Ln2MO4 cathode materials for solid oxide fuel cells

Abstract

One of the major challenges to develop "intermediate temperature" solid oxide fuel cells is finding a novel cathode material, which can meet the following requirements: (1) high electronic conductivity; (2) chemical compatibility with the electrolyte; (3) a matched thermal expansion coefficient (TEC); (4) stability in a wide range of oxygen partial pressure; and (5) high catalytic activity for the oxygen reduction reaction (ORR). In this short review, a survey of these requirements for K 2 NiF 4 -type material with the formula Ln 2 MO 4 , Ln = La, Pr, Nd, Sm; M = Ni, Cu, Fe, Co, Mn, is presented. The composition-dependent TEC, electrical conductivity and oxygen transport property are considered. The Ln 2 MO 4 materials exhibit improved chemical stability and compatibility with most of the traditional electrolytes. The complete fuel cells integrated with Ln 2 MO 4 materials as cathodes show promising results. Furthermore, these materials are considered as cathodes of protonic ceramic fuel cell (PCFC), and/or anodes of high temperature steam electrolysis (HTSE). First results show excellent performances. The versatility of these Ln 2 MO 4 materials is explained on the basis of structural features and the ability to accommodate oxygen nonstoichiometry.intermediate temperature solid oxide fuel cells (ITSOFCs), cathode, K 2 NiF 4 -type structure, oxygen non-stoichiometry

Evaluation of Ln2CuO4 (Ln: La, Pr, Nd) oxides as cathode materials for IT-SOFCs

“…Using mass relaxation technique it was possible to simultaneously evaluate D and K in 600-900 8C temperature range. Activation energy of D was calculated to be 0.13 (2) eV. Results of chemical stability studies in relation to Ce 0.8 Gd 0.2 O 1.9 electrolyte revealed moderately good chemical compatibility of Pr 2 CuO 4 oxide, while La 2 CuO 4 and Nd 2 CuO 4 stability proved to be insufficient.…”

“…High temperature XRD data revealed anisotropic thermal expansion of Pr 2 CuO 4 , smaller along c-axis. Based on reduction experiments performed on TG apparatus, the initial slight oxygen excess d present in the compounds at room temperature was evaluated: La 2 CuO 4.03 (2) , Pr 2 CuO 4.05 (2) and Nd 2 CuO 4.04 (2) . Additionally, it was observed that up to 900 8C in air the oxygen content in the materials does not change considerably.…”

Evaluation of LaxSr2−xFeO4 layered perovskite as potential electrode materials for symmetrical solid oxide fuel cells

“…Most of the compounds with K 2 NiF 4 structure have the ability to accommodate large amount of M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 3 interstitial oxygen ions or generate loss of oxygen vacancies. These advantages make Ln 2 MO 4 as good candidates as cathodes for SOFCs [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. However, only La 0.6 Sr 1.4 MnO 4 was reported to be a promise anode for SOFCs [28] and potential symmetrical electrode for SSOFCs [29] which showed a maximum power density of 59 mW cm -2 at 800 0 C (H 2 as a fuel).…”

A study of nonstoichiometric oxides in the Ln-Ni-O (Ln=La, Pr, Nd) system

“…The mentioned above oxide compositions have potential to be used in microelectronics, catalysis and sensor technology [1][2][3][4]. Most of the rare-earth elements form only RNiO3 compositions.…”