US 2003/0157395 A1 · Simplified direct oxidation fuel cell system

Abstract

A simplified direct oxidation fuel cell system is disclosed. The fuel cell is constructed in such a manner that fuel is added to the cell anode as it is consumed and water is evaporated off at cell cathode so that there is no need for recirculation of unreacted fuel at the cell anode or water at the cell cathode. In addition, carbon dioxide generated from the anodic reaction is passively vented out of the system by using a CO2 gas permeable membrane material integrated as part of the anode chamber construction. It is thus possible that, the CO2 separation from the anode fluid occurs without the recirculation of the anode fluid outside the anode chamber. In one embodiment, the simplified direct oxidation fuel cell includes a gas permeable, liquid impermeable membrane placed in close proximity to the anode to perform the carbon dioxide separation. In accordance with a further aspect of the invention, a fuel container and delivery assembly is provided, which includes separate conduits from separate containers for methanol and water and a leakproof interface. This allows for mixing of water into the methanol solution, to allow for improved ability to adjust the concentration of methanol and water in the system. The fuel container and delivery assembly operates using simple mechanical flow and simplified geometry. This design minimizes loss of methanol and water via carryover and crossover by limiting introduction of those fluids. The passive system in which fuel is added as it is consumed and CO2 separated, both without pumping, ultimately will increase net power provided to the load due to low parasitic losses.

Claims36

Dependent claims

A direct oxidation fuel cell system, comprising:

(A) a fuel source;
(B) a direct oxidation fuel cell, having:
(i) a membrane electrode assembly, including;
(a) a protonically conductive, electronically non-conductive membrane electrolyte, having an anode face and an opposing cathode face;
and
(b) a catalyst coating disposed on each of said anode face and said cathode face, whereby electricity-generating reactions occur upon introduction of an associated fuel solution from said fuel source including anodic dissociation of said fuel solution into carbon dioxide, protons and electrons, and a cathodic combination of protons, electrons and oxygen from an associated source of oxygen, producing water;
and
(ii) an anodic diffusion layer disposed in intimate contact with said anode face of said membrane electrode assembly and having a plurality of openings therein to allow said associated fuel solution to pass through to said anode face, as fuel is consumed at said anode;
(iii) a cathodic diffusion layer disposed in intimate contact with said cathode face of said membrane electrode assembly and having a plurality of openings therein to allow oxygen to pass through to said cathode face of said membrane electrode assembly;
(C) a gas permeable layer comprised substantially of a gas permeable material, said gas permeable layer being disposed generally parallel to said anodic diffusion layer, such that said fuel solution can pass between said anodic diffusion layer and said gas permeable layer, and carbon dioxide that is released as fuel is consumed at said anode face, passes through said gas permeable layer and is vented from said fuel cell, whereby carbon dioxide is removed from said fuel cell without active transport mechanisms;
and
(D) gas permeable layera load coupled across said fuel cell, said load providing a path for said electrons whereby electricity is provided as said electricity-generating reactions proceed.

9 more elements

A direct oxidation fuel cell, comprising:

(A) a membrane electrode assembly, including:
(i) a protonically conductive, electronically non-conductive membrane electrolyte, having an anode face and an opposing cathode face;
and
(ii) a catalyst coating disposed on each of said anode face and said cathode face, whereby electricity-generating reactions occur upon introduction of fuel solution from an associated fuel source, including anodic dissociation of said fuel solution into carbon dioxide, protons and electrons, and cathodic combination of protons, electrons and oxygen from an associated source of oxygen, producing water;
(B) an anodic diffusion layer disposed in intimate contact with said anode face of said membrane electrode assembly, and having a plurality of openings therein to allow said associated fuel mixture to pass through to said anode face as fuel is consumed at said anode;
(C) a cathodic diffusion layer disposed in intimate contact with said cathode face of said membrane electrode assembly and having a plurality of openings therein to allow oxygen to pass through to said cathode face of said membrane electrode assembly;
and
(D) a gas permeable, fluid impermeable membrane disposed generally parallel to said anodic diffusion layer, such that said fuel solution can pass between said anodic diffusion layer and said gas permeable membrane to separate carbon dioxide that is released at said anode face and to vent carbon dioxide from said fuel cell, whereby carbon dioxide is removed from said fuel cell without active transport mechanisms.

5 more elements

Dependencies are inferred from the claim text.

Simplified direct oxidation fuel cell system

Life of this patent

Simplified direct oxidation fuel cell system

Life of this patent

Abstract

Claims36