Electrical conduction in Ga3+-doped SnP2O7/polytetrafluoroethylene inorganic–organic composite electrolytes

In this study, dense polytetrafluoroethylene (PTFE)/Sn 1− x Ga x P 2 O 7 ( x  = 0.05, 0.10, 0.15, 0.20) inorganic–organic composite electrolytes were prepared. The result of SEM images indicates that all the composite electrolytes are sufficiently uniform and dense. The conductivities which is given consideration to the influence of Ga 3+ doping level increase in the order: σ ( x  = 0.20) <  σ ( x  = 0.15) <  σ ( x  = 0.10) <  σ ( x  = 0.05). The highest conductivity 1.9 × 10 −2  S cm −1 is observed for PTFE/Sn 1− x Ga x P 2 O 7 ( x  = 0.05) in wet O 2 at 225 °C. The H 2 /O 2 fuel cells using PTFE/Sn 1− x Ga x P 2 O 7 ( x  = 0.05, 0.10) as electrolytes generate the maximum power densities of 63 mW cm −2 for x  = 0.05 and 36.3 mW cm −2 for x  = 0.10 at 150 °C, respectively.