Optimization of Infiltration Techniques Used to Construct Ni/YSZ Anodes

Abstract

A range of Ni-containing solutions have been infiltrated into a symmetrical tubular half-cell composed of a slip-casted, porous yttria-stabilized zirconia (YSZ) anode support, Ni-YSZ functional layers, a YSZ electrolyte, and a second, outer porous YSZ anode support layer, aiming at the development of high performance anodes that are tolerant to redox-cycling. A combination of surface wettability experiments and optical and electron microscopy imaging has been used to determine how well these solutions penetrate the porous YSZ matrix, then correlating these results with the electrochemical performance in humidified H2 environments at 800 ⁰C. It is shown that the addition of the Triton-X-100 surfactant to the infiltration solution results in excellent penetration of the YSZ matrix, while the use of urea as a Ni complexing agent does not give good wettability, thus leaving a Ni-rich layer on the outer anode surface. Overall, the use of a two-step process, involving several infiltrations with Ni nitrate solutions containing Triton-X-100, followed by several infiltrations with urea-containing solutions, leads to the best cell performance as well as the best Ni distribution inside the anode layers.