Beijing Key Laboratory of New Energy Material and Technology

Beijing, China

Beijing Key Laboratory of New Energy Material and Technology

Beijing, China

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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 5 more authors.
International Journal of Hydrogen Energy | Year: 2012

A novel dual-phase oxygen permeation membrane based on ion-conducting Ce 0.8Sm 0.2O 2-δ (SDC) and mixed conducting PrBaCo 2O 5+δ (PBCO) is presented. There is no obvious reaction between the two phases under preparation and oxygen permeation conditions. The percolative network of mixed conducting phase PBCO can be formed in SDC-PBCO composite when the ratio of PBCO is not less than 40 vol.%. Above this threshold, the oxygen permeability of SDC-PBCO membrane increases with increasing SDC content. Compared with pure PBCO membrane, the oxygen permeability of percolative SDC-PBCO composites is improved due to the 3D diffusion ability of SDC, which can shorten the tortuosity of the oxygen diffusion path in layered PBCO. The maximum oxygen flux based on 0.6-mm-thick SDC-PBCO (6/4) is 2.38 × 10 -7 mol cm -2 s -1 at 925 °C. The dependence of the oxygen permeation flux on the membrane thickness demonstrates that the bulk diffusion is the limiting step at thickness higher than 0.8 mm and the surface exchange may play an important role when the thickness is below that. Incorporation of SDC into PBCO can not only improve the oxygen permeability but also enhance the structural stability. The SDC-PBCO (6/4) dual-phase membrane is a promising candidate for oxygen separation application. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.


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.


Xie 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 | Chen T.,University of Science and Technology Beijing | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2011

Aluminum doped Sr2MgMoO6-δ (SMMO) was synthesized via citrate-nitrate route. Dense samples of Sr2Mg 1-xAlxMoO6-δ (0 ≤ x ≤ 0.05) were prepared by sintering the pellets at 1500 °C in air and then reducing at 1300 °C in 5%H2/Ar. The electrical conductivity strongly depended on the preparing atmosphere, samples reduced in 5%H2/Ar exhibited higher conductivity than those unreduced. Al-doping increased remarkably the electrical conductivity of Sr2Mg1-xAlxMoO 6-δ. The reduced samples displayed a relatively stable electrical conductivity under oxygen partial pressure (Po2) from 10-19 to 10-14 atm at 800 °C, and exhibited an excellent recoverability in electrical conductivity when cycled in alternative air and 5%H2/Ar atmospheres. Sr2Mg0.95Al 0.05MoO6-δ material showed a good chemical compatibility with LSGM and GDC electrolytes below 1000 °C, while there was an obvious reaction with YSZ. Al-doping improves the anode performance of SMMO in half-cell of Pt/Sr2Mg1-xAlxMoO 6-δGDCPt in H2 fuel. The present results demonstrate that Sr2Mg1-xAlxMoO6-δ is a potential anode material for intermediate temperature-Solid Oxide Fuel Cells (IT-SOFCs). © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.


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.


Xie 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 | Du Z.,University of Science and Technology Beijing | And 5 more authors.
Journal of Physical Chemistry C | Year: 2012

Double-perovskite materials of composition Sr 2Mg 1-xCo xMoO 6-δ (SMCMO, x = 0 to 0.7) were evaluated as potential SOFC anode materials. Their lattice structures, electrical and ionic conductivity, thermal expansion coefficient (TEC), and electrochemical performance were investigated as a function of Co content. Co doping was found to increase the TEC of the Sr 2MgMoO 6-δ material; however, the TEC was within the range of the commonly used La 0.8Sr 0.2Ga 0.8Mg 0.2O 3-δ (LSGM) electrolyte. SMCMO also showed good chemical compatibility with the LSGM electrolyte at temperatures below 1300 °C. Both the electronic and ionic conductivity increased with increasing Co doping. To investigate the effect of Co doping on the conduction properties of SMCMO, we performed first-principle calculations. From these results, the weak Co-O bond is considered to be responsible for the enhanced ionic conductivity of SMCMO materials. The substitution of Co was also found to increase the sinterability of SMCMO, resulting in a decrease in the polarization resistance of the SMMO electrode. Single-cell tests indicated the potential ability of the Co-doped SMMO to be used as SOFC anodes. © 2012 American Chemical Society.


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.


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 | Zhou X.,University of Science and Technology Beijing | And 2 more authors.
International Journal of Hydrogen Energy | Year: 2013

The anode materials La0.3Sr0.7Ti1-xCr xO3-δ (LSTC, x = 0, 0.1, 0.2) with cubic structure were prepared via solid state reaction route. The influence of Cr content on the properties of LSTC as anode and interconnect materials for solid oxide fuel cells (SOFCs) was investigated. The Cr-doping decreased the lattice parameter while increased the sinterability of LSTC materials. The total electrical conductivity decreased with Cr doping level, from 230 S cm-1 for x = 0 to 53 S cm-1 for x = 0.2. The total electrical conductivity exhibited good stability and recoverability in alternative atmospheres of air and 5% H2/Ar, showing excellent redox stability. The cell testing showed that the anode performance of LSTC was enhanced somewhat by Cr doping. The present results indicated that the prepared La0.3Sr 0.7Ti1-xCrxO3-δ can be potential anode and interconnect materials for SOFCs.Copyright © 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights.


Li X.,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 | Zhou X.,University of Science and Technology Beijing | And 4 more authors.
International Journal of Hydrogen Energy | Year: 2010

A-site-deficient (La0.3Sr0.7)1-xTiO 3-δ materials were synthesized by conventional solid-state reaction. The A-site deficiency limit in (La0.3Sr0.7) 1-xTiO3-δ was below 10 mol% in 5%H2/Ar at 1500 °C. A-site deficiency level promoted the sintering process of (La 0.3Sr0.7)1-xTiO3-δ. The ionic conductivity increased but the electronic conductivity decreased with increasing A-site deficiency level. The ionic conductivity of (La0.3Sr 0.7)0.93TiO3-δ sample was as high as 0.2-1.6 × 10-2 S/cm in 500-950 °C and 1.0 × 10 -2 S/cm at 800 °C, over twice of La0.3Sr 0.7TiO3-δ. Its electrical conductivity was in the range of 83-299 S/cm in 50-950 °C and 145 S/cm at 800 °C. A-site deficiency improved the thermal stability of (La0.3Sr 0.7)1-xTiO3-δ and ensured the material with a stable electrical performance in different atmospheres. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.


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.


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.

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