Nanostructured Molybdenum-Oxide Anodes for Lithium-Ion Batteries: An Outstanding Increase in Capacity

This work aimed at synthesizing MoO(3) and MoO(2) 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 MoO(3) phase, while calcination in vacuum produced the reduced form MoO(2) 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 MoO(x) particles. MoO(3) formed platelet particles that were larger than those observed for MoO(2). MoO(3) showed stable thermal behavior until approximately 800 °C, whereas MoO(2) showed weight gain at approximately 400 °C due to the fact of re-oxidation and oxygen uptake and, hence, conversion to stoichiometric MoO(3). Electrochemically, traditional performance was observed for MoO(3), which exhibited a high initial capacity with steady and continuous capacity fading upon cycling. On the contrary, MoO(2) 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 MoO(2) may be attributed to its higher surface area and better electrical conductivity as observed in surface area and impedance investigations.