Rare earth Nickelate electrodes containing heavily doped ceria for reversible solid oxide fuel cells

Abstract

The electrochemical performance of composite rare-earth nickelate-rare-earth doped ceria oxygen electrodes, with a high level of rare-earth doping in ceria are reported. Additionally, the chemical stability of these compositions is reported at both the sintering (1240 °C) and operating temperature (800 °C). Specifically, a lanthanum nickelate La 2 NiO 4+δ (LNO) −50 mol% lanthanum doped ceria (LDC50) oxygen electrode and a neodymium nickelate Nd 2 NiO 4+δ (NNO) −50 mol% neodymium doped ceria (NDC50) oxygen electrode are tested in solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) modes and compared to a composite (La 0.75 Sr 0.25 ) 0.95 MnO 3±δ (LSM)-8 mol% yttria stabilized zirconia (YSZ) electrode. The LNO–LDC50 oxygen electrode reaches a current density which is approximately three times that of the LSM-YSZ electrode in SOFC mode at 0.7 V and approximately two times the LSM-YSZ electrode at 1.2 V in SOEC mode. Similarly the NNO-NDC50 oxygen electrode reaches a current density which is approximately two times and approximately one and a half times that of LSM-YSZ at 0.7 V and 1.2 V respectively. Oxygen surface exchange results for LNO and NNO are also reported which show different oxygen exchange kinetics during oxidation versus reduction steps. • Rare-earth nickelate oxygen electrodes have been stabilized and are reversible. • Nickelates show equally good performance in SOFCs and SOECs. • Symmetrical cells provide corroboration of results from full cells.