Evaluation of La2NiO4 as Anode Material for Solid Oxide Electrolyser Cells
High temperature electrolysis is based on solid oxide electrolyser cells (SOEC) which adopt design concepts and materials developed for solid oxide fuel cells (SOFC). In this work the promising SOFC cathode material La2NiO4+δ is investigated with respect to its suitability as anode for SOEC application. Important material properties characterising electrical conductivity and oxygen transport kinetics are determined on densely sintered samples of La2NiO4+δ. In addition, its performance as air electrode is investigated on asymmetric cells under anodic polarisation at current densities of up to -410 mAcm-2 by means of impedance analysis and I-V measurements. Electrochemical characterisation is conducted at 800°C and 0.2 bar oxygen partial pressure and the long-term stability is studied over several thousand hours. Special emphasis is put on the effect of Cr-poisoning on the oxygen exchange kinetics and SOEC anode performance in dry and humid atmospheres. Results from post-test examination of porous electrode structures as well as dense samples of La2NiO4+δ by microstructural analysis with SEM-EDX and AFM are presented.