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"Currently, single systems of photovoltaic cells which are connected together—mostly lead-based batteries and vast amounts of cable—are in use. Solar panels on the roof with a battery in the cellar. This takes up a lot of space, needs frequent maintenance and is not optimally efficient," says Ilie Hanzu from TU Graz's Institute of Chemistry and Technology of Materials. "We want to make a battery and solar cell hybrid out of two single systems which is not only able to convert electrical energy but also store it." Hanzu and his team— in cooperation with Graz Centre for Electron Microscopy (ZFE)—are entering largely unknown scientific territory. In the SolaBat project, they want to develop a new, application-relevant concept and test its capability. The key to success lies in the new combination of functional materials. Hanzu explains: "In the hybrid system, high-performance materials share their tasks in the solar cell and in the battery. We need materials that reliably fulfil their respective tasks and that are also electrochemically compatible with other materials so that they work together in one device." Instead of environmentally damaging cobalt-containing electrodes, eco-friendly titanates will be used as the active materials. Polymer-based cells—in other words, organic solar cells— could also be used. "We have to know what happens when the materials come into contact with each other. For this reason, our project partner, the Centre for Electron Microscopy, is investigating the underlying fundamental interface effects and reactions," say Hanzu. The other three work packages of the project concentrate on materials for the photovoltaic side and the battery side as well as the compatibility of materials and the assembly of both components into one device. The advantages of a "two in one" hybrid system are obvious: It would be space saving, efficient and comparatively simple to manage. In the SolaBat project, the basics are being developed and tested, but even at this early stage, a variety of potential applications of such a system are on the horizon—from mobile batteries and car batteries to larger solar panels. Hanzu explains: "Our preliminary work was very promising and I'm confident that at the end of SolaBat, we will be able to present a working concept of a photovoltaic battery hybrid. Where, exactly, such a system will find application is too early to say, but the possibilities are in any case manifold." Moreover, different applications have different needs. "With batteries in micro applications or small appliances, such as smartphones, space saving is primary and weight secondary. In the case of car batteries, in contrast, weight is the most important parameter, space not so much." Explore further: New low-cost battery could help store renewable energy

Brandstatter H.,Institute of Chemistry and Technology of Materials | Wohlmuth D.,Institute of Chemistry and Technology of Materials | Bottke P.,Institute of Chemistry and Technology of Materials | Pregartner V.,Institute of Chemistry and Technology of Materials | Wilkening M.,Institute of Chemistry and Technology of Materials
Zeitschrift fur Physikalische Chemie | Year: 2015

The monoclinic polymorph of Li2TiO3 (β-form) is known to be a relatively poor Li ion conductor. Up to now, no information is available on how the ion transport properties change when going from well-ordered crystalline Li2TiO3 to a structurally disordered form with the same chemical composition. Here, we used high-energy ball milling to prepare nanocrystalline, defect-rich Li2TiO3; ion dynamics have been studied via impedance spectroscopy. It turned out that ball milling offers the possibility to enhance long-range ion transport in the oxide by approximately 3 orders of magnitude. Its effect on the oxide ceramic is two-fold: besides the introduction of a large number of defects, the originally μm-sized crystallites are decreased to crystallites with a mean diameter of less than 50 nm. This process is accompanied by a mechanically induced phase transformation towards the α-form of Li2TiO3; besides that, a significant amount of amorphous materials is produced during milling. Structural disorder in nanocrystalline as well as amorphous Li2TiO3 is anticipated to play the capital role in governing Li ion dynamics of the sample finally obtained. © 2015 Walter de Gruyter.

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