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Minano, Spain

Eshetu G.G.,Helmholtz Institute Ulm | Eshetu G.G.,Karlsruhe Institute of Technology | Armand M.,CIC ENERGIGUNE | Scrosati B.,Italian Institute of Technology | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2014

The advent of ionic liquids (ILs) as eco-friendly and promising reaction media has opened new frontiers in the field of electrochemical energy storage. Beyond their use as electrolyte components in batteries and supercapacitors, ILs have unique properties that make them suitable as functional advanced materials, media for materials production, and components for preparing highly engineered functional products. Aiming at offering an in-depth review on the newly emerging IL-based green synthesis processes of energy storage materials, this Review provides an overview of the role of ILs in the synthesis of materials for batteries, supercapacitors, and green electrode processing. It is expected that this Review will assess the status quo of the research field and thereby stimulate new thoughts and ideas on the emerging challenges and opportunities of IL-based syntheses of energy materials. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Palomares V.,University of the Basque Country | Serras P.,University of the Basque Country | Villaluenga I.,University of the Basque Country | Hueso K.B.,University of the Basque Country | And 2 more authors.
Energy and Environmental Science | Year: 2012

Energy production and storage have become key issues concerning our welfare in daily life. Present challenges for batteries are twofold. In the first place, the increasing demand for powering systems of portable electronic devices and zero-emission vehicles stimulates research towards high energy and high voltage systems. In the second place, low cost batteries are required in order to advance towards smart electric grids that integrate discontinuous energy flow from renewable sources, optimizing the performance of clean energy sources. Na-ion batteries can be the key for the second point, because of the huge availability of sodium, its low price and the similarity of both Li and Na insertion chemistries. In spite of the lower energy density and voltage of Na-ion based technologies, they can be focused on applications where the weight and footprint requirement is less drastic, such as electrical grid storage. Much work has to be done in the field of Na-ion in order to catch up with Li-ion technology. Cathodic and anodic materials must be optimized, and new electrolytes will be the key point for Na-ion success. This review will gather the up-to-date knowledge about Na-ion battery materials, with the aim of providing a wide view of the systems that have already been explored and a starting point for the new research on this battery technology. © 2012 The Royal Society of Chemistry.

Layered transition metal oxides (LTMOs) have a long tradition of success as effective electrode materials for power storage applications. However, the growing demand for improved technologies has motivated a strong interest in developing new generations of this class of materials. First-principles calculations, in particular density functional theory (DFT), have become an important tool to gain atomic-level understanding and speed up the search of new materials in general. An important structural ingredient of LTMOs is the weak van der Waals (vdW) forces that hold layers together. Unfortunately, conventional DFT approaches have serious shortcomings to treat these dispersion interactions. This is an uneasy position for the role of DFT in describing such layered-type structural materials. Recent exciting developments in DFT allow us now to tackle this problem head on. Here we have employed newly developed vdW-inclusive methods based on improved nonlocal density functionals to thoroughly explore the role of vdW forces in key thermodynamic and kinetic properties of alkali (Li, Na, and K) and alkaline-earth (Mg, Ca, and Sr) ion insertion into α-V2O5. We find that vdW forces help to stabilize inserted ions and, therefore, increase average voltages compared to the values obtained with conventional non-vdW-inclusive DFT methods. Added to this, activation energies for ion diffusion significantly increase as a consequence of a proper account for vdW interactions. These results highlight the relevance of vdW forces to ion intercalation and dynamics in LTMOs in general. © 2014 American Chemical Society.

Pergolesi D.,Japan International Center for Materials Nanoarchitectonics | Fabbri E.,Japan International Center for Materials Nanoarchitectonics | Cook S.N.,Imperial College London | Roddatis V.,CIC ENERGIGUNE | And 2 more authors.
ACS Nano | Year: 2012

Biaxially textured epitaxial thin-film heterostructures of ceria and 8 mol % yttria-stabilized zirconia (8YSZ) were grown using pulsed laser deposition (PLD) with the aim to unravel the effect of the interfacial conductivity on the charge transport properties. Five different samples were fabricated, keeping the total thickness constant (300 nm), but with a different number of heterointerfaces (between 4 and 60). To remove any potential contribution of the deposition substrate to the total conductivity, the heterostructures were grown on (001)-oriented MgO single-crystalline wafers. Layers free of high-angle grain boundaries and with low density of misfit dislocations were obtained, as revealed by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) analysis. The crystallographic quality of these samples allowed the investigation of their conduction properties, suppressing any transport effects along grain boundaries and/or interfacial dislocation pathways. Electrochemical impedance spectroscopy (EIS) and secondary ion mass spectroscopy (SIMS) measurements showed that for these samples the interfacial conductivity has a negligible effect on the transport properties. © 2012 American Chemical Society.

Hueso K.B.,University of the Basque Country | Armand M.,CIC ENERGIGUNE | Rojo T.,University of the Basque Country
Energy and Environmental Science | Year: 2013

The progress in the research and development of high temperature sodium batteries suggests that all-solid-state batteries with inorganic or polymer solid electrolytes are promising power sources for a wide range of applications due to their high thermal stability, reliability, long-cycle life and versatile geometries. The electrolytes play a fundamental role in terms of current (power) density, the time stability, and the safety of batteries and, as a result, their continuous improvement and innovation are indeed critical to success. In fact, inorganic solid electrolytes pave the way for improving the cost-effective development of rechargeable sodium batteries. This review describes a state-of-the-art overview of most of the Na+ conductors for use as electrolytes in sodium/sulphur and ZEBRA batteries. The emphasis of this article is on inorganic solid electrolytes, especially, ceramic and glass-ceramic electrolytes as promising alternatives applicable to all solid-state batteries. As part of a continuous effort to find new materials that operate at room temperature and moderate temperatures, NASICON electrolytes will also be considered. Polymer electrolytes based on poly(ethylene oxide) (PEO) are also very suitable for all solid-state batteries. Hence, the review focuses on ion transport based on the observed conductivity, electrolyte preparation, safety and environmental impact. © 2013 The Royal Society of Chemistry.

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