Optimization of Infiltration Techniques Used to Construct Ni/YSZ Anodes

A range of Ni-containing solutions, including an aqueous solution containing the Triton-X surfactant, and aqueous or ethanolic solutions containing urea, 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. 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 H-2 environments at 800 degrees C. It is shown that the addition of Triton-X-100 surfactant to the infiltration solution results in excellent penetration of the Ni phase deep into the YSZ matrix, while the use of urea as a Ni complexing, agent leaves a Ni-rich layer on the outer anode surface. Importantly, the use of a two-step process, involving several vacuum-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. (C) 2014 The Elecdochemical Society. All rights reserved.