Browsing by Author "Zhang, Shixiong"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Nanostructured Molybdenum-Oxide Anodes for Lithium-Ion Batteries: An Outstanding Increase in Capacity
    (MDPI, 2021) Wang, Hua; Li, Tianyi; Hashem, Ahmed M.; Abdel-Ghany, Ashraf E.; El-Tawil, Rasha S.; Abuzeid, Hanaa M.; Coughlin, Amanda; Chang, Kai; Zhang, Shixiong; El-Mounayri, Hazim; Tovar, Andres; Zhu, Likun; Julien, Christian M.; Mechanical and Energy Engineering, School of Engineering and Technology
    This work aimed at synthesizing MoO3 and MoO2 by a facile and cost-effective method using extract of orange peel as a biological chelating and reducing agent for ammonium molybdate. Calcination of the precursor in air at 450 °C yielded the stochiometric MoO3 phase, while calcination in vacuum produced the reduced form MoO2 as evidenced by X-ray powder diffraction, Raman scattering spectroscopy, and X-ray photoelectron spectroscopy results. Scanning and transmission electron microscopy images showed different morphologies and sizes of MoOx particles. MoO3 formed platelet particles that were larger than those observed for MoO2. MoO3 showed stable thermal behavior until approximately 800 °C, whereas MoO2 showed weight gain at approximately 400 °C due to the fact of re-oxidation and oxygen uptake and, hence, conversion to stoichiometric MoO3. Electrochemically, traditional performance was observed for MoO3, which exhibited a high initial capacity with steady and continuous capacity fading upon cycling. On the contrary, MoO2 showed completely different electrochemical behavior with less initial capacity but an outstanding increase in capacity upon cycling, which reached 1600 mAh g−1 after 800 cycles. This outstanding electrochemical performance of MoO2 may be attributed to its higher surface area and better electrical conductivity as observed in surface area and impedance investigations.
  • Thumbnail Image
    Item
    Silver Nanocoating of LiNi0.8Co0.1Mn0.1O2 Cathode Material for Lithium-Ion Batteries
    (MDPI, 2023-04-23) Li, Xintong; Chang, Kai; Abbas, Somia M.; El-Tawil, Rasha S.; Abdel-Ghany, Ashraf E.; Hashem, Ahmed M.; Wang, Hua; Coughlin, Amanda L.; Zhang, Shixiong; Mauger, Alain; Zhu, Likun; Julien, Christian M.; Mechanical and Energy Engineering, School of Engineering and Technology
    Surface coating has become an effective approach to improve the electrochemical performance of Ni-rich cathode materials. In this study, we investigated the nature of an Ag coating layer and its effect on electrochemical properties of the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material, which was synthesized using 3 mol.% of silver nanoparticles by a facile, cost-effective, scalable and convenient method. We conducted structural analyses using X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy, which revealed that the Ag nanoparticle coating did not affect the layered structure of NCM811. The Ag-coated sample had less cation mixing compared to the pristine NMC811, which could be attributed to the surface protection of Ag coating from air contamination. The Ag-coated NCM811 exhibited better kinetics than the pristine one, which is attributed to the higher electronic conductivity and better layered structure provided by the Ag nanoparticle coating. The Ag-coated NCM811 delivered a discharge capacity of 185 mAh·g-1 at the first cycle and 120 mAh·g-1 at the 100th cycle, respectively, which is better than the pristine NMC811.