Oxide ion conductivity in La0.8Sr0.2Ga0.8Mg0.2-XNiXO3 perovskite oxide andapplication for the electrolyte of solid oxide fuel cells

Although hole conduction was present, it was found that doping with Ni was effective in improving the oxide ion conductivity in La0.8Sr0.2Ga0.8Mg0.2O3 based perovskite oxides. Considering the ionic transport number and the el ectrical conductivity, the optimized composition for Ni doped samples was L a0.8Sr0.2Ga0.8Mg0.13Ni0.07O3 (LSGMN). In this composition, electrical condu ctivity was found to be virtually independent of the oxygen partial pressur e from 1 to 10(-21) atm. Consequently, the oxide ion conductivity was still dominant in this optimized composition. In agreement with the improved oxi de ionic conductivity, the power density of the solid oxide fuel cell using LaGaO3 as an electrolyte increased by doping with a small amount of Ni on the Ga site. In particular, the power density of 224 mW/cm(2) at 873 K, whi ch is the maximum power density in the cells using LaGaO3 based oxide as th e electrolyte, was attained using LSGMN in spite of the use of electrolyte plates with a thickness of 0.5 mm. Therefore, LSGMN is highly attractive fo r the electrolyte material of low temperature operating SOFCs. (C) 2001 Klu wer Academic Publishers.