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6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Li(MoO2)2 by Materials Project

Li(MoO2)2 is Spinel structured and crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share corners with twelve MoO6 octahedra. The corner-sharing octahedra tilt angles range from 56–60°. There are two shorter (2.05 Å) and two longer (2.09 Å) Li–O bond lengths. There are two inequivalent Mo+3.50+ sites. In the first Mo+3.50+ site, Mo+3.50+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six equivalent LiO4 tetrahedra and edges with six MoO6 octahedra. There are a spread of Mo–O bond distances ranging from 2.06–2.16 Å. In the second Mo+3.50+ site, Mo+3.50+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six equivalent LiO4 tetrahedra and edges with six MoO6 octahedra. There are four shorter (2.17 Å) and two longer (2.18 Å) Mo–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Li1+ and three Mo+3.50+ atoms. In the second O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Li1+ and three Mo+3.50+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li(MoO2)3 by Materials Project

Li(MoO2)2MoO2 crystallizes in the orthorhombic Cmmm space group. The structure is two-dimensional and consists of two molybdenum molecules; four water molecules; and one Li(MoO2)2 sheet oriented in the (0, 0, 1) direction. In the Li(MoO2)2 sheet, Li1+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Li–O bond lengths are 2.04 Å. Mo+3.67+ is bonded in a linear geometry to two equivalent O2- atoms. Both Mo–O bond lengths are 1.81 Å. O2- is bonded in a bent 150 degrees geometry to one Li1+ and one Mo+3.67+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Li11(MoO2)12 by Materials Project

Li11(MoO2)12 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are seven inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with five LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 2–12°. There are a spread of Li–O bond distances ranging from 2.19–2.40 Å. In the second Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 3–9°. There are a spread of Li–O bond distances ranging from 2.22–2.31 Å. In the third Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 2–10°. There are a spread of Li–O bond distances ranging from 2.22–2.28 Å. In the fourth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with five LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 3–11°. There are a spread of Li–O bond distances ranging from 2.11–2.47 Å. In the fifth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with five LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 1–12°. There are a spread of Li–O bond distances ranging from 2.14–2.49 Å. In the sixth Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 5–6°. There are a spread of Li–O bond distances ranging from 2.22–2.35 Å. In the seventh Li1+ site, Li1+ is bonded to six O2- atoms to form LiO6 octahedra that share corners with six MoO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 3–5°. There are a spread of Li–O bond distances ranging from 2.16–2.34 Å. There are six inequivalent Mo+3.08+ sites. In the first Mo+3.08+ site, Mo+3.08+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with five LiO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 3–6°. There are a spread of Mo–O bond distances ranging from 2.12–2.22 Å. In the second Mo+3.08+ site, Mo+3.08+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with five LiO6 octahedra, edges with five LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 5–12°. There are a spread of Mo–O bond distances ranging from 2.14–2.21 Å. In the third Mo+3.08+ site, Mo+3.08+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with five LiO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 2–11°. There are a spread of Mo–O bond distances ranging from 2.13–2.21 Å. In the fourth Mo+3.08+ site, Mo+3.08+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six LiO6 octahedra, edges with five LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 3–12°. There are a spread of Mo–O bond distances ranging from 2.17–2.21 Å. In the fifth Mo+3.08+ site, Mo+3.08+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six LiO6 octahedra, edges with five LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 5–11°. There are a spread of Mo–O bond distances ranging from 2.17–2.23 Å. In the sixth Mo+3.08+ site, Mo+3.08+ is bonded to six O2- atoms to form MoO6 octahedra that share corners with six LiO6 octahedra, edges with six LiO6 octahedra, and edges with six MoO6 octahedra. The corner-sharing octahedra tilt angles range from 1–6°. There are a spread of Mo–O bond distances ranging from 2.12–2.17 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded to two Li1+ and three Mo+3.08+ atoms to form OLi2Mo3 square pyramids that share corners with four OLi3Mo3 octahedra, corners with five OLi2Mo3 square pyramids, and edges with eight OLi3Mo3 octahedra. The corner-sharing octahedra tilt angles range from 2–10°. In the second O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with four OLi3Mo3 octahedra, corners with two OLi2Mo3 square pyramids, edges with ten OLi3Mo3 octahedra, and edges with two equivalent OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–3°. In the third O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with four OLi3Mo3 octahedra, corners with two OLi2Mo3 square pyramids, edges with ten OLi3Mo3 octahedra, and edges with two OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–4°. In the fourth O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with four OLi3Mo3 octahedra, corners with two OLi2Mo3 square pyramids, edges with ten OLi3Mo3 octahedra, and edges with two OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–4°. In the fifth O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with four OLi3Mo3 octahedra, corners with two OLi2Mo3 square pyramids, edges with eleven OLi3Mo3 octahedra, and an edgeedge with one OLi2Mo3 square pyramid. The corner-sharing octahedra tilt angles range from 0–4°. In the sixth O2- site, O2- is bonded to two Li1+ and three Mo+3.08+ atoms to form OLi2Mo3 square pyramids that share corners with four OLi3Mo3 octahedra, corners with five OLi2Mo3 square pyramids, edges with seven OLi3Mo3 octahedra, and an edgeedge with one OLi2Mo3 square pyramid. The corner-sharing octahedra tilt angles range from 3–7°. In the seventh O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with five OLi3Mo3 octahedra, a cornercorner with one OLi2Mo3 square pyramid, edges with eight OLi3Mo3 octahedra, and edges with four OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–8°. In the eighth O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with five OLi3Mo3 octahedra, a cornercorner with one OLi2Mo3 square pyramid, edges with eight OLi3Mo3 octahedra, and edges with four OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–10°. In the ninth O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with five OLi3Mo3 octahedra, a cornercorner with one OLi2Mo3 square pyramid, edges with nine OLi3Mo3 octahedra, and edges with three OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–10°. In the tenth O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with five OLi3Mo3 octahedra, a cornercorner with one OLi2Mo3 square pyramid, edges with eleven OLi3Mo3 octahedra, and an edgeedge with one OLi2Mo3 square pyramid. The corner-sharing octahedra tilt angles range from 0–3°. In the eleventh O2- site, O2- is bonded to three Li1+ and three Mo+3.08+ atoms to form OLi3Mo3 octahedra that share corners with five OLi3Mo3 octahedra, a cornercorner with one OLi2Mo3 square pyramid, edges with eight OLi3Mo3 octahedra, and edges with four OLi2Mo3 square pyramids. The corner-sharing octahedra tilt angles range from 0–3°. In the twelfth O2- site, O2- is bonded to two Li1+ and three Mo+3.08+ atoms to form OLi2Mo3 square pyramids that share corners with five OLi3Mo3 octahedra, corners with four OLi2Mo3 square pyramids, and edges with eight OLi3Mo3 octahedra. The corner-sharing octahedra tilt angles range from 3–8°.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Hierarchically structured MoO 2 /dopamine-derived carbon spheres as intercalation electrodes for lithium-ion batteries

A hydrogen peroxide initiated sol-gel process involving molybdenum transformation in the presence of dopamine (Dopa) hydrochloride excess produced the metastable precipitate composed of polydopamine (PDopa) spheres coated with Dopa preintercalated molybdenum oxide, (Dopa) x MoO y @PDopa. The hydrothermal treatment (HT) of the (Dopa) x MoO y @PDopa precursor resulted in the simultaneous carbonization of Dopa and molybdenum reduction generating MoO 2 nanoplatelets distributed and confined on the surface of the Dopa-derived carbon matrix (HT-MoO 2 /C). The consecutive annealing (An) of the HT-MoO 2 /C sample at 600 °C under Ar atmosphere led to the formation of MoO 2 with increased Mo oxidation state and improved structural stability (AnHT-MoO 2 /C). Annealing had also further facilitated interaction between the molybdenum-derived and Dopa-derived components resulting in the modification of the carbon matrix confirmed by Raman spectroscopy. Morphology of both materials is best described as Dopa-derived carbon spheres decorated with MoO 2 nanoplatelets. These integrated metal oxide and carbon structures were tested as electrodes for lithium-ion batteries in the potential window that corresponds to the intercalation mechanism of charge storage. The AnHT-MoO 2 /C electrode showed enhanced electrochemical activity, with an initial specific discharge capacity of 260 mAh/g and capacity retention of 67% after 50 cycles, compared to the HT-MoO 2 /C electrode which exhibited an initial specific discharge capacity of 235 mAh g –1 and capacity retention of 47% after 50 cycles. The rate capability experiments revealed that the capacity of 93 mAh/g and 120 mAh/g was delivered by the HT-MoO 2 /C and AnHT-MoO 2 /C electrodes, respectively, when the current density was increased to 100 mA/g. Here, the improved specific capacity, electrochemical stability, and rate capability achieved after annealing were attributed to higher crystallinity of MoO 2 , increased oxidation state of Mo, and formation of the tighter MoO 2 /carbon contact accompanied by the annealing assisted interaction between MoO 2 and Dopa-derived carbon.

25 ENERGY STORAGE↗
DOE OSTI2022

Mesoporous MoO 2 thin films for high rate Li + storage: Effect of crystallinity and porous structure

MoO 2 has attracted much recent attention as a high capacity energy storage material. While much of the current work on MoO 2 has been focused on the high capacity four-electron reduction, this reaction is limited to slow charging process due to the large volume change and phase transitions involved. In this study we focus on one-electron insertion reactions and demonstrate that ordered mesoporous thin films of MoO 2 can show signatures of pseudocapacitive charge storage. Mesoporous MoO 2 (mp-MoO 2 ) thin films were treated at different temperatures between 350 and 700 °C to explore the role of crystallinity and nanoscale structure on charging dynamics. The porosity and pore size decreased while the crystallinity and grain size increased as the calcination temperature increased. Materials processed at 600 °C showed the best electrochemical performance due to an optimized combination of high crystallinity and small grain size. These materials could be charged and discharged in 24 s while still achieving a Li + storage capacity of 158 mAh/g. While such thin film systems do not constitute a practical energy storage device, the work here provides structural design parameters for the production of future bulk nanoporous materials.

25 ENERGY STORAGE↗
DOE OSTI2021

Controlling MoO 2 and MoO 3 phases in MoO x /CNTs nanocomposites and their application to anode materials for lithium-ion batteries and capacitors

Molybdenum oxides (MoO 2 and MoO 3 ) are attractive anode materials for Li- and Na- ion batteries. Although there have been extensive studies on them individually, systematic and comparative studies are still lacking. Here, we demonstrate a facile and straightforward synthesis method to control the phase and oxidation state in the MoO x /CNTs nanocomposites via hydrothermal reaction followed by heat-treatment. By changing the gas atmosphere during the annealing process, well-dispersed MoO 2 /CNTs and MoO 3 /CNTs nanocomposites are formed without altering their overall morphology. This strategy enables us to investigate the true structure-property correlation of MoO x /CNTs nanocomposites by comparing the structure and electrochemical properties of MoO 2 /CNTs and MoO 3 /CNTs. When tested as anode materials for lithium-ion batteries, both HT-MoO 2&3 /CNTs electrodes show much-improved cycling stability and rate performance compared to the rod-shaped bulk MoO 3 electrode. In situ Mo K-edge x-ray absorption spectroscopy (XAS) has been further employed to compare and elucidate Li + storage mechanisms of both electrodes. When employed to the negative electrode of a high-power lithium-ion capacitor (LIC), the LIC full-cell composed of HT-MoO 3 /CNTs negative and activated carbon positive electrodes demonstrates impressive energy and power densities (~ 90 Wh kg –1 with 2000 W kg –1 ) and excellent cycling stability (96.8 % capacity retention after 300 cycles), revealing the versatility of the MoO x /CNTs electrodes in energy applications.

25 ENERGY STORAGE↗