Samsung Fuel Cell with Rotating Disk Electrodes and Dual Catalysts Resists Carbon Monoxide Poisoning

Samsung SDI Co., Ltd. (Yeongtong-gu, Suwon-si, Gyeonggi-do, KR)  earned U.S. Patent Patent 7,670,713 for a fuel cell with a rotating disk electrode that increases the life-span of a proton exchange membrane fuel cell  by reducing deterioration of the catalysts which results from catalyst poisoning by carbon monoxide (CO) generated as a by-product during the fuel cell operation. 

The catalyst layer includes a first catalyst which is supported on a carbon carrier and a second catalyst which is supported on an inorganic oxide carrier. The first catalyst includes an alloy of Pt and a metal selected from the group consisting of Co, Ni, and a mixture thereof, and the second catalyst includes an alloy of Pt and a metal selected from the group consisting of Co, Ni, and a mixture thereof.  Acetylene black, graphite, Vulcan, an activated carbon, carbon nano-tubes, carbon nano-fibers, carbon nano-wires, carbon nano-horns, or carbon nano-rings are used as a carbon carrier.

A second catalyst which is supported on an inorganic oxide carrier has a preferential oxidation reaction for CO, so that it prevents catalyst poisoning by CO and thus improves the life-span of the fuel cell.

It is preferable that the mixture ratio of the Pt and the metal on the first and the second catalysts is in a weight ratio ranging from 1:0.1 to 1:0.5, and more preferably 1:0.4 to 1:0.5.

A fuel cell electrode includes a catalyst layer and an electrode substrate supporting the catalyst layer and including a conductive substrate. The catalyst layer includes a first catalyst supported on a carbon supporter and a second catalyst supported on an inorganic oxide supporter. The first catalyst includes an alloy of Pt and a metal selected from the group consisting of Co, Ni, and a mixture thereof, and the second catalyst includes an alloy of Pt and a metal selected from the group consisting of Co, Ni, and a mixture of them according to Samsug inventors Chan Kwak, Hee-Tak Kim and Myoung-Ki Min

The fuel supplier supplies a fuel to the electricity generating element, and the oxidant supplier supplies an oxidant to the electricity generating element. The fuel is a hydrocarbon-based material such as methanol, ethanol, natural gas, and the like, and examples of the oxidant are air and oxygen. 

FIG. 1 is a view of a structure of a Samsung fuel cell system with Rotating Disk Electrodes  and 

FIG. 2 is a graph of measured current using Rotating Disk Electrodes (RDEs) according to Example 1 and Comparative Example 1.  An electrode for a fuel cell was fabricated by the same method as in Example 1, except that a catalyst where Pt was supported on the carbon carrier in a weight ratio ranging from 1:0.5 was used. 

The electrodes fabricated in Example 1 and Comparative Example 1 were tested using a rotating disk electrode. Electrochemical measurements were performed in a three electrode-one compartment glass cell. The counter electrode was a platinum foil and the reference electrode was Ag/AgCl. Methanol was added to a 0.5 M H2SO4 electrolyte to artificially produce carbon monoxide. The current density was measured at 0.6 V (SHE) with time and the measurement results shown in FIG. 2.

As shown in FIG. 2, the fuel cell electrode according to Example 1 of the present invention shows an improved performance over that of Comparative Example 1, since the CO bound to the catalyst is easily detached from the catalyst during operation of the fuel cell. 

Samsung SDI Co Ltd  recently posted a below-forecast operating profit on price falls in rechargeable batteries and costs from new production start-ups, but expects solid demand growth for displays and batteries in 2010. In December 2009, SB LiMotive, a joint venture between South Korea's Samsung SDI and Germany’s Robert Bosch,  announced plans to invest 500 billion won (some $410 million) in an electric vehicle battery plant by 2015.

The new plant, which will be built in the southeastern city of Ulsan, South Gyeongsang Province, will produce secondary batteries used in hybrid electric vehicles from 2011. The joint venture is targeting a 30 percent share in the global auto battery market by 2015.