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 Mg²⁺-ions, not every Li⁺-ion host material is suitable for the other ions. One exception is V₂O₅, which recently was successfully used as high voltage cathode for Na⁺- and Mg²⁺-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-V₂O₅, including top-down and bottom-up techniques.⁷ In this work, V₂O₅-nanofibres were synthesized by ultrasonication and electrochemical deposition. Anodization of vanadium metal yielded V₂O₅-nanotubes, while hydrothermal synthesis results in hollow V₂O₅-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 V₂O₅ and its interaction with Li⁺-, Na⁺- and Mg²⁺-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 V₂O₅-nanospheres, (b) electrodeposited V₂O₅ and (c) ultrasonicated V₂O₅

 

¹B. Dunn, H. Kamath, J.-M. Tarascon, Science, 334 (2011) 928

²M. Armand, J.-M. Tarascon, Nature, 451 (2008) 652

³J. B. Goodenough, J. Solid State Electrochem., 16 (2012) 2019

⁴J. O. Besenhard, M. Winter, ChemPhysChem, 3 (2002) 155

⁵G. Gershinsky, H. D. Yoo, Y. Gofer, D. Aurbach, Langmuir, 29 (2013) 10964

⁶D. W. Su, S. X. Dou, G. X. Wang, J. Mater. Chem., 2 (2014) 11185

⁷A. S. Arico, P.Bruce, B. Scrosati, J.-M. Tarascon, W. van Schalkwijk, Nature, 4 (2005) 366