Spark-plasma-sintered barium zirconate based proton conductors for solid oxide fuel cell and hydrogen separation applications

Abstract

Proton conducting ceramics exhibit high levels of bulk proton conductivity at intermediate temperatures (500-700 o C). However, this material class has not been widely utilized in energy conversion and storage applications due to the blocking behavior of the grain boundary proton conduction. A better understanding of proton conduction in these materials requires a systematic study of the sintering conditions that determine microstructure and ultimately the electrical properties. In this work, spark plasma sintering with high heating rates was employed to prepare a state-of-the-art BaZr 0.9 Y 0.1 O 3-δ (BZY) proton conductor for studies focused on the behavior of proton conduction at the grain boundary interfaces. The ceramics prepared by the SPS method resulted in an ultra-fine grain size of approximately 200 nm. The large grain boundary interfacial area was used as a "tool" to investigate the interfacial conduction in these materials systems. Samples displayed a lowered grain boundary conductivity and a higher activation energy compared with the literature results on conventionally prepared materials. The lower bulk conductivity is interpreted with reference to polymorphs of BZY sintered at different temperatures. The combined effect led to a lower total conductivity of the SPS densified BZY ceramics.

Effect of synthesis atmosphere on the proton conductivity of Y-doped barium zirconate solid electrolytes

“…Therefore, the OPM is a suitable alternative to synthesize high quality SOFC electrolytes. Even though most of those methods produced sinteractive ceramic powders, solving the first challenge, comparison of the electrical performance of consolidated powders using those powders is difficult due to different experimental conditions (steam concentration, water adsorption [43,48]) for evaluation of the electrical conductivity.…”

Improved Conductivity of Spark Plasma Sintered Ho-Substituted BaZrO3 Electrolyte Ceramics for IT-SOFCs

“…The maximum total conductivity in 3% humidified O 2 atmosphere is found to be 4.91 × 10 –2 S-cm –1 at 700 °C for BZH20 sample. This result provides the highest-class conductivity among all reported trivalent cation substituted BaZrO 3 ceramics followed spark plasma sintering. − For comparison, this result is presented in Table and therefore, this material is suitable as an electrolyte for IT-SOFCs.…”

X-ray Micro-Computed Tomography: A Powerful Device to Analyze the 3D Microstructure of Anode-Electrolyte in BaZr0.8Y0.2O3 Protonic Ceramic Electrochemical Cells and the Reduction Behavior

“…The major limitation of BZY is its grain boundary resistance that limits its total conductivity [20][21][22]. Moreover, the highly refractive nature of BZY requires high sintering temperatures (1600-1700 • C) and long annealing times (>24 h), to achieve dense membranes with large grains and, hence, increase its performances [23,24].…”