Effect of Two Different ZnO Addition Strategies on the Sinterability and Conductivity of the BaZr_0.4Ce_0.4Y_0.2O_3−δ Proton-Conducting Ceramic Electrolyte

Abstract

A comparative study has been made to relate the effect of different addition strategies for the sintering aid of ZnO (∼1 wt %) on the performance of the BaZr0.4Ce0.4Y0.2O3−δ (BZCY442) electrolyte in order to improve the sinterability and conductivity of this material more efficiently. Two samples, Zn-doped BaCe0.4Zr0.4Y0.15Zn0.05O3−δ (BZCYZn, internal doping) and BZCY–ZnO (BZCY442 mixed with ZnO, external addition), were synthesized. The BZCYZn crystallized at a single phase after sintering at 1350 °C, and the segregation of Y2O3 was observed in BZCY–ZnO in the same conditions. The relative densities of the BZCYZn and BZCY–ZnO samples sintered at 1350 °C for 5 h were 98 and 94%, respectively. The high total conductivity in BZCYZn benefited from the low barrier height at the grain boundary core determined by the Mott–Schottky space charge layer model, which was 0.15 V for BZCYZn and 0.26 V for BZCY–ZnO. A cell with BZCYZn as the electrolyte generated a power density of 414.5 mW cm–2 at 700 °C. The total ionic transport number of BZCYZn was determined to be ∼0.90 at 600 °C under fuel cell conditions.

Dual-phase Yb-doped La2Ce2O7 materials for fuel flexible SOFCs

“…This decrease can be attributed to the higher mobility of holes and proton dehydration in the structure. 50 This phenomenon also extends a possible explanation for the decrease in the OCV value. We performed an EIS of the cell under OCV conditions to isolate the resistance contribution (ohmic resistance, R o ; polarization resistance, R P ) in the constructed cell.…”

“…The MPD of this study is well comparable with the LCO and BZCY-based electrolyte. 5,26,50,52–54 This research demonstrates enhancement in MPD when compared to the La 1.85 Y 0.15 Ce 2 O 7 electrolyte-based SOFC. 31 However, it should be noted that some literatures have reported high performances, which are based on doped LCO; for example, Zhang et al 1 achieved the MPD of 1031 mW cm −2 at 700 °C and Wu et al 8 reported the MPD of 897 mW cm −2 at 700 °C by utilizing La 1.85 Mg 0.15 Ce 2 O 7− δ electrolyte.…”

“…It has been reported in the literature that there exists a comparable potential barrier height at the grain boundary core for proton conducting electrolytes related to BZCY. 50,51…”

“…It has been reported in the literature that there exists a comparable potential barrier height at the grain boundary core for proton conducting electrolytes related to BZCY. 50,51 3.4. EPD of La 1.95 Yb 0.05 Ce 2 O 7 powders Among the ceramics of La 2Àx Yb x Ce 2 O 7 , the highest ionic conductivity is exhibited by La 1.95 Yb 0.05 Ce 2 O 7 (at x = 0.05).…”

A New Composite Proton Conductor as a High-Performance Electrolyte toward Low-Temperature Protonic Ceramic Cells

“…Therefore, lowering their sintering temperature while maintaining high proton conductivity is critical for PCC practical application . Adding sintering aids such as NiO, ZnO, etc., is an effective strategy to increase the sintering activity of BZCY proton conducting electrolytes. − For instance, after adding NiO, BZCY sintered with NiO at 1400 °C has a higher proton conductivity and a comparable relative density to the bare one sintered at 1600 °C . Nonetheless, it usually results in some degree of electronic conductivity, especially at high temperatures.…”