Active Electrode for Ammonia Direct Utilization and the Reactivity of Metal Component in High-Temperature SOFCs

Abstract

We have been conducting the international collaboration study on “Green ammonia synthesis and utilization by solid electrolysis cells for maritime application” between Germany and Japan (term:2022-2024) under the SICORP program of Japan Science and Technology Agency (JST). The contributors of this project are AIST, Kyoto University, and Morimura SOFC Technology from Japan side and Fraunhofer IKTS and EDL from German side.The purpose of this project is to establish a new concept for energy loop based on the ammonia synthesis and utilization with maritime application. The task of Japan side is to make a new anode material for direct utilization of ammonia (cracking and oxidation of NH3 component) and degradation mechanism at anode. Addition of BaO into Ni/YSZ anode improved the decomposition rates of NH3 and anode performance in NH3 fuels. We have succeeded the decomposition rate of NH3 over 99.9 % with an optimum addition amounts of BaO into Ni-YSZ electrode. An excellent performance of BaO-added Ni-YSZ cermet electrode was observed with a stable performance over 80 hours operation.Preliminary analysis using secondary ion mass spectrometry (SIMS) indicated possible nickel nitride (NiN) formation in the Ni/YSZ substrate of commercial cells exposed to NH3 and possible degradation mechanisms are considered taking into account the thermodynamics and electrochemical oxidation.This presentation will show the recent progress of this research.