bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of Li-Ion Diffusion Rates Using Gitt in Cells with 3D Structured Intercalation Cathode Materials
Authors: Gotcu-Freis Petronela , Pfleging Wilhelm , Seifert Hans Jürgen 
Published: February 2020

The public demand for high power energy storage systems is on a continuous ascending path. Efforts are directed towards the development of advanced lithium-ion electrodes, e.g. modified surface architectures. Direct laser patterning of thin and thick film electrode materials is a fairly new technical approach which enables an increase of capacity retention especially for high charging and discharging rates (Figure 1). It is assumed that an appropriate three dimensional surface topography influences the diffusion kinetics of Li-ions in the electrode materials through the electrolyte, whereas critical mechanical tensions during charging/discharging can be avoided and ohmic losses are significantly reduced inside the electrochemical cell.
The goal of this work was to enable quantitative studies of lithiation/delithiation rates which contribute to a better understanding of electrochemical intercalation/deintercalation processes in laser modified electrodes. The simplest quantitative approach to determine the rate of Li-ion insertion in the active material and the rate of Li-ion transport in the electrolyte is expressed by diffusion coefficient values. For this purpose, one of the most common coulometric titration technique, the galvanostatic intermittent titration technique (GITT) has been involved.
Electrochemical measurements were performed using the Swagelok® cell design for both, full and half-cell types, using graphite and metallic lithium as counter electrodes, respectively. The results of Li-ions diffusion rates are presented for laser structured and unstructured lithium -metal oxide cathode materials. The focus is set on composite thick film electrode materials containing binder, conductive carbon and layered intercalation lithium cobalt oxide (LiCoO2), which is the main cathode material used nowadays in many commercial lithium-ion cells. A main challenge for GITT was to evaluate suitable measurement parameters such as current pulse length, charge/discharge rate and relaxation time for each specific cell system. The results obtained were evaluated and compared to literature data.
Flower-like Co3O4 As an Anode Material for High Performance Li-Ion Batteries
Authors: Jadhav Harsharaj S. , Park Chan-Jin 
Published: February 2020

The development of anode material with high specific capacity is the key issue in present lithium ion batteries (LIBs) technology. Recently, transition metal oxides have attracted much attention as an anode material for LIBs due to its high theoretical capacity (~700 mA h/g), long cycle life and high rate performances. Among various metal oxides, cobalt oxide (Co3O4) has been intensively investigated as a promising anode material for LIBs owing to its high theoretical capacity (890 mAh g-1), which is nearly two times higher than that delivered by conventional carbonaceous anodes. However, Co3O4 can suffer from poor cyclability and low rate capability, due to a large volume change and serious aggregation during charge/discharge cycling. Different proposals have been suggested to address this issue based on the tailored morphology, formation of nanocomposites with conductive additives and nano-size fabrication of Co3O4 electrode materials. In addition, various Co3O4 materials including nanotubes, nanorods, nanoneedles, nanospheres, platelets and nanowires have been synthesized and showed signiﬁcantly improved lithium ion storage properties compared to their bulk counterparts. In this study, the electrochemical properties of flower-like Co3O4 synthesized by simple urea-assisted chemical co-precipitation strategy with porous structure were investigated.
A facile urea-assisted template free, surfactant less chemical co-precipitation method and subsequent calcination (400-600 oC) for 2 h was pursued to obtain pure cobalt oxide (Co3O4) sample. The synthesized sample exhibited the cubic spinel structure and flower-like morphology. The obtained morphology is assembled by nanorods rising from common center, and the nanorods were comprised of interconnected particles with porous structure. The changes in the surface area and porosity of the flower like structure have been induced by manipulating the calcination temperature, resulting in significant impact on the electrochemical properties. Electrochemical investigation showed that the flower-like Co3O4 exhibited excellent cycling stability (1452 mA h g-1 at 0.5 C up to 300 cycles) and superior rate capability (reversible specific capacity of 880 mA h g-1 at 10 C). The obtained flower-like Co3O4 materials showed excellent cycle life and high rate capability, making it promising for applications in high-power LIBs.
Formation of Aligned Nanotubular TiSx Structures by Thermal Treatment of TiO2 in H2S
Authors: Kirchgeorg Robin , Hahn Robert , Schmuki P. 
Published: February 2020

This talk will present the formation of highly aligned nanotubular TiSx electrodes consisting of self-organized TiO2 nanotubes formed by thermal heat treatment in H2S gas. Depending on the annealing time and temperature several mixtures of titanium oxy-sulfides can be formed. Even a complete transformation into TiS2 is possible under the right conditions. The formed TiSx layers show a slightly modified tubular structure compared to the original TiO2 nanotubes, but still offer a high surface area in form of tubular structure. The formed TiSx were characterized by SEM, XRD, XPS and tested regarding their battery performance as a cathode material for lithium ion batteries.
References concering high temperature treatments in reactive gas envoirment:
Y.-C. Nah, I. Paramasivam, R. Hahn, N. K Shrestha and P. Schmuki, Nanotechnology 21 (2010) 105704
R. Hahn, F. Schmidt-Stein, J. Salonen, S. Thiemann, Y. Song, J. Kunze, V.-P. Lehto and Patrik Schmuki, Angew. Chem. Int. Ed. 48 (2009) 7236 –7239
The Electrochemical Properties of Hyperbranched Polymer Nanocoated Cathode Materials
Authors: Lin Yueh-Wei , Wu Wei-Hsin , Tsai Li-Duan , Fang Jason 
Published: February 2020

We introduce a novel type of surface nanostructured cathode materials. This approach relies on hyperbranched polymer beforehand directed nanoscale coating. The polymer coating successfully forms a uniform coverage onto the surface of the active materials. TEM photograph shows that lithium metal oxide particle is well decorated by polymer coating with 10 nm thickness.
Cycling performance (Figure 1) of modified electrode is comparing with pristine electrode at 1C charge rate with cut-off voltage 4.4V. Even after 300 cycles, the cells with modified electrode maintain at higher capacity level. On the other hand, the cells with pristine electrode quickly fade out.
These results demonstrate that the polymer coating effectively prevents the direct contact between electrodes and electrolytes that are highly vulnerable to electrochemical decomposition at high voltage conditions. Polymeric coating can also behave as interfacial protection layer that suppress the undesired interfacial reactions.
In-Situ X-Ray Imaging Study on the Cross-Sectional Distribution of Li-Ion Concentration in Electrolyte of Li-Ion Battery
Authors: Yamashige Hisao , Furuta Noritoshi , Mukouyama Masato , Kawamura Keiji , Ota Hisayoshi , Nonaka Takamasa , Kawaura Hiroyuki 
Published: February 2020

In the previous studies, we observed the three-dimensional distribution of various Co-oxidation states in LiCoO2 (LCO) active materials. It was found that as a LCO electrode is charged, the surface of the electrode is preferentially oxidized than the inside area [1].
In this study, we researched the cross-sectional distribution of Li-ion concentration in the electrolyte of Li-ion battery by using an in-situ X-ray imaging method. In order to use this method we first created a special test cell, which models the cross-section of a positive electrode, separator, and negative electrode in a cell. While charging and discharging the cell, we observed how the cross-sectional distribution of Li-ion in the separator and negative electrode changed. Figure 1 illustrates the X-ray image of the cross section structure of the cell: the positive electrode, separator, and negative electrode and their interfaces. Figure 2 shows how the degree of X-ray transmission of the cross section changes before and 15 and 30-second after the cell is charged at 5C current. Before the cell was charged, the transmission degrees of the negative electrode and separator were the same, demonstrating that the Li-ion concentration was equally distributed across them. However, 15-second after the cell was charged, the transmission degrees in the negative electrode increased, and the degree of the electrode surface (the side close to the separator) became higher than that of the inside (the side close to the Cu collector). We expect that charging made the Li-ion concentration in the negative electrode decrease and the concentration of the surface became lower than that of the inside. As for analysis on the separator, the transmission degree on the negative electrode side of the separator became higher than that on the positive electrode side, demonstrating that the Li-ion concentration on the negative electrode side decreased after the cell was charged and that on the positive electrode side increased. Additionally, the concentration was more largely distributed 30-second after the cell was charged than 15-second after.
In summary, we succeeded in applying the in-situ X-ray imaging method for identifying the Li-ion distribution in the negative electrode and separator during charging.
References:
[1] H. Yamashige, et al. 52th Battery Symposium, Nagoya, 9th Nov 2010.
Enrichment of Novel Electroactive Bacteria from Sediments via Potentiostatic Growth
Authors: Doyle Lucinda , Wuertz Stefan , Marsili Enrico 
Published: February 2020

Sediments are usually enriched in electrochemically active microorganism via growth at defined potential, either in Microbial Fuel Cells or in potentiostat-controlled electrochemical cells. Despite the great microbial diversity of sediments from natural and man-made environment, most electrochemical enrichments select a small group of dissimilatory metal-reducing microorganisms.
In this study, we aim to enrich novel electrochemically active strains in sediments from various equatorial environments. Sediment inocula from urban waterways, industrial area, and mines were tested in long-term enrichment experiments at controlled anodic potentials. In addition to the conventional voltamperometric characterization, the biofilm, formed at the working electrode was subjected to Electrochemical Impedance Spectroscopy (EIS) over a wide range of potentials. EIS of the biofilms reveal several charge transfer routes at different potentials and with different characteristic times. Furthermore, EIS enable monitoring the long-term changes of the electroactive biofilm and quantifying the effect of biofilm accumulation on the conductivity of the biofilm/electrode interface.
Electrochemical analysis is coupled with meta-genomic and meta-transcriptomics to reveal novel electrochemically active microorganisms and to understand their charge transfer mechanism. The understanding of the microbe/electrode interaction in the sediments will help controlling the dynamic of metal cycling in urban sediments. Furthermore, novel electrochemically active microorganism will find application in bioremediation and environmental sensing applications.
The Morphology and Electrochemical Properties of Pt and GDC Nano Composite Films Using Co-Sputtering Method
Authors: Lee Yoon Ho , Cha Suk Won , Cho Gu Young , Ji Sanghoon , Park Joonho , Chang Ikwhang 
Published: February 2020

Solid oxide fuel cell (SOFC) has a potential of next generation energy conversion device for high energy conversion rate and clean emission. However it requires high temperature above 800oC due to low kinetics of electrolyte and electrode materials. Lowering operating temperature to 400~600oC allows high system stability, various material selection, fast start-up and convenient sealing. There were several studies to lower the operating temperature with structural and material approach. Among these, application of nano fabrication to electrode and electrolyte is one of the most promising candidates because thickness of electrolyte and TPB density of electrodes are strongly affects to the cell performance.
Up to now, several structures and materials for low temperature operation have been presented however, PVD based nano-porous Pt is dominantly used for cathode because conventional mixed conducting oxides shows poor electronic conduction and large overpotential at a certain temperature between 400~600oC.
Pt electrodes for LT-SOFCs are usually fabricated by physical vapor deposition (PVD) to increase TPB density because it can easily control grain and pore size into nanometer scale. However increased surface energy and mobility of nano sized Pt accelerates coarsening even at a low temperature operation.
In a metallurgical research area, several methods to enhance heat resistance of metals and one of the most effective methods are known as dispersion hardening. By uniform dispersion (<1% by weight) of thermally stable oxide nano particles (<50nm) in to metals, it prevents thermal degradation even in a high temperature.
In this research we used GDC as a dispersion oxide material to enhance physical and electrochemical property of Pt because it has high ionic conductivity and electronic conductivity among oxide electrolytes.
Pt & GDC nano composite electrodes were fabricated under co-sputtering using Pt and GDC target. 50mtorr of argon background gas pressure was maintained during sputtering and various sputtering power between 50~200W on Pt and GDC were applied to differentiate the composition.
Fabricated electrodes are treated at 500oC for an hour to characterize morphological change and analyzed by electron scanning microscopy. Finally, fabricated electrodes are applied into YSZ pellet and evaluated electrochemical properties.
Understanding the Relationship of Nanostructure to Performance in Additive Free TiO2 Anodes for Lithium-Ion Batteries
Authors: Chadha Tandeep Singh , Tripathi Alok Mani , Mitra Sagar , Subramanian Venkat R. , Biswas Pratim 
Published: February 2020

TiO2 has recently emerged as a potential material for use as anodes for lithium ion batteries owing to its low cost, abundance and high chemical stability. There has been considerable interest in nanostructured thin films for this application since they offer higher surface area and thus better performance compared to bulk films. The performance of the anodes has previously been correlated to the particle size in these nanostructures. However, morphology and crystal orientation of the nanostructure have not yet been co-related to the performance of the battery. Also, current fabrication methods consist of multiple steps involving the use of carbon as conducting material and binders for adhering the active material to the current collector substrate. These, in addition to increasing the cost of fabrication, also pose a safety concern for high rate applications.
In this study, we present the fabrication of TiO2 nanostructures using a single step gas phase method directly on the current collector. Aerosol Chemical Vapor Deposition (ACVD) process has been successfully used for single step synthesis of nanostructured TiO2 with different morphologies by controlling the aerosol dynamics in the process. One dimensional (columnar) single crystal TiO2 nanostructures and granular structures were synthesized on stainless steel substrates (current collector) by the ACVD process. The electrochemical performance of these nanostructures was tested in a half-cell assembly against Li/Li+.
Single crystalline columnar structures exhibited enhanced specific capacity compared to the polycrystalline granular structures for the same structure height (Figure 1). The difference in performance of the columnar structures and the granular structures widens with increasing charging rates indicating the sluggish diffusion kinetics in the granular structures. This reduced performance of the granular structures was attributed to the presence of grain boundaries and the different crystallographic orientation in the structures. Further the performance of the columnar and granular nanostructures depended on the height of the structures. Mass transfer characteristics of the different morphologies were studied using electrochemical impedance spectroscopy (EIS) and Galvanic Intermittent Titration Technique (GITT). Transport modelling of lithium in the nanostructure will be used to understand the correlation between the nanostructure and performance of the anodes.
Hierarchically Structured N-Doped Carbon/Sulfur Composite Electrodes with a High Sulfur Loading for Application in Li/S Batteries
Authors: Brezesinski Torsten , Schneider Artur , Sommer Heino , Janek Juergen 
Published: February 2020

Rechargeable batteries have been receiving increasing attention over the past decade, in particular with regard to grid-storage and electric vehicle energy storage applications. Among the broad range of cathode materials, elemental sulfur (S) has the highest theoretical specific capacity of 1675 mAh/g, thereby making it one of the most promising positive electrode materials today.[1] The use of sulfur for next-generation lithium batteries is also highly desirable from the viewpoint of costs and sustainability. However, there are several issues related to safety and cyclability that have been preventing commercial application of the Li/S technology. For example, deleterious side reactions on the lithium metal anode and dissolution of reactive intermediates (polysulfides) during cycling have been shown to cause severe capacity fading.
Several approaches to addressing the problem of the “quasi-liquid” cathode have been reported and the use of lightweight nanostructured materials such as carbon to trap the generated polysulfides seems to provide a viable solution. In recent years, many such carbon/sulfur nanocomposite electrodes have been described in the literature. In the vast majority, however, the sulfur content and loading, and thus, also the areal capacity was too low for practical applications.[2] Both of these key parameters strongly affect the overall performance of Li/S batteries.
Here, we report on the preparation and electrochemical properties of hierarchically structured N-doped carbon/sulfur composite electrodes. Highly conductive (ionic liquid-derived) carbon monoliths with a nitrogen content of approx. 10% have been fabricated by facile hard templating and cathodes thereof with a sulfur content of 60% and loadings in the range of 1–4 mg/cm2 tested both in coin- and pouch-type cells. Stable specific capacities of greater than or equal to 700 mAh/g could be achieved over 200 cycles at a rate of C/5. For electrodes with the highest loading, this corresponds to an areal capacity of approx. 3.0 mAh/cm2. Literature reports on sulfur cathodes with similar areal capacities are scarce.[3] Besides the cycling performance, the cell chemistry has also been investigated, for example, by means of in operando synchrotron-based X-ray diffraction. Possible failure mechanisms will be discussed.
[1] Manthiram, A. Acc. Chem. Res.
2013, 46, 1125–1134.
[2] Lee, S. W., Shao-Horn Y. Nat. Nanotechnol.
2010, 5, 531–537.
[3] Song, J.; Wang, D. Adv. Funct. Mater.
2013, 24, 1243–1250.
Experimental Study on Performance Improvement of Laminar Flow-Based Fuel Cell
Authors: Ejiri Eiji , Kubota Shotaro 
Published: February 2020

The polymer electrolyte fuel cell (PEFC) is one of the promising candidates for the next generation power sources, however, there have still remained some issues such as manufacturing cost, material durability, fuel crossover and difficulty in water management. Almost all of these issues are attributed to the membrane used. The laminar flow-based fuel cell (LFFC), which is actually membraneless, has recently been proposed to overcome these issues. In LFFC, liquid fuel and liquid oxidant are supplied, flowing parallel with a thin boundary of diffusion zone, across which protons travel and electricity is generated.
This study aimed to improve the performance of LFFC and identify the factors that significantly influence the fuel cell performance. Here, the basic performance of a single cell LFFC, such as OCV and I-V characteristics, was investigated experimentally in conjunction with the internal flow visualization. Methanol solution was used as fuel and hydrogen peroxide solution or air was used as oxidant. Solutions were supported by sulfuric acid to enhance ionic conductivity. In I-V characteristics measurements, experimental parameters such as flow rate, oxidant concentration, operating temperature were varied to see how these parameters influenced the performance.
The results showed that the fuel cell performance was improved at higher operating temperature and oxidant concentration, however, performance improvement was not achieved at higher fuel flow rate. The results also showed that reduction of the electrode length along the flow direction decreased the influence of the boundary layer depletion and thereby improved the fuel cell performance. It was also revealed that the fuel cell performance was improved by reducing the distance between the electrodes. In conclusion, oxidant was more important than fuel in LFFC.