Direct evidence of antisite defects in LiFe0.5Mn0.5PO4via atomic-level HAADF-EELS

Abstract

Using comprehensive transmission electron microscopy (TEM) techniques, the associations between the Mn dopant content, microstructure and improved rate performance of LiFe (1Àx) Mn x PO 4 (0 # x # 0.5) were well established. Via the synergistic mechanism including both templating and chelating effects contributed by cetyltrimethyl ammonium bromide (CTAB) and citric acid, a series of LiFe (1Àx) Mn x PO 4 (0 # x # 0.5) olivine crystals with adjustable Mn doping content were synthesized. No impurity phase was detected. Accidentally, a novel type of roughness phenomenon at the particle boundaries of LiFe (1Àx) Mn x PO 4 particles was observed, which depended on citric acid chelation. At the atomic level, the Mn ions were confirmed to be homogeneously substituted at the iron sites, which were furthermore examined by the combined analysis of electron energy loss spectroscopy (EELS), high angle annular dark-field (HAADF) imaging, magnetic susceptibility measurements and X-ray diffraction (XRD).Li/Fe antisite defects were found in the doped LiFe (1Àx) Mn x PO 4 rather than in pure LiFePO 4 by HAADF-EELS acquired from a single-atom column at high spatial resolution. The rate performance of LiFe 0.9 Mn 0.1 PO 4 and LiFe 0.8 Mn 0.2 PO 4 was improved compared to that of LiFePO 4 . Our findings might provide new insights into the understanding of Li-ion battery cathode materials with Mn dopant from a microstructural point of view.

Density functional theory study of lithium diffusion at the interface between olivine-type LiFePO4and LiMnPO4

“…We have calculated the strains at the interfaces between the LiFePO4 and LiMnPO4 and the results are listed in Table II (100), (010) and (001) From Figs. 4c, 4d and 4e, it can be seen that the VB from the Mn 3d is lower than that from the Fe 3d in energy, which agrees with the less electronegativity of Mn [52].…”

Recent Progress in Defective Carbon‐Based Oxygen Electrode Materials for Rechargeable Zink‐Air Batteries

“…[17d] Moreover, connecting STEM with energy disperse spectroscopy (EDS) [27] or electron energy loss spectroscopy (EELS) [28] could achieve element identification at defects even in sub-angstrom scale. Aberration correction in scanning transmission electron microscopy (STEM) provides a great enhancement of resolution without raising the acceleration voltage, and the corresponding signal receiver of annular dark field (ADF) are widely used in defect detecting.…”

“…[17d] Moreover, connecting STEM with energy disperse spectroscopy (EDS) [27] or electron energy loss spectroscopy (EELS) [28] could achieve element identification at defects even in sub-angstrom scale. [29] What's more, X-ray absorption spectra (XAS), including both near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), plays an increasingly significant role in distinguishing doping defects toward oxidation states, geometric configuration and binding condition. [30] Brunauer-Emmett-Teller (BET) analysis based on N 2 adsorption isotherm data can suggest the amount of edge or pores to a certain degree, [31] which correlates to the catalytic efficiency.…”

Crucial Role of Site Disorder and Frustration in Unusual Magnetic Properties of Quasi-2D Triangular Lattice Antimonate Na4FeSbO6

“…Tackling such a problem experimentally requires the use of local probe measurements in addition to bulk probe measurements, because the latter are insensitive to a small amount of disorder. A particularly challenging case to deal with is antisite disorder, which often takes place when a system contains cations of similar sizes [20][21][22][23][24][25][26]. The present work is concerned with the antisite disorder in the layered oxide Na 4 FeSbO 6 [27].…”