The use of inorganic fillers is an interesting strategy to improve the electrochemical performances of PBI membranes for application as electrolytes in HT-PEMFCs. Here, we prepared several mesoporous silica (SBA-15) based hybrids, functionalised with different moieties, namely acidic (SO3H-), basic (NH2-), and amphoteric (SO3H-NH2) units. The electrochemical properties of the resulting electrolytes were investigated in terms of proton transport and functional tests by varying the silica functionalization degree in the range 10-70 mol%, as well as the particles loading in the polymer (0-30 wt%). The actual effectiveness of the SBA-15 functionalization process in improving the electrolyte properties was compared with both the unfilled membrane and the one filled with pristine SBA-15. The best conductivity (∼90 mS cm-1 at 120 C, 30%RH) was obtained with PBI composites loaded with 30 wt% of non-functionalized SBA-15. The use of fillers functionalized with acidic, basic of amphoteric groups did not lead to improvements with respect to pure SBA-15. This could be related to the set up of significant interactions between the functionalised fillers and H3PO4, which negatively influence the proton mobility. Encouraging MEA results (power peak >320 mW cm-2) were obtained in case of membranes based on pure SBA-15. These performances make the SBA-15/PBI composites particularly interesting for application in HT-PEMFCs.
Influence of variously functionalized SBA-15 fillers on conductivity and electrochemical properties of PBI composite membranes for high temperature polymer fuel cells
ANGIONI, SIMONE;VILLA, DAVIDE CARLO;CATTANEO, ALICE SILVIA;MUSTARELLI, PIERCARLO;QUARTARONE, ELIANA
2015-01-01
Abstract
The use of inorganic fillers is an interesting strategy to improve the electrochemical performances of PBI membranes for application as electrolytes in HT-PEMFCs. Here, we prepared several mesoporous silica (SBA-15) based hybrids, functionalised with different moieties, namely acidic (SO3H-), basic (NH2-), and amphoteric (SO3H-NH2) units. The electrochemical properties of the resulting electrolytes were investigated in terms of proton transport and functional tests by varying the silica functionalization degree in the range 10-70 mol%, as well as the particles loading in the polymer (0-30 wt%). The actual effectiveness of the SBA-15 functionalization process in improving the electrolyte properties was compared with both the unfilled membrane and the one filled with pristine SBA-15. The best conductivity (∼90 mS cm-1 at 120 C, 30%RH) was obtained with PBI composites loaded with 30 wt% of non-functionalized SBA-15. The use of fillers functionalized with acidic, basic of amphoteric groups did not lead to improvements with respect to pure SBA-15. This could be related to the set up of significant interactions between the functionalised fillers and H3PO4, which negatively influence the proton mobility. Encouraging MEA results (power peak >320 mW cm-2) were obtained in case of membranes based on pure SBA-15. These performances make the SBA-15/PBI composites particularly interesting for application in HT-PEMFCs.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
