Research Highlights

The Technological Source for Hydrogen Vehicles (2010.10.5)

2011-03-17 919

Hydrogen as an alternative source of energy is one of the key elements in building environment-friendly vehicles that do not emit carbon dioxide. Currently, the market for hydrogen vehicles is fiercely competitive among countries with large automobile markets like Korea, Japan, and the United States; the drive is to develop a way to sophisticate the existing technology at low cost and for large quantities.

The problem is that the vehicles are much too expensive to become commercialized and they have certain drawbacks. Mid-sized hydrogen automobiles cost up to 90,000 US dollars; the fuel cell is low in durability and needs to be changed after 2,000 hours of operation because carbon monoxides gather around the catalyst platinum, decreasing the capacity of the cell in the form of gradual poisoning.

But recently, a new discovery was made to solve this problem by Professor Moon Jeong Park, Assistant Professor at the Department of Chemistry and member of POSTECH WCU, Division of Advanced Material Science, with PhD candidate Sung Yeon Kim. The new technology challenges the common idea that pure ion conducting substances have high electrolyte conductivity and endure high temperature up to 165 Celsius degrees while maintaining excellent conductive properties. The team’s achievement was published online on October 5, 2010, by Nature Communications, a branch of the Nature Publishing Group.

Professor Park’s team is the first to discover a nanostructured polymer electrolyte that can prevent the gradual poisoning of carbon monoxides of platinum catalysts because it performs high hydrogen conductivity at high temperature up to 180 Celsius degrees without water as a solvent. Also impressive is that the electrolyte works in an environment of high terms, exceeding the developmental goals specified in 2009 by the United States Department of Energy (DOE), which were set at 25 percent in humidity and 120 Celsius degrees in temperature.

The new substance, named SnMBm, performed a conductivity rate of 0.045 S/cm at 165 Celsius degrees. This is three times higher than Nafion that has been used for hydrogen fuel cells until now, whose conductivity at the same temperature was 0.014 S/cm. Flexible and durable, the substance can even be controlled by increasing the density of the ionic liquid or changing the polymer, and its production costs are one tenth compared to Nafion, which is only made of carbon and hydrogen.

Interestingly enough, the team has proved that a mixture of an ion conductive substance and a non-conductive substance makes an electrolyte much more conductive than one with only pure ion conducting substances. Professor Park’s team verified that an electrolyte made of SnMBm is ten times higher in conductivity compared to an electrolyte formed of pure Sn because a short-cut becomes created for the hydrogen to pass through as the SnMBm forms a nanostructure of 10nm.

Professor Park commented: “Our discovery is essential for the commercialization of hydrogen vehicles, for it works in an environment of high temperature and no humidity.” She further added: “We are expecting this substance to become a significant part in the development of fuel cells, because it has this crucial strength among polymer electrolytes.”