Synthesis, Tailoring and Characterization of V2O5-Cathodes for High Performance Li+-, Na+- and Mg2+-Ion Batteries

Battery technology based electric energy storage devices are inevitable on the way to electromobility and the widespread application of renewable energies like wind- or solar-power. 1 Until now, Li + -ion batteries represent the state of art technology meeting best the demands of high energy- and power-densities. However issues related to high costs and safety still require improvement. 2,3 One strategy to tackle those issues is to replace the costly Li-metal by other, more abundant metals, such as Na or Mg. 4 Due to the different ionic, electronic and chemical properties of Li + -, Na + - and Mg 2+ -ions, not every Li + -ion host material is suitable for the other ions. One exception is V 2 O 5 , which recently was successfully used as high voltage cathode for Na + - and Mg 2+ -ion intercalation. 5,6 Similar to the research on Li-ion battery electrode materials, where people pursue the strategy of electrode nanostructuring in order to increase the rate capability and hence the power density, a wide variety of synthesis techniques was applied to obtain nano-V 2 O 5 , including top-down and bottom-up techniques. 7 In this work, V 2 O 5 -nanofibres were synthesized by ultrasonication and electrochemical deposition. Anodization of vanadium metal yielded V 2 O 5 -nanotubes, while hydrothermal synthesis results in hollow V 2 O 5 -nanospheres. In order to characterize and specify the different electrode morphologies and performances, electrochemical, spectroscopic and microscopic techniques were applied (see Figure 1). In addition, fundamental studies on V 2 O 5 and its interaction with Li + -, Na + - and Mg 2+ -ions were conducted making use of Scanning Tunneling Microscopy (STM) and the Electrochemical Quartz Crystal Microbalance technique (EQCM). Figure 1 . SEM images of (a) hollow V 2 O 5 -nanospheres, (b) electrodeposited V 2 O 5 and (c) ultrasonicated V 2 O 5 1 B. Dunn, H. Kamath, J.-M. Tarascon, Science, 334 ( 2011 ) 928 2 M. Armand, J.-M. Tarascon, Nature, 451 ( 2008 ) 652 3 J. B. Goodenough, J. Solid State Electrochem., 16 ( 2012 ) 2019 4 J. O. Besenhard, M. Winter, ChemPhysChem, 3 ( 2002 ) 155 5 G. Gershinsky, H. D. Yoo, Y. Gofer, D. Aurbach, Langmuir, 29 ( 2013 ) 10964 6 D. W. Su, S. X. Dou, G. X. Wang, J. Mater. Chem., 2 ( 2014 ) 11185 7 A. S. Arico, P.Bruce, B. Scrosati, J.-M. Tarascon, W. van Schalkwijk, Nature, 4 ( 2005 ) 366 Figure 1