an aqueous salt solution and the method comprises producing hydrogen in the cathode chamber and forming in that chamber from the hydrogen, electrolyte and particles a system akin to a fluidized bed whereby the hydrogen bubbles upwardly through the electrolyte, the method further comprising collecting the hydrogen so produced.
63. A method of claim 59, wherein the particles have an average diameter of less than about 100 nm.
64. A method of claim 59, wherein the particles have an average diameter of less than about 50 nm.
Type: Application
Filed: Mar 10, 2008
Publication Date: Nov 13, 2008
Inventor: Robert Brian Dopp (Marietta, GA)
Application Number: 12/045,625
International Classification: C25B 1/02 (20060101); C25B 9/00 (20060101); C25B 9/18 (20060101);