Células a combustível de membrana de troca aniônica de alto desempenho baseadas em ionômeros sólidos

Abstract

Alkaline polymer electrolyte fuel cells (APEFC) have received increased attention in recent years as an alternative to well-established PEMFC because the alkaline medium enables more efficient and faster electrochemical reactions using nonnoble catalysts. The development of stable and conductive polymeric materials employed as anion-exchange membranes (AEM) and anion-exchange ionomers (AEI) has been the focus of substantial efforts. In this work, ETFE (poly(ethylene-cotetrafluoroethylene)) powders were electron-beamed radiation-grafted (RG) with vinylbenzyl chloride (VBC) monomer and then either aminated with trimethylammonium (TMA) or N-methylpyrrolidinium (MPY). The resulting powders were employed as the AEI in the gas diffusion electrodes in single cell H2/O2 APEFCs (along with RG-AEMs). The results showed that the degree of grafting (DoG), and consequently the ionexchange capacity (IEC), are strongly dependent on the radiation dose. RG-AEI made from ETFE irradiated at 100 kGy (total absorbed dose) and functionalised with TMA (ETFE100TMA) and MPY (ETFE100MPY) exhibit IEC values of 2.05 and 1.91 meq.mol-1, respectively. The H2/O2 power density curves (Fig. 1) for APEFC with ETFE100TMA in both anode and cathode; ETFE100MPY in both anode and cathode, and ETFE100TMA in anode and ETFE100MPY in cathode, revealed high performances (> 800 mW cm-2). The best performance was observed for with the ETFE100TMA anode and ETFE100MPY cathode (maximum power density of 1.1 W.cm-2).