Method and apparatus for enhancing power density of direct liquid fuel cells
A fuel cell includes a direct liquid fuel cell and a humidifier. The direct liquid fuel cell includes an air intake channel for providing oxidant to the fuel cell and an exhaust channel for exhausting depleted oxidant. The humidifier forms a fluid connection between the air intake channel and the exhaust channel.
1. A fuel cell, comprising:
(a) a direct liquid fuel cell, comprising:
(i) an anode,
(ii) a cathode,
(iii) an electrolyte, between the anode and the cathode,
(iv) a fuel inlet, in contact with the anode, for providing fuel to the anode;
(v) a fuel outlet, in contact with the anode and in fluid connection with the fuel inlet, for removing depleted fuel and/or product gases from the anode;
(vi) an air inlet, in contact with the cathode, for providing oxidant to the cathode; and
(vii) a air outlet, in contact with the cathode and in fluid connection with the air inlet, for exhausting depleted oxidant and product gases/liquids from the cathode; and
(b) a humidifier;
wherein the humidifier forms a fluid connection between the air intake channel and the air outlet; and
the humidifier transfers fuel from the air outlet to the air inlet.
2. The fuel cell of claim 1 , wherein the direct liquid fuel cell comprises a direct methanol fuel cell.
3. The fuel cell of claim 1 , wherein the humidifier is a cross-flow humidifier.
4. The fuel cell of claim 1 , wherein the humidifier has a parallel flow field design.
5. The fuel cell of claim 1 , wherein the direct liquid fuel cell is capable of generating at least 100 watts.
6. The fuel cell of claim 1 , wherein the direct liquid fuel cell is capable of generating at least 300 watts.
7. The fuel cell of claim 1 , wherein the air stoichiometry of the fuel cell is from 1.0 to 3.0.
8. The fuel cell of claim 1 , wherein the air stoichiometry of the fuel cell is from 1.0 to 2.0.
9. The fuel cell of claim 1 , wherein the air stoichiometry of the fuel cell is from 1.0 to 1.7.
10. The fuel cell of claim 1 , wherein the fuel comprises methanol.
11. The fuel cell of claim 1 , wherein the fuel comprises sodium borohydride or potassium borohydride.
12. The fuel cell of claim 1 , wherein the fuel cell produces a current density of at least 50 mA/cm 2 at an air stoichiometry of at most 3.0.
13. The fuel cell of claim 1 , wherein the fuel cell produces a current density of at least 100 mA/cm 2 at an air stoichiometry of at most 3.0.
14. The fuel cell of claim 1 , wherein the fuel cell produces a current density of at least 150 mA/cm 2 at an air stoichiometry of at most 3.0.
15. The fuel cell of claim 1 , wherein the fuel cell produces a current density of at least 200 mA/cm 2 at an air stoichiometry of at most 3.0.
16. The fuel cell of claim 1 , wherein the humidifier transfers water from the air outlet to the air inlet.
17. The fuel cell of claim 16 , wherein at least a portion of the water is in a gaseous phase.
18. The fuel cell of claim 1 , wherein the humidifier transfers heat from the air outlet to the air inlet.
19. The fuel cell of claim 1 , wherein the direct liquid fuel cell is capable of generating at least 50 watts.