Synthesis of a 3D network of Pt nanowires by atomic layer deposition on carbonaceous template

The formation of a 3D network composed of free standing and interconnected Pt nanowires is achieved by a two-step method, consisting of conformal deposition of Pt by atomic layer deposition (ALD) on a forest of carbon nanotubes and subsequent removal of the carbonaceous template. Detailed characterization of this novel 3D nanostructure was carried out by transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS). These characterizations showed that this pure 3D nanostructure of platinum is self-supported and offers an enhancement of the electrochemically active surface area by a factor of 50

Electrodeposition of adherent submicron to micron thick manganese dioxide films with optimized current collector interface for 3D Li-ion electrodes

Three-dimensional (3D) configuration of high-performance energy storage devices has been the subject of ongoing investigations targeting their integration in autonomous microelectronic systems. In this study we demonstrate a route toward the realization of high capacity cathode material for 3D thin-film lithium-ion (Li-ion) batteries. Electrolytic manganese dioxide (EMD) film can be applied as a Li-ion intercalation electrode upon its conversion to lithium manganese dioxide (LiMn2O4 or LMO) by solid-state reaction. The main challenges of depositing thicker EMD film directly on the current collector often lay in achieving a good film adhesion and preventing oxidation of non-noble current collectors such as TiN, Ni. To improve the adhesion of the EMD films we modify the surface of the current collector by means of thin-film or seed layer coatings, which also prevent the oxidation of the underlying current collector substrate during the anodic deposition process. As a result submicron to micron thick EMD films with good adhesion were deposited on various current collectors. The acidity of the electrolyte solutions was varied depending on the type of the surface coating or current collector used. The mechanism of the EMD film growth and morphology on different substrates was examined. Compatibility of the proposed current collector interface modification for the electrodeposition of conformal thick EMD films on high-aspect ratio microstructures was demonstrated. A method of EMD film conversion to LMO at low-temperature on different substrates was shown as the path toward their application in 3D Li-ion batteries

Local solid-state modification of nanopore surface charges

The last decade, nanopores have emerged as a new and interesting tool for the study of biological macromolecules like proteins and DNA. While biological pores, especially alpha-hemolysin, have been promising for the detection of DNA, their poor chemical stability limits their use. For this reason, researchers are trying to mimic their behaviour using more stable, solid-state nanopores. The most successful tools to fabricate such nanopores use high energy electron or ions beams to drill or reshape holes in very thin membranes. While the resolution of these methods can be very good, they require tools that are not commonly available and tend to damage and charge the nanopore surface. In this work, we show nanopores that have been fabricated using standard micromachning techniques together with EBID, and present a simple model that is used to estimate the surface charge. The results show that EBID with a silicon oxide precursor can be used to tune the nanopore surface and that the surface charge is stable over a wide range of concentrations.Comment: 10 pages, 6 figure

Carbon nanostructures for enabling microstructured energy storage devices

Commercial Li_ion batteries are based on liquid electrolytes which are considered unsafe as the organic solvents they contain are volatile and flammable. As an alternative, Li_ion batteries with solid electrolytes are proposed. Solid-state batteries need to be made in form of a thin-film stack to compensate for the low ion conductivity through the solid electrolyte. However, these batteries in their current planar format have low energy density. Solid-state batteries with higher energy density and similar power density are possible, if the architecture of the thin film battery is changed from planar to microstructured. This can be achieved by depositing the active materials as a thin-film stack with sub-micrometer thicknesses over these microstructured surfaces. To this date no commercial battery of this type is available. In this thesis, several challenges regarding the fabrication of this type of batteries were investigated. In particular, nanostructured graphitic carbon layers where explored. High aspect-ratio carbon nanosheets (CNS) were used as model material to study conformal deposition of pinhole free thin electrolyte films by electrodeposition. Thin planar graphitic carbon films with nano roughness were investigated as adhesion promotor for nanoporous electrolytic manganese dioxide films to be used as cathode in our 3D Li-ion thin-film batteries. Carbon nanosheets (CNS) layers were used as high surface area carbon nanostructures. The CNS consist of a maze of electrically interconnected thin graphitic carbon sheets which are oriented vertically with respect to the substrate. CNS form a self-supported, high aspect ratio network with a sheet thickness ranging from a few nanometers to tens of nanometer and with sheet heights up to 2 micrometer. The planar graphitic carbon layers were obtained with process of growing CNS, however, in this case, the process was interrupted right after the nucleation stage, providing graphitic carbon films with few tens of nanometers. In the first part of thesis an extensive electrochemical characterization of CNS layers with different morphology and surface area (height) in aqueous and non- aqueous electrolyte solutions was performed. During this investigation a direct correlation between electrochemical capacitance, wettablity and functional surface groups on CNS sheets was determined. Moreover, the electrochemical capacitance of the CNS layers was used to determine the area enhancement of these structures. An area enhancement 120x per micrometer of CNS was found. One of the biggest challenges in the fabrication of a microstructured battery is the ability to conformally coat high aspect ratio microstructures with active battery materials. This is especially difficult for the solid electrolyte. As the solid electrolyte is directly sandwiched between two active electrodes, it is required to be electronically insulating. Hence, the electrolyte film needs to be pinhole free. In this thesis we have used the high aspect ratio CNS layer as a template to investigate the conformal deposition of electrically insulating poly(phenylene oxide) or PPO films. So far, PPO films had only been electrodeposited on planar surfaces. According to literature, these films were electrically insulating but ionically conductive. In this thesis we were able to conformally coat about 10nm thin PPO films over the CNS layers. The as-deposited PPO films were pinhole-free, electrically insulating and showed some ionic conductivity. The planar graphitic carbon film was used as a conductive seed layer to investigate the growth and electrochemical properties of electrolytic manganese dioxide (EMD) battery electrode. The graphitic carbon coating provided an excellent adhesion between the TiN substrate and EMD which significantly improved the electrochemical performance compared to EMD layers for example grown on platinum seed. Moreover, with the help of these graphitic carbon films, up to 500 nm thick EMD films could be grown, which was not possible neither with Pt nor TiN current collectors. Finally, a working half-cell was composed based on the developed graphitic carbon adhesion layer, EMD thin-film cathode and thin PPO as solid Li-ion electrolyte. However, due to the ultrathin thickness of PPO, the attempts to build full battery were unsuccessful. It is suggested that the PPO can serve as ion conductive buffer or protective layer rather than the main solid electrolyte in the stack. Even though the half-cell materials and processes are fully transferable to a microstructured substrate, further research will be required to build a full 3D thin-film battery.status: publishe

The Role of New Media in the Political and Social Landscape of Armenia

Звернено увагу на сучасні тенденції розвитку медіаландшафту Вірменії. Показано вплив нових медіа на порядок денний традиційних ЗМІ, який зростає із збільшенням кількості новинних сайтів й актуалізацією соціальних мереж, що дає змогу створити зручну платформу для обговорення питань місцевого значення громадами столиці й далеко за її межами. Проаналізовано альтернативні джерела інформації та запропоновано шляхи уникнення безвідповідальної журналістики.The report gives an expert analysis of the modern trends in the media landscape of Armenia, and expounds the influence of new media on traditional media. This influence is expanding as news sites and social networks develop and increase in number, providing convenient platforms for geographically distant capital communities to discuss local issues. The piece also reviews alternative sources of information and considers how irresponsible journalism may be avoided

Electrolytic Manganese Dioxide Coatings on High Aspect Ratio Micro-Pillar Arrays for 3D Thin Film Lithium Ion Batteries

In this work, we present the electrochemical deposition of manganese dioxide (MnO2) thin films on carbon-coated TiN/Si micro-pillars. The carbon buffer layer, grown by plasma enhanced chemical vapor deposition (PECVD), is used as a protective coating for the underlying TiN current collector from oxidation, during the film deposition, while improving the electrical conductivity of the stack. A conformal electrolytic MnO2 (EMD) coating is successfully achieved on high aspect ratio C/TiN/Si pillar arrays by tailoring the deposition process. Lithiation/Delithiation cycling tests have been performed. Reversible insertion and extraction of Li+ through EMD structure are observed. The fabricated stack is thus considered as a good candidate not only for 3D micorbatteries but also for other energy storage applications

Mapping Digital Media: Armenia

The Mapping Digital Media project examines the global opportunities and risks created by the transition from traditional to digital media. Covering 60 countries, the project examines how these changes affect the core democratic service that any media system should provide: news about political, economic, and social affairs.Recent years have seen a rapid expansion of the internet in Armenia, not only among the residents of the capital city and other urban areas, but also in remote regions of the country. It was particularly noticeable in 2010–2011, when the number of internet users increased by almost 40 percent.The report finds that, overall, digitization has increased the diversity of media outlets and their news offer, and the plurality of opinions expressed. Yet the lack of independence of regulatory institutions, non-transparent media ownership, flawed broadcast legislation, and the slow pace of digital switch-over continue to obstruct the development of the media sector. Television, the main source of information, is still largely controlled by the authorities. There is widespread hidden censorship as a result of political pressure on media outlets, which especially affects the news and political output on television. Most media outlets remain dependent upon large businesses and the political elite, with which they have become integrated

Electrolytic Manganese Dioxide Coatings on High Aspect Ratio Micro-Pillar Arrays for 3D Thin Film Lithium Ion Batteries

In this work, we present the electrochemical deposition of manganese dioxide (MnO₂) thin films on carbon-coated TiN/Si micro-pillars. The carbon buffer layer, grown by plasma enhanced chemical vapor deposition (PECVD), is used as a protective coating for the underlying TiN current collector from oxidation, during the film deposition, while improving the electrical conductivity of the stack. A conformal electrolytic MnO₂ (EMD) coating is successfully achieved on high aspect ratio C/TiN/Si pillar arrays by tailoring the deposition process. Lithiation/Delithiation cycling tests have been performed. Reversible insertion and extraction of Li⁺ through EMD structure are observed. The fabricated stack is thus considered as a good candidate not only for 3D microbatteries but also for other energy storage applications.status: publishe