Nanointegrated, High-Performing Cobalt-Free Bismuth-Based Composite Cathode for Low-Temperature Solid Oxide Fuel Cells

Abstract

Cost-effective cathodes that actively catalyze the oxygen reduction reaction (ORR) are one of the major challenges for the technological advancement of low-temperature solid oxide fuel cells (LT-SOFCs). In particular, cobalt has been an essential element in electrocatalysts for efficiently catalyzing the ORR; nevertheless, the cost, safety, and stability issues of cobalt in cathode materials remain a severe drawback for SOFC development. Here, we demonstrated that by appropriate nanoengineering, we can overcome the inherent electrocatalytic advantages of cobalt-based cathodes to achieve comparable performance with a cobalt-free electrocatalyst on a bismuth-based fast oxygen ion-conducting scaffold that simultaneously enhances the performance and stability of LT-SOFCs. Consequently, the peak power density of the SOFCs reaches 1.2 W/cm at 600 °C, highest performance of a cobalt-free-based cathode that has been ever reported. In addition, by the surface-protecting effect of covered nanoelectrocatalysts, the evaporation of highly volatile bismuth is greatly suppressed, resulting in an 80% improvement in performance durability, the best among all reported bismuth-based fuel cells.

Robust in situ exsolved nanocatalysts on perovskite oxide as an efficient anode for hydrocarbon fueled solid oxide fuel cells

“…The other three characteristic peaks (P2, P3 and P4) are closely related to the gas conversion process in the electrodes, such as hydrogen/oxygen adsorption and dissociation and ionization steps. 54–58 As shown in Fig. 6c, all the peak areas for the cell with the LPBM 0.6 F 0.4 –GDC anode are much higher than those for the other single cells, indicating that the LPBM 0.8 F 0.2 –GDC anode exhibits better performance in each anode sub-step reaction process.…”

Recent advances, practical challenges, and perspectives of intermediate temperature solid oxide fuel cell cathodes

“…19, where R1 (red) indicates the process of ion transport, R2 (blue) indicates surface chemical reactions, and R3 (dark yellow) indicates gas diffusion. 306 The intermediate peak R2 associated with surface chemical reactions shows strong dependency on p O 2 and its intensity in DRT plots also shows strong correlation with p O 2 and is considered the rate-limiting step. The above-mentioned examples show that DRT analysis has been successfully employed to deconvolute impedance plots for cases with similar relaxation times, resulting in better understanding of individual electrochemical processes occurring in SOFC cathodes.…”

“…216 The p O 2 dependence of ASR for LSM-i-ESB (LSM-infiltrated ESB (Bi 0.8 Er 0.2 ) 2 O 3 ) at 650 °C shows a dependence value of 0.1 for ASR HF , and dependence of 0.7 for ASR LF . 306 This indicates that ASR LF is related to surface chemical reactions, whereas ASR HF is related to oxygen ion transport between solid phases. In the case of Nd 0.75 Sr 0.25 Co 0.8 Fe 0.2 O 3− δ (NSCF) + LSGM symmetrical cells at low p O 2 range (<0.1 atm), ASR HF showed dependence of 1, and ASR LF showed dependence of 0.24 at 700 °C.…”

Promotion of oxygen reduction and evolution by applying a nanoengineered hybrid catalyst on cobalt free electrodes for solid oxide cells

“…Their chemical stability is limited, which together with the volatilization and diffusion of cobalt during high-temperature sintering cause various cell fabrication issues. [15][16][17] Furthermore, cobalt is price volatile and it may become resource-limited due to the rocketing demand of cobalt oxide for lithium-ion batteries. 16 Finally, it is considered carcinogenic.…”