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Zhang C.,University of Science and Technology Beijing | Zhao H.,University of Science and Technology Beijing | Zhao H.,Beijing Key Laboratory of New Energy Material and Technology
Solid State Ionics | Year: 2010

The electrical conduction behavior of Sr substituted proton conductor Ba1 - xSrxCe0.9Nd0.1O 3 - δ (x = 0-0.2) synthesized via citrate-nitrate method was investigated by various concentration cell measurements and electrochemical impedance spectroscopy. The structural distortion with Sr substitution obviously decreased the oxygen ion contribution but increased the proton and total ion transference number in both hydrogen-rich and oxygen-rich atmospheres. The increasing structural distortion with Sr content led to a significant decrease in oxygen ion conductivity, whilst slightly reducing proton conductivity. Sr substituted BaCeO3-based compounds seem to be good proton conductors with further modification of the proton conductivity. © 2010 Elsevier B.V. All rights reserved. Source


Chen J.,University of Science and Technology Beijing | Zhao H.,University of Science and Technology Beijing | Zhao H.,Beijing Key Laboratory of New Energy Material and Technology | He J.,University of Science and Technology Beijing | Wang J.,University of Science and Technology Beijing
Rare Metals | Year: 2011

A Si/MgO composite anode material was prepared by a simple magnesium reduction process using silicon oxide and magnesium as starting reactants. The feasibility of this process is discussed from the thermodynamic viewpoint. The resultant composite material is mainly composed of Si and MgO components. MgO, acting as a buffer layer, can accommodate the large volume change of active Si during the charge/discharge process, thus the cycling stability is improved. Electrochemical tests demonstrate that the first charge and discharge capacities of the synthesized Si/MgO composite anode are ca. 1380 and 1046 mAh.g -1, respectively, with an initial coulomb efficiency of ca. 76%. The magnesium reduction process provides a novel idea for the synthesis of Si-based anode materials. © The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg 2011. Source


Du Z.,University of Science and Technology Beijing | Zhao H.,University of Science and Technology Beijing | Zhao H.,Beijing Key Laboratory of New Energy Material and Technology | Shen Y.,University of Science and Technology Beijing | And 4 more authors.
Journal of Materials Chemistry A | Year: 2014

Perovskites La0.3Sr0.7Ti1-xCo xO3 (LSTCs, x = 0.3-0.6) are systematically evaluated as potential cathode materials for solid oxide fuel cells. The effects of Co substitution for Ti on structural characteristics, thermal expansion coefficients (TECs), electrical conductivity, and electrochemical performance are investigated. All of the synthesized LSTCs exhibit a cubic structure. With Rietveld refinement on the high-temperature X-ray diffraction data, the TECs of LSTCs are calculated to be 20-26 × 10-6 K-1. LSTC shows good thermal cycling stability and is chemically compatible with the LSGM electrolyte below 1250 °C. The substitution of Co for Ti increases significantly the electrical conductivity of LSTC. The role of doping on the conduction behavior is discussed based on defect chemistry theory and first principles calculation. The electrochemical performances of LSTC are remarkably improved with Co substitution. The area specific resistance of sample La 0.3Sr0.7Ti0.4Co0.6O3 on the La0.8Sr0.2Ga0.8Mg0.2O 3-δ (LSGM) electrolyte in symmetrical cells is 0.0145, 0.0233, 0.0409, 0.0930 Ω cm2 at 850, 800, 750 and 700 °C, respectively, and the maximum power density of the LSGM electrolyte (400 μm)-supported single cell with the Ni-GDC anode, LDC buffer layer and LSTC cathode reaches 464.5, 648, and 775 mW cm-2 at 850 °C for x = 0.3, 0.45, and 0.6, respectively. All these results suggest that LSTC are promising candidate cathode materials for SOFCs. 2014 This journal is © the Partner Organisations. Source


Chen T.,University of Science and Technology Beijing | Zhao H.,University of Science and Technology Beijing | Zhao H.,Beijing Key Laboratory of New Energy Material and Technology | Xie Z.,University of Science and Technology Beijing | And 3 more authors.
Journal of Power Sources | Year: 2013

Dual-phase oxygen permeation membrane has become much attractive due to its tailorable properties. On the premise of forming percolative network separately, decreasing the volume percentage of electronic conducting phase can increase the oxygen permeability of dual-phase membrane. However, the conventional ceramic route limits the decrease in threshold of the content of electronic conducting phase. In this work, a coating strategy is employed to fabricate a novel dual-phase membrane with 20 vol.% PrBaCo 2O 5+δ (PBCO) dispersing in 80 vol.% Ce 0.8Sm 0.2O 2-δ (SDC) matrix, where the fiber-shaped PBCO forms percolative network and provides sufficient electronic conductivity. The prepared SDC-PBCO membrane with 1 mm thickness exhibits very high oxygen permeability, 3.81 × 10 -7 mol cm -2 s -1 at 940 °C, due to the high volume percentage of SDC. This preparation strategy can be applied to other dual-phase membranes to improve the oxygen permeation performance. © 2012 Elsevier B.V. All rights reserved. Source


Zhang C.,University of Science and Technology Beijing | Zhao H.,University of Science and Technology Beijing | Zhao H.,Beijing Key Laboratory of New Energy Material and Technology
Electrochemistry Communications | Year: 2011

A novel cathode material BaCe 0.4Sm 0.2Co 0.4O 3-δ composed of two phases BaCe 1-x(Sm/Co) xO 3-δ and BaCo 1-x(Sm/Ce) xO 3-δ was prepared in situ via the citric-nitrate route and its performance as cathode material for proton conducting solid oxide fuel cell (SOFC-H) was characterized. BaCe 0.4Sm 0.2Co 0.4O 3-δ exhibited simultaneous protonic, electronic, and oxygen ionic conduction in air, leading to a good electrode performance. The polarization resistance of the novel cathode material in symmetrical cell was 0.36 Ω cm 2 with Pt as the current collector at 700 °C in wet air. The electrode performance can be further improved through microstructure optimization. It also showed good thermal expansion compatibility with BaCe 0.8Sm 0.2O 3-δ electrolyte over a 100 h duration test. BaCe 0.4Sm 0.2Co 0.4O 3-δ is a promising cathode material for SOFC-H. © 2011 Elsevier B.V. All Rights Reserved. Source

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