Field of the Invention The present invention relates to packaging for storing metal-air battery cells and devices that contain metal-air battery cells. More particularly, the present invention relates to a packaging that substantially prevents water and other debris from entering the packaging and permits the release of hydrogen out of the packaging. The packaging also restricts the ingress of oxygen into the packaging.

Background of the Invention Most high-drain portable electronic devices are powered by secondary or rechargeable batteries. Examples of such high-drain devices are cellular telephones, notebook computers, camcorders, and cordless hand-tools. The reason primary batteries are unattractive in such applications is that the life-span of a typical primary or single-use batteries is so short, and the cost so high, that they ultimately prove too costly for long-term use. In addition, their weight alone would discourage a person from carrying enough primary batteries for a long-term operation of the device. For example, a cellular telephone with alkaline batteries would last about as long as a single charge of a nickel-metal-hydride battery, but in the long term, cost far more per unit energy. A nickel-metal hydride battery, though initially expensive, costs only pennies to recharge.

New primary battery technologies have emerged that have, in principle at least, the ability to offer sufficient energy and power at a sufficiently low cost to make these batteries attractive for high-drain portable devices. One such technology is metal-air batteries, for example zinc-air batteries. In a zinc-air battery, one of the electrodes of the battery uses oxygen that can be supplied by ambient oxygen. Since oxygen is available everywhere, a zinc-air battery need house only one consumable electrode. Because of this, the energy

capacity per unit weight is magnified greatly. Unfortunately, the intrinsic benefits of electrochemical cells that use air as an electrode are attended by some serious technical problems.

One problem concerns the metal-air batteries needed for oxygen. Although zinc-air batteries have high energy densities, they are moderately low on power. To increase their power, large amounts of oxygen must be supplied. Increasing the batteries'access to oxygen is sometimes accomplished by designing the metal-air batteries or the housings that encase one or more metal-air batteries with relatively large and/or numerous openings. However, increasing the size and number of openings may also increase the likelihood that water and other debris may contact or enter the metal-air batteries. Increasing the size may also cause water vapor to leave the batteries, resulting in battery desiccation. Both of these occurrences may increase the likelihood that the battery will malfunction.

However, a metal-air battery's exposure to oxygen is preferable when the battery supplies energy, such as when a device connected to the battery is turned on. During non-use times, it is preferable for the battery to cut off from outside contaminates, as well as oxygen and carbon dioxide.

Another problem concerns the production of hydrogen. During operation and during storage of some metal-air batteries, the batteries may produce hydrogen due to the natural corrosion of a zinc oxide. During normal operation, the production of hydrogen can be released to the outside ambient air through the same openings by which oxygen and other gases enter the batteries. However, in the storage context, the competing interest of storing the batteries in an air tight enclosure to limit the batteries'exposure to carbon dioxide, oxygen, water and other debris may counter the need to release hydrogen from the enclosure.

Enclosing the batteries in an air tight packaging may prevent the hydrogen from leaving the packaging and cause the packaging to expand and possibly burst.

Summary of the Invention The present invention provides a package for encasing an electrochemical device requiring an ambient gas. The package has an enclosure capable of encasing the electrochemical device that is substantially impermeable to oxygen so that the ingress of oxygen into the packaging is restricted. Restricting access to oxygen may increase battery life. The packaging also permits the egress of hydrogen out of the packaging, which can build up during the storage of metal-air batteries. The package is made of a substantially air-

impermeable material that is sealed to enclose the device. A hole is formed in the packaging and that hole is covered with'a one way valve sticker or other material that can be adhered to the packaging to restrict the flow of gases, water and other debris through the hole and into the packaging. The sticker also permits the diffusion of hydrogen gases out of the packaging so as to prevent the packaging from expanding to a volume that may cause the packaging to rupture. The material behaves as a one way valve for the release of gases out of the packaging.

The invention will be described in connection with certain preferred embodiments, with reference to the following illustrative figures so that it may be more fully understood.

With reference to the figures, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

Brief Description of the Drawings FIG. 1 is a perspective view of a prismatic metal-air battery cell.

FIG. 2 is a set of illustrations from front and side of an embodiment of a packaging configuration.

Detailed Description of the Preferred Embodiment Referring now to the drawings, as shown in FIG. 1, a metal-air battery cell 101 has a casing with holes 105 for the egress and ingress of air through the casing. The ingress of air is a necessary operation for the proper functioning of a metal-air battery cell 101. One or a multiple of the battery cells 101 can electrically connected and housed in a battery casing to form a battery pack.

Referring to FIG. 2, a gas impermeable bag 500 encloses a battery pack 520 holding at least metal-air battery cell. The bag 500 has a hole 505. The hole 505 is covered by a one way valve 510 to prevent the egress or ingress of air except through the one way valve 510.

The one way valve 510 permits hydrogen gas to escape from the enclosure of the bag 500.

Hydrogen gas may be produced when the zinc anode of the metal-air battery cell corrodes.

This hydrogen gas should be released from the bag to prevent the bag from expanding considerably and possibly causing the bag 500 to rupture. An example of a suitable one way valve is the product V45 Aromafine, which is made by Bosch@ and is typically used for storing coffee. This one way valve 510 permits the release of hydrogen out of the bag 500 and prevents the flow of oxygen into the bag 500.

The gas impermeable bag 500 can made of a flexible plastic, a foil plastic laminate, or any other air impermeable material that protects the battery pack 520 from the outside environment. The one way valve 510 is attached to the bag 500 and covers the hole 505. The valve 510 is adhered to the bag through an adhesive, by thermally bonding the valve 510 to the bag 500, or by any other method that will form an air tight seal with the bag 500.

In the alternative, the one way valve 510 can be replaced with an air permeable sticker or alternative air permeable material. The air permeable sticker permits hydrogen gas diffuse out of the bag 500. The sticker also prevents water and other debris from entering the bag.

The following examples are descriptions of the use of the present invention. These examples are not meant to limit the scope of the invention, but are merely examples of specific embodiments.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.