Fuel cell assembly having feed-back sensor

• US 8,889,307 B2
• Filed: 08/20/2008
• Issued: 11/18/2014
• Est. Priority Date: 08/20/2007
• Status: Active Grant

• Current Assignee: Fuel Cell Technology Sweden AB
• Original Assignee: MyFC AB (myFC Holding AB)
• Inventors: Lundblad, Anders, Ekstrom, Henrik, Jonsson, Eric
• Primary Examiner(s): Ruddock, Ula C
• Assistant Examiner(s): AMPONSAH, OSEI K
• Application Number:
  US12/674,491
• Publication Number:
  US 20110151345A1
• Time in Patent Office: 2,281 Days
• Field of Search: 429/429, 429/38, 429/432, 429/34
• US Class Current: 429/429
• CPC Class Codes: H01M 2008/1095 Fuel cells with polymeric electrolytes
• CPC Class Codes: H01M 2250/30 Fuel cells in portable systems, e.g. mobile phone, laptop
• CPC Class Codes: H01M 8/04089 of gaseous reactants
• CPC Class Codes: H01M 8/04223 during start-up or shut-down; Depolarisation or activation, e.g. purging; Means for short-circuiting defective fuel cells
• CPC Class Codes: H01M 8/04225 during start-up
• CPC Class Codes: H01M 8/04302 applied during start-up
• CPC Class Codes: H01M 8/04552 of the individual fuel cell
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/04567 of auxiliary devices, e.g. batteries, capacitors
• CPC Class Codes: H01M 8/04753 of fuel cell reactants
• CPC Class Codes: H01M 8/04798 of fuel cell reactants
• CPC Class Codes: H01M 8/0494 of fuel cell stacks
• CPC Class Codes: H01M 8/04955 Shut-off or shut-down of fuel cells
• CPC Class Codes: H01M 8/1097 Fuel cells applied on a support, e.g. miniature fuel cells deposited on silica supports
• CPC Class Codes: H01M 8/241 with solid or matrix-supported electrolytes
• CPC Class Codes: Y02B 90/10 Applications of fuel cells in buildings
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

A sensor cell (1010) for control purposes usable in an assembly (1000) of fuel cells of the type having a membrane electrode assembly (MEA) interposed between an anode gas diffusion layer and a cathode gas diffusion layer, and first and second current collectors coupled to the anode and cathode gas diffusion layers (GDL), respectively. The sensor cell (1010) is preferably coupled so that it shares the negative current collector (1050) with last fuel cell in the in-plane fuel cell assembly (1000), and is short-circuited by a resistor (1070) to provide a voltage signal, indicative of the status of the assembly in operation.

Claims

1. A fuel cell assembly, comprising:

an in-plane fuel cell assembly comprised of a plurality of power generating fuel cells connected in series and placed on a surface next to each other on the surface in series with edges of each fuel cell being adjacent in a planar side-by-side manner next to each other on the surface, each power generating fuel cell comprising an anode, each fuel cell producing a current by combusting hydrogen, from a fuel feed passing through the assembly,

wherein the hydrogen passes, in a series manner, through the series-connected power generating cells in a series manner by passing through a first cell of the series-connected power generating cells where a part of the hydrogen is consumed and then passing through a second cell of the series-connected power generating cells where another part of the hydrogen is consumed before passing to a third cell of the series-connected power generating cells where yet another part of the hydrogen is consumed,

the hydrogen not consumed by a final power generating fuel cell being a residual fuel,

the plurality of power generating fuel cells having a gas outlet which discharges all the residual fuel;

a separate sensor fuel cell located at the gas outlet of the power generating fuel cells, said separate sensor fuel cell being non-operative as a power generating fuel cell, said separate sensor fuel cell receiving all of the residual fuel discharged from the power generating fuel cells and then consuming the received residual fuel, said consumption of the residual fuel driving said separate sensor fuel cell to generate a feedback electric signal to make a determination based on a hydrogen concentration in the residual fuel when the residual fuels enters the separate sensor fuel cell and, based on the determination of the hydrogen concentration in the residual fuel when the residual fuels enters the separate sensor fuel cell, control one of the group consisting of i) a quantity of the fuel feed passing through the assembly, and ii) a power draw from the fuel cell assembly,

wherein when too much hydrogen is being supplied to said power generating fuel cells, said determination is that too much fuel feed is being supplied to said power generating fuel cells,

wherein when too little hydrogen is being supplied to said power generating fuel cells, said determination is that too little fuel feed is being supplied to said power generating fuel cells;

wherein,

said separate sensor fuel cell has the same general constitution as the power generating cells in the assembly, including comprising an anode gas diffusion layer (GDL), a cathode gas diffusion layer (GDL), a membrane electrode assembly (MEA) interposed between said anode GDL and said cathode GDL, an air access adjacent the cathode gas diffusion layer providing air access to a first side of the membrane electrode assembly, and a hydrogen access adjacent the anode gas diffusion layer providing hydrogen flow access at an opposite, second side of the membrane electrode assembly, the cathode gas diffusion layer (GDL) providing a gas pathway from a first side of said cathode gas diffusion layer (GDL) to an opposite, second side of said cathode gas diffusion layer (GDL),

the sensor fuel cell is electrically coupled to share a negative current collector with a last fuel cell of the series-connected fuel cells by the sensor fuel cell being placed on an anode current collector extended from the last fuel cell with the anode gas diffusion layer of the sensor fuel cell placed in contact with the extended anode current collector,

the anode and the cathode of the separate sensor fuel cell are connected with each other via a resistor (R) so that a current generated by the separate sensor fuel cell provides a voltage signal across the resistor (R) representing a voltage of the separate sensor fuel cell based on the hydrogen concentration in the residual fuel consumed by the separate sensor fuel cell, the voltage signal across the resistor being continuously measured by the sensor fuel cell as the feedback electric signal; and

a control electronics programmed to,

i) responsive to the voltage signal being based on the hydrogen in the residual fuel consumed by said separate sensor fuel cell indicating fuel consumption in the power generating cells, make the determination when too much and when too little hydrogen is being supplied to the power generating cells, and

ii) regulate at least one of i) a supply of hydrogen to the assembly by regulating the quantity of the fuel feed passing through the assembly, and ii) the power draw from the assembly in response to the voltage of the separate sensor fuel cell, and

wherein each power generating fuel cell is free of any resistor between the anode and the cathode of said each power generating fuel cell,

the first side of the membrane electrode assembly is outside of the hydrogen flow, and

the anode of said separate sensor fuel cell is connected to the anode of the power generating fuel cells, and

wherein,

said separate sensor fuel cell is smaller than the power generating cells in the assembly, and the fuel cell assembly is free of any powered cooling elements.

2. A fuel cell assembly as claimed in claim 1, comprising a source of pressurized gas that provides the hydrogen, and a dead end valve at the gas outlet of the fuel cell device, wherein said separate sensor fuel cell is placed after the power generating fuel cells in the gas flow direction but before the dead end valve.

3. A fuel cell assembly as claimed in claim 1, wherein the resistor is dimensioned as follows for said sensor fuel cell having a working voltage of U_work:

R =U_work/I_reg

wherein

I_reg=E_gas ×

I_nom×

N, and

E_gas is the excess gas supplied to the sensor fuel cell, I_reg is the current through the sensor fuel cell for an assembly of N cells having a nominal current of I_nom.

4. A fuel cell assembly as claimed in claim 1, wherein the resistor has a resistance of 0.5-2 Ohms.

5. A fuel cell assembly as claimed in claim 1, wherein the control electronics programmed to, responsive to the determination of the hydrogen concentration in the residual fuel, regulate both of i) the supply of hydrogen to the assembly by regulating the quantity of the fuel feed passing through the assembly, and ii) the power draw from the assembly in response to the voltage of the separate sensor fuel cell.

6. An electrical device, comprising a fuel cell assembly as claimed in claim 1, which is a mobile phone charger that provides a power source for a mobile phone.

7. An apparatus comprising a unit operating by electric power, and a chargeable battery, comprising means for connecting a portable electronic device comprising a fuel cell assembly as claimed in claim 1.

8. An apparatus as claimed in claim 7, comprising a plurality of fuel cell units, suitably each unit comprising 3-8 cells, connected in parallel with respect to gas flow and electrical current, each unit having one respective separate sensor fuel cell, and further comprising a DC/DC-converter connected to each fuel cell unit and power control electronics,

wherein the signal from each separate sensor fuel cell is used by each power control unit to control the output power so that all hydrogen gas is consumed, irrespective if the flow is different in the different fuel cell units.

9. Method of operating a fuel cell assembly as claimed in claim 1, said method comprising the steps of:

supplying hydrogen gas to the fuel cells;

via the air access, providing air to a region adjacent the cathode gas diffusion layer and the first side of the membrane electrode assembly;

via the hydrogen access, providing the hydrogen gas to a region adjacent the anode gas diffusion layer and the second side of the membrane electrode assembly;

monitoring the voltage of the separate sensor fuel cell to determine the hydrogen concentration in the residual fuel entering the separate sensor fuel cell;

during operation, continuously monitoring the voltage of the separate sensor fuel cell;

when the voltage of the separate sensor fuel cell deviates from a predefined value, performing a control function to adjust the performance of the assembly.

10. Method as claimed in claim 9, further comprising the steps of:

when the sensor voltage drops during operation, decreasing the power draw from the cell assembly; and

when the voltage does not increase enough, momentarily stopping the power draw.

11. A fuel cell assembly as claimed in claim 1, wherein the cell voltage of the last fuel cell of the series-connected fuel cells is between 0.1 and 0.5 V.

12. A fuel cell assembly as claimed in claim 1, wherein the cell voltage of the last fuel cell of the series-connected fuel cells is between 0.1 and 0.3 V.

13. A fuel cell assembly as claimed in claim 1, wherein an output power of the fuel cell assembly is in a range of 0.5-2.5 Watts.

14. A portable, electrical device charger, comprising a fuel cell assembly as claimed in claim 13, in combination with a battery, a fuel canister supplying the fuel cell assembly, and a first DC/DC converter that charges the battery, wherein the first DC/DC converter is powered from the fuel cell assembly, an output power of the electrical device charger is in a range of 1-3 W, and the fuel cell assembly, the fuel cell, the control electronics, and the first DC/DC converter are located within a plastic case.

15. The electrical device charger of claim 14, further comprising a second DC/DC converter, a female USB connector connected to the second DC/DC converter and receiving a 5 V supply from the second DC/DC converter.

16. The electrical device charger of claim 14, wherein the fuel canister is a metal hydride hydrogen canister, and the battery is a Li-ion battery.

17. The electrical device charger of claim 14, wherein i) when the voltage signal across the resistor from the sensor fuel cell is lower than a predetermined value indicates a lack of hydrogen and the control electronics decreases a voltage from the first DC/DC-controller such that less current will be charged into the battery or the second DC/DC convertor from power supplied by the fuel cell assembly, and ii) when the voltage signal across the resistor from the sensor fuel cell is higher than the predetermined value, the control electronics increases a voltage from the first DC/DC-controller such that more current will be charged into the battery or the second DC/DC convertor from the power supplied by the fuel cell assembly.

18. A portable, mobile phone charger, comprising a fuel cell assembly as claimed in claim 1, in combination with a battery, a fuel canister supplying the fuel cell assembly, and a first DC/DC converter that charges the battery, wherein the first DC/DC converter is powered from the fuel cell assembly, and the fuel cell assembly, the fuel cell, the control electronics, and the first DC/DC converter are located within a plastic case.

19. A portable, mobile electronic device charger, comprising a fuel cell assembly as claimed in claim 1, in combination with a battery, a fuel canister supplying the fuel cell assembly, and a first DC/DC converter that charges the battery, wherein the first DC/DC converter is powered from the fuel cell assembly, and the fuel cell assembly, the fuel cell, the control electronics, and the first DC/DC converter are located within a plastic case.

20. A fuel cell assembly as claimed in claim 1, further comprising a gas canister which provides the hydrogen, a battery that is charged from the power generating cells, and a plastic casing, wherein, the fuel cell assembly is portable and enclosed within the plastic case.

21. The fuel cell assembly as claimed in claim 20, further comprising:

a first DC/DC converter that charges the battery, wherein the first DC/DC converter is powered from the power generating cells,

a second DC/DC converter,

a female USB connector connected to the second DC/DC converter and receiving a 5 V supply from the second DC/DC converter.

22. The fuel cell assembly as claimed in claim 21, wherein,

i) when the voltage signal across the resistor from the sensor fuel cell is lower than a predetermined value indicates a lack of hydrogen and the control electronics decreases a voltage from the first DC/DC-controller such that less current will be charged into the battery or the second DC/DC convertor from power supplied by the fuel cell assembly, and

ii) when the voltage signal across the resistor from the sensor fuel cell is higher than the predetermined value, the control electronics increases a voltage from the first DC/DC-controller such that more current will be charged into the battery or the second DC/DC convertor from the power supplied by the fuel cell assembly.