DIRECT FORMIC ACID FUEL CELL PERFORMING REAL TIME MEASUREMENT AND CONTROL OF CONCENTRATION OF FORMIC ACID AND OPERATION METHOD THEREOF

Abstract

Provided are a direct formic acid fuel cell capable of maintaining performance constantly through implementing the real time measurement and control of formic acid concentration.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a direct formic acid fuel cell according to a first example of the present invention, which performs in real time measurement and control of concentration of formic acid;

FIG. 2 is a schematic diagram illustrating a direct formic acid fuel cell according to a second example of the present invention, which performs in real time measurement and control of concentration of formic acid;

FIG. 3 is a schematic view illustrating a micro pH measuring device, which is adapted to examples of the present invention, for concentration measurement of formic acid of the direct formic acid fuel cell;

FIG. 4 is a schematic view illustrating a micro conductivity measuring device, which is adapted to examples of the present invention, for concentration measurement of formic acid of the direct formic acid fuel cell;

FIG. 5 is a graph illustrating variation in a pH value to the formic acid concentration according to the examples of the invention;

FIG. 6 is a graph illustrating a result of detection response time of formic acid concentration upon pH measurement according to the examples of the invention;

FIG. 7 is a graph illustrating variation in conductivity value to the formic acid concentration according to the examples of the invention; and

FIG. 8 is a graph illustrating a result of detection response time of formic acid concentration upon conductivity measurement according to the examples of the invention.

Claims

1. A direct formic acid fuel cell comprising: a unit cell composing of an anode, a polymer electrolytic membrane, and a cathode, or a stack of the unit cells;a formic acid supply device for supplying formic acid, which is fuel, to the anode of the unit cell;an air/oxygen supply device for supplying air or oxygen to the cathode of the unit cell;a concentration measuring device connected to the formic acid supply device and measuring in real time a concentration of a portion of formic acid to be supplied to the anode; anda controller receiving the measured concentration value from the concentration measuring device, comparing the measured value with a predetermined range of concentration, and controlling in real time the concentration of formic acid to be supplied to the anode depending upon the real time measurement of the concentration measuring device in such a manner that the measured value does not deviate from the predetermined rage of concentration.

2. The direct formic acid fuel cell according to claim 1, wherein the concentration measuring device is a pH measuring device connected to the formic acid supply device and measuring in real time a pH value of hydrogen ions produced through dissociating a portion of formic acid to be supplied to the anode, and the controller is a controller receiving the pH value measured by the pH measuring device, comparing the measured pH value with a predetermined pH range, and controlling in real time the concentration of formic acid to be supplied to the anode depending upon the real time measurement of the pH measuring device in such a manner that the measured pH value does not deviate from the predetermined pH range.

3. The direct formic acid fuel cell according to claim 1, wherein the concentration measuring device is a conductivity measuring device connected to the formic acid supply device and measuring in real time conductivity values of hydrogen ions and formate ions produced through dissociating a portion of formic acid to be supplied to the anode, and the controller is a controller receiving the conductivity values measured by the conductivity measuring device, comparing the measured conductivity values with a predetermined conductivity range, and controlling in real time the concentration of formic acid to be supplied to the anode depending upon the real time measurement of the conductivity measuring device in such a manner that the measured conductivity values do not deviate from the predetermined conductivity range.

4. The direct formic acid fuel cell according to claim 1, wherein the formic acid supply device comprises: a pure or high concentration formic acid storage unit;an adequate concentration formic acid storage unit supplied with water discharged from the cathode or water from a separate water supply, and connected to the pure or high concentration formic acid storage unit, and storing formic acid with its concentration regulated;a valve opening and closing to supply the pure or high concentration formic acid from the pure or high concentration formic acid storage unit to the adequate concentration formic acid storage unit according to a control signal of the controller; anda pump supplying adequate concentration formic acid from the adequate concentration formic acid storage unit to the anode.

5. The direct formic acid fuel cell according to claim 4, wherein the adequate concentration formic acid storage unit is supplied with formic acid discharged from the anode.

6. The direct formic acid fuel cell according to claim 1, wherein the formic acid supply device comprises: a pure or high concentration formic acid storage unit;a water storage unit storing water discharged from the cathode or water from a separate water supply;a mixer mixing the pure or high concentration formic acid supplied from the pure or high concentration formic acid storage unit with water supplied from the water storage unit to provide adequate concentration formic acid;a pump supplying water from the water storage unit to the mixer according to a control signal of the controller;a pump supplying pure or high concentration formic acid from the pure or high concentration formic acid storage unit to the mixer according to a control signal of the controller; anda pump supplying adequate concentration formic acid from the mixer to the anode.

7. The direct formic acid fuel cell according to claim 6, wherein the mixer is supplied with the formic acid discharged from the anode in order for the formic acid to be mixed together.

8. The direct formic acid fuel cell according to claim 2, wherein the concentration measuring device is a pH measuring device comprising a reference electrode composed of a calomel electrode, an Ag/AgCl electrode, or an Hg/Hg2SO4 electrode, and a body electrode composed of fluoro resin and epoxy resin.

9. The direct formic acid fuel cell according to claim 8, wherein an outer cover of the pH measuring device is made of polypropylene (PP), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), carbon, polytetrafluoroethylene (PTFE), ethylene-propylene-diene-terpolymer (EPDM), alumina, nickel, SUS 316, or glass.

10. A method of operating a direct formic acid fuel cell, comprising: measuring in real time a concentration of a portion of formic acid to be provided to an anode before the formic acid is provided to the anode (S1); andcomparing the measured concentration value with a predetermined concentration range, controlling in real time the concentration of formic acid to be supplied to the anode depending upon the real time measurement in such a manner that the measured concentration value does not deviate from the predetermined concentration range, and providing the anode with the formic acid (S2).

11. The method according to claim 10, wherein in the step S1, a pH value of hydrogen ions produced by dissociating a portion of formic acid is measured in real time before the formic acid is provided to the anode, and in the step S2, the measured pH value is compared with a predetermined pH range, the concentration of formic acid to be supplied to the anode is controlled in real time depending upon the real time pH measurement in such a mauler that the measured pH value does not deviate from the predetermined pH range, and provides the anode with the formic acid.

12. The method according to claim 11, wherein the pH measurement is carried out with reliability of 95% or more in connection with the variation in formic acid concentration in such a manner that upon variation in formic acid concentration, the measured pH value is stabilized into a constant value within 1 to 5 seconds.

13. The method according to claim 11, wherein the predetermined pH range is 1.34 to 0.42.

14. The method according to claim 10, wherein in the step S1, conductivity values of hydrogen ions and formate ions produced by dissociating a portion of formic acid is measured in real time before the formic acid is provided to the anode, and in the step S2, the measured conductivity value is compared with a predetermined conductivity range, the concentration of formic acid to be supplied to the anode is controlled in real time depending upon the real time conductivity measurement in such a manner that the measured conductivity values do not deviate from the predetermined conductivity range, and provides the anode with the formic acid.

15. The method according to claim 14, wherein the conductivity value is stabilized into a constant value within 1 to 5 seconds in connection with variation in formic acid concentration.

16. The method according to claim 14, wherein the predetermined conductivity range is 9.5 to 12 mS/cm.