New Publication in Nature Materials
Research at the HI ERN remains top-notch, including in the field of electrochemical energy conversion.
Effective polymeric proton conductors play an important role in making conversion processes – in a fuel cell, for example - as efficient as possible. In high-temperature fuel cells (operating temperature 140 to 220 °C.), in which so far in most cases polybenzimidazoles doped with phosphoric acid have been used as proton conductors, problems often occur at high temperatures. One example is the partial evaporation of phosphoric acid (boiling point 213 °C), which reduces the proton conductivity of the membrane. In addition, phosphoric acid molecules are deposited on the catalysts of high-temperature fuel cells during operation, which significantly reduces their efficiency.
Researchers of HI ERN (Research Department Electrocatalytic Interface Engineering) together with german (group of Dr. V. Atanasov at the Institute of Chemical Process Engineering at University of Stuttgart) and american colleagues around Dr. Y. S. Kim at the Los Alamos National Lab have now published their solution to this problem in the renowned Nature Materials journal.
It includes a reduction in the performance-inhibiting phosphoric acid content of the electrodes through the use of a polymer solid acid (2,3,5,6-tetrafluorostyrene-4-phosphonic acid) as the electrode ionomer, which, unlike phosphoric acid, even doesn’t evaporate at temperatures above 200 °C.
The use of a polymer solid acid in fuel cell electrodes enables an increase in the performance of electrochemical energy conversion of more than 50 %. This finding is significant as it provides a way of using phosphonated polymers in high performance fuel cells under hot and dry operating conditions.