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Title: Electron Transfer Governed Crystal Transformation of Tungsten Trioxide upon Li Ions Intercalation

Abstract

Reversible insertion/extraction of ions into a host lattice constitutes the fundamental operating principle of rechargeable battery and electrochromic materials. It is far more commonly observed that insertion of ions into a host lattice can lead to structural evolution of the host lattice, and for the most cases such a lattice evolution is subtle. However, it has never been clear as what kind of factors to control such a lattice structural evolution. Based on tungsten trioxide (WO3) model crystal, we use in situ transmission electron microscopy (TEM) and first principles calculation to explore the nature of Li ions intercalation induced crystal symmetry evolution of WO3. We discovered that Li insertion into the octahedral cavity of WO3 lattice will lead to a low to high symmetry transition, featuring a sequential monoclinic→tetragonal→cubic phase transition. The first principle calculation reveals that the phase transition is essentially governed by the electron transfer from Li to the WO6 octahedrons, which effectively leads to the weakening the W-O bond and modifying system band structure, resulting in an insulator to metal transition. The observation of the electronic effect on crystal symmetry and conductivity is significant, providing deep insights on the intercalation reactions in secondary rechargeable ion batteries andmore » the approach for tailoring the functionalities of material based on insertion of ions in the lattice.« less

Authors:
; ; ; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1340869
Report Number(s):
PNNL-SA-120073
Journal ID: ISSN 1944-8244; 48379; KP1704020
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Applied Materials and Interfaces; Journal Volume: 8; Journal Issue: 37
Country of Publication:
United States
Language:
English
Subject:
Tungsten trioxide; ion intercalation; phase transformation; in situ TEM; first principles calculation; electron transfer; insulator to metal transition; Environmental Molecular Sciences Laboratory

Citation Formats

Wang, Zhiguo, He, Yang, Gu, Meng, Du, Yingge, Mao, Scott X., and Wang, Chongmin. Electron Transfer Governed Crystal Transformation of Tungsten Trioxide upon Li Ions Intercalation. United States: N. p., 2016. Web. doi:10.1021/acsami.6b06581.
Wang, Zhiguo, He, Yang, Gu, Meng, Du, Yingge, Mao, Scott X., & Wang, Chongmin. Electron Transfer Governed Crystal Transformation of Tungsten Trioxide upon Li Ions Intercalation. United States. doi:10.1021/acsami.6b06581.
Wang, Zhiguo, He, Yang, Gu, Meng, Du, Yingge, Mao, Scott X., and Wang, Chongmin. 2016. "Electron Transfer Governed Crystal Transformation of Tungsten Trioxide upon Li Ions Intercalation". United States. doi:10.1021/acsami.6b06581.
@article{osti_1340869,
title = {Electron Transfer Governed Crystal Transformation of Tungsten Trioxide upon Li Ions Intercalation},
author = {Wang, Zhiguo and He, Yang and Gu, Meng and Du, Yingge and Mao, Scott X. and Wang, Chongmin},
abstractNote = {Reversible insertion/extraction of ions into a host lattice constitutes the fundamental operating principle of rechargeable battery and electrochromic materials. It is far more commonly observed that insertion of ions into a host lattice can lead to structural evolution of the host lattice, and for the most cases such a lattice evolution is subtle. However, it has never been clear as what kind of factors to control such a lattice structural evolution. Based on tungsten trioxide (WO3) model crystal, we use in situ transmission electron microscopy (TEM) and first principles calculation to explore the nature of Li ions intercalation induced crystal symmetry evolution of WO3. We discovered that Li insertion into the octahedral cavity of WO3 lattice will lead to a low to high symmetry transition, featuring a sequential monoclinic→tetragonal→cubic phase transition. The first principle calculation reveals that the phase transition is essentially governed by the electron transfer from Li to the WO6 octahedrons, which effectively leads to the weakening the W-O bond and modifying system band structure, resulting in an insulator to metal transition. The observation of the electronic effect on crystal symmetry and conductivity is significant, providing deep insights on the intercalation reactions in secondary rechargeable ion batteries and the approach for tailoring the functionalities of material based on insertion of ions in the lattice.},
doi = {10.1021/acsami.6b06581},
journal = {ACS Applied Materials and Interfaces},
number = 37,
volume = 8,
place = {United States},
year = 2016,
month = 9
}
  • Single-crystal nanowires of hexagonal tungsten trioxide in a large scale have been successfully prepared by a simple hydrothermal method without any templates and catalysts. Uniform h-WO{sub 3} nanowires with diameter of 25-50 nm and length of up to several micrometers are obtained. It is found that the morphology and crystal form of the final products are strongly dependent on the amount of the sulfate and pH value of the reaction system. The electrochemical performances of the as-prepared h-WO{sub 3} nanowires as anodic materials of Li-ion batteries have also been investigated. It deliveres a discharge capacity of 218 mAh g{sup -1}more » for the first cycle. In addition, the cycle ability of the nanocrystals is superior to that of bulk materials, which implies the morphology and particle size have the influence on the electrochemical performances. - Graphical abstract: The large-scale synthesis of single-crystal hexagonal tungsten oxides nanowires has been successfully realized by a simple hydrothermal method without any templates and catalysts. Uniform h-WO{sub 3} nanowires with diameters of 25-50 nm and length of up to several micrometers are obtained. The electrochemical performances of the nanowires as anode materials of Li-ion batteries have also been investigated. These 1D nanostructures exhibit better cycle ability than that of bulk materials, which indicates the morphology and particle size have the influences on the electrochemical performances.« less
  • The ESR spectra of single crystal and amorphous thin films of WO/sub 3/ have been measured in the temperature range 77--300 /sup 0/K. In the case of single crystal the observed resonance lines were identified as due to Mo/sup 5 +/ ions. The observed values are: g/sub I/ = 1.776, g/sub II/ = 1.796, and g/sub III/ = 1.833 and the hyperfine splitting constants are A/sub I/ = 0.0029, A/sub II/ = 0.0026, and A/sub III/ = 0.0074. In the case of thin-film broad resonance absorption at g = 2.012 and g = 1.918 was observed for colorless film whichmore » on electrocoloration showed an additional resonance at g = 1.75. The temperature dependence of the electrical conductivity and spin density gave activation energies of 0.21 and 0.04 eV, respectively.« less
  • A hexagonal form of WO{sub 3} (a = 7.3244(6), c = 7.6628(5) {angstrom}, z = 6) was synthesized by the low temperature sintering of an ammonium peroxo-polytungstate precursor. This compound, the N/W ratio of which is 0.015 at most, is not identical to reported hexagonal WO{sub 3} from WO{sub 3}{center dot}1/3 H{sub 2}O because its c-axis is significantly shorter than that of the latter (7.798 {angstrom}). Powder XRD profile refinements were performed in the space group P6{sub 3}/mcm. The authors found two kinds of structural models that showed reasonably good profile agreement (R {approx} 0.07). Both models are built upmore » of remarkably distorted WO{sub 6} octahedra, in which part of the O-O distances are very short (2.32 {approximately} 2.42 {angstrom}). Electrochemical intercalation of lithium into the present WO{sub 3} framework work was investigated using a Li{vert bar}LiPF{sub 6}{vert bar}WO{sub 3} cell. It was found that Li was intercalated reversibly up to the composition Li{sub 1.0}WO{sub 3}.« less
  • Energy-loss spectra were measured by backscattering 500-eV electrons from films of WO/sub 3/ grown on single-crystal W(100), and from single crystals of Na/sub x/WO/sub 3/ (0.35 < x < 0.86) and ReO/sub 3/ which were cleaved in ultrahigh vacuum. The spectrum of a crystal with x = 0.61 was nearly identical to the surface loss function Im(-(epsilon + 1)/sup -/1) calculated from epsilon measured by optical reflectivity on a crystal with x = 0.65. For x = 0.61, two plasmons are observed, ..omega../sub -/ = 1.90 eV, and ..omega../sub +/ = 6.5 eV. ..omega../sub -/ scales approximately as x/sup 1/2/more » and is assigned to the conduction-electron resonance. The plasmon lifetime tau/sub p/ = 1.9 x 10/sup -/15 sec determined from the observed linewidth agrees well with a value for the conduction-electron relaxation time tau/sub e/ = 2.1 x 10/sup -/15 sec we obtained from previously reported reflectivity data, but is shorter than a value tau/sub c/ = 6.7 x 10/sup -/15 sec we estimated from previously reported dc conductivity data. The higher-energy plasmon ..omega../sub +/ is assigned to a screened longitudinal resonance of an interband excitation near 5 eV. ..omega../sub +/ is essentially independent of x for 0 < or = x < 0.9. By fitting epsilon between 0 and 10 eV with a model dielectric function, we found a value for the mean effective conduction electron mass m* = 0.80m/sub e/, the interband contribution to the static dielectric constant epsilon/sub s/ = 4.35, and values for parameters characterizing the interband resonance. Taking these latter parameters to be independent of x, we calculated the bulk and surface loss functions for different x values. These calculations indicate that mode hybridization is unimportant for x < 1 in the bronzes. The effects of damping or joint density-of-states width, screening, and mode interference on the plasmon spectra are discussed. It is shown that ReO/sub 3/ and Ag metal have dielectric and energy-loss functions which are similar to the tungsten bronzes.« less