A Low-Lewis-Acid-Strength Cation Cs⁺-Doped Double Perovskite for Fast and Durable Oxygen Reduction/Evolutions on Protonic Ceramic Cells

Abstract

Improving the reaction kinetics and durability of air electrodes on protonic ceramic cells is effective for their commercialization but challenging. Here, we report our electrode design via a low-Lewis-acid-strength cation (Cs+) doping strategy on a double perovskite oxide with a detailed formula of PrBa0.9Cs0.1Co2O5+δ (PBCsC). At 600 °C, the PBCsC electrode demonstrates a low area-specific resistance (ASR) value of 0.3 Ω cm2 within 100 h without significant degradation due likely to the electron pair shift by the polarization distribution of ionic Lewis acid strength at A and B sites. At 650 °C, a full cell with the PBCsC electrode displays an encouraging peak power density of 1.66 W cm–2 in the fuel cell (FC) mode, a high current density of −2.85 A cm–2 (at 1.3 V) in the electrolysis (EC) mode, good operational stability in dual modes of FC and EC, and promising cycling durability of 20 cycles in ∼80 h.

An active and durable air electrode with self-generated nanoparticles decorated on the surface for reversible oxygen-ionic ceramic electrochemical cells

“…2d, the O 1s spectrum likely exhibits four peaks at binding energies of 529, 530, 532, and 534 eV, respectively, corresponding to lattice oxygen (O lat ), high oxidation oxygen (O ho ), adsorbed oxygen (O ads ), and adsorbed water (H 2 O ads ). 46 It has been reported that the ratio of adsorbed oxygen to lattice oxygen can be used to assess the oxygen reaction activity of an electrode material. 47 A higher O ads /O lat ratio may indicate a higher ORR activity accordingly.…”

“…For example, at 800 °C SCN–PSCN shows and values of 1.22 × 10 −3 cm s −1 and 3.73 × 10 −4 cm 2 s −1 , respectively; these values are analogous to recently reported high-performance air electrodes. 13,46 To investigate more details of oxygen reaction kinetics on the SCN–PSCN electrode, we collected EIS of the SCN–PSCN air electrode with different oxygen partial pressures ( p O 2 ) at 700 °C. The EIS measured at different partial pressures of oxygen (Fig.…”

Surface Chemistry Modulation of BaGd0.8La0.2Co2O6−δ As Active Air Electrode for Solid Oxide Cells

“…Owing to its higher mixed ionic-electronic conductivity and oxygen surface exchange coefficient, cobaltite-based perovskite/double perovskite air electrodes such as La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3−δ (LSCF) , and LnBaCo 2 O 5+δ (LnBC, Ln = rare earth metals) − have been extensively researched for use in IT-SOCs. Compared with the state-of-the-art LSCF air electrode, LnBC offers faster oxygen surface exchange and bulk diffusion kinetics.…”

An Active and Contaminants-Tolerant High-Entropy Electrode for Ceramic Fuel Cells

“…To improve the economic competitiveness of SOFCs technology, a general strategy is to reduce the operating temperatures to an intermediate temperature range (600–800 °C). , However, as the operating temperature is reduced, the polarization resistance of electrodes, especially cathodes, is greatly increased, resulting in an insufficient power output of SOFCs at intermediate temperatures. To date, continuous innovative design strategies of perovskite-type cathodes have been applied to develop a series of mixed ionic–electronic conductors (MIECs) with high electrocatalytic activity for the oxygen reduction reaction (ORR), such as La x Sr 1– x Co y Fe 1– y O 3−δ (LSCF), Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3−δ (BSCF), and LnBaCo 2 O 5+δ (Ln = lanthanide elements). , It is generally accepted that typical alkaline-earth metal ions (e.g., Ba 2+ , Sr 2+ , and Ca 2+ ) with larger ionic size and lower oxidation state are often doped into the A-site of perovskite-type oxides to introduce more oxygen vacancies, thus accelerating the ORR kinetics . However, detrimental effects of enrichment or segregation of these alkaline-earth metal elements (driven by the electrostatic interactions and elastic energy minimization) on the cathode surface or the cathode–electrolyte interface under realistic operating conditions have been widely observed and reported .…”