Development of composite LaNi0·6Fe0.4O3-δ-based air electrodes for solid oxide fuel cells with a thin-film bilayer electrolyte

Electrophoretic Deposition and Characterization of the Doped BaCeO3 Barrier Layers on a Supporting Ce0.8Sm0.2O1.9 Solid-State Electrolyte

“…The electrochemical study was performed using a laboratory setup comprising a B2901A precision source/measure unit (Keysight, Colorado Springs, CO, USA) and an RTM3004 oscillograph (Rohde&Schwarz, Munich, Germany) operated by a program written in LabVIEW and a Parstat 3000A potentiostat/galvanostat (Ametek Scientific Instruments, Oak Ridge, TN, USA). To prepare the samples for the electrochemical study, the BCSCuO barrier layers were deposited on one or both sides of the SDC electrolyte disks (relative density of 97–98% and 550 μm in thickness) using polypyrrole or Pt conducting surface coatings and sintered at 1450 °C for 5 h. Then, platinum electrodes with an effective area of 0.204 cm 2 were brushed symmetrically on the opposite sides of the disks and sintered at 900 °C for 2 h. The activation of the platinum electrodes was performed by the infiltration of solutions of Ce and Pr nitrates, as described elsewhere [ 45 ]. The sample was installed in the measuring tubular cell with an internal air electrode and an external hydrogen electrode.…”

“…Then, at 600 °C, the oxidizing atmosphere in the anode channel (outside the tube) was gradually replaced with humidified hydrogen (3% H 2 O, 5 L/h flow rate). The OCV measured by the electrochemical sensor of the measuring cell (the cell description is given in [ 45 ]) was 1127 mV, indicating good settling strength of the sample to be measured. Further, measurements were carried out with the recording of the OCV values on the sample and the impedance spectrum under OCV conditions at 600 °C, 700 °C, and 800 °C.…”

Opportunities, Challenges and Prospects for Electrodeposition of Thin-Film Functional Layers in Solid Oxide Fuel Cell Technology

“…Co-free LaNi 0.6 Fe 0.4 O 3− δ (LNF) perovskite has been reported as having high chemical stability in Cr-containing environments, high electronic conductivity and excellent electrochemical activity in SOFCs with composite air electrodes based on doped ceria [ 57 , 58 , 59 ]. However, LNF tends to react with zirconia-based electrolytes when prepared by conventional solid-state sintering at temperatures above 1000 °C with the formation of a La 2 Zr 2 O 7 insulating layer and it is necessary to introduce a buffer layer to prevent the electrode–electrolyte interaction [ 59 ]. The sintering temperature can be significantly reduced using electrodeposition methods, including modified CAED.…”

Nickel-Containing Perovskites, PrNi0.4Fe0.6O3–δ and PrNi0.4Co0.6O3–δ, as Potential Electrodes for Protonic Ceramic Electrochemical Cells

“…In the present work, we characterize PrNi 0.4 M 0.6 O 3–δ (where M = Fe, Co) compounds as possible electrode materials for PCFCs. The justification for selecting these compositions is based on the parent lanthanum-based perovskite phases, i.e., LaNi 1–x Fe x O 3–δ (LNF), which demonstrate a good combination between thermal expansion and electrical conductivity [ 30 , 31 , 32 , 33 , 34 ]. In detail, LNF exhibit extremely low thermal expansion coefficients (around (11.5–12.5)·10 −6 K −1 [ 30 ]) compared to complex oxides based on simple (Ba 0.5 Sr 0.5 CoO 3–δ , Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3–δ ) or double (GdBaCo 2 O5 5+δ NdBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ ) cobaltites; the thermal expansion coefficients of the latter are much higher, falling in a range of (15–30)·10 −6 K −1 [ 32 ].…”

“…In detail, LNF exhibit extremely low thermal expansion coefficients (around (11.5–12.5)·10 −6 K −1 [ 30 ]) compared to complex oxides based on simple (Ba 0.5 Sr 0.5 CoO 3–δ , Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3–δ ) or double (GdBaCo 2 O5 5+δ NdBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ ) cobaltites; the thermal expansion coefficients of the latter are much higher, falling in a range of (15–30)·10 −6 K −1 [ 32 ]. Along with desirable thermal functions, the total conductivity of LNF attains 200–1000 S cm −1 depending on the iron/nickel ratio [ 33 ]; this allows such materials to be utilized as current collectors instead of the Pt electrodes or as an electronic component of composite materials [ 31 , 34 ]. However, electrochemical performance of the LNF electrodes is insufficient [ 35 ], since they exhibit predominantly electronic behavior instead of mixed ionic–electronic conduction; this fact can be explained by a low oxygen deficiency variation in LNF (3–δ ≈ 3) that provides a negligible amount of oxygen vacancies and, correspondingly, low oxygen-ionic conductivity.…”