Hygroscopic solid inorganic proton conductor composite polymer electrolytes

9 Hygroscopic solid inorganic proton conductor composite polymer electrolytes 

Hygroscopic solid inorganic proton conductors as membrane fillers increase the number of protonic carriers and thus improve the hydrophilic character of the membranes. Among the inorganic solid proton conductors, °° ° ° zirconium phosphates, heteropolyacids, metal hydrogen sulphate and a few others are of special interest for their potential role in developing high temperature composite membranes for PEMFCs. 

2 Composite polymer electrolytes based on zirconium phosphate 

Chalkova et studied the effects of ZP particle size, structure and distribution in a membrane on the performance of Nafion /ZP composite membranes in PEMFCs at high temperatures and low RH. They synthesised Nafion /ZP composite membranes with different structures containing in situ precipitated ZP, crystalline layer-structured a-zirconium hydrogen phosphate (Zr(HP04) 2H2O) (a-ZPL), and three-dimensional-network zirconium hydrogen phosphate H30-Zr2(P04)3 (ZPTD). The difference in performance of composite Nafion /ZP membranes containing ZP in different structures was more pronounced at 120 °C than at 80 °C, particularly at 13 and 26% RH. 

The Nafion /a-ZPL composite membranes demonstrated the best performance for all RH values. The advantage of these membranes over Nafion /ZPTD and Nafion /ZP in situ membranes was especially obvious at 13% RH. The current density obtained at a cell voltage of 0.6 V for the Nafion /a-ZPL membrane at 13% RH was 10 times higher than that of an unmodified recast Nafion membrane at 26% RH. Membranes with 10% 

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