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  Electrochemical cellsRelated Patent Categories: Chemistry: Electrical Current Producing Apparatus, Product, And Process, Fuel Cell, Subcombination Thereof Or Methods Of Operating, Having Means For Active Material Generation Or Regeneration, By Electrical CurrentThe Patent Description & Claims data below is from USPTO Patent Application 20070092769. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATION [0001] This application claims priority from U.S. Ser. No. 10/438,318, filed on May 15, 2003, which is incorporated herein by reference in its entirety. TECHNICAL FIELD [0002] This invention relates to electrochemical cells. BACKGROUND [0003] An electrochemical cell is a device capable of providing electrical energy from an electrochemical reaction, typically between two or more reactants. Generally, an electrochemical cell includes two electrodes, called an anode and a cathode, and an electrolyte disposed between the electrodes. In order to prevent direct reaction of the active material of the anode and the active material of the cathode, the electrodes are electrically isolated from each other by a separator. [0004] In one type of electrochemical cell, sometimes called a hydrogen fuel cell, the anode reactant is hydrogen gas, and the cathode reactant is oxygen (e.g., from air). At the anode, oxidation of hydrogen produces protons and electrons. The protons flow from the anode, through the electrolyte, and to the cathode. The electrons flow from the anode to the cathode through an external electrical conductor, which can provide electrical energy. At the cathode, the protons and the electrons react with oxygen to form water. [0005] In another type of electrochemical cell, called a metal-air cell, oxygen is reduced at the cathode, and a metal (e.g., zinc) is oxidized at the anode. Electrons flow from the anode to the cathode through an external electrical conductor, which can provide electrical energy. Oxygen can be supplied to the cathode from the atmospheric air external to the cell through one or more air hole(s) in the cell housing. An electrolytic solution (e.g., an alkaline electrolyte, such as a potassium hydroxide solution) in contact with the electrodes contains ions that flow through the separator between the electrodes to maintain charge balance throughout the cell during discharge. [0006] Metal-air cells can experience carbonation, in which the alkaline electrolyte in the cathode absorbs carbon dioxide, resulting in the precipitation of carbonate salts (such as potassium carbonate or sodium carbonate). These salts can have a detrimental effect on the cell by, for example, blocking cathode pores or air access holes on the cathode side of the cell envelope. A result can be that the cathode has less access to the oxygen it needs to function. [0007] Furthermore, a metal-air cell can experience water exchange with its environment, as a result of the difference in the relative humidity of the environment and the equilibrium vapor pressure of the cell electrolyte. When the ambient air is drier (i.e., has a lower partial pressure of water vapor) than the electrolyte, the cell can lose water to the environment and dry out. On the other hand, when the ambient air is wetter (i.e., has a higher partial pressure of water vapor) than the electrolyte, the cell can gain water, such that the cathode ultimately floods with electrolyte solution. In either case, a consequence is that the cell can lose its ability to support heavy currents. Additionally, when the cathode is flooded with electrolyte solution, the electrolyte solution can eventually leak out of the air access holes. SUMMARY [0008] In general, an electrochemical cell includes an electrochemical hydrogen generator connected to a hydrogen fuel cell. The hydrogen generator and the fuel cell can be electrically and/or mechanically connected. [0009] In one aspect, an electrochemical cell includes an electrochemical hydrogen generator and a hydrogen fuel cell. The electrochemical hydrogen generator has a first cathode which generates hydrogen gas, and a first anode which is adjacent to the first cathode. The hydrogen fuel cell includes a second anode which oxidizes hydrogen gas, and a second cathode which is adjacent to the second anode. The first anode is electrically connected to the second cathode, and the first cathode is electrically connected to the second anode. [0010] In another aspect, an electrochemical cell includes an electrochemical hydrogen generator in series electrical connection with a hydrogen fuel cell. [0011] In some embodiments, the electrochemical hydrogen generator includes a first cathode which generates hydrogen gas and a first anode which is adjacent to the first cathode. The hydrogen fuel cell can include a second anode which oxidizes hydrogen gas and a second cathode which is adjacent to the second anode. In some cases, the first anode is electrically connected to the second cathode and the first cathode is electrically connected to the second anode. [0012] In some embodiments, the hydrogen fuel cell includes a second anode which oxidizes hydrogen gas and a second cathode which is adjacent to the second anode. [0013] In some cases, the hydrogen generator includes a gas outlet, and the hydrogen fuel cell includes a gas inlet in fluid communication with the gas outlet. The hydrogen generator can have a first housing. The hydrogen fuel cell can include a second housing. In some embodiments, the first housing is releasably engageable with the second housing. In some cases, the hydrogen fuel cell and the hydrogen generator are disposed within a single housing. [0014] The hydrogen generator can include a hydrogen-generating anode. The hydrogen-generating anode can be a metal (e.g., zinc, aluminum, titanium, zirconium, and tin). The hydrogen-generating anode can include a hydrogen storage composition (e.g., a metal hydride or a misch metal alloy). [0015] In some cases, the hydrogen fuel cell has an acidic polymer membrane electrolyte. [0016] In some embodiments, the electrochemical cell further includes a controller. The electrochemical cell can further include a sensor. The sensor can be connected to the controller. [0017] In another aspect, an electrochemical cell includes an electrochemical hydrogen generator and a hydrogen fuel cell. The hydrogen generator has a first cathode which generates hydrogen gas, and a first anode which is opposed to the first cathode. The hydrogen fuel cell has a second anode which oxidizes hydrogen gas, and a second cathode which is opposed to the second anode. There is a coupling between the hydrogen generator and the hydrogen fuel cell. The coupling fluidly connects the first cathode to the second anode. [0018] In some embodiments, the hydrogen generator further includes a first housing within which the first anode and the first cathode are disposed. In some cases, the hydrogen fuel cell further includes a second housing within which the second anode and the second cathode are disposed. The second housing can be releasably engageable with the first housing. [0019] The first anode can be electrically connected to the second cathode. [0020] In another aspect, a method of generating an electrical current includes forming an electrical connection between a first anode of an electrochemical hydrogen generator and a second cathode of a hydrogen fuel cell, and forming an electrical connection between a first cathode of the electrochemical hydrogen generator and a second anode of the hydrogen fuel cell. Continue reading... Full patent description for Electrochemical cells Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Electrochemical cells patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. 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