Systematic analysis of electron energy-loss near-edge structures in Li-ion battery materials

Abstract

Electron energy-loss near-edge structures of O-K edges of LiCoO2 and LiFePO4 with bonding states assigned by DFT analysis.

STEM‐EELS analysis of the interface structures of composite ASS‐LIB electrodes fabricated via aerosol deposition

“…Figure 2A-C shows the spatial distributions of three different chemical components of Ti and O of pristine LATP particles isolated by applying NMF to the data cube from the same areas as figures (B-D), the corresponding spectral components of which are shown as components (aʹ), (bʹ) and (cʹ). The O-K spectra of a series of representative LIB materials with different local structures were recently investigated and reported, 24 which helped interpret the present results. The main component in the thicker region (spectrum (cʹ)) was derived from Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 , the NASICON structure having the tetrahedral PO 4 and octahedral TiO 6 units 25 similar to LiFePO 4 or LiCoPO 4 olivine structures, 24 where the tetravalent titanium (Ti 4+ ) is partially replaced by the equivalent amount of Al 3+ and Li + to ensure local electrical neutrality.…”

“…The O-K spectra of a series of representative LIB materials with different local structures were recently investigated and reported, 24 which helped interpret the present results. The main component in the thicker region (spectrum (cʹ)) was derived from Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 , the NASICON structure having the tetrahedral PO 4 and octahedral TiO 6 units 25 similar to LiFePO 4 or LiCoPO 4 olivine structures, 24 where the tetravalent titanium (Ti 4+ ) is partially replaced by the equivalent amount of Al 3+ and Li + to ensure local electrical neutrality. The O-K ELNES of (cʹ) exhibits a characteristic shoulder (indicated by an arrow) and no appreciable peak structure between ZLP and the first plasmon peak around 7 eV ( Figure S3), suggesting that Figure 2C and the spectrum (cʹ) correspond to a lithiated state.…”

“…Figure A‐C illustrates the spatial distributions of the respective NMF‐resolved spectral components (aʹ)‐(cʹ). The O‐K ELNES in (aʹ) coincided well with that of LCO, as revealed in the spatial distribution (A), whereas the minor distribution of this phase on the LATP side was presumably due to the interface not being flat in the projected direction but instead being a plateau or step. The O‐K and Ti‐L 2,3 ELNES of component (bʹ) were almost identical to those of Figure (cʹ), corresponding to Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 in the main body of the LATP particle, though the onset of the Ti‐L 2,3 ELNES was shifted slightly to the lower energy side.…”

“…The spectral component (bʹ) was distributed in the area between the thicker NASICON structure and the Al-rich surface area, the O-K ELNES and its pre-peak of which resembled those of battery materials with a spinel structure. 24 This similarity suggests that component (bʹ) can likely be ascribed to a Li-deficient Al-Ti-O compound, the composition of which almost corresponds to Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 with reduced Ti also owing to the oxygen deficiency. However, these phases found near the surface of the pristine particle could form during TEM sample preparation procedures, that is, crushing and grinding the pristine bulk material.…”

Single-atom-layer traps in a solid electrolyte for lithium batteries

“…2c, the Li-K signal was collected in an EELS line scan running across two adjacent 2D defects. In order to confirm that the~62 eV signal acquired during the line scan is indeed Li-K rather than Ti-M 1 39 , EELS was performed to the La-rich (Li-poor) and Lapoor (Li-rich) layers of LLTO ( Supplementary Fig. 6a), which differed greatly in Li content but exhibited the same Ti content 7,34,40 .…”