Boosting the Electrode Reaction Kinetics of SSOFCs by the Synergistic Effect of Nanoparticle Codecoration on Both the Cathode and Anode
Yang Zhang, Hailei Zhao, Min Zhang, Zhihong Du, Wanbing Guan, Subhash C. Singhal, Konrad Świerczek
Abstract
A novel (SmBa)0.9Mn1.8Co0.2O5+δ (SBMCo) electrode is elaborately designed for symmetrical solid oxide fuel cells (SSOFCs). In operating conditions, the SBMCo material is codecorated with exsolved metallic cobalt for the anode and cobalt oxide for the cathode. The electrochemical impedance spectroscopy (EIS) results combined with distribution of relaxation times (DRT) analysis reveal that the rate-limiting step for hydrogen oxidation at the anode is the adsorbed hydrogen dissociation process, while for the oxygen reduction at the cathode, it is the charge transfer process. The exsolved nanoparticles on the SBMCo backbone of Co and Co3O4 significantly promote the corresponding rate-limiting steps and enable the decorated electrodes to exhibit remarkable catalytic activity toward hydrogen oxidation and oxygen reduction, respectively. When fueled with humidified hydrogen, the constructed symmetrical cell based on the designed SBMCo electrodes with the 300 μm La0.8Sr0.2Ga0.8Mg0.2O3−δ (LSGM) electrolyte-supported configuration delivers an attractive maximum power density of 712 mW cm–2 at 900 °C. The results demonstrate that the elaborate design of the codecorated anode and cathode from a single parent compound is a promising route for the development of candidate electrodes for SSOFCs.