ABSTRACT
Next generation Li-ion batteries will require negative electrode materials with energy densities many-fold higher than that found in the graphitic carbon currently used in commercial Li-ion batteries. While various nanostructured alloying-type anode materials may satisfy that requirement, such materials do not always exhibit long cycle lifetimes and/or their processing routes are not always suitable for large-scale synthesis. Here, we report on a high-performance anode material for next generation Li-ion batteries made of nanoporous Sn powders with hierarchical ligament morphology. This material system combines both long cycle lifetimes (more than 72% capacity retention after 350 cycles), high capacity (693 mAh/g, nearly twice that of commercial graphitic carbon), good charging/discharging capabilities (545 mAh/g at 1 A/g, 1.5C), and a scalable processing route that involves selective alloy corrosion. The good cycling performance of this system is attributed to its nanoporous architecture and its unique hierarchical ligament morphology, which accommodates the large volume changes taking place during lithiation, as confirmed by synchrotron-based ex-situ X-ray 3D tomography analysis. Our findings are an important step for the development of high-performance Li-ion batteries.
ABSTRACT
An aqueous synthetic route at 95 °C is developed to reach selectively three scarcely reported vanadium oxyhydroxides. Häggite V2O3(OH)2, Duttonite VO(OH)2, and Gain's hydrate V2O4(H2O)2 are obtained as nanowires, nanorods, and nanoribbons, with sizes 1 order of magnitude smaller than previously reported. X-ray absorption spectroscopy provides evidence that vanadium in these phases is V+IV. Combined with FTIR, XRD, and electron microscopy, it yields the first insights into formation mechanisms, especially for Häggite and Gain's hydrate. This study opens the way for further investigations of the properties of novel V+IV (oxyhydr)oxides nanostructures.
