High surface area micro fuel cell architecture
The present invention relates to compact and high power density fuel cells. The fuel cells generate electrical energy and include a three-dimensional (3-D) architecture. The 3-D architectures include active surfaces whose dimensions may be varied during fuel cell design in three dimensions. Fabrication of the 3-D architectures may use wafer-processing technologies such as etching and deposition on etched surfaces. Fuel cells described herein provide power densities (power per unit volume or mass) at levels not yet seen in the fuel cell industry; some fuel cells are small enough to fit in a cell phone and power the cell phone.
1 . A fuel cell for generating electrical energy, the fuel cell comprising:
a set of cells arranged on at least one chassis, each cell including
an anode structure that extends from the at least one chassis and supports a hydrogen catalyst,
a cathode structure that extends from the at least one chassis and supports a cathode catalyst, and
an electrolyte disposed to electrically isolate the anode structure from the cathode structure and permit passage of ions between the anode structure and the cathode structure;
a hydrogen distribution channel configured to deliver hydrogen to the anode structures in the set of cells; and
an oxygen distribution channel configured to deliver oxygen to the cathode structures in the set of cells.
2 . The fuel cell of claim 1 wherein the at least one chassis is substantially planar and the anode structure and the cathode structure extend about normal to the substantially planar chassis.
3 . The fuel cell of claim 2 wherein the oxygen distribution channel is about parallel to the planar chassis and the hydrogen distribution channel for each anode structure is about normal to the planar chassis.
4 . The fuel cell of claim 2 wherein the anode structure and the cathode structure include substantially tubular dimensions and include a central axis that is about normal to the planar chassis.
5 . The fuel cell of claim 2 wherein the anode structure includes a dimension normal to the planar chassis that is greater than a dimension for the anode structure that it parallel to the planar chassis.
6 . The fuel cell of claim 1 wherein the anode structure for the set of cells extends from a first chassis and the cathode structure for the set of cells extends from a second chassis.
7 . The fuel cell of claim 1 wherein at least one chassis includes a wafer substrate and the anode structure for each cell is etched from a material deposited onto the wafer substrate.
8 . The fuel cell of claim 1 further comprising electrical connectivity to the anode structure and the cathode structure.
9 . The fuel cell of claim 8 wherein electrical connectivity to the anode structure is separate from electrical connectivity to the cathode structure.
10 . The fuel cell of claim 8 further comprising independent electrical connectivity each anode structure and each cathode structure in the fuel cell.
11 . The fuel cell of claim 1 wherein the anode structure includes a porous structure and the hydrogen catalyst is coated onto surfaces of the porous structure.
12 . The fuel cell of claim 1 wherein the cathode structure includes a porous structure and the cathode catalyst is coated onto surfaces of the porous structure.
13 . The fuel cell of claim 1 further comprising multiple electrical outputs.
14 . The fuel cell of claim 1 wherein the fuel cell is configured to provide a voltage range for electrical energy output by the fuel cell.
15 . The fuel cell of claim 1 wherein the fuel cell does not include a dc/dc converter.
16 . The fuel cell of claim 1 wherein the fuel cell includes a redundant number of cells relative to electrical energy output for the fuel cell.
17 . The fuel cell of claim 16 wherein less than 80 percent of the cells in the fuel cell are used to generate electrical energy for the fuel cell.
18 . The fuel cell of claim 17 further comprising a controller that determines which cells in the fuel cell are used to generate electrical energy.
19 . The fuel cell of claim 1 wherein the fuel cell is included in a portable electronics device.
20 . The fuel cell of claim 19 wherein the fuel cell includes a first voltage supply to a first component in the electronics device and a second voltage supply to a second component, where the first voltage supply is less than the second voltage supply.
21 . The fuel cell of claim 20 wherein the electronics device is a cell phone and the first component is one of a screen for the cell phone, a transmitter for the cell phone, or a CPU for the cell phone.
22 . The fuel cell of claim 1 wherein the fuel cell occupies less than about 5 cubic centimeters.
23 . The fuel cell of claim 22 wherein the fuel cell occupies less than about 1 cubic centimeter.
24 . The fuel cell of claim 1 wherein the fuel cell provides a power density greater than about 20 watts per cubic centimeter.
25 . The fuel cell of claim 24 wherein the fuel cell provides a power density greater than about 100 watts per cubic centimeter.
26 . A fuel cell for generating electrical energy, the fuel cell comprising:
a set of cells arranged on at least one chassis, each cell including
an anode structure that extends from the at least one chassis and supports a hydrogen catalyst,
a cathode structure that extends from the at least one chassis and supports a cathode catalyst, and
an electrolyte disposed to electrically isolate the anode structure from the cathode structure and permit passage of ions between the anode structure and the cathode structure;
a hydrogen distribution channel configured to deliver hydrogen to the anode structures in the set of cells; and
an oxygen distribution channel configured to deliver oxygen to the cathode structures in the set of cells,
wherein the fuel cell provides a power density of greater than about 20 Watts/cubic centimeter according to a volume of the fuel cell.
27 . The fuel cell of claim 26 wherein the fuel cell provides a power density greater than about 100 watts per cubic centimeter.
28 . The fuel cell of claim 26 further comprising independent electrical connectivity each anode structure and each cathode structure in the fuel cell.
29 . The fuel cell of claim 26 wherein the anode structure includes a porous structure and the hydrogen catalyst is coated onto surfaces of the porous structure.
30 . The fuel cell of claim 26 wherein the fuel cell is configured to provide a voltage range for electrical energy output by the fuel cell.
31 . The fuel cell of claim 26 wherein the fuel cell includes a redundant number of cells relative to electrical energy output for the fuel cell.
32 . The fuel cell of claim 26 wherein the fuel cell occupies less than about 1 cubic centimeter.
33 . A fuel cell for generating electrical energy, the fuel cell comprising:
a set of cells arranged on at least one chassis, each cell including
an anode structure that extends from the at least one chassis and supports a hydrogen catalyst,
a cathode structure that extends from the at least one chassis and supports a cathode catalyst, and
an electrolyte disposed to electrically isolate the anode structure from the cathode structure and permit passage of ions between the anode structure and the cathode structure;
a hydrogen distribution channel configured to deliver hydrogen to the anode structures in the set of cells;
an oxygen distribution channel configured to deliver oxygen to the cathode structures in the set of cells; and
independent electrical connectivity to the anode structure and the cathode structure in each cell.
34 . The fuel cell of claim 33 wherein electrical connectivity to the anode structure is separate from electrical connectivity to the cathode structure.
35 . The fuel cell of claim 33 further comprising independent electrical connectivity each anode structure and each cathode structure in the fuel cell.
36 . The fuel cell of claim 33 further comprising multiple electrical outputs.
37 . The fuel cell of claim 33 wherein the fuel cell is configured to provide a voltage range for electrical energy output by the fuel cell.
38 . The fuel cell of claim 33 wherein the fuel cell does not include a dc/dc converter.
39 . The fuel cell of claim 33 wherein the fuel cell includes a redundant number of cells relative to electrical energy output for the fuel cell.
40 . The fuel cell of claim 39 wherein less than 80 percent of the cells in the fuel cell are used to generate electrical energy for the fuel cell.
41 . The fuel cell of claim 40 further comprising a controller that determines which cells in the fuel cell are used to generate electrical energy.
42 . The fuel cell of claim 41 wherein the fuel cell occupies less than about 1 cubic centimeter.
43 . The fuel cell of claim 42 wherein the fuel cell provides a power density greater than about 100 watts per cubic centimeter.
44 . A method of fabricating a fuel cell, the method comprising:
forming a set of set of anode structures that each extend from at least one planar chassis and a set of set of cathode structures that each extend from the at least one planar chassis;
forming electrical connectivity with the set of anode structures and the set of cathode structures;
depositing an anode catalyst onto surfaces of the set of anode structures;
depositing a cathode catalyst onto surfaces of the set of cathode structures; and
depositing an electrolyte at least partially between the set of anode structures and the set of cathode structures.
45 . The method of claim 44 wherein forming a set of set of anode structures includes etching the set of anode structures from a material deposited onto a wafer substrate.
46 . The method of claim 45 wherein the substrate is included in the at least one support chassis.
47 . The method of claim 45 wherein forming the electrical connectivity for the set of anode structures includes:
etching a set of vias in the substrate; and
depositing a conductive material in the set of vias.
48 . The method of claim 44 wherein depositing the cathode catalyst includes pumping a catalyst suspension including the cathode catalyst into a cavity including the set of cathode structures.
49 . The method of claim 48 further comprising applying heat to the cavity to evaporate solvent used in the catalyst suspension.
50 . The method of claim 44 further comprising:
blocking inlet and outlet ports to the fuel cell; and
pumping the electrolyte into the closed volume.