3 research outputs found
Electrochemical Synthesis and Application of Ge-Sn-O Nanostructures as Anodes of Lithium-Ion Batteries
This work demonstrates the possibility of electrochemical formation of Ge-Sn-O nanostructures from aqueous solutions containing germanium dioxide and tin (II) chloride at room temperature without prior deposition of fusible metal particles. This method does not require complex technological equipment, expensive and toxic germanium precursors, or binding additives. These advantages will make it possible to obtain such structures on an industrial scale (e.g., using roll-to-roll technology). The structural properties and composition of Ge-Sn-O nanostructures were studied by means of scanning electron microscopy and X-ray photoelectron spectroscopy. The samples obtained represent a filamentary structure with a diameter of about 10 nm. Electrochemical studies of Ge-Sn-O nanostructures were studied by cyclic voltammetry and galvanostatic cycling. Studies of the processes of lithium-ion insertion/extraction showed that the obtained structures have a practical discharge capacity at the first cycle ~625 mAh/g (specific capacity ca. 625 mAh/g). However, the discharge capacity by cycle 30 was no more than 40% of the initial capacity. The obtained results would benefit the further design of Ge-Sn-O nanostructures formed by simple electrochemical deposition
Effect of Vinylene Carbonate Electrolyte Additive on the Process of Insertion/Extraction of Na into Ge Microrods Formed by Electrodeposition
Layers of germanium (Ge) microrods with a core–shell structure on titanium foils were grown by a metal-assisted electrochemical reduction of germanium oxide in aqueous electrolytes. The structural properties and composition of the germanium microrods were studied by means of scanning and transmission electron microscopy. Electrochemical studies of germanium nanowires were carried out by impedance spectroscopy and cyclic voltammetry. The results showed that the addition of vinylene carbonate (VC) in the electrolyte significantly reduced the irreversible capacity during the first charge/discharge cycles and increased the long-term cycling stability of the Ge microrods. The obtained results will benefit the further design of Ge microrods-based anodes that are formed by simple electrochemical deposition
Effect of Silicate Additive on Structural and Electrical Properties of Germanium Nanowires Formed by Electrochemical Reduction from Aqueous Solutions
Layers of germanium (Ge) nanowires (NWs) on titanium foils were grown by metal-assisted electrochemical reduction of germanium oxide in aqueous electrolytes based on germanium oxide without and with addition of sodium silicate. Structural properties and composition of Ge NWs were studied by means of the scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and Raman spectroscopy. When sodium silicate was added to the electrolyte, Ge NWs consisted of 1–2 at.% of silicon (Si) and exhibited smaller mean diameter and improved crystallinity. Additionally, samples of Ge NW films were prepared by ultrasonic removal of Ge NWs from titanium foils followed with redeposition on corundum substrates with platinum electrodes. The electrical conductivity of Ge NW films was studied at different temperatures from 25 to 300 °C and an effect of the silicon impurity on the thermally activated electrical conductivity was revealed. Furthermore, the electrical conductivity of Ge NW films on corundum substrates exhibited a strong sensor response on the presence of saturated vapors of different liquids (water, acetone, ethanol, and isopropanol) in air and the response was dependent on the presence of Si impurities in the nanowires. The results obtained indicate the possibility of controlling the structure and electrical properties of Ge NWs by introducing silicate additives during their formation, which is of interest for applications in printed electronics and molecular sensorics