Properties and development of Ni/YSZ as an anode material in solid oxide fuel cell: A review

In recent times, synthesis, development and fabrication of anode component of solid oxide fuel cell (SOFC) have gained a significant importance, especially after the advent of anode supported SOFC The function of the anode electrode involves the facilitation of fuel gas diffusion, oxidation of the fuel, transport of electrons and transport of by-product of the electrochemical reaction. Although impressive progress has been made in the development of alternative anode materials with mixed conducting properties and few of the other composite cermets, Ni/YSZ continues to be the most sought after anode for high temperature SOFC applications. Despite of its poor carburization and sulfidation capabilities during the operation of SOFC directly on hydrocarbons, Nil YSZ continues to be the most opted anode electrode material due to its high catalytic activity for hydrogen oxidation, methane reforming, high electronic and ionic conductivity and stability. Present review focuses on the various aspects pertaining to Ni/YSZ as an anode in SOFC. Various factors that influence the ohmic, activation and the concentration polarization contribution of anode while using Nil YSZ are discussed. Importance of optimizing the composition, microstructure and porosity to minimize the above mentioned polarizations are discussed extensively. Various synthesis methods that are used in the preparation of optimized NiO/YSZ composite powder and the methods that are adopted to fabricate anode component are provided in detail in the article. Information on Ni/YSZ anode failure and strategies to improve the long term stability are also discussed exhaustively. Parameters that influence the carburization and sulfidation of Ni/YSZ while using hydrocarbons as fuel are elaborated in this article and means to minimize the same are also discussed. (C) 2014 Elsevier Ltd. All rights reserved.