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Catalytic electrode with gradient porosity and catalyst density for fuel cells

A fuel cell and catalyst technology, applied in fuel cells, battery electrodes, solid electrolyte fuel cells, etc., can solve the problems of poor electron transfer performance Pt active surface degradation or elimination, separation, etc.

Inactive Publication Date: 2012-01-11
FLORIDA STATE UNIV RES FOUND INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, a significant problem inherent in the conventional process is that the addition of a binder at the fabrication stage tends to detach the carbon nanotubes in the electrocatalyst layer, resulting in poor electron transport performance and degradation or elimination of the Pt active surface.

Method used

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  • Catalytic electrode with gradient porosity and catalyst density for fuel cells
  • Catalytic electrode with gradient porosity and catalyst density for fuel cells
  • Catalytic electrode with gradient porosity and catalyst density for fuel cells

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Effect test

Embodiment 1

[0067] Exemplary gradient catalyst structures were prepared by sequentially filtering a 25 wt% single-walled carbon nanotube (SWNT) / 75 wt% carbon nanofiber (CNF) suspension and a carbon nanofiber (CNF) suspension under full vacuum. As shown in Figure 2(a), the carbon nanofibers are randomly entangled to form a highly porous second layer with a porosity of 90.8% and an average pore diameter of 85 nm, while adding 25 wt% of fine-sized single-walled carbon The nanotubes form smaller pores in the single wall carbon nanotube / carbon nanofiber layer. As a result, the single-walled carbon nanotube (SWNT) / carbon nanofiber (CNF) first layer has a larger surface area (24m 2 / g) much larger surface area (105m 2 / g). After depositing Pt on the multi-layer buckypaper by electrochemical deposition, the energy dispersive X-ray spectroscopy (EDS) analysis in Fig. 2(b) shows a gradient distribution of Pt, with more than 70% of the Pt distributed in a single layer of 7 μm thickness. Walled ca...

Embodiment 2

[0071] Despite the relatively large Pt particle size, Pt / multilayer buckypaper (LBP) with tailored gradient structures has shown promising Pt utilization and support stability. Given the negligible improvement in anode oxygen reduction reaction (ORR) activity using Pt / multilayer buckypaper (LBP), this high cell performance is believed to result from the inventive microstructure of the gradient catalyst structure. To evaluate the effect of microstructure on fuel cell performance, two conventional single-layer buckypaper membrane electrode assemblies were compared in terms of polarization curves and electrochemical impedance spectroscopy (EIS). Conventional buckypaper is composed of a mixture of single-walled carbon nanotubes and carbon nanofibers (with a weight ratio of 1:3, called SF13, or a weight ratio of 1:9, called SF19), and has a thickness of 14 μm. Since Pt was deposited on each conventional buckypaper and Pt / multilayer buckypaper (LBP) under the same conditions, each c...

Embodiment 3

[0075] In the durability study of single-wall carbon nanotube / nanofiber buckypaper catalyst support for proton exchange membrane fuel cell completed by W.Zhu et al. (Journal of the Electrochemical Society "Journal of Electrochemical Society" (2009)) , single-walled carbon nanotube (SWNT) / carbon nanofiber (CNF) buckypaper with Pt catalyst nanoparticles showed good durability under accelerated degradation test conditions simulated in the cathode environment of a proton exchange membrane fuel cell. The reason for good durability is generally considered to be high corrosion resistance due to high graphitization of carbon nanofibers. Subsequently, the Pt / multilayer buckypaper (LBP) based Pt / multilayer buckypaper (LBP ) The durability of the catalyst support of the membrane electrode assembly. Figure 5 Polarization curves at different time courses during the 200-hour durability test are shown. The mass activity measured at 900mV after working for 200 hours has only lost 57.6% of ...

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Abstract

A membrane electrode assembly (110) for a fuel cell (100) comprising a gradient catalyst structure (120 or 140) and a method of making the same. The gradient catalyst structure (120 or 140) can include a plurality of catalyst nanoparticles, e. g. , platinum, disposed on layered buckypaper. The layered buckypaper can include at least a first layer and a second layer and the first layer can have a lower porosity compared to the second layer. The gradient catalyst structure (120 or 140) can include single-wall nanotubes, carbon nanofibers, or both in the first layer of the layered buckypaper and can include carbon nanofibers in the second layer of the layered buckypaper. The membrane electrode assembly (110) can have a catalyst utilization efficiency of at least 0. 35 gcat / kW or less.

Description

[0001] Statement Regarding Federally Sponsored Research or Development [0002] The US Government has rights in this invention pursuant to Contract No. 023106 between the US Army Communications Electronics Research, Development, and Engineering Center and Florida State University. technical field [0003] The present invention relates to the field of membrane electrode assemblies for proton exchange membrane fuel cells. Background technique [0004] Fuel cells are considered by many to be promising sources of power for a wide range of devices, including automobiles, and other subjects for portable and stationary use. Fuel cells can provide high energy efficiency and relatively fast start-up. In addition, fuel cells are capable of generating electricity without producing the kinds of environmental pollution that is characteristic of many other power sources. Therefore, fuel cells are a solution to meet critical energy needs, while fuel cells also reduce environmental pollu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/90H01M8/10H01M4/88B82B3/00B01J23/00
CPCH01M8/0234H01M4/8892H01M4/8807H01M4/8657H01M4/92B82Y30/00Y02E60/521H01M8/0245C04B2235/5288H01M4/8642H01M8/1004H01M4/926Y02P70/50Y02E60/50H01M4/90B01J23/00B82B3/00H01M4/88
Inventor 郑建平梁智勇王奔张春朱伟
Owner FLORIDA STATE UNIV RES FOUND INC
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