Electrode structure
An electrode structure of a fuel cell for power generation comprises an anodic structure, a cathodic structure, and an ionic exchange membrane disposed between the anodic and cathodic structures. The anodic and cathodic structures respectively are formed by multi-layer structures, to reduce the fuel crossover from the anodic structure to the cathodic structure, to reduce the catalysts applied amount, and to increase an output electrical energy of the fuel cell. The multi-layer structure of the anodic structure comprises a thin platinum alloy black layer, a Pt alloy layer disposed on the carbon material, and a substrate.
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1. Field of the Invention
The invention relates to an electrode structure, and in particular to an electrode structure of a fuel cell for power generation.
2. Description of the Related Art
In general, fuel cells having an anodic structure, a cathodic structure and an ionic exchange membrane generate power by converting chemical energy to electrical energy by electro-chemical reaction therebetween. In the process of electro-chemical reactions have the fuel oxidation and oxygen reduction. The fuel oxidation reaction of the anodic structure releases hydrogen ions, electrons and carbon dioxides. The oxygen reduction reaction of cathodic structure combines with anodic hydrogen ions, and the electrons releases water. In a conventional fuel cell, however, crossover of the liquid, colloidal, solid or gaseous organic fuel (e.g., alcohol, aldehyde or acid) from the anodic to cathodic structure is inevitable. Part of the fuel and water without reacting with the anodic catalyst directly pass through the ionic exchange membrane and reach the cathodic structure, resulting in a decrease of the catalytic reaction performance of the cathodic structure. A mixed potential is formed by the fuel on the cathodic structure produced oxidation reaction and with the nearby oxygen produced reduction reaction, thus reducing output voltage, output electrical power and fuel utilization of the fuel cell. Further, crossover of fuel results in the swell of the electrode adhesive between the cathodic electrode and the ionic exchange membrane, thus accelerating aging of the cathodic structure.
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There is fuel oxidation reaction in the cathode, when the fuel of anodic structure permeates through the cathodic structure. The cathodic practical potential VB has gone down and the output voltage of the fuel cell has decreasing. It is understood that crossover of the fuel from the anodic structure throughout the cathodic structure is an unwanted situation.
The platinum alloy carbon support layer 112 of the anodic structures A1 or the platinum alloy black layer 121 of the anodic structure A2 must be thickened can solve the problems such as fuel crossover caused by the described liquid, gel, solid or gaseous organic fuel (e.g., alcohol, aldehyde or acid) The fuel path D1 is relatively short and the thickened platinum alloy carbon support layer 112 can avoid the crossover of the fuel, however, cracks form on the platinum alloy carbon support layer 112 and lowers the utilization of the catalyst adjacent to the ionic exchange membrane 2 when the platinum alloy carbon support layer 112 is too thick.
Note that the fuel path D2 of the anodic structure A2 is longer than the fuel path D1 of the anodic structures A1. If the platinum alloy black layer 121 of the anodic structure A2 is thickened, the product of fuel reaction, e.g. carbon dioxide, requires more time to travel through the fuel path D2, thus, the efficiency of the fuel cell decreases. In general, the cost of the platinum alloy carbon support layer 112 or the platinum alloy layer black 121 is substantially 70% of the total material of a fuel cell. Thus, the thickened platinum alloy carbon support layer 112 or the thickened platinum alloy black layer 121 increases the fuel cell material cost.
Based on the defects caused by the described fuel crossover of the liquid, gel, solid or gaseous organic fuel, e.g. alcohol, aldehyde or acid and the low catalyst utilization, the invention provides an electrode structure utilizing a small amount of catalyst in a catalytic layer to lower fuel crossover, consume the fuel in the anodic structure, avoid the fuel from the anode structure diffusion to the cathodic structure, increase the output voltage of the fuel cell.
BRIEF SUMMARY OF THE INVENTIONThe aim of the invention at the provides an electrode structure applied to fuel cell, decreased the fuel of the liquid, gel, solid or gaseous organic fuel, e.g. alcohol, aldehyde or acid crossover. It can increase the output voltage of the fuel cell and power density, and than decrease the total material cost of the fuel cell caused by lessen catalyst amount.
An electrode structure of a fuel cell for power generation comprises an anodic structure, a cathodic structure, and an ionic exchange membrane disposed between the anodic and cathodic structures. The anodic structure sequentially comprises a thin platinum alloy black layer disposed next to the ionic exchange membrane, a platinum alloy carbon support layer and a substrate layer. The thin platinum alloy black layer comprises plurality of platinum alloy particles and appropriately polymers. The platinum alloy particles applied to catalyze the anode catalyst by platinum (Pt) combined with components such as Sn, Mo, Rh, W, Pd, Ir or Au. The thin platinum alloy black layer is a thin and dense catalyst layer.
The invention provides an electrode structure having a low fuel crossover and high reaction discharge efficiency with respect to the conventional anode structure, to eliminate aging of the cathode structure.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGSThe invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
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To specify the electrode structure in the following description, the carbon support layer 135 with the first catalytic platinum alloy carbon concentration is defined as a low catalytic platinum alloy carbon support layer, and the carbon support layer 136 with the second platinum alloy carbon support layer is defined as a high catalytic platinum alloy carbon support layer.
The high catalytic platinum alloy carbon support layer 136 comprises a plurality of high platinum alloy carbon support particles 117 and an appropriately polymers 118, and the low catalytic platinum alloy carbon support layer 135 comprises a plurality of low platinum alloy carbon support particles 133 and an appropriately polymers 118. The first thin platinum alloy black layer 132 comprises a appropriately polymers 118 and a plurality of platinum alloy particles 115, and the platinum alloy particles 115 are linked by the polymers 118 to form the first thin platinum alloy black layer 132. The high platinum alloy carbon support particles 117 are linked by the polymers 118 to form the high catalytic platinum alloy carbon support layer 136. The low platinum alloy carbon support particles 133 comprise a plurality of carbon support particles 116 and the platinum alloy particles 115. The low platinum alloy carbon support particles 133 are linked by the polymers 118 to form the low catalytic platinum alloy carbon support layer 135. The high platinum alloy carbon support particles 117 comprise the carbon support particles 116 and the platinum alloy particles 115. The low platinum alloy carbon support particles 133 differs from the platinum alloy particles 115 in that the amount of the platinum alloy particles 115 of the high platinum alloy carbon support particles 117 is greater than the amount of the platinum alloy particles 115 of the low platinum alloy carbon support particles 133. Additionally, the first thin platinum alloy black layer 132 is preferably covered on the surface of the ionic exchange membrane 2 or the platinum alloy carbon support layer 131.
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The following cathode structures C1, C2, C3, C4 and C5 are five exemplary embodiments of the cathode structure 72.
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A theoretical simulation is applicable in describing the superiority of the platinum alloy carbon support layer 712 and the first thin platinum alloy black layer 711 of the anodic structure 71 of the invention. The concentration of the methanol fuel distributed in the catalytic layer (e.g. platinum alloy carbon support layer or platinum alloy black layer) can be substantially calculated by the following expressions, wherein
c(y) represents a function of concentration distribution of the methanol fuel, y represents locations of the methanol fuel located in the catalytic layer, ko represents a reaction constant, Ly represents a thickness of the catalytic layer, Da represents a diffusion coefficient of the methanol fuel located in the catalytic layer, Df represents a diffusion coefficient of the methanol fuel located in the substrate, δ represents a thickness of the substrate, and μ represents the equivalent potential.
The conventional anodic structures A1, A2 and the anodic structure 71 of the invention, for example, are incorporated into the described three expressions, and the results are respectively represented by three different catalytic layers A, B and C in Table 1. The 20% PtRu/C of the catalytic layer A represents having 20% Pt and Ru alloy particles of platinum alloy carbon support layer 112 of the conventional anodic structure A1, the the catalytic layer B containing PtRu black represents the platinum alloy black layer 121 of the conventional anodic structure A2, and the catalytic layer C containing the platinum alloy carbon support layer 712 and the thin platinum alloy black layer 711 represents the platinum alloy carbon support layer 712 and the first thin platinum alloy black layer 711 of the anodic structure 71 of the invention.
Table 1 represents the required thickness and weight of the catalytic layers A, B and C, to prevent the methanol fuels crossover from anode to cathode. Based on the table 1. The amount of total catalyst of the catalytic layer C is less than that of the catalytic layers A and B at half. Thus, the cost of catalytic material of the catalytic layer C is lower than that of the catalytic layers A and B.
The invention provides the combination of the platinum alloy carbon support layer 712 and the first thin platinum alloy black layer 711 of the anodic structure 71, to solve the fuel crossover problems of the conventional arts. Thus, the defects the required thickness of the platinum alloy carbon support layer 112 of the conventional anodic structure A1 can be reduced, the path of carbon dioxide in the platinum alloy carbon support layer 112 of the anodic structure A2 is reduced, the reaction power density is increased, and the cost of material of the fuel cell is reduced.
While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Claims
1. An electrode structure for a fuel cell for power generation, the electrode structure comprising:
- a cathodic structure;
- an ionic exchange membrane disposed next to the cathodic structure; and
- an anodic structure sequentially comprising a first thin platinum alloy black layer disposed next to the ionic exchange membrane, a platinum alloy carbon support layer and a first substrate layer.
2. The electrode structure as claimed in claim 1, wherein the platinum alloy carbon support layer comprises a high catalytic platinum alloy carbon support layer, a low catalytic platinum alloy carbon support layer, a combination of the high catalytic platinum alloy carbon support layer and the low catalytic platinum alloy carbon support layer, a combination of the low catalytic platinum alloy carbon support layer and a non-catalytic carbon support layer, or a combination of the high catalytic platinum alloy carbon support layer and the non-catalytic carbon support layer.
3. The electrode structure as claimed in claim 2, wherein the non-catalytic carbon support layer comprises a plurality of carbon support particles and a appropriately polymers dispersed on surfaces of the carbon support particles, and the carbon support particles are linked by the polymers to form the non-catalytic carbon support layer, and the carbon support particles are conductive and anti-corrosive carbon material.
4. The electrode structure as claimed in claim 2, wherein the high catalytic platinum alloy carbon support layer comprises a plurality of high platinum alloy carbon support particles containing a plurality of platinum alloy particles, and the low catalytic platinum alloy carbon support layer comprises a plurality of low platinum alloy carbon support particles containing the platinum alloy particles, wherein the amount of the platinum alloy particles of the high platinum alloy carbon support particles is greater than the amount of the platinum alloy particles of the low platinum alloy carbon support particles.
5. The electrode structure as claimed in claim 1, wherein the ionic exchange membrane is made of Nafion®/Nafion® derivatives, non-perfluoro chemicals and derivatives thereof, or hydrocarbon.
6. The electrode structure as claimed in claim 1, wherein the first thin platinum alloy black layer covers the surface of the ionic exchange membrane.
7. The electrode structure as claimed in claim 1, wherein the first thin platinum alloy black layer covers the surface of the platinum alloy carbon support layer.
8. The electrode structure as claimed in claim 1, wherein the first substrate layer comprises a carbon substrate.
9. The electrode structure as claimed in claim 1, wherein the first thin platinum alloy black layer comprises a appropriately polymers and a plurality of platinum alloy particles linked by the polymers, to form the first thin platinum alloy black layer.
10. The electrode structure as claimed in claim 1, wherein the platinum alloy carbon support layer comprises a plurality of carbon support particles, a plurality of platinum alloy particles, and a appropriately polymers dispersed on surfaces of the carbon support particles, wherein the carbon support particles are linked by the polymers to form the platinum alloy carbon support layer.
11. The electrode structure as claimed in claim 1, wherein the cathodic structure sequentially comprises a second substrate and a carbon support layer disposed next to the ionic exchange membrane.
12. The electrode structure as claimed in claim 11, wherein the carbon support layer comprises a platinum catalytic carbon support layer and a non-catalytic carbon support layer.
13. The electrode structure as claimed in claim 12, wherein the platinum catalytic carbon support layer comprises a plurality of platinum catalytic carbon supports and a appropriately polymers, wherein the platinum catalytic carbon supports comprise a plurality of carbon support particles and a plurality of platinum catalytic particles dispersed on surfaces of the carbon support particles, and the platinum catalytic particles are linked by the polymers to form the platinum catalytic carbon support layer.
14. The electrode structure as claimed in claim 11, wherein the carbon support layer covers the second substrate.
15. The electrode structure as claimed in claim 11, wherein the carbon support layer covers the surface of the ionic exchange membrane.
16. The electrode structure as claimed in claim 11, wherein the second substrate comprises a carbon substrate.
17. The electrode structure as claimed in claim 1, wherein the cathodic structure sequentially comprises a platinum black layer disposed next to the ionic exchange membrane, a non-catalytic carbon support layer and a second substrate.
18. The electrode structure as claimed in claim 17, wherein the platinum black layer comprises a plurality of platinum catalytic particles and a appropriately polymers, and the platinum catalytic particles are linked by the polymers to form the platinum black layer.
19. The electrode structure as claimed in claim 17, wherein the non-catalytic carbon support layer comprises a plurality of carbon support particles and a appropriately polymers, and the carbon support particles are linked by the polymers to form the non-catalytic carbon support layer.
20. The electrode structure as claimed in claim 1, wherein the cathodic structure sequentially comprises a second thin platinum alloy black layer disposed next to the ionic exchange membrane, a carbon support layer and a second substrate.
21. The electrode structure as claimed in claim 20, wherein the second thin platinum alloy black layer covers the ionic exchange membrane.
22. The electrode structure as claimed in claim 20, wherein the carbon support layer covers the second substrate.
23. The electrode structure as claimed in claim 20, wherein the second substrate comprises a carbon substrate.
24. The electrode structure as claimed in claim 20, wherein the second thin platinum alloy black layer comprises a plurality of platinum alloy particles and a appropriately polymers, and the platinum alloy particles are linked by the polymers to form the second thin platinum alloy black layer.
25. The electrode structure as claimed in claim 20, wherein the carbon support layer comprises a platinum catalytic carbon support layer disposed next to the second thin platinum alloy black layer and a non-catalytic carbon support layer.
26. The electrode structure as claimed in claim 25, wherein the platinum catalytic carbon support layer comprises a plurality of platinum catalytic carbon support particles and a appropriately polymers, and the platinum catalytic carbon support particles comprises a plurality of carbon support particles and a plurality of platinum catalytic particles dispersed on surfaces of the carbon support particles, and the platinum catalytic carbon support particles are linked by the polymers to form the platinum catalytic carbon support layer.
27. The electrode structure as claimed in claim 25, wherein the non-catalytic carbon support layer comprises a plurality of carbon support particles and a appropriately polymers dispersed on surfaces of the carbon support particles, and the carbon support particles are linked by the polymers to form the non-catalytic carbon support layer.
28. The electrode structure as claimed in claim 1, wherein the cathodic structure sequentially comprises a second thin platinum alloy black layer disposed next to the ionic exchange membrane, a platinum catalytic layer and a second substrate.
29. The electrode structure as claimed in claim 28, wherein the platinum catalytic layer covers the second substrate.
30. The electrode structure as claimed in claim 28, wherein the second thin platinum alloy black layer covers the surface of the ionic exchange membrane.
31. The electrode structure as claimed in claim 28, wherein the second substrate comprises a carbon substrate.
32. The electrode structure as claimed in claim 28, wherein the second thin platinum alloy black layer comprises a plurality of platinum alloy particles and a appropriately polymers, and the platinum alloy particles are linked by the polymers to form the second thin platinum alloy black layer.
33. The electrode structure as claimed in claim 28, wherein the platinum catalytic layer comprises a combination of a platinum black layer and a non-catalytic carbon support layer, or a combination of the platinum black layer and a platinum catalytic carbon support layer.
34. The electrode structure as claimed in claim 33, wherein the platinum catalytic carbon support layer comprises a plurality of platinum catalytic carbon support particles and a appropriately polymers, and the platinum catalytic carbon support particles comprises a plurality of platinum catalytic particles dispersed on surfaces of the carbon support particles, and the platinum catalytic carbon support particles are linked by the polymers to form the platinum catalytic carbon support layer.
35. The electrode structure as claimed in claim 33, wherein the non-catalytic carbon support layer comprises a plurality of carbon support particles and a appropriately polymers dispersed on surfaces of the carbon support particles, and the carbon support particles are linked by the polymers to form the non-catalytic carbon support layer.
36. The electrode structure as claimed in claim 28, wherein the platinum catalytic layer comprises a plurality of platinum catalytic particles and an appropriately polymers, and the platinum catalytic particles are linked by the polymers to form the platinum catalytic layer.
37. The electrode structure as claimed in claim 1, wherein the fuel cell generates power by use of a fuel.
38. The electrode structure as claimed in claim 37, wherein the fuel comprises an organic fuel.
39. The electrode structure as claimed in claim 38, wherein the organic fuel comprises an available fuel containing alcohol, aldehyde or acid.
40. The electrode structure as claimed in claim 39, wherein the available fuel comprises liquid, gel, solid or gaseous types.
41. An electrode structure, comprising:
- a cathodic structure;
- an ionic exchange membrane disposed next to the cathodic structure; and
- an anodic structure sequentially comprising a first thin platinum alloy black layer disposed next to the ionic exchange membrane, a platinum alloy carbon support layer and a first substrate layer, wherein the platinum alloy carbon support layer comprises at least one first platinum alloy carbon support layer and at least one second platinum alloy carbon support layer, and the at least one first platinum alloy carbon support layer is not greater than the at least one second platinum alloy carbon support layer.
42. The electrode structure as claimed in claim 41, wherein the at least one first platinum alloy carbon support layer and the at least one second platinum alloy carbon support layer are substantially between 10 to 90 wt %.
43. The electrode structure as claimed in claim 41, wherein the at least one first platinum alloy carbon support layer is not less than 10 wt %.
44. The electrode structure as claimed in claim 41, wherein the at least one second platinum alloy carbon support layer is not greater than 90 wt %.
45. The electrode structure as claimed in claim 41 further comprising a non-catalytic carbon support layer disposed between the platinum alloy carbon support layer and the first substrate layer.
46. The electrode structure as claimed in claim 1, wherein wherein the non-catalytic carbon support layer comprises a plurality of carbon support particles and a appropriately polymers, and the carbon support particles are linked by the polymers to form the non-catalytic carbon support layer.
47. The electrode structure as claimed in claim 46, wherein the carbon support particles are conductive or anti-corrosive carbon material.
48. The electrode structure as claimed in claim 41, wherein the ionic exchange membrane is made of Nafion®/Nafion® derivatives, non-perfluoro chemicals and derivatives thereof, or hydrocarbon.
49. The electrode structure as claimed in claim 41, wherein the first thin platinum alloy black layer is deposited on the ionic exchange membrane.
50. The electrode structure as claimed in claim 41, wherein the first thin platinum alloy black layer is deposited on the platinum alloy carbon support layer.
51. The electrode structure as claimed in claim 41, wherein the first thin platinum alloy black layer comprises a appropriately polymers and a plurality of platinum alloy particles linked by the polymers, to form the first thin platinum alloy black layer.
52. The electrode structure as claimed in claim 41, wherein the platinum alloy carbon support layer comprises a plurality of carbon support particles, a plurality of platinum alloy particles, and a appropriately polymers dispersed on surfaces of the carbon support particles, wherein the carbon support particles are linked by the polymers to form the platinum alloy carbon support layer.
53. An electrode structure, comprising:
- a cathodic structure;
- an ionic exchange membrane disposed next to the cathodic structure; and
- an anodic structure sequentially comprising a first thin platinum alloy black layer disposed next to the ionic exchange membrane, a platinum alloy carbon support layer and a first substrate layer, wherein the platinum alloy carbon support layer comprises one of at least one first platinum alloy carbon support layer and at least one second platinum alloy carbon support layer, and at least one of the at least one first platinum alloy carbon support layer and the at least one second platinum alloy carbon support layer is substantially between 10 to 90 wt %.
54. The electrode structure as claimed in claim 53, wherein the at least one first platinum alloy carbon support layer is not less than 10 wt %.
55. The electrode structure as claimed in claim 53, wherein the at least one second platinum alloy carbon support layer is not greater than 90 wt %.
56. The electrode structure as claimed in claim 53 further comprising a non-catalytic carbon support layer disposed between the platinum alloy carbon support layer and the first substrate layer.
57. The electrode structure as claimed in claim 56, wherein wherein the non-catalytic carbon support layer comprises a plurality of carbon support particles and a appropriately polymers, and the carbon support particles are linked by the polymers to form the non-catalytic carbon support layer.
58. The electrode structure as claimed in claim 57, wherein the carbon support particles are conductive or anti-corrosive carbon material.
59. The electrode structure as claimed in claim 57, wherein the first substrate layer comprises carbon paper, carbon cloth, carbon fiber or carbon plate.
60. The electrode structure as claimed in claim 53, wherein the ionic exchange membrane is made of Nafion®/Nafion® derivatives, non-perfluoro chemicals and derivatives thereof, or hydrocarbon.
61. The electrode structure as claimed in claim 53, wherein the first thin platinum alloy black layer is deposited on the ionic exchange membrane.
62. The electrode structure as claimed in claim 53, wherein the first thin platinum alloy black layer is deposited on the platinum alloy carbon support layer.
63. The electrode structure as claimed in claim 53, wherein the first thin platinum alloy black layer comprises a appropriately polymers and a plurality of platinum alloy particles linked by the polymers, to form the first thin platinum alloy black layer.
64. The electrode structure as claimed in claim 53, wherein the platinum alloy carbon support layer comprises a plurality of carbon support particles, a plurality of platinum alloy particles, and a appropriately polymers dispersed on surfaces of the carbon support particles, wherein the carbon support particles are linked by the polymers to form the platinum alloy carbon support layer.
65. A power generation fuel cell, comprising:
- a fuel; and
- an electrode structure used to actuate the fuel to generate electricity, comprising: a cathodic structure; an ionic exchange membrane disposed next to the cathodic structure; and an anodic structure sequentially comprising a first thin platinum alloy black layer disposed next to the ionic exchange membrane, a platinum alloy carbon support layer and a first substrate layer.
66. The power generation fuel cell as claimed in claim 65, wherein the fuel comprises an organic fuel.
67. The power generation fuel cell as claimed in claim 66, wherein the organic fuel comprises an available fuel containing alcohol, aldehyde or acid.
68. The power generation fuel cell as claimed in claim 67, wherein the available fuel comprises liquid, gel, solid or gaseous types.
Type: Application
Filed: Dec 29, 2006
Publication Date: Jul 5, 2007
Applicant: INDUSTRIAL TECHNOLOGY RESEARCH INSTITUTE (HSINCHU)
Inventors: Chiu-Ping Huang (Hsinchu City), Kan-Lin Hsueh (Hsinchu County), Li-Duan Tsai (Hsinchu City), Sung-Chun Chang (Taipei City), Fu-Chi Wu (Taipei County), Du-Yuan Yu (Taoyuan County)
Application Number: 11/618,154
International Classification: H01M 4/96 (20060101); H01M 8/10 (20060101); H01M 4/92 (20060101);