Direct oxidation fuel cells with improved cathode gas diffusion media for low air stoichiometry operation
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
H01M-008/24
H01M-008/00
출원번호
US-0722081
(2010-03-11)
등록번호
US-8785070
(2014-07-22)
발명자
/ 주소
Lu, Guoqiang
Wang, Chao-Yang
Akiyama, Takashi
출원인 / 주소
Panasonic Corporation
대리인 / 주소
McDermott Will & Emery LLP
인용정보
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1
초록▼
A cathode for use in a direct oxidation fuel cell (DOFC) comprises a gas diffusion medium (GDM) including a backing layer and a microporous layer comprising a fluoropolymer and an electrically conductive material, wherein loading of the fluoropolymer in the microporous layer is in the range from abo
A cathode for use in a direct oxidation fuel cell (DOFC) comprises a gas diffusion medium (GDM) including a backing layer and a microporous layer comprising a fluoropolymer and an electrically conductive material, wherein loading of the fluoropolymer in the microporous layer is in the range from about 10 to about 60 wt. %. In use, a concentrated solution of a liquid fuel is supplied to an anode and an oxidant to the cathode of the fuel cell, and the fuel cell may be operated at a low oxidant stoichiometry ξc not greater than about 2.5.
대표청구항▼
1. A method of operating a direct oxidation fuel cell (DOFC) system, wherein the system comprises: (i) at least one membrane electrode assembly which includes a cathode, an anode and an electrolyte positioned therebetween, said cathode comprises, in direct overlying sequence, a catalyst layer, a mic
1. A method of operating a direct oxidation fuel cell (DOFC) system, wherein the system comprises: (i) at least one membrane electrode assembly which includes a cathode, an anode and an electrolyte positioned therebetween, said cathode comprises, in direct overlying sequence, a catalyst layer, a microporous layer and a gas diffusion medium (GDM), wherein said microporous layer comprises an electrically conductive material and a fluoropolymer which is in a range about 10 wt. % to about 60 wt. %, wherein said microporous layer has a thickness ranging from about 10 to about 50 μm and an average pore size between about 10 and about 500 nm, and said GDM comprises a backing layer, and (ii) a liquid/gas separator, the method comprising: supplying a concentrated solution of a liquid fuel to said anode and an oxidant to said cathode which produces water, wherein some of the produced water is transported to the liquid/gas separator and subsequently supplied to the anode; andoperating said at least one membrane electrode assembly at a low oxidant stoichiometry ξc not greater than about 4; wherein ξc=0.42(γ+2)3ηfuelppsat and ξc is the oxidant stoichiometry, γ is the ratio of water to fuel in the fuel supply, psat is the water vapor saturation pressure corresponding to the cell temperature, p is the cathode operating pressure, and ηfuel is the fuel efficiency. 2. The method according to claim 1, wherein: said fluoropolymer comprises poly(tetrafluoroethylene) (PTFE). 3. The method according to claim 2, wherein: said electrically conductive material comprises carbon particles or nanofibers. 4. The method according to claim 3, wherein: loading of said carbon particles or nanofibers in said microporous layer is in the range from about 0.5 to about 5 mg/cm2. 5. The method according to claim 1, wherein: said backing layer comprises carbon paper or woven or non woven cloth having a porosity greater than about 70%. 6. The method according to claim 1, comprising operating said at least one membrane electrode assembly at a low oxidant stoichiometry ξc not greater than about 2.5. 7. The method according to claim 5, wherein: said GDM has a fluropolymer loading in a range of from about 5 wt. % to about 30 wt. %. 8. The method according to claim 1, wherein: said concentrated solution of liquid fuel is a solution of about 5 M to about 25 M methanol and said oxidant is air. 9. The method according to claim 8, comprising operating said at least one membrane electrode assembly at a low oxidant stoichiometry ξc not greater than about 2.5, a steady-state power density not less than about 70 mW/cm2, and a temperature of about 60°C. 10. A method of operating a direct oxidation fuel cell (DOFC) system, wherein the system comprises at least one membrane electrode assembly which includes a cathode, an anode and an electrolyte positioned therebetween, said cathode comprises, in direct overlying sequence, a catalyst layer, a microporous layer and a gas diffusion medium (GDM), said microporous layer comprises an electrically conductive material loaded in an amount from about 0.5 to about 5 mg/cm2 and (b) a fluoropolymer loaded in a range from about 10 wt. % to about 60 wt. %, in the microporous layer, wherein said microporous layer has a thickness ranging from about 10 to about 50 μm and an average pore size between about 10 and about 500 nm, said GDM comprises a backing layer which includes carbon paper or woven or non-woven cloth having a porosity greater than about 70%, the method comprising: supplying a concentrated solution of a liquid fuel to said anode and an oxidant to said cathode; andoperating said at least one membrane electrode assembly at a low oxidant stoichiometry ξc not greater than about 8; wherein ξc=0.42(γ+2)3ηfuelppsat and ξc is the oxidant stoichiometry, γ is the ratio of water to fuel in the fuel supply, psat is the water vapor saturation pressure corresponding to the cell temperature, p is the cathode operating pressure, and ηfuel is the fuel efficiency. 11. The method according to claim 10, comprising operating said at least one membrane electrode assembly at a low oxidant stoichiometry ξc of less than about 4. 12. The method according to claim 10, comprising operating said at least one membrane electrode assembly at a low oxidant stoichiometry ξc not greater than about 2.5 13. The method according to claim 10, wherein the system further comprises a liquid/gas separator for receiving water produced at the cathode and wherein at least some of the water produced at the cathode is subsequently supplied to the anode.
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이 특허에 인용된 특허 (1)
Surampudi Subbarao (Glendora CA) Narayanan Sekharipuram R. (Altadena CA) Vamos Eugene (La Canada CA) Frank Harvey A. (Encino CA) Halpert Gerald (Pasadena CA) Olah George A. (Beverly Hills CA) Prakash, Aqueous liquid feed organic fuel cell using solid polymer electrolyte membrane.
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