| 1. |
- Hu, Huiqing, et al.
(författare)
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Fabrication of electrolyte-free fuel cell with Mg0.4Zn0.6O/Ce0.8Sm0.2O2-delta-Li0.3Ni0.6Cu0.07Sr0.03O2-delta layer
- 2014
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Ingår i: Journal of Power Sources. - : Elsevier BV. - 0378-7753 .- 1873-2755. ; 248, s. 577-581
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Tidskriftsartikel (refereegranskat)abstract
- Electrolyte-free fuel cell (EFFC) which holds the similar function with the traditional solid oxide fuel cell (SOFC) but possesses a completely different structure, has draw much attention during these years. Herein, we report a complex of MZSDC LNCS (Mg0.4Zn0.6O/Ce0.8Sm0.2O2-delta-Li0.3Ni0.6Cu0.07Sr0.03O2-delta) for EFFC that demonstrates a high electrochemical power output of about 600 mW cm(-2) at 630 degrees C. The co-doped MZSDC is synthesized by a co-precipitation method. Semiconductor material of LNCS is synthesized by direct solid state reaction. The microstructure and morphology of the composite materials are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive Xray spectrometer (EDS). The performance of the cell with a large size (6 x 6 cm(2)) is comparable or even better than that of the conventional solid oxide fuel cells with large sizes. The maximum power output of 9.28 W is obtained from the large-size cell at 600 degrees C. This paper develops a new functional nanocomposite for EFFC which is conducive to its commercial use.
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| 2. |
- Hu, Huiging, et al.
(författare)
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Time-dependent performance change of single layer fuel cell with Li0.4Mg0.3Zn0.3O/Ce0.8Sm0.2O2-delta composite
- 2014
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 39:20, s. 10718-10723
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Tidskriftsartikel (refereegranskat)abstract
- A Large-size engineering single layer fuel cell (SLFC) consisting of a nano-structured Li0.4Mg0.3Zn0.3O2-delta/Ce0.8Sm0.2O2-delta (LMZSDC) composite with an active area of 25 cm(2) (6 cm x 6 cm x 0.1 cm) is successfully fabricated. The SLFC is evaluated by testing the cell durability with a time-dependent degradation using an H-2 fuel and an air oxidant at 600 degrees C for over 120 h. A maximum power of 12.8 W (512 mW cm(-2)) is achieved at 600 degrees C. In the initial operation stage around 50 h, the cell's performance decreases from 12.8 to 11.2 W; however, after this point, the performance was consistently stable, and no significant degradation is observed in the current density or the cell performance. The device performed excellently at low temperatures with a delivered power output of more than 250 mW cm(-2) at a temperature as low as 400 degrees C. By curve fitting the X-ray photoelectron spectroscopy (XPS) results, the ratio of Ce3+/(Ce3++Ce4+) before and after the long-time operation is analyzed. The ratio increased from 28.2% to 31.4% in the electrolyte which indicates a reduction occurs in the beginning operation that causes an initial performance loss for the device power output and OCV. Electrochemical impedance analyses indicate that the LMZSDC had a high ionic transport, and the device had quick dynamic processes and, thus, a high fuel cell performance. The LMZSDC is a new type of ionic material that has been successfully applied to SLFCs.
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| 3. |
- Abbas, Ghazanfar, et al.
(författare)
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Electrochemical study of nanostructured electrode for low-temperature solid oxide fuel cell (LTSOFC)
- 2014
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Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 38:4, s. 518-523
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Tidskriftsartikel (refereegranskat)abstract
- Zn-based nanostructured Ba0.05Cu0.25Fe0.10Zn0.60O (BCFZ) oxide electrode material was synthesized by solid-state reaction for low-temperature solid oxide fuel cell. The cell was fabricated by sandwiching NK-CDC electrolyte between BCFZ electrodes by dry press technique, and its performance was assessed. The maximum power density of 741.87 mW-cm(-2) was achieved at 550 degrees C. The crystal structure and morphology were characterized by X-ray diffractometer (XRD) and SEM. The particle size was calculated to be 25 nm applying Scherer's formula from XRD data. Electronic conductivities were measured with the four-probe DC method under hydrogen and air atmosphere. AC Electrochemical Impedance Spectroscopy of the BCFZ oxide electrode was also measured in hydrogen atmosphere at 450 degrees C.
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| 4. |
- Chen, Mingming, et al.
(författare)
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Ceria-carbonate composite for low temperature solid oxide fuel cell : Sintering aid and composite effect
- 2014
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 39:23, s. 12309-12316
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the effect of carbonate content on microstructure, relative density, ionic conductivity and fuel cell performance of Ce0.8Sm0.2O1.9-(Li/Na)(2)CO3 (SDC-carbonate, abbr. SCC) composites is systematically investigated. With the addition of carbonate, the nanoparticles of ceria are well preserved after heat-treatment. The relative densities of SCC pellets increase as the carbonate content increases or sintering temperature rises. Especially, the relative density of SCC2 sintered at 900 degrees C is higher than that of pure SDC sintered at 1350 degrees C. Both the AC conductivity and DC oxygen ionic conductivity are visibly improved compared with the single phase SDC electrolyte. Among the composites, SDC-20 wt% (Li/Na)(2)CO3 (SCC20) presents high dispersion, relative small particle size, and the dense microstructure. The optimized microstructure brings the best ionic conductivity and fuel cell performance. It is hoped that the results can contribute the understanding of the role of carbonate in the composite materials and highlight their prospective application.
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| 5. |
- Fan, Liangdong, et al.
(författare)
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Understanding the electrochemical mechanism of the core-shell ceria-LiZnO nanocomposite in a low temperature solid oxide fuel cell
- 2014
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 2:15, s. 5399-5407
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Tidskriftsartikel (refereegranskat)abstract
- Ceria based solid solutions have been considered some of the best candidates to develop intermediate/low temperature solid oxide fuel cells (IT/LT-SOFCs, 600-800 degrees C). However, the barrier to commercialization has not been overcome even after numerous research activities due to its inherent electronic conduction in a reducing atmosphere and inadequate ionic conductivity at low temperatures. The present work reports a new type of all-oxide nanocomposite electrolyte material based on a semiconductor, Li-doped ZnO (LixZnO), and an ionic conductor, samarium doped ceria (SDC). This electrolyte exhibits superionic conductivity (>0.1 S cm(-1) over 300 degrees C), net-electron free and excellent electrolytic performances (400-630 mW cm(-2)) between 480 and 550 degrees C. Particularly, defects related to interfacial conduction and the intrinsic and extrinsic properties of ions are analysed. An internal or interfacial redox process on two-phase particles is suggested as a powerful methodology to overcome the internal short-circuit problem of ceria-based single phase materials and to develop new advanced materials for energy related applications. The combination of the above promising features makes the SDC-LiZnO nanocomposite a promising electrolyte for LTSOFCs.
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| 6. |
- Jing, Yifu, et al.
(författare)
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Enhanced conductivity of SDC based nanocomposite electrolyte by spark plasma sintering
- 2014
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 39:26, s. 14391-14396
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Tidskriftsartikel (refereegranskat)abstract
- Recently, ceria-based nanocomposites have been considered as promising electrolyte candidates for low-temperature solid oxide fuel cells (LTSOFC) due to their dual-ion conduction and excellent performance. However, the densification of these composites remains a great concern since the relative low density of the composite electrolyte is suspected to deteriorate the durability of fuel cell. In the present study, the ionic conductivity of two kinds of SDC-based nanocomposite electrolytes processed by spark plasma sintering (SPS) method was investigated, and compared to that made by conventional cold pressing followed by sintering (normal processing way). The density of solid electrolyte can reach higher than 95% of the theoretical value after SPS processing, while the relative density of the electrolyte pellets by normal processing way can hardly approach 75%. The structure and morphology of the sintered pellets were characterized by XRD and SEM. The ionic conductivity of samples was measured by electrochemical impedance spectroscopy (EIS). The results showed that the ionic conductivity of the two kinds of electrolytes treated with SPS was significantly enhanced, compared with the electrolyte pellets processed through the conventional method. The profile of impedance curve of the electrolytes was altered as well. This study demonstrates that the conductivity of SDC based nanocomposite electrolyte can be further improved by adequate densification process.
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| 7. |
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| 8. |
- Khan, M. Ajmal, et al.
(författare)
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Effect of titania concentration on the grain boundary conductivity of calcium-doped ceria electrolyte
- 2014
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 40:7, s. 9775-9781
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Tidskriftsartikel (refereegranskat)abstract
- A solid-state technique was used to synthesize ceria-based (CDC-xT, in which x=0-1 mol%) solid electrolyte ceramics. The effects of doping the ceramic solid electrolyte (CDC) with titanium oxide were studied with regard to densification, crystal structure, morphology, electro-impedance spectroscopy and fuel cell performance. TiO2 doping afforded materials a 95% relative density at 940 degrees C, approximately 200 degrees C lower than the temperature required without titanium oxide. The addition of titanium oxide (TiO2) reduced the CDC sintering temperature and significantly improved the grain boundary conduction. The minimum grain boundary resistivity was obtained at 0.8 mol% TiO2. X-ray diffraction (XRD) results showed that the lattice parameters enhanced with increased titanium oxide concentrations up to 0.8 mol%, revealing the solubility limit for Caria's fluorite structure. The optimum doping level (0.8 mol%) is provided maximum conductivity. Conductivities were measured using EIS (Electrochemical Impedance Spectroscopy) with a two-probe method, and the activation energies were calculated using the Arrhenius plots. The maximum power density (660 mW/cm(2)) was achieved with CDC 0.8T electrolyte at 650 degrees C using LiCuZnNi oxide electrodes.
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| 9. |
- Ma, Ying, et al.
(författare)
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Study on GDC-KZnAl composite electrolytes for low-temperature solid oxide fuel cells
- 2014
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 39:30, s. 17460-17465
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Tidskriftsartikel (refereegranskat)abstract
- Development of low-temperature solid oxide fuel cells (LTSOFC) is now becoming a mainstream research direction worldwide. The advancement in the effective electrolyte materials has been one of the major challenges for LTSOFC development. To further improve the performance of electrolyte, composite approaches are considered as common strategies. The enhancement on ionic conductivity or sintering behavior ceria-based electrolyte can either be done by adding a carbonate phase to facilitate the utilization of the ionic-conducting interfaces, or by addition of alumina as insulator to reduce the electronic conduction of ceria. Thus the present report aims to design a composite electrolyte materials by combining the above two composite approaches, in order to enhance the ionic conductivity and to improve the long-term stability simultaneously. Here we report the preparation and investigation of GDC-KAlZn materials with composition of Gd doped ceria, K2CO3, ZnO and Al2O3. The structure and morphology of the samples were characterized by XRD, SEM, etc. The ionic conductivity of GDC-KAlZn sample was determined by impedance spectroscopy. The composite samples with various weight ratio of GDC and KAlZn were used as electrolyte material to fabricate and evaluate fuel cells as well as investigate the composition dependent properties. The good ionic conductivity and notable fuel cell performance of 480 mW cm(-2) at 550 degrees C has demonstrated that GDC-KAlZn composite electrolyte can be regarded as a potential electrolyte material for LTSOFCs.
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| 10. |
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