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  • 1.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Semiconductor-ionic Materials for Low Temperature Solid Oxide Fuel Cells2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Solid oxide fuel cell (SOFC) is considered as an attractive candidate for energy conversion within the fuel cell (FC) family due to several advantages including environment friendly, use of non-noble materials and fuel flexibility. However, due to high working temperatures, conventional SOFC faces many challenges relating to high operational and capital costs besides the limited selection of the FC materials and their compatibility issues. Recent SOFC research is focused on how to reduce its operational temperature to 700 ºC or lower. Investigation of new electrolytes and electrode materials, which can perform well at low temperatures, is a comprehensive route to lowering the working temperature of SOFC. Meanwhile, semiconductor-ionic materials based on semiconductors (perovskite/composite) and ionic materials (e.g. ceria based ion conductors) have been identified as potential candidates to operate in low temperature range with adequate SOFC power outputs.

    This investigation focuses on the development of semiconductor-ionic materials for low temperature solid oxide fuel cell (SOFC) and electrolyte-layer free fuel cell (EFFC). The content of this work is divided into four parts:

    First part of the thesis consists of the work on conventional SOFC to build knowledge and bridge from conventional SOFC to the new EFFC. Novel composite electrode (semiconductor) materials are synthesized and studied using established electrochemical and analytical methods such as x-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The phase structure, morphology and microstructure of the composite electrodes are studied using XRD and SEM, and the weight loss is determined using TGA. An electrical conductivity of up to 143 S/cm of as-prepared material is measured using DC 4 probe method at 550 ºC. An electrolyte, samarium doped ceria (SDC) is synthesized to fabricate a conventional three component SOFC device. The maximum power density of 325 mW/cm2 achieved from the conventional device at 550 ºC.

    In the second part of the thesis, semiconductor-ionic materials based on perovskite and composite materials are prepared for low temperature SOFC and EFFC devices. Semiconductor-ionic materials are prepared via nanocomposite approach based on two-phase semiconductor electrode and ionic electrolyte. This semiconductor-ionic functional component was shown to integrate all fuel cell components anode, electrolyte and cathode functions into a single component, i.e. “three in one”, resulting in enhanced catalytic activity and improved SOFC performance.

    The third part of the thesis addresses the development and optimization of the EFFC technologies by studying the Schottky junction mechanism in such semiconductor-ionic type devices. Perovskite and functional nanocomposites (semiconductor-ionic materials) are developed for EFFC devices. Materials characterizations are performed using a number of standard experimental and analytical techniques. Maximum power densities from 600 mW/cm2 up to 800 mW/cm2 have been achieved at 600 ºC.

    Fourth part of the thesis describes the theoretical simulation of EFFCs. In this work, an updated numerical model is applied in order to study the EFFC device, which introduces some modifications to the existing relations for traditional fuel cell models. The simulated V-I and P-I curves have been compared with experimental curves, and both types of curves show a good consistency.

  • 2. Fan, L.
    et al.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    He, C.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Nanocomposites for "nano green energy" applications2017In: Bioenergy Systems for the Future: Prospects for Biofuels and Biohydrogen, Elsevier, 2017, p. 421-449Chapter in book (Refereed)
    Abstract [en]

    The efficient conversion of fuel's chemical energy into electricity in solid oxide fuel cell (SOFC), one of the promising candidates to replace the current combustion process, requires highly active cell components for quick charge transfer and reaction kinetics in the current low-temperature range. Operation at low temperatures enables the deployment of nanostructured materials, while the nanostructured cell components with improved electric properties further assist the reduction of the temperature for given power output. One of the major issues of the single-phase nanoparticle is its aggregation properties under harsh fuel-cell condition, which could be overcome or alleviated by the advanced approaches. Nanocomposite approach not only addresses the instability and some intrinsic issues with the single-phase materials but also brings the interesting synergetic electric properties with multifunctionality. We summarize the research activities in a range of nanocomposite materials in SOFCs in finding the positive roles to improve the cell components (anode, electrolyte, and cathode) electrochemical performances and cell efficiency for green energy applications.

  • 3.
    Liu, Yanyan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Meng, Yuanjing
    Zhang, Wei
    Wang, Baoyuan
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Xia, Chen
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Faculty of Physics and Electronic Science, Hubei University, Wuhan, Hubei 430062, PR China.
    Industrial grade rare-earth triple-doped ceria applied for advanced low-temperature electrolyte layer-free fuel cells2017In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 42, no 34, p. 22273-22279Article in journal (Refereed)
    Abstract [en]

    In this study, the mixed electron-ion conductive nanocomposite of the industrial-grade rare-earth material (Le(3+), Pr3+ and Nd3+ triple-doped ceria oxide, noted as LCPN) and commercial p-type semiconductor Ni0.8Co0.15Al0.05Li-oxide (hereafter referred to as NCAL) were studied and evaluated as a functional semiconductor-ionic conductor layer for the advanced low temperature solid oxide fuel cells (LT-SOFCs) in an electrolyte layer-free fuel cells (EFFCs) configuration. The enhanced electrochemical performance of the EFFCs were analyzed based on the different semiconductor-ionic compositions with various weight ratios of LCPN and NCAL. The morphology and microstructure of the raw material, as prepared LCPN as well the commercial NCAL were investigated and characterized by Xray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive X-ray spectrometer (EDS), respectively. The EFFC performances and electrochemical properties using the LCPN-NCAL layer with different weight ratios were systematically investigated. The optimal composition for the EFFC performance with 70 wt% LCPN and 30 wt% NCAL displayed a maximum power density of 1187 mW cm(-2) at 550 degrees C with an open circuit voltage (OCV) of 1.07 V. It has been found that the well-balanced electron and ion conductive phases contributed to the good fuel cell performances. This work further promotes the development of the industrial-grade rare-earth materials applying for the LTSOFC technology. It also provides an approach to utilize the natural source into the energy field.

  • 4. Lu, Yuzheng
    et al.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei Univ, Peoples R China.
    Wang, Baoyuan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Hubei Univ, Peoples R China.
    Wang, Jun
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Nanotechnology Based Green Energy Conversion Devices with Multifunctional Materials at Low Temperatures2017In: RECENT PATENTS ON NANOTECHNOLOGY, ISSN 1872-2105, Vol. 11, no 2, p. 85-92Article, review/survey (Refereed)
    Abstract [en]

    Background: Nanocomposites (integrating the nano and composite technologies) for advanced fuel cells (NANOCOFC) demonstrate the great potential to reduce the operational temperature of solid oxide fuel cell (SOFC) significantly in the low temperature (LT) range 300-600 degrees C. NANOCOFC has offered the development of multi-functional materials composed of semiconductor and ionic materials to meet the requirements of low temperature solid oxide fuel cell (LTSOFC) and green energy conversion devices with their unique mechanisms. Description: This work reviews the recent developments relevant to the devices and the patents in LTSOFCs from nanotechnology perspectives that reports advances including fabrication methods, material compositions, characterization techniques and cell performances. Conclusion: Finally, the future scope of LTSOFC with nanotechnology and the practical applications are also discussed.

  • 5.
    Mi, Youquan
    et al.
    China Univ Geosci, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Mat, Wuhan 430074, Hubei, Peoples R China..
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. China Univ Geosci, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Mat, Wuhan 430074, Hubei, Peoples R China.
    Zhu, Bin
    China Univ Geosci, Fac Phys & Elect Sci, Hubei Collaborat Innovat Ctr Adv Mat, Wuhan 430074, Hubei, Peoples R China.;Loughborough Univ Technol, Dept Aeronaut & Automot Engn, Fac Mat Sci & Chem, Loughborough LE11 3TU, Leics, England..
    Raza, Rizwan
    COMSATS Inst Informat Technol, Dept Phys, Lahore 54000, Pakistan..
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Riess, Ilan
    Technion Israel Inst Technol, Dept Phys, IL-3200003 Haifa, Israel..
    Experimental and physical approaches on a novel semiconducting-ionic membrane fuel cell2018In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 43, no 28, p. 12756-12764Article in journal (Refereed)
    Abstract [en]

    Semiconducting-ionic membranes (SIMs) have exhibited significant superiority to replace the conventional ionic electrolytes in solid oxide fuel cells (SOFCs). One interesting phenomenon is that the SIMs can successfully avoid the underlying short-circuiting issue and power losses while bringing significantly enhanced power output. It is crucial to understand the physics in such devices as they show distinct electrochemical processes with conventional fuel cells. We first presented experimental studies of a SIM fuel cell based on a composite of semiconductor LiCo0.8Fe0.2O2 (LCF) and ionic conductor Sm-doped CeO2 (SDC), which achieved a remarkable power density of 1150 mW cm(-2) at 550 degrees C along with a high open circuit voltage (OCV) of 1.04 V. Then, for the first time we used a physical model via combining a semiconductor-ionic contact junction with a rectifying layer which blocks the electron leakage to describe such unique SIM device and excellent performance. Current and power are the most important characteristics for the device, by introducing the rectifying layer we described the SIM physical nature and new device process. This work presented a new view on advanced SIM SOFC science and technology from physics.

  • 6. Qiao, Z.
    et al.
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. Hubei University, Wuhan, Hubei, China.
    Cai, Y.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Wang, H.
    Qiao, J.
    Zhu, B.
    Electrochemical and electrical properties of doped CeO2-ZnO composite for low-temperature solid oxide fuel cell applications2018In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 392, p. 33-40Article in journal (Refereed)
    Abstract [en]

    Zinc oxide (ZnO) as a multi-function semiconductor is widely known for photocatalysis and electronic applications but exceptionally new in Solid State Ionics. In this study, a new semiconducting-ionic conductor is reported for solid oxide fuel cells (SOFCs) applications by composing ZnO with an ionic conductor La/Pr co-doped CeO2 (LCP) in various mass ratios. The prepared composites acting as membranes are sandwiched between two Ni0.8Co0.15Al0.05LiO2-δ (NCAL) electrodes to construct fuel cells. A remarkable maximum power output of 1055 mW cm−2 is attained along with a high open circuit voltage (OCV) of 1.04 V at 550 °C by the fuel cell using an optimal composition of 7LCP-3ZnO. The electrical properties of the composites as a function of LCP/ZnO ratio are studied through EIS measurements and polarization curves. It has been found that the composite of 7LCP-3ZnO exhibits a higher ionic conductivity than other composite samples at 475–550 °C, while possessing both high electronic and ionic conduction. Our further investigation also verifies the appreciable protonic conduction in LCP-ZnO, suggesting that the developed composite is a triple O2-/H+/e− conducting material. Additionally, rectification characteristic of the best-performance cell is also measured to interpret the high OCVs and power outputs of LCP-ZnO fuel cells.

  • 7.
    Raza, Rizwan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. COMSATS Institute of Information Technology, Pakistan.
    Ullah, M. K.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Rafique, A.
    Ali, A.
    Arshad, S.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology. Hubei University, China.
    Low-temperature solid oxide fuel cells with bioalcohol fuels2017In: Bioenergy Systems for the Future: Prospects for Biofuels and Biohydrogen, Elsevier, 2017, p. 521-539Chapter in book (Refereed)
    Abstract [en]

    Energy and environmental issues become key factors for sustainable development of society and national economy. Sustainable energy targeting opportunities for economic friendly growth of a country are commonly recognized. The growing interest is focused on the renewable energy resources because of the global energy demands increasing day by day. To meet the demands, an extensive research is aimed to develop sustainable energy devices such as solar cells, rechargeable batteries, and fuel cells. In recent years, solid oxide fuel cell (SOFC) among fuel-cell types has got more attention especially due to its fuel flexibility (e.g., different hydrocarbons, alcohols, and gasoline/diesel), high efficiency, and low emission. Thus, LTSOFC fed by direct bioethanol is receiving considerable attention as a clean, highly efficient for the production of both electricity and high-grade waste heat. These multifuel advantages provide the opportunities to develop an advanced SOFC system especially bioalcohol SOFC systems. This is a very dynamic area for SOFC applications with a promising future. It may create great energy savings and pollution reductions, if the bioalcohol fuel-based-technologies in these applications come into practical use.This chapter is focused on the development of LTSOFC operated by direct bioalcohol (bioethanol and biomethanol) for sustainable development. The content of this chapter is divided into three parts: (i) development of materials, (ii) characterization and analysis, (iii) demonstration of the nanocomposite materials in a bioalcohol FC, and (iv) case studies. Such bioalcohol FC research and development can enhance the use of sustainable/renewable energy for the society, and results achieved for applications have great potential to revolutionize the energy technology in an environmentally friendly and sustainable way.

  • 8. Wang, Baoyuan
    et al.
    Cai, Yixiao
    Xia, Chen
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Kim, Jung-Sik
    Liu, Yanyan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Dong, Wenjing
    Wang, Hao
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Li, Junjiao
    Raza, Rizwan
    Zhu, Bin
    KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID.
    Semiconductor-ionic Membrane of LaSrCoFe-oxide-doped Ceria Solid Oxide Fuel Cells2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 248, p. 496-504Article in journal (Refereed)
    Abstract [en]

    A novel semiconductor-ionic La0.6Sr0.4Co0.2Fe0.8O3-delta (LSCF)-Sm/Ca co-doped CeO2 (SCDC) nanocomposite has been developed as a membrane, which is sandwiched between two layers of Ni0.8Co0.15Al0.05Li-oxide (NCAL) to construct semiconductor-ion membrane fuel cell (SIMFC). Such a device presented an open circuit voltage (OCV) above 1.0 V and maximum power density of 814 mW cm(-2) at 550 degrees C, which is much higher than 0.84 V and 300 mW cm(-2) for the fuel cell using the SCDC membrane. Moreover, the SIMFC has a relatively promising long-term stability, the voltage can maintain at 0.966 V for 60 hours without degradation during the fuel cells operation and the open-circuit voltage (OCV) can return to 1.06 V after long-term fuel cell operation. The introduction of LSCF electronic conductor into the membrane did not cause any short circuit but brought significant enhancement of fuel cell performances. The Schottky junction is proposed to prevent the internal electrons passing thus avoiding the device short circuiting problem.

  • 9.
    Wang, Baoyuan
    et al.
    Hubei Univ, Fac Phys & Elect Sci, Hubei Key Lab Ferro & Piezoelect Mat & Devices, Wuhan 430062, Hubei, Peoples R China..
    Zhu, Bin
    Hubei Univ, Fac Phys & Elect Sci, Hubei Key Lab Ferro & Piezoelect Mat & Devices, Wuhan 430062, Hubei, Peoples R China.;China Univ Geosci, Fac Mat Sci & Chem, Engn Res Ctr Nanogeo Mat, Minist Educ, 388 Lumo Rd, Wuhan 430074, Hubei, Peoples R China..
    Yun, Sining
    Xian Univ Architecture & Technol, Sch Mat & Mineral Resources, Funct Mat Lab, Xian 710055, Shaanxi, Peoples R China..
    Zhang, Wei
    Hubei Univ, Fac Phys & Elect Sci, Hubei Key Lab Ferro & Piezoelect Mat & Devices, Wuhan 430062, Hubei, Peoples R China..
    Xia, Chen
    Hubei Univ, Fac Phys & Elect Sci, Hubei Key Lab Ferro & Piezoelect Mat & Devices, Wuhan 430062, Hubei, Peoples R China..
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Cai, Yixiao
    Donghua Univ, State Key Lab Modificat Chem Fibers & Polymer Mat, Text Pollut Controlling Engn Ctr, Minist Environm Protect,Coll Environm Sci & Engn, 2999 Renmin North Rd, Shanghai 201620, Peoples R China..
    Liu, Yanyan
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Wang, Yi
    Max Planck Inst Solid State Res, Heisenbergstr 1, D-70569 Stuttgart, Germany..
    Wang, Hao
    Hubei Univ, Fac Phys & Elect Sci, Hubei Key Lab Ferro & Piezoelect Mat & Devices, Wuhan 430062, Hubei, Peoples R China..
    Fast ionic conduction in semiconductor CeO2-delta electrolyte fuel cells2019In: NPG ASIA MATERIALS, ISSN 1884-4049, Vol. 11, article id 51Article in journal (Refereed)
    Abstract [en]

    Producing electrolytes with high ionic conductivity has been a critical challenge in the progressive development of solid oxide fuel cells (SOFCs) for practical applications. The conventional methodology uses the ion doping method to develop electrolyte materials, e.g., samarium-doped ceria (SDC) and yttrium-stabilized zirconia (YSZ), but challenges remain. In the present work, we introduce a logical design of non-stoichiometric CeO2-delta based on non-doped ceria with a focus on the surface properties of the particles. The CeO2-delta reached an ionic conductivity of 0.1 S/cm and was used as the electrolyte in a fuel cell, resulting in a remarkable power output of 660 mW/cm(2) at 550 degrees C. Scanning transmission electron microscopy (STEM) combined with electron energy-loss spectroscopy (EELS) clearly clarified that a surface buried layer on the order of a few nanometers was composed of Ce3+ on ceria particles to form a CeO2-delta@CeO2 core-shell heterostructure. The oxygen deficient layer on the surface provided ionic transport pathways. Simultaneously, band energy alignment is proposed to address the short circuiting issue. This work provides a simple and feasible methodology beyond common structural (bulk) doping to produce sufficient ionic conductivity. This work also demonstrates a new approach to progress from material fundamentals to an advanced low-temperature SOFC technology.

  • 10.
    Wang, Xunying
    et al.
    Hubei University Wuhan, China.
    Afzal, Muhammad
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Deng, Hui
    Hubei University Wuhan, China.
    Dong, Wenjing
    Hubei University Wuhan, China.
    Wang, Baoyuan
    Hubei University Wuhan, China.
    Mi, Youquan
    Hubei University Wuhan, China.
    Xu, Zhaoyun
    Hubei University Wuhan, China.
    Zhang, Wei
    Hubei University Wuhan, China.
    Feng, Chu
    Hubei University Wuhan, China.
    Wang, Zhaoqing
    Hubei University Wuhan, China.
    Wu, Yan
    China University of Geosciences Wuhan, China.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    La0.1SrxCa0.9-xMnO3-δ -Sm0.2Ce0.8O1.9 composite material for novel low temperature solid oxide fuel cells2017In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 42, no 27, p. 17552-17558Article in journal (Refereed)
    Abstract [en]

    Lowering the operating temperature of the solid oxide fuel cells (SOFCs) is one of the world R&D tendencies. Exploring novel electrolytes possessing high ionic conductivity at low temperature becomes extremely important with the increasing demands of the energy conversion technologies. In this work, perovskite La0.1SrxCa0.9-xMnO3-δ (LSCM) materials were synthesized and composited with the ionic conductor Sm0.2Ce0.8O1.9 (SDC). The LSCM-SDC composite was sandwiched between two nickel foams coated with semiconductor

    Ni0.8Co0.15Al0.05LiO2- δ (NCAL) to form the fuel cell device. The strontium content in theLSCM and the ratios of LSCM to SDC in the LSCM-SDC composite have significant effects on the electrical properties and fuel cell performances. The best performance has been achieved from LSCM-SDC composite with a weight ratio of 2:3. The fuel cells showed OCV over 1.0 V and excellent maximum output power density of 800 mW/cm2 at 550 ºC. Device processes and ionic transport processes were also discussed.

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