Blend formed by oxygen deficient MoO 3−δ oxides as lithium-insertion compounds

Abstract

Oxygen deficient Mo x O y 200 nm-thick particles were synthesized by a citrate sol-gel method using ammonium heptamolybdate tetrahydrate as a source of Mo and heat treated with a small fraction of zirconia under reducing atmosphere. The samples were investigated by Xray powder diffraction (XRD), thermal gravimetric analysis (TGA), scanning electron microscope (SEM) and Raman spectroscopy (RS). The structural analyses show that the composite is a blend formed by layered α-MoO 3 , orthorhombic oxygen deficient phases MoO 3-δ with δ=0.25 (γ-Mo 4 O 11) and α-ZrMo 2 O 8. The insertion of lithium into the lattice was performed by electrochemical method. Redox peaks were observed for the MoO 3-δ composite attributed to distinct Li +-ion insertion/extraction reactions in the MoO 3 and Mo 4 O 11 hosts. The cyclic performance revealed improved reversibility, rate capability, and electrochemical stability of the ZrMo 2 O 8-decorated composite with respect to the bare molybdenum oxides. At C/10 rate, the composite delivered a stable reversible capacity of 135 mAh g-1 after the 50 th cycle. At a rate of 2C the reversible capacity is maintained at 118 mAh g-1 , approximately twice the capacity observed for the MoO 3 particles alone.

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

“…The small values of the residual and reliability parameters ( R p , R w , and χ 2 ) of the Rietveld refinement indicate the successful identification of the orthorhombic and monoclinic phases of MoO 3 and MoO 2 powders, respectively, even in the presence of some impurity phases as in the case of MOV. The lattice parameters obtained from Rietveld refinement are in good agreement with values of our previous work as well as other literature [ 22 , 66 , 67 , 68 ]. A careful examination of the MoO 2 sample calcinated in vacuum reveals the presence of a small amount of Mo-suboxides such as Mo 4 O 11 , Mo 8 O 23 , and Mo 9 O 26 ( Table 1 ).…”

Amorphous Mo5O14-Type/Carbon Nanocomposite with Enhanced Electrochemical Capability for Lithium-Ion Batteries

“…This tunnel-like structure accommodates oxygen deficiency via oxygen vacancies and crystallographic shear planes. The formation of an intermediate compound Mo m O 3m−1 between Mo VI O 3 and Mo IV O 2 during the reduction of MoO 3 has been reported many times [15,45,46], but here, despite the previous claims, we obtained a stable phase with the O/Mo ratio of 2.8.…”

“…Nanosized Mo m O 3m−1 particles were prepared with low crystallinity [13,14]. Blended hybrid was fabricated [15]. Composites with addition of an electronically-conductive carbonaceous materials were synthesized [12,[16][17][18][19].…”

Growth, characterization and performance of bulk and nanoengineered molybdenum oxides for electrochemical energy storage and conversion

“…Oxygen deficient MoO3- nanoparticles (200 nm thick) were prepared by a citrate sol-gel using ammonium heptamolybdate tetrahydrate as a source of Mo and heat treated with a small fraction of zirconia under reducing atmosphere [446]. The structural analyses reveal that the Outstanding improvement in electrochemical performance is obtained for the Mo5O14 encapsulated by carbon (325 mAh g -1 at the 50 th cycle at 70 mA g -1 ) in comparison with the carbon-free MoO3 (95 mAh g -1 ).…”