Appeal 2007-0492
Application 10/810,960
1 BACKGROUND
2 Fuel cells operate by bringing a fuel, such as hydrogen gas, to the anode region of
3 the fuel cell, and an oxidizing agent, such as oxygen gas, to the cathode region of the fuel
4 cell. (10/810,960 specification (hereafter, "Specification") at 1.) The anode and the
5 cathode regions are separated physically by an ion-permeable but electrically insulating
6 membrane that permits protons (derived from the hydrogen gas) to pass, but not the
7 hydrogen molecules. (Id. at 10.) The specification further explains that an external
8 circuit connecting the anode region to the cathode region provides the lowest energy path
9 for electrons (the membrane being an insulator). (Id.) According to the specification, in
10 the cathodic region, protons, electrons, and oxygen combine in electrochemical reactions
11 to form water. (Id.) If an electrically operated device (e.g., a light bulb or motor) forms
12 part of the external electrical circuit, useful work is done along with the electrochemical
13 reactions. (Id. at 11.)
14 According to Appellants, a conventional source of oxygen for fuel cells is air,
15 which is about 20–21% oxygen by volume. (Specification at 13.) According to
16 Appellants, among the benefits of higher oxygen concentration in the cathodic region are
17 an increase in power density, easier recovery of the by-product water from the cell, and
18 more efficient operation of the fuel cell due to fewer impurities in the oxygen stream.
19 (Id. at 16–17.) Appellants further state that conventional methods of increasing the
20 amount of oxygen to the cathode region of the fuel cell include fans and compressors.
21 (Id. at 12.)
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