Scientific Program

Conference Series Ltd invites all the participants across the globe to attend 3rd International Conference on Electrochemistry Berlin, Germany.

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Day 1 :

ElectroChemistry 2017 International Conference Keynote Speaker Evgeny Katz photo
Biography:

Evgeny Katz received his Ph.D. in Chemistry from the Frumkin Institute of Electrochemistry (Moscow) in 1983. He was a senior researcher at the Institute of Photosynthesis (Pushchino), Russian Academy of Sciences (1983-1991), a Humboldt fellow at the Technische Universität München (Germany) (1992-1993), and a research associate professor at the Hebrew University of Jerusalem (1993-2006). Since 2006 he is Milton Kerker Chaired Professor at the Department of Chemistry and Biomolecular Science, Clarkson University, NY (USA). He has (co)authored over 400 papers in the areas of biocomputing, bioelectronics, biosensors and biofuel cells. Thomson Reuters included him in the list of the world’s top 100 chemists over the past 10 years as ranked by the impact of their published research. Professor Katz was also included in the list of top cited chemists prepared by the Royal Society of Chemistry with the worldwide rank 378 based on his Hirsch-index, which is currently 81.

Abstract:

Implantable devices harvesting energy from biological sources and based on electrochemical transducers are currently receiving high attention. The energy collected from the body can be utilized to activate various microelectronic devices. This talk is an overview of the recent research activity in the area of enzyme-based biofuel cells implanted in biological tissue and operating in vivo. The electrical power extracted from the biological sources presents use for activating microelectronic devices for biomedical applications. While some microelectronic devices can work within a fairly broad range of electrical operating conditions, others, such as pacemakers, require precise voltage levels and voltage regulation for correct operation. Thus, certain classes of electronic devices powered by implantable energy sources will require careful attention not only to energy and power considerations, but also to voltage scaling and regulation. This requires appropriate interfacing between the energy harvesting device and the energy consuming microelectronic device. The talk focuses on the problems in the present technology as well as offers their potential solutions. Lastly, perspectives and future applications of the implanted biofuel cells will be also discussed. The considered examples include a pacemaker and a wireless signal transfer system powered by implantable biofuel cell extracting electrical energy from biological sources. The design of implanted biofuel cells operating in vivo promises for future various medical electronic implants powered by implanted biofuel cells and resulting in bionic human- machine hybrids. Aside from biomedical applications, one can foresee bioelectronic self-powered “cyborgs” based on various animals which can operate autonomously using power from biological sources and used for environmental monitoring, homeland security and military applications. In all bioelectronic systems, regardless their applications and complexity, the power sources will be highly important, and implanted biofuel cell are promising devices for providing electrical power extracted from the internal physiological resources. 

 

ElectroChemistry 2017 International Conference Keynote Speaker Yong Lei photo
Biography:

Yong Lei is a Chair Professor at the Technical University of Ilmenau in Germany. His current research interests focuses on template-based nanostructuring, energy-related devices (sodium-ion battery, supercapacitors and PEC cells) and optoelectronic applications of functional nanostructures and surface nano-patterns. So far he has authored 131 papers in SCI-indexed journals and 2 patents, many of them are published in first-class scientific journals, such as Nature Nanotechnology, Nature Communications, Journal of the American Chemical Society, Angewandte Chemie, Advanced Materials, Advanced Functional Materials, ACS Nano, Advanced Energy Materials, Energy & Environmental Science, Chemical Society Reviews, Progress in Materials Science, Nano Energy. Prof. Lei also received a few prestigious large projects in Europe and Germany, including ERC (European Research Council) Starting Grant and ERC Proof of Concept Grant, BMBF (Federal Ministry of Education and Research of Germany) and DFG (German Research Foundation).

Abstract:

Functional nanostructures have drawn intensive attention with the development of miniaturization of modern and future devices. Realization of such nanostructures presents an important task for nanotechnology research and device applications. To address this challenge, template-based method provides a perfect approach owing to the geometrical characteristics of the templates. We have developed template-based nanostructuring techniques using anodic aluminum oxide (AAO) nanopore arrays and polystyrene spheres with scalable, parallel and fast processes.[1] Employing these techniques, three-dimensional and surface nanostructures have been fabricated. The obtained nanostructures possess large-scale arrayed configuration, high structural density, perfect regularity and cost-effectiveness, and are highly desirable for constructing energy conversion and storage devices, including solar water splitting,[2-6] supercapacitors[7-9] and rechargeable sodium-ion batteries.[10-13] The device performances demonstrated that the obtained nanostructures benefit these applications through the precise control over the structural features enabled by the geometrical characteristics of the templates.[14,15] These achievements indicate the high potential and importance of template-based nanostructuring techniques for both basic research and device applications. Especially, we proposed recently a multiple nanostructuring concept using a binary-pore AAO template,[16] indicating a new perspective of template-based nanostructuring for device functionalization.

  • Advances in Electrochemistry | Theoretical and Computational Electrochemistry | Electroanalytical Chemistry | Electrochemical Energy Conversion and Storage | Bioelectrochemistry
Location: Berlin, Germany
Speaker
Biography:

Rolando Guidelli obtained his degree in Chemistry at Florence University, Italy, and was appointed by Florence University as a lecturer in Electrochemistry. He was then promoted to full professor of Electrochemistry at the age of 32 years in the Faculty of Science of Florence University. His scientific interests have been focused on electrode kinetics, structure of metal/water interfaces, and bioelectrochemistry. He has won several distinguished prizes in the field of electrochemistry and has published more than 230 papers in reputed journals and several book chapters. Furthermore, he has served as the organizer of several conferences in the field. 

Abstract:

The most direct method for verifying the functional activity of channel-forming peptides and proteins consists in monitoring the flow of physiologically relevant inorganic ions, such as Na+, K+ and Cl, along the ion channels. Measurements of average and single channel currents across bilayer lipid membranes (BLMs) interposed between two aqueous solutions are extensively employed to this end. A major drawback of BLMs is their fragility, high sensitivity toward vibrations and mechanical shocks, and low resistance to electric fields. To overcome this problem, metal-supported tethered BLMs (tBLMs) have been devised, where the BLM is anchored to the metal via a hydrophilic spacer that replaces the water phase on the metal side. However, only mercury-supported tBLMs can measure and regulate the flow of the above inorganic ions, thanks to mercury liquid state and high hydrogen overpotential. Thus, they react to the presence of proteins, charges and physical forces in a dynamic and responsive manner, by reorganizing upon interaction with external perturbations and mimicking the functionality of living cell membranes. The potential of Hg-supported tBLMs is illustrated by the use of different electrochemical techniques. Moreover, a tBLM formed on a mercury cap electrodeposited on a platinum microdisk yields a micro tBLM that maintains the same fluidity and lipid lateral mobility as on a hanging mercury drop and allows the recording of single channel currents and of two-photon fluorescence lifetime images of lipid rafts and gel-phase microdomains, opening the way to its use in high throughput screening applications.

Speaker
Biography:

Grzegorz Milczarek received his PhD and D.Sc. degree from Faculty of Chemical Technology at Poznan University of Technology (Poznan, Poland). Currently hi is a Professor at the same university. He is also a head of the Division of General and Analytical Chemistry. His research areas  include: electrocatalysis, preparation of new materials for energy conversion and storage, preparation of chemically modified electrodes to be used as electrochemical sensors. He has published over 50 peer reviewed publications.

Abstract:

Lignin is an abundant biopolymer on earth, present in all woods and grasses. In its native form, it is insoluble in any solvent and therefore useless for solution chemistry, in spite of its documented antioxidant properties. On the other hand, chemical derivatives of lignin (technical lignins) are produced in the quantities of millions tons per annum as a by-product in the production of cellulose from wood or other plant materials. Depending on the technology used, technical lignins differ in molecular weight, chemical composition and the structure of chemical moieties that make them soluble in organic solvent or even in water. Of particular interest are lignosulfonates that exhibit both poly-electrolyte and poly-phenol character due to the presence of ionisable and hydrophilic sulfonic moieties and substituted phenol groups responsible for their reducing properties. In this report, we demonstrate that technical lignosulfonates can be used as both reducing and stabilizing agents for cost-effective synthesis of various nanoparticles including noble metal nanoparticles and transition metal hexacyanoferrates that show valuable multifunctional electrochemical properties. The obtained hybrid materials show multiple redox activity due to the presence of lignin-derived quinones. Therefore, such materials can be used as energy storing materials or sensing platforms for electrochemical sensors (see for example Fig. 1). Lignosulfonates and lignosulfonate-stabilized nanoparticles can be also introduced into chemically or electrochemically polymerized conducting polymers e.g. polyaniline, poly-pyrrole and poly-ethylenedioxythiophene. 

Speaker
Biography:

Akiyoshi Manabe is General Manager of Water Electrolysis & Energy PJ team in De Nora Permelec Ltd. He finished master degree of Tokyo Institute of Technology. After that, he has developed a new development project at the forefront by Chlorine Engineers corp. Ltd., a brother company of current company. His main development of technology is as follows, activated cathode coating (low hydrogen overvoltage) for chlor-alkaline plan cell (1977-1981), Supercritical extraction of CO2 gas (1983-1992), Lithium ion secondary battery with Canada Moli Energy, NEC and Mitsui & CO., Ltd (1992-1998), Technology development of chlor-alkaline (1998-2010), He has moved to De Nora Permelec Ltd  since 2013, and devotes more focus to AWE plant technology and to promote business creation. Technology development of AWE (1999-2017)

Abstract:

Global warming caused by CO2 gas can no longer be ignored. Therefore, we are trying to contribute to reducing the problem with our electrolytic technology accumulated so far in our company. Our target is to develop a large AWE plant with high performance and contribute to problem solving. The performance of AWE is largely classified and influenced by four factors of anode, cathode, separator and cell structure of electrolyzer. Here, the results of electrodes and separators are mainly explained in our evaluation. Considering the use of renewable energy as standard, electricity always fluctuates in the operation of AWE. Therefore, the components of the cell must be sufficient resistant to such fluctuations. Electrode: There are two types of activated coating to reduce the overvoltage of electrode. Our investigation revealed that the anode coating of thermal decomposition is not enough tough, but the dispersion electroplating such as Raney Ni showed good durability against 100 times shutdown. During the shutdown of operation, revers current pass through in the cell. The revers current deteriorates the electrode performance and the phenomena causes difficult for anode coating life. Each saving of anode oxygen overvoltage of thermal and electroplating is around 50 mV and 100 mV compared with bare Ni. Separator: In the AWE, electrolyte is the same in both anode chamber and cathode chamber, so that diaphragm instead of ion exchange membrane can be used as separator. The point of its performance is that low cell voltage and high purity gas can be obtained. Currently, AGFA and KHI diaphragm are considered to be applicable to large-scale AWE plants. The performance of our AWE plant was around1.8 V at 5 kA/m2., 80 deg. C. Its performance is affected by the electrode to be used. The differences in cell voltage occur from 100 mV to 200 mV.

 

 

Speaker
Biography:

Prof. K. Boniface Kokoh is developing electrocatalytic materials for sustainable energy conversion and storage. He manages an electrocatalysis group that prepares electrode nanomaterials that are suitable to each application. His research topics concern hydrogen production in a solid polymer electrolyte water electrolyzer, abiotic electrodes design for hybrid biofuel cells and the CO2 electroreduction to platform molecules.

Abstract:

Statement Glucose is an environmentally friendly and sustainable carbohydrate that is actually a cyclized aldehyde in aqueous solution i.e. a hemiacetal. Its selective oxidation by the anomeric carbon in C1-position without any function protection is of great interest for cogeneration because the electrochemical process enables converting this highly functionalized organic molecule into electricity, heat and added-value chemicals. For this objective, we decide to synthesize effective nanomaterials towards glucose conversion at the anode and the oxygen reduction reaction (ORR) in the cathodic side of a fuel cell. The physical characterizations of the prepared materials and their electrochemical analysis at each half-cell, permitted to optimize the activity of the electrodes according to their elemental composition and structure. Furthermore, a constructed direct glucose fuel cell (DGFC) delivered an open-circuit voltage of 1.1 V in 0.5 mol L-1 NaOH and an outstanding output power of 2 mW cm-2. Complementary analytical techniques were employed to quantify the reaction processes involved in each compartment, determine the reaction products resulted from the glucose transformation and thereby, to understand reaction mechanisms of the glucose oxidation and the ORR over the synthesized electrode materials used in alkaline medium. As results, the identification of gluconate as the sole reaction product in the anodic side showed a selective 2-electron conversion of glucose, while the ORR proceeded through a 4-electron pathway over the designed cathode catalyst

Speaker
Biography:

Shozo Yanagida is an emeritus professor of Osaka University and a research director of “Research Association for Technological Innovation of Organic Photovoltaics” (RATO) of University of Tokyo.  Since he was promoted to a professor of newly established  “Koza” (research course) of Graduate School of Engineering in Osaka University (1980), he had contributed to photochemical conversion of solar energy, e.g., excellent photocatalyses of both nano-sized (quantized) ZnS and poly- & oligo-paraphenylene.  When he was staying at SERI (now ENREL) as a visiting professor of Dr. A. Nozik’s group in 1984, he understood that organic molecules and their aggregates are kinds of quantum dots themselves.  He has his expertise in evaluation of dye-sensitized solar cells, i.e., molecular structured photovoltaics, and passion in improving photo-conversion efficiency and long-term durability of solar cells in view of unidirectional electron flow and electron lifetime in solar cell devices.

Abstract:

So-called perovskite solar cells (PSC) are composed of PbI64- (MeNH3+)4 salt, where PbI64- plays an essential role as an effective solar light sensitizer with keeping semiconducting property even when aligned each other. Density-functional-theory-based molecular modeling (DFT/MM) using reported X-ray crystallographic structure of PbI64-/MeNH3+/H2O salt (named FOLLIB in Cambridge Structural Data) validates that the packing unit consisting of {(PbI64-)9[(MeNH3+)2-H2O]2(MeNH3+-H2O)2(MeNH3+)2}28-  should show  UV/Vis absorption spectrum at lmax=424 nm (pale yellow color) as observed for the PbI64- crystal.  DFT/MM of the FOLLIB horizontal aligned component, [(PbI6 4-[(MeNH3+)2-H2O]2(MeNH3+-H2O)2(MeNH3+)2/(PbI6 4-)2)4- verifies that the component has narrow energy gap of 0.3eV, predicting excellent semiconducting property of the PbI64- alignment with MeNH3+.  Three H2O-free PbI64-/MeNH3+ aligned components, PbI64-(MeNH3+)4, [PbI64-(CH3NH3+)3]- and [PbI64-(CH3NH3+)2]2- are molecular modeled and verified to have UV/Vis spectra at lmax=570nm, lmax762nm, and lmax=945nm, respectively.  Mixtures of them will be colored black, which is consistent with observable black coloration of PbI64- alignments with MeNH3+ in amorphous solute state. It is further verified that PbI64- undergoes van der Waals and Coulomb interactions both with electron accepting layers, i.e., nc-TiO2 in PSC of nc-TiO2/MeNH3PbI3/spiro-OMeTAD and with electron donating layer, i.e., spiro-OMeTAD in the PSC.  The molecular orbital structure and electrostatic potential map verifies formation of tight interaction between them.   The electron density-based alignment PbI64- validates unidirectional electron transport at both interfaces, resulting in high open-circuited voltage (Voc) of ~1.0 eV in PSC.  In addition, the semi-conducting sensitizing layer of PbI64-/MeNH3+ components validates excellent short-circuited photocurrent (Jsc), and respectable fill factor of PSC.   The PbI64--aligned solar cell will be regarded as a kind of quantum dot solar cell 

 

Speaker
Biography:

Andrés G. Muñoz is a senior scientist passionate about fundamental questions of electroplating of semiconductors and metals. He has gained his expertise by working with renowned scientists from the German electrochemistry school at the Heinrich-Heine University of Düsseldorf and the Research Centre Jülich. After being distinguished with an Alexander von Humboldt fellowship, he succeeded in combining his wide background in electrochemistry with surface science on joining the Institute for Solar Fuels and Energy Storage Materials at the Helmholtz-Center in Berlin. He resolved fundamental questions of interfacial photoelectrochemical processes in solar energy conversion systems. Presently, his is also involved in projects concerning the application of electrodeposition to improve the corrosion 

Abstract:

Solar water splitting tandem devices are a promising route for building a carbon-neutral energy infrastructure based on hydrogen as a fuel. The development horizon suggests the use of technologically advanced semiconductor materials, mainly III-V ones, due to its fast technical realization. The coupling of high-efficiency photovoltaics with electrochemical water splitting processes (two in one systems) requires from smart conditioning methods to turn semiconductor surfaces electrochemical active (figure 1). Particularly, the decoration of with noble metals, such as Pt and Rh is one of the most pursued approaches in the design of photocathodes to be integrated in tandem-type devices. Electroplating is preferred method due to its simplicity, its low cost and its power for accessing hidden places in complicated geometrical shapes (structured surfaces with enhanced photonic properties). The optical and electrocatalytic performance of deposited metal films can be enhanced by achieving a particular size and distribution of their nano-dimensioned grains. The chemical composition of the electrolytic bath, the applied potential program and illumination intensity constitute the main tools to do this.Electroplating of noble metals, however, triggers interfacial reactions generating chemical and electronic surface transformations. This is due to the complex multi-electron transfer involved in the metal phase formation and the particular high thermodynamic redox potential. Therefore, the selection of a galvanic method must balance coupled interfacial processes with desired properties of the electrocatalytic film. The complex picture of electrocrystallization of Rh will be discussed in the light of experiments performed on silicon, InP and GaInP. These systems are characterized by the formation of an interfacial oxide film separating electrocatalytic particles from the absorbing semiconductor. The composition and electronic structure of this latter builds a particular energetic pathway chart that defines the electrode performance. 

 

Speaker
Biography:

Pascal Boulet has completed his PhD in 2001 from both the University of Lyon (France) the University of Geneva (Switzerland). He then moved to University College London (England) as a postdoctoral fellow for two years. Since 2003 he is associate professor at the Aix-Marseille University (France) where he works on materials for energy using computational chemistry tools. He has published over than 50 papers in reputed journals.  

Abstract:

The phenomenon of deposition of a monolayer amount of metal atoms onto a dissimilar, more noble metal electrode at a potential more anodic than expected from the Nernstian equilibrium potential was recognized about 70 years ago but it was not before 1974 that Kolb, Gerischer and Przasnyski explained theoretically this concept known as the underpotential deposition (UPD) DVupd. Using over 20 couples of metals these authors found that DVupd followed the simple, linear equation DVupd =½Df, where Df is the difference in work functions between the adsorbate and the substrate. For most of the metal couples investigated, the relation was verified. However, this seemingly oversimplified relation was soon after contradicted by Bewick and Thomas’ experiments on the deposition of Tl and Pb on Ag single crystal electrodes. Thenceforth, there has been tremendous works achieved by several authors to refine the microscopic understanding of the UPD process. These theoretical works were often accompanied by numerical simulation approaches at the atomistic level (Monte Carlo and kinetic Monte Carlo techniques) and quantum mechanical calculations. However, despite the increase of computer and softwares capabilities the models used in these studies cannot fully capture the whole complexity involved in the UPD process and simplified model systems had to be used. In this paper, we will review the microscopic theory of UPD and the results obtained from computational, atomistic approaches. We will show the assets but also the weaknesses, and the foreseeable improvements in particular in the realm of the density-functional theory.

Speaker
Biography:

Dr. Jian Zhang received his PhD degree from the institute of coal chemistry, University of Chinese Academy of Science in 2014. He worked as a post-doctor from Oct. 2014 to Jan. 2015. Since February 2015, he joined Professor Feng's group as a post-doctor in Center for Advancing Electronics Dresden (cfaed) & Department of Chemistry and Food Chemistry, Technische Universitaet Dresden. He has his expertise in developing novel electrocatalysts for water splitting and oxygen reduction by engineering the interfaces and electronic properties of active sites. 

Abstract:

Large scale and sustainable production of hydrogen from water using the efficient and cost-effective electrocatalytic/photocatalytic/photoelectrocatalytic water splitting devices, e.g., water-alkali electrolyzers, is greatly promising for the future hydrogen economy. To this end, efficient, durable, and low-cost electrocatalysts are required to reduce the kinetic overpotentials of hydrogen evolution reaction (HER). Noble metal platinum (Pt) has been recognized as the most active and robust HER electrocatalyst with a near-zero onset overpotential and a high anodic current density. Unfortunately, the large-scale employment of Pt catalysts for hydrogen production is severely limited by its scarcity and high cost.

  For the HER in an alkaline solution, the kinetic process involves two steps: the prior water dissociation (Volmer step) and the subsequent combination of the adsorbed hydrogen (H*) into molecular hydrogen. Thus, once an electrocatalyst facilitates the initial water dissociation step on the surface, the HER performance will be improved. In this regard, we developed and design the novel electrocatalysts through engineering active sites for the water dissociation. For example, we demonstrate a novel out-diffusion strategy for synthesizing MoNi4 electrocatalysts, which can efficiently speed up the sluggish the Volmer step of the HER process in alkaline solution. The computational and experimental results reveal the fact that the kinetic energy barrier of the initial Volmer step is substantially reduced on the MoNi4 electrocatalysts. The as-constructed MoNi4 electrocatalysts supported by MoO2 cuboids exhibited an excellent electrocatalytic HER activity in 1 M KOH aqueous solution with an extremely low overpotential of ~15 mV at a current density of 10 mA cm-2 and a low Tafel slope of 30 mV decade-1, which are highly comparable to the results for the Pt and superior to those for state-of-the-art Pt-free electrocatalysts. Benefiting from its scalable preparation and excellent stability, the developed MoNi4 electrocatalyst is highly promising for practical water-alkali electrolyzer.

Speaker
Biography:

Qamar Abbas received his PhD degree in technical sciences from Graz University of Technology (Austria) in 2011. The same year he joined the Institute of Chemistry and Technical Electrochemistry (ICTE) at Poznan University of Technology, Poznan, Poland where he worked as a post doc in WELCOME project funded by the Fundacja na rzecz Nauki Polskiej (FNP) from 2011 to 2015. Since Jan 2016, he is assistant researcher at the ICTE and his research interests are related with optimization of supercapacitor performance in aqueous and organic electrolytes under testing conditions and corrosion investigations and mitigation of stainless steel type alloys in aqueous media.

Abstract:

Supercapacitors (SCs) generally use activated carbon (AC) electrodes and organic electrolytes e.g. 1 mol L-1 TEABF4 in acetonitrile due to the energy vs voltage square dependence. However, due to the flammable character of acetonitrile, environment-friendly and low cost alternatives e.g. neutral aqueous Li2SO4 (pH = 6.5-7.0) exhibiting moderate voltages up to 1.5 V in SCs have been recently proposed. Such voltage exceeding water stability of 1.23 V is due to large over-potential for di-hydrogen evolution at the negative carbon electrode caused by local downshift of pH. Lately, by introducing potassium iodide (KI) in aqueous Li2SO4, AC/AC hybrid cells operating up to 1.6 V displayed high capacitance as a result of hybridization of a battery-type positive electrode and capacitor-type negative one. The battery-type performance of the positive electrode is associated with redox reactions 2I- ↔ I2 + 2e- enhancing greatly the capacity of the positive electrode than for the negative one, C+>>C-, and using equation for capacitors in series 1/C = 1/C+ + 1/C-, capacitance of cell is equal to negative electrode capacitance.

Here, we show that hybrid capacitors in aqueous KI+Li2SO4 (pH = 6.5) using symmetric carbon configuration losses capacitance upon cycling/floating at 1.5 V. When using microporous carbons as positive and negative electrodes, the former reaches to +0.692 V vs SHE, and when implementing mesoporous electrodes, the negative electrode reaches to -0.985 V vs SHE well below the di-hydrogen evolution potential (-0.46 V vs SHE). Hence, both systems display capacitance loss under cycling/floating at 1.5 V. We implement asymmetric configuration using mesoporous carbon as positive electrode to better trap iodide species, and microporous carbon as negative one to improve hydrogen storage, to balance the system. TPD, Raman, Gas adsorption and electrochemical data on electrodes and cells (Figure 1) proves that the oxidation of positive electrode and hydrogen production on negative electrode are reduced, improving the cyclability, capacitance and energy efficiency of the cell up to 10,000 cycles.

 

Speaker
Biography:

Dr. Ik-Soo Shin was born in 1975 in Korea, and obtained Ph.D. degree from Seoul National University (SNU) in 2007. He was a postdoctoral fellow at the University of Texas at Austin, and SNU. Currently he is an assistant professor at Soongsil University, in Korea. His research interests include the design and development of biosensors based on electrochemical method.

Abstract:

Recently, the use of electrochemiluminescence (ECL) has drawn great attention due to its advantages such as high sensitivity, wide linear response range, good reproducibility and easy operation. However, ECL sensing of small molecules is still a great challenge because most of ECL detection methods have been developed via specific biomacromolecular recognition such as antibody-antigen and aptamer-protein interactions. In the talk, I will introduce about one of recent researches, the ECL chemodosimeter for the rapid determination of cyanider. A organometallic iridium(III) complex (1) with phenyl isoquinoline main ligands is rationally designed and synthesized for the ECL “turn-on” molecular probe, and the dicyanovinyl branch attached to the end of the main ligand plays as a role of recognition site for cyanide. Upon the reaction with cyanide in aqueous solution, 1 displays drastically enhanced ECL emission with widely linear correlation between 0-0.40 mM of cyanide when the concentration of 1 is fixed to 10 uM. The method can be successfully applied in direct determination of cyanide in tab water, and the result shows that it is versatile enough for the rapid point-of-care determination of cyanide in the presence of interferences even with high reliability and reproducibility. Theoretical studies were carried out for the rational design of the probe by predicting its HOMO/LUMO energy levels as well as electronic distributions. This ECL-based chemodosimetric sensor suggests a new and versatile analysis platform for rapid determination of molecular toxins in real samples

Speaker
Biography:

Shijian CHEN is a professor at Chongqing University. His research areas are wide-band-gap semiconductor based materials and devices; new energy materials and material design from the first-principles computational. His current research specifically focuses on new materials for production of hydrogen fuel from water. Before he joined Chongqing University, he was an Australian Postdoctoral Fellow (APD) at Monash University from 2008 to 2012, and as an Alexander von Humboldt research fellow at University of Hannover from 2007-2008. He is the author of over 50 peer-reviewed publications with more than 1000 citations. He received PH.D at Chinese Academy of Sciences at 2006.

Abstract:

The design and development of high-efficiency and non-noble metal hydrogen evolution reaction (HER) electrocatalysts with optimized nanostructures for human clean and sustainable energy systems has attracted significant research interest over the past years. Herein, self-supported transition-metals poly-phosphides (TMP) (such as CoP3, WP2) nanoneedle arrays on carbon cloth were topotactically fabricated by in situ phosphidation of a transition-metals oxides nanoneedle arrays precursor. Such a binder-free flexible HER electrocatalysts with integrated three-dimensional nanostructures can not only provide a large surface area to expose abundant active sites, but also facilitate electrolyte penetration for electrons and electrolyte ions, which exhibit superior bifunctional electrocatalytic activity and durability for both the HER and OER. In addition, density functional theory (DFT) calculations indicate a low kinetic energy barrier for H atom adsorption on the TMP surface which guarantees the excellent catalytic activity of the catalyst. The excellent electrocatalytic activity makes the present 3D structured TMP electrocatalysts promising catalysts for large scale highly pure hydrogen evolution by electrochemical water splitting.

  • Electrochemical surface science | Batteries and energy sources | Organic and Organometallic Electrochemistry

Session Introduction

Ruiyong Chen

Joint Electrochemistry Lab, KIST, Saarland University,Germany

Title: High voltage aqueous redox flow batteries
Speaker
Biography:

Dr. Ruiyong Chen received his Ph.D. degree (summa cum laude) in 2011 in physical chemistry from the Saarland University, Saarbrücken, Germany. He is currently a habilitation candidate at the Saarland University and a project leader at the KIST Europe. He has expertise in synthesis and characterization of electrode materials for energy storage systems and energy-efficient electrolysis. He has developed new two lithium intercalation cathode materials with disordered rock-salt structure for improving reversible capacity (up to 400 mAh g-1) for lithium ion batteries. He is currently developing new high voltage aqueous electrolytes for stationary energy storage using redox flow batteries.

Abstract:

Redox flow batteries are promising for large-scale energy storage applications due to their economy and scalability, in comparison with other energy storage systems. In addition, redox flow batteries have unique character of decoupled energy storage and power generation capability. Aqueous redox flow battery systems may offer safe operation, low cost and fast ionic mobility (power generation) in comparison with non-aqueous systems. However, due to the limits in the electrochemical stability window of water, aqueous systems can generally only be operated with low cell voltage (< 1.5 V). Conventional aqueous flow batteries have thus low energy density (< 30 Wh L-1), which is far below that for Li-ion batteries. Non-aqueous electrolytes using organic solvents, although can offer wide electrochemical window, suffer from low ionic conductivity, low solubility for active species and safety concerns. To access high cell voltage in aqueous systems, Chen et al., have recently developed new aqueous ionic liquid electrolytes with widened electrochemical window of about 3 V, using a concentrated aqueous solution of 1-butyl-3-methylimidazolium chloride (BMImCl). Herein, we explore various ionic liquid-based electrolytes and compatible redox couples (soluble species and semi-solid suspension utilizing solid-state cation/anion intercalation reactions) in the attempt to obtain redox flow batteries with high cell voltage and high energy density.

Speaker
Biography:

Oliver Clemens has obtained his PhD in 2012 years from Saarland University, Germany, followed by postdoctoral studies at the University of Birmingham, UK. He is group leader of the Joint Research Laboratory Nanomaterials, TU Darmstadt and KIT, Germany since May 2013. At the beginning of 2017 he became a junior professor (Qualifikationsprofessor) within the Materials Science Department at the TU Darmstadt, Germany within an Emmy Noether Fellowship from the German Research Foundation. He has published more than 36 papers (November 2016) in reputed journals.

Abstract:

Building batteries based on a shuttle of fluoride ions is of interest due to the high stability of fluoride as a charge carrier. Therefore, wide potential windows can be accessible in such battery systems allowing for high energy densities. So far, fluoride ion batteries (FIBs) are mainly fabricated as all solid state batteries using conversion based electrodes. However, conversion reactions are well-known to result in limited battery lifetime due to the large volume changes which arise during the cycling of the battery. In addition, high overpotentials (crystallization, charge transfer) can have a tremendous impact on battery kinetics. To improve battery kinetics, we aim to develop intercalation based fluoride ion batteries with high capacities and high voltage. In this respect, perovskite and perovskite related compounds (e. g. Ruddlesdon-Popper type structures) will be shown to serve as host lattices which can intercalate/deintercalate large amounts of fluoride ions, with theoretical capacities reaching ~ 130 mAh/g and being comparable to lithium ion battery systems. We highlight that such materials can outperform CuF2 as a high voltage cathode in agreement with by DFT based calculations. Latest developments on the identification of suitable anode materials will be described in addition to an overview of current limitations of anion based battery systems. Finallly, we will elucidate structure chemical factors which enable selectivity for the intercalating species for cation (e. g. Li and Na) in comparison to anion based batteries.

Speaker
Biography:

Dr. Xiangyu Zhao has his expertise in electrochemical energy storage including electrochemical hydrogen storage and rechargeable batteries such as chloride ion batteries, lithium ion batteries and magnesium batteries. He received his PhD in Materials Science at the Nanjing Tech University in 2010 and then joined the same university. Meanwhile, from 1/2012 to 12/2013, he was awarded by the Guest Scientist Fellowship and worked at Karlsruhe Institute of Technology. He is (co-)author of 9 patent applications and has more than 60 papers published in international journals such as Angew Chem Int Ed, Adv Energy Mater and Energy Environ Sci.

Abstract:

Alternative battery chemistries beyond lithium ion and using abundant electrode materials have been developed. Chloride ion battery (CIB) is a new rechargeable battery based on Cl- anion transfer. This battery shows a variety of electrochemical couples with theoretical energy densities up to 2500 Wh l-1, which is superior to those of conventional lithium ion batteries. Abundant material resources such as Mg, Ca, Na and metal chlorides (e.g., FeCl3, CuCl2 and MgCl2) can be sustainable electrode candidates. The CIB includes a metal chloride/metal electrochemical couple and an ionic liquid electrolyte allowing chloride ion transfer, as reported in the proof-of-principle study of CIB operated at room temperature. The problem is that the metal chloride cathode can react with chloride ions in the electrolyte, leading to the formation of soluble complex anion. This electrode dissolution and the subsequent shuttle would limit the use of metal chloride cathode in the liquid electrolyte system. Metal oxychlorides with higher stability have been proved to be new cathode materials for CIBs. Metal oxychloride/metal systems could also show high theoretical energy densities during the chloride ion transfer. By carbon incorporation in the cathode or optimization of electrolyte composition, more than 70% of the theoretical discharge capacity of single-electron cathode such as FeOCl or VOCl could be delivered. A preliminary study on the multi-electron VOCl2 cathode was also reported in the electrode system using VOCl as cathode and Mg/MgCl2 composite as anode. Besides inorganic electrode materials in rechargeable batteries, organic electrode materials, in particular polymers, have been attracting much attention, due to their advantages of good electrochemical performance, high stability, abundant chemical elements, structural tunability and designing flexibility. Chloride ion doped polymer materilals have been studied and developed as new cathodes for chloride ion batteries. Reversible reversible redox reactions and superior cycling stability were obtained.

Speaker
Biography:

Dr. Amedeo Capobianco earned his PhD in 2008 at University of Salerno, where he now works as an assistant professor. His current research interests include the theoretical treatment of charge transport phenomena in biochemical systems and in organic materials.

Abstract:

Singly ionized DNA exhibits long range hole transport (HT) covering distances up to 200 Å [1]. Hole transport has great biochemical and technological relevance, as it controls the site distribution of the oxidative damage in DNA and makes DNA a potential conduit for nanoelectronics, used both as template and as active component. Different mechanisms for the hole transport have been invoked so far: ion gated transport, thermal activated hopping, and superexchange among others. Independent of the kinetic mechanism, the of hole transfer in oxidized DNA is modulated by the complex mosaic of low-lying electronic states, whose accessibility depends on the effective in-situ hole energies of nucleobases and the electronic couplings between interacting nucleobases. The hole energies for adenine (A) and guanine sites were previously quantified by using voltammetry, the influence of hydrogen bonds on the oxidation potential was also determined. Information for cytosine oxidation was inferred by spectroelectrochemistry experiments. Here we have focused our attention on electronic coupling parameters. The latter have been estimated by the lowering of the oxidation potential observed for DNA oligonucleotides containing an increasing number of stacked homo-purine nucleobases. Voltammetric data were interpreted in terms of the two state model (Figure 1). Experimental  results were further confirmed by theoretical computations carried out at the full quantum level for single and double stranded oligonucleotides including sugar-phosphate backbone and solvation. The observed lowering of the oxidation potential for single stranded oligonucleotides containing an increasing number of adjacent adenines amounts to ca 0.3 V for the AA step, in good agreement with theoretical predictions. That result suggests that adenine tracts give rise to delocalized hole domains (Figure 1), greatly facilitating hole transport in DNA [7]. Although stacking interactions are found to be less effective in stabilizing the positive charge on adjacent guanines inside a strand, our results confirm that guanine tracts constitute a very efficient trap for the hole 

Speaker
Biography:

Dr. Teko W. Napporn is a Researcher of French National Center for Scientific Research (CNRS) and also Adjunct professor at the Institute of Advanced Sciences of Yokohama National University. He is developing nanostructured electrocatalysts for energy conversion (Fuel cells) and storage (batteries and water electrolysis). His research topics deal with the surface structural effect in electrochemistry at electrified Solid-Liquid Interfaces, hybrid biofuel cells. He is also involved in the development of single chamber solid oxide fuel cell.

Abstract:

Gold at nanoscale fascinated scientists who developed important research topics over physics, chemistry, medicine and biotechnology. The last three decades, various innovative investigations emerged for determining the role of size, the morphology on the unexpected properties observed for gold at nanoscale. In electrocatalysis, gold nanoparticles (AuNPs) were often used to understand the intrinsic relationship between their size, morphology and activity towards two main reactions: (i) the electrooxidation of organic molecules that have a great interest as fuel in fuel cell applications, and (ii) the oxygen reduction reaction (ORR). Electrocatalysis investigations on support-less gold nanorods have shown that it is a challenge to study the intrinsic properties of their surface through their interaction with a reactive molecule. Our recent results on gold nanospheres revealed that the size of these nanomaterials plays a key role in their electrochemical response. Therefore spherical gold nanoparticles (AuNSs) with a mean diameter from 4 to 15 nm were successfully synthesized. UV-visible spectroscopy, Transmission electron microscopy, and Under-Potential Deposition of lead (UPD) were used for determining their morphology, size and approaching their surface crystallographic structure. UPD of lead reveals that their crystallographic facets are affected by their size and the growth process. In alkaline medium, the oxidation of glucose was used to evaluate their electroactivity. As results, small AuNSs exhibited drastic increase of catalytic activity (fig. 1). This feature might result in the high specific area and reactivity of the surface electron induced by their small size. The study of the reaction mechanism was investigated by in situ Fourier transform infrared reflectance spectroscopy. Gluconolactone and gluconate were identified respectively as the intermediate and the final reaction product of the glucose electrooxidation.

Speaker
Biography:

Milko van der Boom completed his B.Sc. in Chemical Engineering at the Amsterdam University of Applied Sciences and his M.Sc. degree in Inorganic Chemistry at the University of Amsterdam. In 1994, he enrolled as a doctoral student at the Weizmann Institute of Science, where he studied Organometallic Chemistry; he was awarded his Ph.D. degree with distinction in 1999. After three years of postdoctoral work at Northwestern University, where he studied the formation of functional organic films, he returned as a faculty member to the Weizmann Institute’s Department of Organic Chemistry. His interdisciplinary materials chemistry research focuses on metalloorganic-oriented synthetic and mechanistic studies. Prof. van der Boom's prizes and honors include an Alon Fellowship from the Israel Council for Higher Education, the Henri Gutwirth Prize from the Technion, and the Israel Chemistry Society's Prize for Excellent Young Chemists. He is the first incumbent of the Bruce A. Pearlman Professional Chair.

Abstract:

Directional electron-transfer events are the basis of many technologically important systems and biological processes. In this study, we demonstrate how the distance over which electron transfer occurs through organic materials can be controlled and extended. Coating of conductive surfaces with nanoscale layers of redox-active metal complexes allows the electrochemical addressing of additional but distant layers that are otherwise electrochemically silent. We also show that our composite materials can pass electrons selectively in directions that are determined by the positioning of redox-active metal complexes and the distances between them. These electron-transfer processes can be made dominantly uni- or bidirectional. Our design strategy involves 1) a set of isostructurally well-defined metal complexes with different electron affinities, 2) a scalable metal-organic spacer, and 3) a versatile assembly approach that allows systematic variation of material composition, structure, and electron transfer properties. We control the electrochemical communication between interfaces by the deposition sequence of the components and the length of the spacer, and therefore we are able to program the bulk properties of the assemblies.

Speaker
Biography:

Michal Lahav completed her BSc and PhD studies in Chemistry (cumma sum laude) in 2001 at the Hebrew University of Jerusalem. She was a postdoctoral researcher at the Weizmann Institute of Science for two years before she moved to Harvard University, where she studied nanochemistry. After two years of postdoctoral work in the United States, she returned to Israel and started to work as a scientific advisor at the Weizmann Institute of Science. She was appointed as an Associate Staff Scientist in the Department of Organic Chemistry in 2011. Her interdisciplinary materials chemistry research is related to the self-assembly of metallo-organic materials for energy storage and for electrochromics whose products are now being patented. Her work is related to fundamental understanding of the formation and electronic properties of these metallo-supramolecular architectures. Dr. Michal Lahav’s prizes and honors include the Dr. Maxine Singer Prize for Outstanding Staff Scientists, the Baruch Zinger Award for Academic Excellency, the IVS Excellence Award for Surface Science Expertise and the Schmidt Prize. 

Abstract:

Stepwise deposition from solution, combined with metal-ligand coordination, has served as a powerful tool for generating functional architectures on surfaces. Such systems might find many applications in molecular electronics, sensor, and solar cells. More significantly, owing to their interesting electrochromic (EC) behavior, redox-active metallo-organic assemblies are promising candidates for use in smart windows. In this study, we used a dip-coating process to generate EC molecular assemblies (MA) from metal polypyridyl complexes cross-linked with a palladium salt. These complexes are considered ideal chromophores for fabricating EC materials, due to their excellent stability and light absorption that significantly depends on their oxidation state. Varying the number of pyridine moieties was used to control (i) the materials’ stability, (ii) color, (iii) redox-chemistry, and (iv) the film growth (i.e., linear vs. exponential). Our observations also demonstrated that minor structural differences (i.e., the pyridine-bipyridine bond order, X) at the molecular level become apparent in stability and EC properties, (Figure 1). The MAs exhibit very high coloration efficiencies (CEs) and are extremely stable. Furthermore, we demonstrate  solid-state devices.

Speaker
Biography:

Marie-Christine Record has completed her PhD in 1992 from Montpellier University (France) and postdoctoral studies from Ecole Centrale Paris (France). She was an associate professor at Montpellier University from 1996 to 2004 and from 2004, she is full professor at the Aix-Marseille University (France) where she works on the elaboration of thin films materials for energy. She has published more than 80 papers in reputed journals and has been serving as an editorial board member of repute. 

Abstract:

Electrochemical deposition may provide an alternative process to physical deposition methods for peparing semiconducting thin films. Indeed by contrast to other methods, electrochemical deposition is a low cost, room temperature production technique, which works without vacuum atmosphere and allows one to cover substrates with complex shapes. The shortcoming of electrochemical deposition is limited control on the size, stoichiometry and crystallinity of deposits. The electrochemical atomic layer deposition (EC-ALD) method was put forward in 1991 by Gregory and Stickney. This method is based on the alternate underpotential deposition (UPD) of atomic layers of the elements to make up a compound, combining advantageously the technique of electrochemical deposition and that of atomic layer deposition (ALD). Underpotential deposition is a surface-limited electrochemical phenomenon, which makes the deposition generally limited to an atomic layer. In every cycle one monolayer of the compound is obtained, and the thickness of the deposit will only depend on the number of cycles. Each cycle consists in a series of individual steps, and each step can be optimized independently, resulting in well-controlled deposits. In the first part of this talk, I will describe the EC-ALD method and I will expose the advantages of this method compared to those of physical ones of ALD type and compared to those of other electrochemical methods. Then, I will detail the EC-ALD experiment platform designed and constructed in our group. Finally, I will present some results we got with this equipment for the electrodeposition of CoSb3 and Sb2Se3 compounds. 

Speaker
Biography:

Mitsuharu Tabuchi is an inorganic synthetic chemist using wet-chemical process for oxide-based positive electrode material of lithium-ion battery. His synthetic experiences above 15 years were constructed mainly to get homogeneous LiFeO2-Li2MnO3 solid solution. The constructed synthetic route is also effective for preparing LiNi1/2Mn1/2O2-Li2MnO3 one. He has also characterization experience using 57Fe Mössbauer spectroscopy and X-ray Rietveld analysis to know charge compensation mechanism for LiFeO2-Li2MnO3 system. He found also Fe and Ni substituted Li2MnO3 and it has high-potential for practical use, because it can be prepared largely by chemical company (Tanaka Chemical Corporation) and then is electrochemically tested by battery manufacturer (NEC Corporation) as power-source of electronic vehicle (EV).

Abstract:

Li-excess positive electrode material (LiMO2-Li2MnO3 solid solution, M=Ni1/2Mn1/2 or Ni1/3Mn1/3Co1/3) is a good candidate as its high-capacity (250 mAh/g) and acceptable discharge voltage above 3.5 V for high energy-density lithium-ion battery to EV and PHEV application. Especially LiNi1/2Mn1/2O2-Li2MnO3 solid solution (Li1+x(NiyMn1-y)1-xO2, 02-Li2MnO3 solid solution [1]. In this work, the synthetic method applies to LiNi1/2Mn1/2O2-Li2MnO3 system [2]. As shown in Fig. 1, the homogeneous precursor can be prepared by low-temperature co-precipitation Ni-Mn hydroxide and hydrothermal treatment with an oxidizer, KClO3 and Li-source, LiOH.H2O at 220 °C. The precursor calcined with LiOH.H2O at 850 °C under N2 atmosphere to obtain better initial electrochemical performance. To improve cycle performance under full-cell configuration, Ti ion substituted for Mn ion by using 30% Ti(SO4)2 aq. solution. Although further effort to establish more facile synthetic method must be needed, the Ni- and Ti- substituted Li2MnO3 is an attractive candidate as high-capacity “Co-free” positive electrode material. We develop Li-excess LiNiO2 as high-capacity and better cyclability using thermal decomposition of Li2NiO3 [3]. AIST found a new 3.5 V-class Fe- and Ni substituted Li2MnO3 positive electrode material with NEC and Tanaka Chemical Co. [4, 5]. These materials are also “Co-free” ones.

Yu-Wu Zhong

Institute of Chemistry, Chinese Academy of Sciences, china

Title: Electro-Active Ruthenium-Amine Conjugated Organometallic Materials
Speaker
Biography:

Yu-Wu Zhong obtained his Ph.D. in July 2004 from the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences (CAS) under the supervision of Prof. Guo-Qiang Lin. From September 2004 to September 2006, he has been a postdoctoral researcher at the University of Tokyo with Prof. Eiichi Nakamura. From October 2006 to September 2009, he worked with Prof Hector D. Abruna at Cornell University as a postdoctoral researcher. In October 2009, he was awarded by the “100 talent” program of CAS and joined Key Laboratory of Photochemistry of the Institute of Chemistry, CAS, to start his independent career. His research interests focus on electro-active and photofunctional organic materials and transition-metal complexes. He has published more that 110 peer-reviewed papers to date. He is currently an associate editor of RSC Advances and editorial board member of Scientific Reports and Science China Chemistry.

Abstract:

Electro-active and electrochromic materials have received a wide range of applications. The incorporation of a metal ion gives rise to new functions that are not present in common organic materials. However, the applications of electro-active organometallic materials are often hampered by their high redox potentials and difficulty in film formation. Recently, we have been interested in the design and construction of electro-active systems with cyclometalated ruthenium and triarylamine as the charge-bearing sites. These materials show strong electronic coupling and multiple reversible redox processes in low positive potential window. After modified with vinyl or triphenyl units, these can be smoothly deposited onto ITO electrode surfaces by in situ electropolymerization. The obtained films exhibit multistate NIR electrochromism with long retention time, good contrast ratio, and low switching potential. The response is about a few seconds. Depending on the number of redox sites, 3 - 5 step redox switching were realized. These films have been used for the demonstrations of flip-flop or flip-flap-flop memory with electrochemical potentials as input signals and absorbance at different wavelengths as output signals. In addition to electropolymerized films, self-assembled monolayer films of these complexes were obtained and they are useful in molecular-scale NIR electrochromism and electrochemically-gated single molecular conductance

Speaker
Biography:

Dr Yan Jiao's research interests involve discovering the origin of electrocatalytic activity possessed by carbon-based materials by computational chemistry. She also aims to design novel carbon-based catalysts for clean energy conversion reactions, including hydrogen evolution reaction, oxygen reduction reaction and carbon dioxide reduction reaction. She obtained her PhD in Chemical Engineering from the University of Queensland, and is currently working as a postdoctoral researcher in the University of Adelaide (UoA). She is the receiver of several awards, including Women's Research Excellence Award by UoA. She has received over 4400 citations and h-index is 19.

Abstract:

The dwindling supply of fossil fuels urge us to explore alternative power sources to drive our highly automotive society. Under this background, establish reliable clean and sustainable energy supplies are of great importance, and using electrochemical method to realize energy conversions hold a great promise. Among these reactions, hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) are the most studied, due to their fundamentality in electrocatalysis and their role in hydrogen production and fuel cells, respectively. Effective candidates for these two reactions are often based on noble metals, while carbon-based metal-free electrocatalysts generally demonstrate poorer activity. Here we report evaluation of a series of heteroatom-doped graphene materials as efficient HER and ORR electrocatalysts by density functional theory calculations, with the input of spectroscopic characterizations and electrochemical measurements. Results of theoretical computations are shown to be in good agreement with experimental observations regarding the intrinsic electrocatalytic activity and the reaction mechanisms for these two reactions. As a result, we establish volcano shaped activity trends for HER and ORR on graphene-based materials, and explore their reactivity origin to guide the design of more efficient electrocatalysts. We predict that by rationally modifying particular experimentally achievable physicochemical characteristics, a practically realizable graphene-based material will have the potential to exceed the performance of the metal-based benchmarks for these two reactions.

Sylvio Indris

Karlsruhe Institute of Technology, Institute for Applied Materials – Energy Storage Systems, Germany

Title: Electrodes and Solid Electrolytes for Li-Ion Batteries: Local Structures, Li-Ion Mobility, and Lithiation Mechanisms
Speaker
Biography:

Sylvio Indris is investigating materials that can be used as electrodes and electrolytes in Li-ion batteries. These materials are prepared by solvothermal/hydrothermal methods, sol-gel techniques, and solid-state reactions. The changes in these materials during operation in these batteries are investigated by diffraction techniques as well as X-ray absorption spectroscopy, solid-state NMR, and Mössbauer spectroscopy. Finally, the results of these investigations are used to optimize the performance of the complete Li-ion battery systems.

Abstract:

Li-ion batteries are used extensively in mobile electronic devices and in electric vehicles due to their high energy and power densities. The performance of these storage systems strongly depends on the materials used inside these batteries as electrodes and electrolytes. In order to improve these batteries, it is important to understand the fundamental diffusion mechanisms and also the fundamental electrochemical reaction mechanisms that occur during charging and discharging of the batteries, i.e. during lithiation and delithiation of the electrodes, and that are responsible for function and degradation of these systems. The changes that occur in the electrode materials during electrochemical cycling are investigated by in situ techniques including diffraction as well as spectroscopic methods [1-3]. These measurements are performed on olivine materials LiMPO4 (M = Fe, Mn, Co) and high-voltage spinel materials LiM’M’’O4 (M’, M’’ = Mn, Co, Ni, Fe) and they reveal the details of the lithiation/delithiation mechanisms and how these are related to the performance of these materials in the batteries. Solid electrolytes might offer an enhanced safety for these systems. Different oxidic, sulfidic, and polymer systems are investigated with respect to Li+ ion mobility by 7Li NMR relaxometry and field-gradient NMR spectroscopy [4-6]. From this, microscopic diffusion parameters such as the average Li ion jump rate t-1 and the activation barrier EA for single Li ion jumps can be extracted, but also the macroscopic transport of the Li ions can be observed. The results of these measurements are compared to those obtained by impedance spectroscopy.