Fluorine-containing oxygen electrodes of the nickelate family for proton-conducting electrochemical cells

In the present work, the anionic doping of a Ba-containing Nd2NiO4+δ mixed conductor is proposed as an efficient means of tuning its functional properties for application as an oxygen/steam electrode material in protonic ceramic electrolysis cells (PCECs). Single-phase Nd1.9Ba0.1NiO4+δFγ (γ = 0, 0.03, 0.05, 0.07 and 0.1) nickelates having a K2NiF4-type structure were prepared and comprehensively characterised in the range from room temperature to 1000 °C. A combination of complimentary techniques, including 4-probe DC electrical measurements, an electron-blocking method, electrochemical impedance spectroscopy and analysis of equivalent circuit schemes and distribution of relaxation times, was employed to reveal the fundamental correlations between electrical properties, oxygen-ionic transport and electrochemical performance of fluorinated nickelates. The highest ionic conductivity in combination with the lowest electrode polarisation resistance was found for the composition with γ = 0.05. The enhanced transport properties of this material were attributed to mixed anion lattice effect. Electrochemical tests of an electrolysis cell based on a proton-conducting BaCe0.5Zr0.3Y0.1Y0.1O3–δ electrolyte with a Nd1.9Ba0.1NiO4+δF0.05 oxygen electrode demonstrated competitive performance compared to state-of-the-art PCECs, thus supporting the prospective viability of the proposed approach.publishe

Electrochemical Activity of Original and Infiltrated Fe-Doped Ba(Ce,Zr,Y)O3-Based Electrodes to Be Used for Protonic Ceramic Fuel Cells

Proton-ceramic fuel cells (PCFCs) are promising devices for electrochemical energy conversion purposes due to their combination of high energy efficiency, environmental friendliness, and high durability. In the present work, the polarization characteristics of promising electrodes for PCFCs based on BaFexCe0.7−xZr0.2Y0.1O3−δ (BCZYFx) are comprehensively studied. Along with the individual BCZYFx electrodes, we investigated a method for improving their electrochemical activity by introducing nanoparticles of PrOx electrocatalysts into the porous structure of the electrode material. According to the experimental data, electroactivation allowed for the polarization resistances of the electrodes at 700 °C to be reduced from 1.16, 0.27, 0.62 Ω°cm2 to 0.09, 0.13, 0.43 Ω°cm2 for x = 0.5, 0.6, and 0.7, respectively. For a PCFC cell with an air electrode of BCZYF0.6 composition activated using PrOx nanoparticles, it was possible to achieve a maximum specific power of 300 mW cm−2 at 750 °C, which is competitive for a single cell with Co-free cathodes. The results obtained provide insight into the processes occurring in the studied electrodes after electroactivation. It is shown how the improvement of electrochemical characteristics of the electrode can be realized by a simple infiltration method in combination with a subsequent thermal treatment

Electrochemical Activity of Original and Infiltrated Fe-Doped Ba(Ce,Zr,Y)O₃-Based Electrodes to Be Used for Protonic Ceramic Fuel Cells

Proton-ceramic fuel cells (PCFCs) are promising devices for electrochemical energy conversion purposes due to their combination of high energy efficiency, environmental friendliness, and high durability. In the present work, the polarization characteristics of promising electrodes for PCFCs based on BaFexCe0.7−xZr0.2Y0.1O3−δ (BCZYFx) are comprehensively studied. Along with the individual BCZYFx electrodes, we investigated a method for improving their electrochemical activity by introducing nanoparticles of PrOx electrocatalysts into the porous structure of the electrode material. According to the experimental data, electroactivation allowed for the polarization resistances of the electrodes at 700 °C to be reduced from 1.16, 0.27, 0.62 Ω°cm2 to 0.09, 0.13, 0.43 Ω°cm2 for x = 0.5, 0.6, and 0.7, respectively. For a PCFC cell with an air electrode of BCZYF0.6 composition activated using PrOx nanoparticles, it was possible to achieve a maximum specific power of 300 mW cm−2 at 750 °C, which is competitive for a single cell with Co-free cathodes. The results obtained provide insight into the processes occurring in the studied electrodes after electroactivation. It is shown how the improvement of electrochemical characteristics of the electrode can be realized by a simple infiltration method in combination with a subsequent thermal treatment