Low temperature solid oxide fuel cells with hierarchically porous cathode nano-network

Chen, Yu; Lin, Ye; Zhang, Yanxiang; Wang, Siwei; Su, Dong; Yang, Zhibin; Han, Min−Koo; Chen, Fanglin

doi:10.1016/j.nanoen.2014.05.010

Cited by 158 publications

(85 citation statements)

References 29 publications

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“…[ 35,36,[74][75][76][77] During the past several decades, numerous strategies have been investigated to increase the performance of SOFC cathode at reduced temperatures, from new materials development to advanced synthesis and microstructural optimization. [ 30,53,[78][79][80][81][82][83][84][85] To date, there are a number of good reviews that focus on electrodes for oxygen reduction reaction (ORR) in SOFCs, as listed in Table 1 . [86][87][88][89][90][91][92][93][94] The contents of these reviews can be classifi ed into three categories: ORR mechanisms, more active electrode materials, and nanostructured cathodes via infi ltration processes.…”

Section: Reviewmentioning

confidence: 99%

Advances in Cathode Materials for Solid Oxide Fuel Cells: Complex Oxides without Alkaline Earth Metal Elements

Chen

Zhou

Ding

et al. 2015

Advanced Energy Materials

250

155

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Solid oxide fuel cells (SOFCs) represent one of the cleanest and most efficient options for the direct conversion of a wide variety of fuels to electricity. For example, SOFCs powered by natural gas are ideally suited for distributed power generation. However, the commercialization of SOFC technologies hinges on breakthroughs in materials development to dramatically reduce the cost while enhancing performance and durability. One of the critical obstacles to achieving high‐performance SOFC systems is the cathodes for oxygen reduction reaction (ORR), which perform poorly at low temperatures and degrade over time under operating conditions. Here a comprehensive review of the latest advances in the development of SOFC cathodes is presented: complex oxides without alkaline earth metal elements (because these elements could be vulnerable to phase segregation and contaminant poisoning). Various strategies are discussed for enhancing ORR activity while minimizing the effect of contaminant on electrode durability. Furthermore, some of the critical challenges are briefly highlighted and the prospects for future‐generation SOFC cathodes are discussed. A good understanding of the latest advances and remaining challenges in searching for highly active SOFC cathodes with robust tolerance to contaminants may provide useful guidance for the rational design of new materials and structures for commercially viable SOFC technologies.

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Section: Reviewmentioning

confidence: 99%

Advances in Cathode Materials for Solid Oxide Fuel Cells: Complex Oxides without Alkaline Earth Metal Elements

Chen

Zhou

Ding

et al. 2015

Advanced Energy Materials

250

155

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“…The LSCF fiber we selected for SOFC cathode is the one generated by electrospinning LSCF precursor with concentration of Reducing the operating temperature of solid oxide fuel cells (SOFCs) to below 650 °C has the potential to significantly reduce the cost (because of a wider selection of less expensive component materials) while enhancing the durability and reliability of SOFC systems. [12][13][14] However, application of nanostructured materials is often limited due to their structural and morphological wileyonlinelibrary.com 1 mmol nitrates in 4 mL N,N-dimethylformamide (DMF), and 6 wt% polyacrylonitrile (PAN). Enhancing the performance of SOFCs at intermediate temperatures (IT) has been a grand challenge for the development of a new generation of low-cost and durable IT-SOFCs.…”

Section: Doi: 101002/aenm201601890mentioning

confidence: 99%

A Highly Efficient and Robust Nanofiber Cathode for Solid Oxide Fuel Cells

Chen

Zhang

et al. 2016

Advanced Energy Materials

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129

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instability. [10] Very recently, 1D nanofiber cathode has shown both enhanced ORR activity and good thermal stability at the operating temperatures. [15][16][17] Moreover, such unique electrode architectures have the advantages of high porosity, good connectivity, and continuous pathway for charge and mass transport. [12,17,18] For example, a cathode composed of nanofibers of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF) and nanoparticles of Gd 0.1 Ce 0.9 O 2 (GDC) demonstrated a peak power density of about1.33 W cm −2 at 800 °C. [17] Further, the use of nanofibers in other work has also showed a reduction in polarization resistance or enhancement in cell performance. [19,20] However, the main concern is that the nanofibers/nanoparticles may not survive at the high operating temperature (750-800 °C) for a long period of time. Further, the nanofiber structure is hard to maintain when a ball-milling process is used for the preparation of electrode ink.In this communication, we report a unique cell design, consisting of a Ni-BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) anode, a GDC electrolyte, and an LSCF fiber cathode, to demonstrate a high-performance, low-temperature (LT)-SOFC. At 600 °C, the cell exhibits an OCV of 1.03 V, a peek power density of ≈0.62 W cm −2 , and a reliable long-term stable performance for 450 h at a constant voltage of 0.7 V when humidified H 2 (3 vol% water vapor) was used as fuel and ambient air as oxidant. Figure 1a schematically shows the fabrication of LSCF fiber mats by electrospinning the precursor solution of LSCF. The fiber mat shows a continuously connected fibrous network (Figure 1b), which was then fired at 950 °C and dispersed in acetone/V006 (mass ratio of 5:1), with a solid loading of 5 wt%. To fabricate a fiber-based cathode, 75 µL of the fiber slurry was then drop-coated on an electrolyte surface (in three times) using a syringe. Figure 1c shows some typical X-ray diffraction (XRD) patterns of a commercial LSCF powder and the LSCF fiber after firing in air at 800 °C for 2 h, suggesting that the phase of the LSCF fiber is similar to that of the commercial LSCF powder (no observable impurities). Figure 1d shows the typical transmission electron microscopy (TEM) images of the porous nanofibers after firing; the diameters of the fibers are ≈200 nm. It is also noted that the fibers are composed of LSCF nanoparticles with sizes of ≈50 nm and pores of ≈50 nm, as revealed by the Scanning Transmission Electron Microscope (STEM) image (inset). Figure 1e is an electron energy-loss spectroscopy (EELS) spectrum from a spot (≈1 nm in diameter) on the fiber in which peaks of O, Fe, Co, and La elements are clearly seen (Sr is out of the range). In addition, the EELS profile scanning (Figure 2f) from the red line in Figure 1d inset indicated a relatively uniform distribution of the elements in the LSCF nanofiber. The LSCF fiber we selected for SOFC cathode is the one generated by electrospinning LSCF precursor with concentration of Reducing the operating temperature of solid oxide fuel cells (SOFCs...

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“…The results that are obtained open interesting perspectives in the field of thermal properties of nanoporous semiconductors and are likely to be useful in the manufacturing of novel sensors or nanofuel cells [26,27]. In relation with the subject discussed in this paper, a new domain of increasing interest is that of thermal rectifiers [28][29][30].…”

Section: Discussionmentioning

confidence: 84%

Size and porosity effects on thermal conductivity of nanoporous material with an extension to nanoporous particles embedded in a host matrix

Machrafi

Lebon

2015

Physics Letters A

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Abstract.A formula for the effective thermal conductivity of nanoporous media is derived, following a thermodynamic approach. An extension to nanocomposites composed of a homogeneous matrix wherein porous nanoparticles are dispersed is proposed as well. The originality of the model is that it is based on extended irreversible thermodynamics, a theory specifically designed for sub-scaled systems. Two different situations are discussed, in the first one, nanoporous silicon with spherical porous inclusions of micro, meso and macro-dimension respectively is considered. The description is validated by comparison with experimental data and five other models. Analysis of the results shows an excellent agreement of our theoretical approach with experiments in the whole range of porous radii, from 2 to 100 nm. In the second part of the work, thermal conductivity of porous silicon nanoparticles embedded in a germanium host matrix is investigated. The coupled influence of the pore and nanoparticles sizes is emphasized.Keywords: nanoporous media, thermal conductivity, phonon scattering, extended thermodynamics IntroductionThe effect of porosity is to decrease considerably the thermal conductivity of crystalline materials, as is observed, for instance, in nanoporous silicon [1][2][3][4][5]. This lowering property has been widely exploited with the objective to reinforce thermal insulation in several systems as microsensors, integrated circuits, semiconductor devices. It has therefore fostered an increasing interest during the last decade. Thermal properties of nanoporous media are generally investigated by referring to, for instance, kinetic theory of phonons [3], molecular simulations [5], Monte Carlo simulations [6], two-component materials [7] or hydrodynamic models [8]. In this work, we take a different route and prefer a thermodynamic approach. To be explicit, we will base our study on extended irreversible thermodynamics (EIT) [9,10], which is a formalism specifically dedicated to the treatment of micro and nano systems and highfrequency processes. For the sake of completeness, the present analysis will be compared to other theoretical models and experimental data.Nanoporous materials are generally made out of a homogeneous matrix wherein nanopores are dispersed. In that respect, such systems are similar to nanocomposites, wherein nanoparticles are embedded in a matrix, the difference being that nanoparticles are replaced by nanopores. A great deal of papers have been devoted to the problem of heat transport in nanofluids and nanocomposites, see for instance the review paper by Michaeledis [11]. In particular, the problem of the overall heat conductivity of the system as a function of the volume fraction of the nanoparticles and their size has drawn much attention. Our purpose in the present work is twofold. Firstly, it is the purpose to study the role of porosity and the size of the pores on the heat conductivity of porous systems, like nanoporous silicon, via our thermodynamic formalism. Secondly, we examine, using t...

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Low temperature solid oxide fuel cells with hierarchically porous cathode nano-network

Cited by 158 publications

References 29 publications

Advances in Cathode Materials for Solid Oxide Fuel Cells: Complex Oxides without Alkaline Earth Metal Elements

Advances in Cathode Materials for Solid Oxide Fuel Cells: Complex Oxides without Alkaline Earth Metal Elements

A Highly Efficient and Robust Nanofiber Cathode for Solid Oxide Fuel Cells

Size and porosity effects on thermal conductivity of nanoporous material with an extension to nanoporous particles embedded in a host matrix

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