Composite of calcium cobaltite with praseodymium-doped ceria: A promising new oxygen electrode for solid oxide cells

Boosted electrochemical performance of ca‐cobaltite‐based composite electrodes for reversible solid oxide cells

“…The R p values at 600°C for the C349 and C349/CGO20 electrodes are ~17 and ~2.6 Ω cm 2 , respectively, achieving ~2.6 and ~0.57 Ω cm 2 , respectively, at 700°C. These values are in line with those recently reported for C349 and C349‐based composites 9,12,13,27,30 . Examples of the fitting results can be found in supplementary Figure S1 and Table S1.…”

“…In the case of the composite electrode, small CGO20 particles are dispersed between the C349 platelets (Figure 2A,B). These microstructural features are concurrent to those observed in References 9,13,18,21 for both electrode cells.…”

“…C349‐based films (C349 and C349/CGO20, ca. 40 vol% CGO20) were screen printed on dense CGO10 electrolytes, using 5 deposited layers following a previous methodology 9 . For this purpose, five repeated depositions were performed, with drying steps at ~60°C between each layer.…”

“…Ca 3 Co 4 O 9+ δ (C349) and Ce 0.8 Gd 0.2 O 2− δ (CGO20) powders were obtained as described in Reference 9. The substrates (Ce 0.9 Gd 0.1 O 1.95 , CGO10 [Praxair]) were uniaxially pressed, followed by isostatic pressing at 200 MPa and sintering at 1500°C.…”

“…However, the loss of Sr at the A‐site deteriorates the electrocatalytic activity over time 8 . In addition, a high thermal expansion mismatch with classical electrolytes limits the cell's durability and suitability 9 . Regarding the development of alternative oxygen electrodes for r‐SOCs, the misfit‐layered calcium cobaltite [Ca 2 CoO 3− δ ] 0.62 [CoO 2 ] (or more commonly Ca 3 Co 4 O 9+ δ , C349) has received special attention, given its similar thermal expansion coefficient (TEC, 9‐10 × 10 −6 °C −1 , at 150°C‐820°C 10 ) to that of the Gd‐doped ceria electrolyte (10‐12 × 10 −6 °C −1 , at 30‐1000°C 11 ) and highly favourable surface‐exchange kinetics 10,12,13 .…”