biostudies-literatureChen XFoundation for Science and TechnologyNational Natural Science Foundation of China5225-5232https://www.ebi.ac.uk/biostudies/studies/S-EPMC9078124biostudies-literatureUnknown8(10)Molten carbonate fuel cells have been commercialized as a mature technology. Due to the liquid electrolyte in molten carbonate fuel cells, gas seal and low contact resistance are easier to achieve than in other fuel cells. Herein, we report an investigation of the viability of a molten oxoacid salt as a novel type of fuel cell electrolyte. In comparison with molten carbonate electrolytes for MCFCs that operate at 500-700 °C, for which a ceramic support matrix is required, the molten proton conductor electrolyte has a lower working temperature range of 150-250 °C. The present study has shown that an electrolyte membrane, in which molten CsH<sub>5</sub>(PO<sub>4</sub>)<sub>2</sub> is held in a matrix made of PBI polymer and SiO<sub>2</sub> powder, has excellent thermal stability, good mechanRSC advancesA proton conductor electrolyte based on molten CsH<sub>5</sub>(PO<sub>4</sub>)<sub>2</sub> for intermediate-temperature fuel cells.PMC907812421761132004Ribeiorinha PLi HZhang YBoaventura MChen XKong XfalseA proton conductor electrolyte based on molten CsH<sub>5</sub>(PO<sub>4</sub>)<sub>2</sub> for intermediate-temperature fuel cells.Molten carbonate fuel cells have been commercialized as a mature technology. Due to the liquid electrolyte in molten carbonate fuel cells, gas seal and low contact resistance are easier to achieve than in other fuel cells. Herein, we report an investigation of the viability of a molten oxoacid salt as a novel type of fuel cell electrolyte. In comparison with molten carbonate electrolytes for MCFCs that operate at 500-700 °C, for which a ceramic support matrix is required, the molten proton conductor electrolyte has a lower working temperature range of 150-250 °C. The present study has shown that an electrolyte membrane, in which molten CsH<sub>5</sub>(PO<sub>4</sub>)<sub>2</sub> is held in a matrix made of PBI polymer and SiO<sub>2</sub> powder, has excellent thermal stability, good mechan2018-01-01T00:00:00Z2018 Jan2025-04-18T12:12:47.513Z2025-04-06T21:50:57.785ZS-EPMC90781243554244810.1039/c7ra12803g