Comparison of Different Perovskite Cathodes in Solid Oxide Fuel Cells

Abstract

This study compares the electrochemical performance of three perovskite cathode materials, La0.6Sr0.4Co0.2Fe0.8O3 (LSCF), Ba0.5Sr0.5Co0.2Fe0.8O3 (BSCF), and Sm0.5Sr0.5Co0.2Fe0.8O3 (SSCF), at different operating temperatures, in order to provide optimal operating condition and performance for different solid oxide fuel cells. Among these three cathodes, BSCF has the highest power density of 39 mW cm−2 at 600 °C, 88 mW cm−2 at 650 °C, and 168 mW cm−2 at 700 °C; LSCF has the highest power density of 263 mW cm−2 at 750 °C and 456 mW cm−2 at 800 °C. The cathode overpotentials have the same trend as the power densities. Activation energies for the total cathode area specific resistance (ASR) are calculated to be 0.44 eV, 0.38 eV, and 0.52 eV for the LSCF, BSCF, and SSCF cathodes, respectively. Stability testing of 100 h shows that the open circuit voltages of the LSCF and BSCF cathodes drop 16.1% and 22.9% at 800 °C, respectively, as well as 15.3% and 11.3% at 600 °C, respectively, indicating that the LSCF cathode is more stable at 800 °C while the BSCF cathode is more stable at 600 °C. This work should provide important guidance for the solid oxide fuel cell designs and properties.

A heavily subtituted manganite in an ordered nanocomposite for long-term energy applications

“…Besides the activation energy Ea is decreased by more than 1 eV (≈2.9 eV for stoichiometric LSM and ≈1.8 eV for LSM-SDC), becoming comparable to LSCo (Ea ≈1.5 eV). Please note that, even though much lower values are expected for porous Co-based bulk electrodes, 43 here the relevant comparison is between dense thin films with potential application as functional layers. In Fig.…”

Understanding the effect of water transport on the thermal expansion properties of the perovskites BaFe0.6Co0.3Nb0.1O3−δ and BaCo0.7Yb0.2Bi0.1O3−δ

“…The SOC air electrode must exhibit high electronic and ionic conductivity, mechanical and chemical stability in the temperature range 500 to 950°C and at the oxygen partial pressure of 1 9 10 -5 to 1 atmosphere. Widely studied air electrodes can be divided into two groups: materials which are predominantly electronic conductors like La 1-x Sr x MnO 3-d (LSM) [4] with poor ionic transport properties, and a group of mixed oxygen and electronic conductors (MIEC) such as Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-d (BSCF) [5][6][7] or La 0.6 Sr 0.4-Co 0.2 Fe 0.8 O 3-d (LSCF) [8,9]. The mixed-conducting class of materials also includes a subclass of tripleconducting oxides (TCOs) [10,11] that exhibits high levels of conductivity of three charge carriers: oxygen ions, protons and electron holes (or electrons).…”

Possible Evidence of a Point of Discontinuity (T*) on the Arrhenius Relationship for the Ba0.5Sr0.5Co1-xFexO3-δ Solid Solutions: A Non-Conventional Analysis

“…1a, a single extrapolation model cannot predict adequately the observed 12 experimental data. By contrast, Arrhenius plots of the experimental data reported by Chen et al appear to consist with at least two 12 activation energies at low and high temperature, respectively, like many 17,18 other interesting examples that can be found across the literature. For example, it is evident in Fig.…”

“…As a consequence of the experimental evidence reported in Fig. 4, it can be hypothesized that there exists a kind of non-Arrhenius behavior 12,17,18 (curvature) instead of the common single-step approximation (see Fig. 1 A great and fascinating variety of chemical and physical events occurs at the electrode/electrolyte interface and, among others, here we can cite the following: molecules adsorption, atoms, and molecules diffusion through the electrode/gas interface, surfaces reconstruction or ions rearrangement, electrons transfer between either the electrode and 1,3 electroactive gas species, or to the various interfaces, and so on.…”