China
Africa
Explore chapters and articles related to this topic
Fundamental Aspects of Solid Oxide Fuel Cells
Published in Radenka Maric, Gholamreza Mirshekari, Solid Oxide Fuel Cells, 2020
Radenka Maric, Gholamreza Mirshekari
The SOFC structure generally consists of a dense solid-state oxygen-ion-conducting electrolyte sandwiched between two porous electrodes (i.e., anodes and cathodes). Figure 1.1 shows a schematic diagram of SOFC. Hydrogen fuel is fed to the anode side in which hydrogen is combined with the oxygen, from the air, entering the cell through the cathode side. On the anode side, the hydrogen-containing fuel burns which results in a drastic reduction of the oxygen concentration on the cathode side. The oxygen ions, passing through the crystal lattice of the ceramic electrolyte [e.g., yttria-stabilized zirconia (YSZ)], react with the oxidized fuel, thereby producing electrons. The generated electrons then pass through the external circuit (from the anode to the cathode). Pure water and heat are the only byproducts of this process. The SOFC reactions are as follows:
Fundamentals of Water Electrolysis
Published in Lei Zhang, Hongbin Zhao, David P. Wilkinson, Xueliang Sun, Jiujun Zhang, Electrochemical Water Electrolysis, 2020
Xiaoxia Yan, Rida Javed, Yanmei Gong, Daixin Ye, Hongbin Zhao
Solid oxide electrolysis was developed in the 1970s by General Electric and Brookhaven National Laboratory, followed by Dornier in Germany. In recent years, a solid oxide electrolyzer cell (SOEC) is composed of an anode and cathode separated by an O2− conducting electrolyte. Yttria-stabilized zirconia, Ni-yttria-stabilized zirconia, and lanthanum strontium manganite-yttria-stabilized zirconia are generally used as the electrolyte, anode, and cathode respectively. The reactions at the electrodes are24: H2O+2e−→H2+2O2−(Cathode)O2−→(1/2)O2+2e−(Anode)
Electrochemistry of Mixed Ionic–Electronic Conductors
Published in P.J. Gellings, H.J.M. Bouwmeester, Electrochemistry, 2019
La0.6 A0.4 Co0.8 Fe0.2 O3−δ (A=La,Ca,Sr) and La0.6 Sr0.4 Co0.8 B0.2 O3−δ (B=Fe,Co,Ni,Cu) are excellent MIECs exhibiting high metallic conductivity. The oxygen ionic conductivity, though a few orders of magnitude lower, is also high compared with other ionic conductors.101,102 The ionic conductivity is of the order of that of yttria-stabilized zirconia. It is reasonable to assume that these compounds fit the model “n = zNi” as the concentration of quasi-free electrons and of Vo⋅⋅ are expected to be of the order of unity per formula and therefore of the same order of magnitude. The electronic conductivity is then much higher than the ionic one because of a large difference in the mobilities, with ve ⪢ vi.
Preparation of yttria-stabilized zirconia film from an aqueous nano-grain suspension for solid electrolyte
Published in Journal of Dispersion Science and Technology, 2019
Fitria Rahmawati, Andini Pratiwi, Witri W. Lestari
Nano-yttria-stabilized zirconia (nano YSZ) was prepared through solid state reaction by mix the prepared nano-zirconia and nano-yttrium dioxide powder. A stoichiometric calculation found for yttrium doping to ZrO2 to produce 0.08 mol vacancies, VO••, was 0.55 mass ratio of ZrO2 to Y2O3. It would produce 8 mol% yttria-stabilized zirconia, 8YSZ. Due to the purity of zirconia powder that was synthesized from zircon sand is 72% as explained in our previous publication.[27] Therefore, for 1 g ZrO2 must be mixed minimum with 1.31 g Y2O3. In this research 1.36 g Y2O3 was used to ensure complete substitution Zr4+ atomic ion lattice with Y3+, YZr′. The mixture was then crushed by hand in an agate mortar for 2 hours, and heated at 1000 °C for 2 hour. The produced yellow-white powder was then analyzed by XRD (Rigaku Miniflex 600 Benchop), to understand its characteristic diffraction peaks by comparing with a YSZ diffraction standard. Crystal structure analysis was conducted by Le Bail method refinement with RIETICA software (a free edition). Surface morphology by SEM analysis (JEOL JED-2300 series) equipped with MeasureIT software (a free edition) for particle size analysis, and also equipped with EDX for point elemental analysis. The functional group analysis was conducted with Fourier Transform Infrared (Prestige-21 Shimadzu).
Wettability of liquid caesium iodine and boron oxide on yttria-stabilized zirconia
Published in Journal of Nuclear Science and Technology, 2018
Hiroto Ishii, Ken Kurosaki, Yukihiro Murakami, Yuji Ohishi, Hiroaki Muta, Masayoshi Uno, Shinsuke Yamanaka
In the present study, we investigated the effects of the lattice direction and the surface roughness on the wettability of liquid CsI by the sessile drop test. Yttria-stabilized zirconia (YSZ) was used as the solid. YSZ possesses the CaF2-type crystal structure which is the same as UO2. The YSZ single crystallines with (100) and (111) planes and the polycrystalline YSZ pellets were selected as the solid samples. Additionally, the same experiments were done for boron oxide (B2O3) instead of CsI to confirm the difference in the wettability to the same solid. The main reasons why B2O3 was selected are (1) a large amount of boron exists in the molten fuel and (2) the surface energy of liquid B2O3 is similar to that of liquid CsI. Furthermore, B2O3 possesses relatively low melting temperature with high chemical stability which allows us to handle it easily.
Local heat transfer enhancement by recirculation flows for temperature gradient reduction in a tubular SOFC
Published in International Journal of Green Energy, 2022
Zezhi Zeng, Changkun Hao, Bingguo Zhao, Yuping Qian, Weilin Zhuge, Yuqing Wang, Yixiang Shi, Yangjun Zhang
Here, V and τ denote volume fraction and tortuosity. The subscript e and l denote SOFC electrode and electrolyte. The electrolyte material in this study is yttria-stabilized zirconia (YSZ). The anode is made from nickel and YSZ, while the cathode is made from strontium doped lanthanum manganite and YSZ. The electronic conductivities of nickel and strontium doped lanthanum manganite are calculated from Eqs. (13) and (14), while the ionic conductivity of the electrolyte is calculated from Eq. (15).