Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Cell enclosure structure – e.g. – housing – casing – container,...
Reexamination Certificate
1999-08-13
2001-07-24
Brouillette, Gabrielle (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Cell enclosure structure, e.g., housing, casing, container,...
C429S171000, C429S174000, C029S623200
Reexamination Certificate
active
06265104
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention generally relates to metal air electrochemical cells.
Batteries are commonly used electrical energy sources. A battery contains a negative electrode, typically called the anode, and a positive electrode, typically called the cathode. The anode contains an active material that can be oxidized; the cathode contains or consumes an active material that can be reduced. The anode active material is capable of reducing the cathode active material. In order to prevent direct reaction of the anode material and the cathode material, the anode and the cathode are electrically isolated from each other by a separator.
When a battery is used as an electrical energy source in a device, such as a cellular telephone, electrical contact is made to the anode and the cathode, allowing electrons to flow through the device and permitting the respective oxidation and reduction reactions to occur to provide electrical power. An electrolyte in contact with the anode and the cathode contains ions that flow through the separator between the electrodes to maintain charge balance throughout the battery during discharge.
In a metal air electrochemical cell, the cathode contains a material that can catalyze the reduction of oxygen which enters the cell as a component of atmospheric air passing through one or more access ports in the container. Zinc oxide, or zincate, is formed in the anode. Thus, the overall electrochemical reaction within the cell results in zinc metal being oxidized to zinc ions and oxygen from the air being reduced to hydroxyl ions. While these chemical reactions are taking place, electrons are transferred from the anode to the cathode, providing power to the device.
Metal-air cells require an air plenum between the cell container and the cathode. Since the cathode does not directly contact the inner surface of the container, electrical contact between these two components must be established in some other way.
In addition, because the container must have air access ports to allow air flow, the sides of the container are not sealed. Therefore, to prevent the electrolyte from leaking out, the top and the bottom of the container must be sealed. Many methods for sealing the ends of the containers of metal-air cells include the use of multiple components, such as cups, grommets and rings.
SUMMARY OF THE INVENTION
The metal-air battery of the invention features a simple design. One or both ends of the cell, or battery, container are sealed with hot melt materials. The use of hot-melt materials makes relatively fast, inexpensive manufacturing processes possible, and allows for a variety of cathode shapes to be used.
In one aspect, the invention features a metal-air cell including (a) a container having a positive end and a negative end; (b) a cathode having an end adjacent to the positive end of the container and an end adjacent to the negative end of the container; (c) an anode; (d) a separator between the cathode and the anode; and (e) a seal between the end of the cathode adjacent to the positive end of the container and the positive end of the container. The seal includes a hot melt material. In some embodiments, the seal consists essentially of hot melt material. In other embodiments, the hot melt material is conductive.
In another aspect, the invention features a metal-air cell including (a) a container having a positive end and a negative end; (b) a cathode having an end adjacent to the positive end of the container and an end adjacent to the negative end of the container; (c) an anode; (d) a separator between the cathode and the anode; and (e) a seal between the end of the cathode adjacent to the negative end of the container and the negative end of the container. The seal includes a hot melt material. In some embodiments, the seal consists essentially of hot melt material. In other embodiments, the hot melt material is conductive.
Hot melt materials are generally solids at room temperature and liquids at elevated temperatures, for example, temperatures above about 60° C., 80° C., or 100° C. The use of a hot melt material in the seal at the positive end of the battery container offers several advantages. First, it obviates the multiple components, such as cups, grommets, and crimping seals, used to seal many metal-air round cells. Second, it provides a tight seal for irregularly shaped cathode tubes. The seal accommodates irregularities, e.g., those that result from manufacturing tolerances. The seal can also accommodate a cathode with a seam, where the cathode is thicker where the separator and barrier overlap. Third, if a conductive hot melt material is used, the material both forms a seal and provides an electrical connection between the cathode current collector and the battery container.
In another aspect, the invention features a method of manufacturing a metal-air cell including (a) placing a hot melt material in a positive end of a container; (b) placing a cathode in the container while heating the container to a temperature sufficient to flow the hot melt material; and (c) pressing the cathode into the hot melt material to form a seal between an end of the cathode and the positive end of the container. The method can also include forming a seal at the negative end of the container using a hot melt material.
In still another aspect, the invention features a method of manufacturing a metal-air cell including (a) placing a hot melt material in a negative end of a container; (b) placing a cathode in the container while heating the container to a temperature sufficient to flow the hot melt material; and (c) pressing the cathode into the hot melt material to form a seal between an end of the cathode and the negative end of the container.
Other features and advantages of the invention will be apparent from the description of the preferred embodiments thereof, and from the claims.
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Hull Matthew
Searle Gary
Brouillette Gabrielle
Fish & Richardson P.C.
Ruthkosky Mark
The Gillette Company
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