High efficiency fuel cell system
A fuel cell comprises an anode comprising an anode catalyst, a cathode comprising a gas diffusion electrode and a cathode catalyst on the gas diffusion electrode, a microfluidic channel contiguous with the anode, and a liquid comprising fuel in the channel. The concentration of the fuel in the liquid is 0.05-0.5 M.
1. A method of generating electricity, comprising operating a fuel cell comprising
an anode comprising an anode catalyst,
a cathode, comprising
a gas diffusion electrode, and
a cathode catalyst on the gas diffusion electrode,
a microfluidic channel contiguous with the anode, and
a liquid comprising fuel and electrolyte, in the channel,
wherein the concentration of the fuel in the liquid is 0.05-0.5M,
the liquid flows through the fuel cell at a stoichiometric fuel flow rate of 3-30 mmol/(A·min.),
the fuel cell produces a current density of at least 100 mA/cm 2 ,
the microfluidic channel has a dimension less than 400 micrometers, and
the liquid is recirculated through the channel.
2. The method of claim 1 , wherein the fuel is methanol.
3. The method of claim 2 , wherein the concentration of the fuel in the liquid is 0.1-0.3M.
4. The method of claim 2 , wherein the concentration of the fuel in the liquid is 0.1-0.2M.
5. The method of claim 2 , wherein the fuel cell produces a current density of at least 150 mA/cm 2 .
6. The method of claim 3 , wherein the liquid flows through the fuel cell at a stoichiometric fuel flow rate of 3-10 mmol/(A·min.).
7. The method of claim 3 , wherein the liquid flows through the fuel cell at a stoichiometric fuel flow rate of 3-7 mmol/(A·min.).
8. The method of claim 3 , wherein the fuel efficiency of the fuel cell is at least 70%.
9. The method of claim 3 , wherein the fuel efficiency of the fuel cell is at least 80%.
10. The method of claim 3 , wherein the fuel efficiency of the fuel cell is at least 85%.
11. The method of claim 3 , wherein the fuel cell produces a current density of at least 150 mA/cm 2 .
12. The method of claim 1 , wherein the liquid flows through the fuel cell at a stoichiometric fuel flow rate of 3-10 mmol/(A·min.), and the fuel is methanol.
13. The method of claim 1 , wherein the liquid flows through the fuel cell at a stoichiometric fuel flow rate of 3-7 mmol/(A·min.), and the fuel is methanol.
14. The method of claim 1 , wherein the fuel efficiency of the fuel cell is at least 80%, and the fuel is methanol.
15. The method of claim 1 , wherein the fuel efficiency of the fuel cell is at least 70%, and the fuel is methanol.
16. The method of claim 1 , wherein the fuel efficiency of the fuel cell is at least 85%, and the fuel is methanol.
17. The method of claim 1 , wherein the channel has a dimension less than 300 micrometers.
18. The method of claim 1 , wherein the channel has a dimension less than 250 micrometers.