Question

Metal hydride-nafion composite electrode with dual proton and electron conductivity

Answer 1

A metal hydride-nafion composite electrode with dual proton and electron conductivity has been fabricated that may have applications for electrochemical storage of hydrogen. The proton conductivity of the composite electrode was measured using electrochemical impedance spectroscopy. Its electron conductivity was calculated from measurements of dc resistance. Ambient conditions were varied to study the effect of humidification and hence degree of hydration of the electrode on proton and electron conductivity of the composite electrode. The metal hydride used was a common form of AB5 alloy made from rare earth and transition element metals. Nafion-117 solution was employed as the source of nafion within the composite. Proton conductivities in the range 0.0074 to 0.0209 S/cm were obtained, while the electron conductivities were higher, in the range 13.9 to 34.7 S/cm. It was found that the proton conductivity of the composite electrode rose with increased hydration, while electron conductivity fell.