Biography:

Klaus D. Becker studied Physics at the University of Göttingen, Germany, where he received his PhD in Physical Chemistry in 1972, Subsequently, he held positions at the University of Bochum and later on at the University of Hannover. In 1995, he was appointed Professor of Physical Chemistry at Braunschweig Institute of Technology, Braunschweig, Germany. His research activities in physical chemistry of solids put particular emphasis on in-situ solid state spectroscopies applied to defects and diffusion and to the microdynamics and reaction kinetics of solids.

Abstract:

Although air is usually used for fuel combustion, it is well known that oxygen enrichment of combustion air enhances the combustion efficiency. Cryogenic oxygen separation is well established for oxygen production at large scale but its costs are relatively high compared to the economic benefit caused by an improved combustion efficiency. Therefore, the development of alternative oxygen separation processes is still an issue. One of the most promising ceramic materials for oxygen separation membranes is the mixed ionic electronic conducting (Ba_0.5Sr_0.5)(Co_0.8Fe_0.2)O_3-δ (BSCF) with its extremely high oxygen vacancy concentration. For 900°C, for example, a value of δ = 0.8 has been reported at an oxygen partial pressure of 10⁻³ bar [1,2].

We report on ⁵⁷Fe Mössbauer in situ studies of the mixed ionic electronic conducting (MIEC) oxide functional materials (Ba_0.5Sr_0.5)(Co_0.8Fe_0.2)O_3-δ, BSCF, conducted between room temperature and 1000 °C in atmospheres of variable oxygen content in order to obtain insight into local coordination and valence of iron at working conditions and into the distribution of oxygen vacancies on their different sites. The magnetically-split room-temperature Mössbauer spectra of BSCF reveal the presence of two inequivalent iron species [3]. Evaluation of signal intensities confirms results from theoretical computations on vacancy formation in BSCF which indicate that formation energies of the various types of oxygen vacancies differ by the order of 0.1 eV only [4,5]. The analysis also shows that the distribution of vacancies is far from random [3]. In the paramagnetic high-temperature phase (T ≥ 315 °C), the quadrupole-split signals demonstrate that local symmetry at iron sites is lower than cubic. At 700, 850, and 1000 °C, Mössbauer centre shifts as well as quadrupole splittings are discussed in respect to stoichiometry-related changes in valence and local coordination of the iron probes.

Biography:

Fouzia Achchaq is Associated Professor at the University of Bordeaux and Researcher at TREFLE Department (Fluids & Transfers) of the I2M Institute and a member of TESLab (Thermal Energy Storage Laboratory), I2M/Abengoa Joint Research Unit. She has expertise in thermal energy storage materials used at high temperatures and contributes to an ANR Project Pc2TES (National Project, 2017-2020).

Abstract:

The conventional resources depletion (coal, gas, oil) and the climate change lead to the need for innovation, requiring the use of renewable energy and appropriate storage technologies. This trend involves the development of effective, reliable and cost-effective energy storage units. Our work focus on advanced energy materials for ultra-compact thermal energy storage at high temperatures (300-600°C).

Thus a theoretical study, based on both literature [1-3] and FactSage 7.0^® software, is performed to compare the stoichiometric peritectic compounds with pure and eutectic ones currently considered (molten salts, metal alloys...). The objective is to know if the peritectics can surpass the performances of these latters.

The theoretical results show that the stoichiometric peritectic compounds can provide, at constant temperature and ambient pressure, a potential energy density much higher than pure and eutectic materials. This is due to their capacity to combine all advantages provided by sensible, latent and thermochemical processes. No cutting-edge technology is required to be developped for using them, contrary to the thermochemical heat storage materials [4]. Moreover, we can envision also to use the peritectic compounds in cascade ways enabling hence a consideration of very wide ranges of temperature and energy density, making them applicable to a wider pan of applications.

These encouraging results fully justify the choice of stoichiometric peritectic compounds.

Now, several experimental attempts are launched to determine the appropriate methods and protocols to synthesize them. To date, our work leads to the successful synthesis of the peritectic compound based on LiOH-LiBr system.

Biography:

Wojciech Olszewski is a Post-Doctoral Research Associate at the ALBA Synchrotron Light Facility. He studies energy materials, and the current research direction is the investigation of the structural stability, local atomic displacements and the force constants during the diffusion process for finding a realistic correlation between the local structure and functional properties of cathode materials.

Abstract:

Ion batteries are a key technology and play a dominant role in today's world. Extensive research efforts have been dedicated to exploring and developing new cathode materials with higher capacities and lifetimes.

Recently, a new family of transition metal carbides and carbonitrides called “MXene” has been synthesized with a layered hexagonal structure and Mn+1AXn chemistry, where M is an early transition metal, A is an A-group element (mostly groups 13 and 14), X is carbon or nitrogen, and n=1, 2, or 3.

MXenes have been found to be promising electrode materials, with capacities close to that of commercially available batteries and an excellent capability to handle high cycling rates. However, studies of correlation of their structural stability and functional properties could help to expand further theirs performances. To address this issue we have performed temperature dependent extended X-ray absorption fine structure (EXAFS) measurements at the Ti K-edge on representative members of the MXene family. Temperature dependent measurements permit to have direct access to the local force constant between the atomic pairs and correlate this information with the battery capacity and ions diffusion rate. Presented results address fundamental structural aspects that define the functional properties of electrode materials for ion batteries.

Biography:

N M Ferreira is a PhD in Physics Engineering (2014), currently is a Post-Doc Researcher at i3N, Physics Department and CICECO, Department of Materials and Ceramic Engineering at University of Aveiro, Portugal. He participated as a collaborator and research fellow in several R&D projects on material science. He is an experienced researcher in study and development of ceramics-based materials, prepared through conventional methods (melting, solid stated), with particular focus on laser processing (crystal growth – LFZ and surface sintering). Present sample characterization skills include various techniques such as, electrical conductivity and magnetic properties of various oxide materials. Current focus materials: thermoelectrics, ferroelectrics and glass matrices doped with transition metals and rare earth for energy storage and conversion applications. Main expertise is related to structural, magnetic and electrical properties of materials prepared by laser processing.

Abstract:

Ceramic oxides are very promising materials for thermoelectric devices, as they exhibit high Seebeck coefficient and could present relatively low electrical resistivity, as well as high chemical stability at high temperatures. Several oxides exhibit anisotropic thermoelectric properties linked to their layered structures. Therefore, texturing methods developing a preferential grain orientation, like the directional growth from the melt, are suitable to enhance the relevant physical properties. These methods have already shown their applicability to this kind of compounds and also in high Tc superconductor materials, namely, through the use of laser floating zone (LFZ) technique. The LFZ process has demonstrated its suitability for the Co-oxide based thermoelectric materials, processed in the last years in our laboratories. In this work, some examples of the versatility and usefulness of the LFZ technique are shown. The LFZ technique allows obtaining very dense, homogeneous and well textured thermoelectric composites. The results put in evidence an improvement due to electrically assisted laser floating zone on the thermoelectric performances when compared with materials processed by LFZ and by conventional techniques.

Biography:

Nataša Zabukovec Logar is a Head of the Department of Inorganic Chemistry and Technology at the National Institute of Chemistry in Ljubljana and Full Professor of Chemistry at the University of Nova Gorica. She obtained her PhD from University of Ljubljana in 1998. In 1995 and 1996 she was a visiting student at the University of Manchester, UK and in 2014, a visiting researcher at the Center for applied energy research in Munich, Germany. She has more than 20 years of experience in the research in the field of porous materials for energy and environmental applications. Her research emphases are development of new materials for gas and heat storage, and studies of metal sorption on porous solids for their use in wastewater and drinking water treatment. She is a treasurer of European Federation of Zeolite Associations and a member of the Synthesis Commission of the International Zeolite Association.

Abstract:

Thermal energy storage is recognized as one of the crucial technologies for enabling more efficient use of fossil fuels and renewable energies by providing the supply-demand balance. Thermochemical heat storage (TCS), which utilise the reversible chemical and physical sorption of gases, mostly water vapour, in solids, is currently considered as the only storage concept with a potential for long-term, also seasonal, heat storage of high enough storage density to be also economically attractive. Under the influence of a heat supply in TCS, water is desorbed from the material, which is then stored separately (an endothermic phenomenon referred to as the charging or activation of material). When water vapour and sorbent are put into contact, there is a heat release (an exothermic phenomenon referred to as a material’s discharge or deactivation). The TCS has a potential to enable an extensive use of a solar thermal energy and residual heat from industry, thus leading to a low carbon energy society. Over the last decade, a lot of attention has been devoted to the development of porous adsorbents, like zeolites, microporous alumino phosphates and metal-organic framework materials for water-adsorption-based thermal energy storage and heat transformations. A good sorption-based energy-storage material should fulfil the following requirements: (i) it should exhibit high water uptake at low relative humidity, (ii) it should be easily regenerated at low temperature, and (iii) it should be highly hydrothermally stable and should enable good cycling (adsorption/desorption) performance. Recently, we have focused on the studies of microporous alumino phosphates, which show remarkable water uptake characteristics, considering the water sorption capacity, as well as superior water uptake regime and thermal stability. The studies of structure-property relationship included diffraction, spectroscopic, calorimetric and computational approaches and enabled the materials optimization. One of the alumino phosphates, AlPO₄-LTA, outperforms all other porous materials tested so far. It exhibits superior energy-storage capacity (495 kWh m^-3) and shows remarkable cycling stability; after 40 cycles of adsorption/desorption its capacity drops by less than 1 wt%. Desorption temperature for this material, is lower from desorption temperatures of other tested materials by 10-15°C. This, for example, implies that regeneration of the material in a solar-energy-storage system should be easily achieved using most common types of solar collectors, e.g. flat plate collectors, even in regions without extended periods of intense solar irradiation.

Biography:

Mustafa Ürgen is presently working in the Metallurgical and Materials Engineering Department of Istanbul Technical University and leading the Surface Technologies group. He has more than 130 journal and conference publications. He received best paper award from IMF (International Metal Finishing Society) - Jim Kape Memorial Medal. The innovative coating he has developed in collaboration with Dr. Ali Erdemir (ANL, Chicago-USA) has received the R&D 100 award in 2009. He has given over 25 invited talks in national and international meetings. He took part as Chair and Organization Committee Member in numerous national and international meetings. He has directed several government and industry-sponsored projects and took part in EU funded projects. His research interest areas are: electrolytic, diffusion, PVD and hybrid-PVD coatings, corrosion, nano patterning of surfaces and energy materials. He is one of the authors of 5 issued and 4 pending patents.

Abstract:

Statement of the Problem: Nickel oxides, hydroxides and oxy hydroxides are promising materials for supercapacitor applications due to their high specific capacity. While indirect production of these nickel based materials is achieved either by chemical or electrochemical routes, the direct production on nickel metal itself has proved challenging. However, direct production should be investigated because it would facilitate the electron transfer required for redox reactions on the electrode surface, leading to much higher capacitances than those of the electrodes prepared with mixing nickel based materials and polymer blends.

Methodology & Theoretical Orientation: In the previous studies conducted in our group, we adapted molten salt electrolysis in KOH to directly synthesize nickel oxides on Ni foam. Here, we use the optimum parameters to synthesize nickel oxides on Ni foam and self-standing nickel nanowires (Ni NW) produced by electro deposition in AAO templates. These structures are characterized by XRD, SEM and Raman spectroscopy. The structure and the capacitance behavior are determined by cyclic voltammetry (CV) and chronopotentiometry in 6 M KOH solution.

Findings: After anodic oxidation, Ni foam and Ni NWs exhibit comparable capacitance behavior and moreover, the inherent capacitance of the Ni NWs is also increased.

Conclusion & Significance: Ni NWs are promising material group for supercapacitor applications similar to Ni foams when they are anodically oxidized by using optimized parameters.

Biography:

Marie Gollsch has a degree in environmental engineering and has been at the German Aerospace Center since 2012. She is part of the research area “Thermochemical Systems” at the department of Thermal Process Technology within the Institute of Engineering Thermodynamics. She specialises in the investigation and evaluation of thermophysical properties of thermochemical storage materials with focus on gas-solid reaction systems with water vapour as gaseous component. Additionally, she has expertise in the study of structural changes of the solid components of gas-solid reaction systems which occur due to the cycling of the storage material.

Abstract:

Thermochemical energy storage (TCS) uses the reaction enthalpy of reversible chemical reactions. This storage technology contains a so far largely untouched potential: in comparison to sensible and latent thermal energy storage, TCS offers potentially higher storage densities, the possibility of long-term storage as well as the option to upgrade the thermal energy. This upgrade can be realised if the reaction system consists of a solid and a gaseous component. For these gas-solid reactions with the generic equation

the equilibrium temperature is dependent on the reaction gas partial pressure: the higher the partial pressure, the higher the reaction temperature. Consequently, the charging of the storage can take place at lower temperatures than the discharging by adjustment of the reaction gas partial pressure.

Currently, a number of water vapour-solid reactions are investigated as thermochemical storage materials [1-4]. Apart from a general suitability of a reaction system for thermochemical storage, special attention has to be paid to the cycling stability of the reaction. This is often done using thermogravimetric analysis [5]. However, past scale-ups have shown that behaviour of bulks differs from that of analysis amounts [6]. The bulk’s changing properties, however, have proven to be crucial for storage reactor design. The investigation of the cycling stability and reaction behaviour of reacting solid bulks has been our motivation to design and build a cycling test bench. In this experimental setup the gaseous reaction partner is water vapour and can be provided at pressures between 5 kPa and 0.5 MPa. Reactor temperatures can be up to 500 °C.

The aim of the presented studies is the automated cycling of about 100 ml solid storage material of reaction systems that have previously shown promise at analysis scale.

Biography:

A novel way to synthesize flexible and conductive reduced graphene oxide (rGO) based papers is reported. The multi wall carbon nanotubes (MWCNTs) are added into rGO to make rGO/MWCNTs nanocomposite papers. Their electrochemical performance is investigated in various electrolytes, such as KOH, LiOH, and NaOH. The super capacitive behavior of the papers is examined via cyclic voltammetry, galvanostatic charging-discharging and electrochemical impedance spectroscopy. Their physical properties are characterized by X-ray diffractometer, Raman spectrometer, surface area analyzer, thermogravimetric analysis and field emission scanning electron microscope. The rGO/MWCNTs paper synthesized with suitable amount of MWCNTs exhibits excellent performance in KOH with specific capacitance of 200 Fg^-1, energy density of 22.5 Whkg^-1 and power density of 115 Wkg^-1 at current density 0.25 Ag^-1. Such high performance of the paper can be used for making future supercapacitors.

Abstract:

Tseung Yuen Tseng is a Lifetime Chair Professor in the National Chiao Tung University. He was the Dean of College of Engineering (2005-2007), the Vice Chancellor of the National Taipei University of Technology, Taipei, Taiwan (2007-2009). He has published over 380 research papers in refereed international journals and invented the base metal multilayer ceramic capacitors, which have become large scale commercial product. He has received Distinguished Research Award from the National Science Council (1995-2001), Academic Award of Ministry of Education (2006), National Endowed Chair Professor (2011), and IEEE CPMT Exceptional Technical Achievement Award (2005) and Outstanding Sustained Technical Contribution Award (2012). He was elected a Fellow of the American Ceramic Society in 1998, IEEE Fellow in 2002 and MRS-T Fellow in 2009.

Biography:

Akira Ishibashi received the BSc, MSc and PhD degrees in Physics in 1981, 1983, and 1990, respectively, all from the University of Tokyo, Japan. During 1982–1983, he was a Research Assistant at LBNL, Berkeley, USA. In 1983, he joined the Research Center of Sony Corporation, Yokohama. He was a Visiting Faculty at Loomis Laboratory, Department of Physics, University of Illinois at Urbana-Champaign, 1990-1991. In Sony he achieved world-first RT CW operation of blue/green laser diodes using ZnMgSSe, in 1993. He was a Visiting Professor at Center for Interdisciplinary Research, Tohoku University, Japan in 1998. Since 2003 he has been a full Professor in leading Nanostructure Physics Lab in RIES, Hokkaido University, Japan. In 2006, he started Hokkaido University Venture Company, C’sTEC Corp., based on Clean Unit System Platform (CUSP). His main target is to realize high-efficiency solar cells exploiting CUSP that helps people live in a high standard.

Abstract:

In orthogonal photon-photo carrier propagation solar cell (MOP³SC), photons propagate in the direction orthogonal to that of the photo carriers. Photons being absorbed in the direction vertical to that of the carrier drift/diffusion, trade-off between photon absorption and carrier collection can be lifted. We can set the stripe-width large enough to absorb all the photons keeping the distance between the p/n electrode distance (= semiconductors layer thickness) short enough to allow most of photo carriers to reach out to the contact metals. Further, by placing those multiple semiconductor stripes, neighboring to each other, with different band-gaps in such an order that the incoming photons first encounter the widest gap semiconductor, then medium-gap ones, and the narrowest at last, we can convert the whole solar spectrum into electricity resulting in high conversion efficiency. The multi-striped solar cell structure is placed at the edge of redirection waveguide in which 3D-propagation photons are redirected to be 2D photons propagating in the waveguide. The waveguide-coupled MOP³SC serves as a concentration photovoltaic system typically operating under a few hundreds to a thousand suns. Using an integrated-paraboloid-sheet as the first layer of the redirection waveguide, we can make the daytime sunlight virtually impinge the rest of the waveguide structure at a right angle. Further, asymmetric waveguide-coupled MOP³SC serves as a highly efficient concentration photovoltaic system thanks to the low temperature rise due to the minimal thermal dissipation and the diffusive light convertibility thanks to the integrated-paraboloid-sheet. The system is also of interest as a high reliability system, because those photons that can damage the bonding of the materials, being converted into electricity already at upstream, never go into the medium or narrow gap semiconductors. Thus, the asymmetric waveguide-coupled MOP³SC would serve as an ultimate high efficiency all-in-one system in the near future.

Biography:

Antonio Abate is a Helmholtz Association Young Group leader fellow at the Helmholtz-Centrum Berlin in Germany and Visiting Professor at Fuzhou University in China.  He is an expert in hybrid organic-inorganic materials for optoelectronics.  His group is currently researching active materials and interfaces to make stable perovskite solar cells.  Before to move to the Helmholtz-Centrum Berlin, Antonio was leading the solar cell research at the Adolphe Merkle Institute, and he was a Marie Skłodowska-Curie Fellow at École Polytechnique Fédérale de Lausanne in Switzerland.  After getting his PhD at Politecnico di Milano in 2011, he worked for 4 years as a postdoctoral researcher at the University of Oxford and the University of Cambridge.

Abstract:

Organic-inorganic perovskites are quickly overrunning research activities in new materials for cost-effective and high-efficiency photovoltaic technologies.  Since the first demonstration from Kojima and co-workers in 2009, several perovskite-based solar cells have been reported and certified with rapidly improving power conversion efficiency.  Recent reports demonstrate that perovskites can compete with the most efficient inorganic materials, while they still allow processing from solution as a potential advantage to deliver a cost-effective solar technology.

Compare to the impressive progress in power conversion efficiency, stability studies are rather poor and often controversial.  An intrinsic complication comes from the fact that the stability of perovskite solar cells is strongly affected by any small difference in the device architecture, preparation procedure, materials composition and testing procedure.

In the present talk, we will focus on the stability of perovskite solar cells in working condition.  We will discuss a measuring protocol to extract reliable and reproducible ageing data.  We will present new materials and preparation procedures, which improve the device lifetime without giving up on high power conversion efficiency.