@conference{
author = "Jugović, Dragana and Milović, Miloš and Barudžija, Tanja and Mitrić, Miodrag",
year = "2022",
abstract = "The development of safe, durable, cheap, and environmentally friendly batteries is one of the most important challenges of modern electrochemistry. Hence, there is an interest in the investigation of aqueous batteries with multivalent ions such as calcium, magnesium, or aluminium. Furthermore, the use of polyanionic compounds as cathode material can provide multi-electron transport. VOPO4·2H2O with its layered structure is a particularly interesting and promising material.
The current study is focused on the investigation of VOPO4·2H2O as cathode material in aluminium aqueous rechargeable cells. According to the literature data, the conventional reflux method is mostly used for the material’s synthesis [1]. Here is presented a sonochemical synthesis as a less time- and energy-consuming method, that starts from the mixture of vanadium(V)-oxide, phosphoric acid and water as a reaction media. The synthesis is done within 20 min.
The characterization of the synthesized material includes X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and cyclovoltammetry (CV).
XRD data were used for both the powders’ phase identification and crystal structure refinement. The structure of the powder was refined in the tetragonal space group P4/nmmZ (No. 129). Crystal structure refinement was based on the Rietveld full profile method [2]. The structure is characterized by infinite layers of PO4 tetrahedra linked to VO6 octahedra by shared oxygen atoms that form 2D sheets in the ab-planes; water molecules are located in the interlayer space. The refined cell parameters, a = b = 6.2136 Å, c = 7.4141 Å, are in good agreement with the literature data. Lattice parameter c is a measure of the interlayer distance, thus varies with water content. The value of the refined c parameter implies that the structure consists two water molecules per formula unit.
The working electrode is prepared from a slurry of sonochemically derived VOPO4·2H2O as an active material, carbon black, and a binder dispersed in a solvent. Two different binders are used: polyvinylidene fluoride (PVDF), 2.4 wt% solution in N-methyl-2-pyrrolidone or Nafion, 5 wt% solution in a mixture of lower aliphatic alcohols and water. Cyclic voltammetry measurements are done in several electrolytes to probe the intercalation of various cations such as magnesium, calcium, and aluminium. The best results are obtained when the electrode is cycled in 1M Al(NO3)3 aqueous solution.
This probably originates in different ionic radii.
During the process of electrode preparation, structural changes in the powder are noticed. The structural changes were followed step by step through the combined XRD and FTIR analysis. It turns out that the structure is prone to release water molecules even when the powder is mixed with carbon black and also with the addition of a solvent, which could lead to the formation of a bilayered vanadyl phosphate. It was shown that using different solvents has a diverse impact on the structure, and consequently on powders’ cyclic performances.",
publisher = "Split : University of Split",
journal = "Book of Abstracts / eESC-IS2022 : 6th International Symposium on Materials for Energy Storage and Conversion, 5. - 8. 7.2022. Bol, island of Brač, Croatia",
title = "Vanadyl phosphate as a host material for aluminium intercalation",
url = "https://hdl.handle.net/21.15107/rcub_dais_13647"
}
