Effect of Alkali Carbonates (Single, Binary, and Ternary) on Doped Ceria: A Composite Electrolyte for Low-Temperature Solid Oxide Fuel Cells

Abstract

Samarium-doped ceria (SDC) carbonate has become an attractive electrolyte for fuel cells because of its remarkable ion conductivity and high performance. Different doped ceria-carbonate (single-carbonate SDC, binary-carbonate SDC, and ternary-carbonate SDC) electrolytes were synthesized by the coprecipitation/oxalate method, to optimize the electrochemical performance. The structure; morphology; and thermal, optical, and surface properties have been studied using a variety of techniques. The X-ray diffraction results confirmed the successful incorporation of samarium into ceria as a crystalline structure and inclusion of carbonate, which is amorphous in nature. To analyze the conduction mechanism, direct current conductivity was measured in a H/O atmosphere. Doped ceria-binary carbonate ((Li/Na)CO-SDC) showed the best conductivity of 0.31 S cm and power density of 617 mW cm, at 600 °C. The enhancement in the ionic conductivity and performance of the composites is due to the contribution of hybrid ions (O, H). The crystallite size of the composites was in the range 21-41 nm. For the calculation of band gaps, optical absorption spectra of the synthesized powders were analyzed, and they showed a red shift with the band gap energy in the range 2.6-3.01 eV, when compared to that of pure ceria (3.20 eV).

New Approach to Improve Ionic Conductivity at Low Temperature by the Decomposition of KHCO3 in the Nanocomposite Electrolyte @

“…All the patterns, which confirm the pure cubic fluorite phase of ceria with Fm m symmetry, were indexed using JCPDS file no.34‐0394. Since the XRD peaks characteristic of the KHCO 3 phase was not observed, it can be assumed that the potassium bicarbonate, coating on LCDC particles, was mostly present in non‐crystalline state, which was reported in the previous studies [17–19] . After attentive examination of XRD in Figure 2 divulging the absence of additional impurities, it is clear that the two cations (Ca 2+ and La 3+ ) were well dissolved in the fluorite‐like lattice.…”

Promising electrochemical study of titanate based anodes in direct carbon fuel cell using walnut and almond shells biochar fuel

“…Binary Carbonate ((Li,Na)2CO3) and doped ceria (SDC) electrolyte named as LN-SDC was prepared using co-precipitation method with molar ratio 2:1. The detailed synthesis steps were described in our previous work [40].…”

Enhanced Ionic Conductivity and Durability of Novel Solid Oxide Fuel Cells by Constructing a Heterojunction Based on Transition and Rare Earth Metal Co-doped Ceria

“…As plotted in Figure d, σ i obtained from EIS is calculated to be 0.124–0.220 S cm –1 in the range of 450 to 550 °C, while σ i obtained from the I–V characteristics is 0.116–0.217 S cm –1 in the same condition. Although the latter σ i is slightly lower than the former one, both of them display remarkable ionic conductivity compared with traditional SOFC. − Activation energy ( E a ) is further acquired by using the following Arrhenius equation Here, the slopes of the Arrhenius plots are related to E a . E a obtained from EIS is calculated to be 0.49 eV, and the one from the I–V characteristics is 0.53 eV, which indicates that the tested electrolyte composite samples are not traditional O 2– conductors due to their ultrahigh ionic conductivity and much lower activation energy .…”