Operando X-ray Diffraction and Double-Edge X-ray Absorption Spectroscopy Studies on a Perfect Zero-Strain Material

Abstract

Metrics & MoreArticle Recommendations * sı Supporting Information ABSTRACT: "Zero-strain" insertion materials are essential for high-performance Li-ion batteries, but the experimental determination of changes in their local structures remains challenging. In this study, we successfully visualized the reaction scheme of a perfect zero-strain material, (Li 0.75 Zn 0.25 )[Li 0.417 Ti 1.583 ]O 4 with a spinel framework, using operando X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). The operando XRD/XAS technique, which provided a series of XRD, Ti K-edge XAS, and Zn K-edge XAS data, can be employed owing to a recently developed tapered undulator and monochromator system. Although previous ex situ XRD measurements indicated the immutable cubic lattice parameter (a c ) during the discharge process, these studies unveiled drastic structural variations occurring on the atomic scale between the charge and discharge reactions, such as differences in the a c , bond distances, and occupancies of the Zn 2+ ions. This dynamic information obtained under operating conditions could be useful not only for understanding the zero-strain reaction scheme but also for designing advanced zero-strain insertion materials with enhanced energy density.

Thermal Behavior of Li1+x[Li1/3Ti5/3]O4 and a Proof of Concept for Sustainable Batteries

“…The Q dis value (= 190.8 mAh g –1 ) is lower than that (∼240 mAh g –1 ) for the DSC measurement, although both LTO/Li cells were discharged down to 0.02 V. The small Q dis is probably due to the low electrical conductivity of the thin Cu current collector (= 5 μm), which was employed to minimize the signals in the in situ HT-XRD patterns. The decrease in Q dis due to the thin Cu current collector was also observed in our previous operando XRD studies on a lithium zinc titanium oxide …”

“…The decrease in Q dis due to the thin Cu current collector was also observed in our previous operando XRD studies on a lithium zinc titanium oxide. 38 Figure 6a shows the in situ HT-XRD patterns of the x = 1.09 sample up to 450 °C, and Figure 6b shows their selective contour plots. At 50 °C, four major diffraction lines are observed at 2θ = 33.6, 35.2, 41.0, and 44.8°, which are assigned to the 311, 222, 400, and 331 diffraction lines of the LTO phase, respectively.…”

Toward Improving the Thermal Stability of Negative Electrode Materials: Differential Scanning Calorimetry and In Situ High-Temperature X-ray Diffraction/X-ray Absorption Spectroscopy Studies of Li2ZnTi3O8 and Related Compounds

“…The initial discharge and charge curves together with Coulombic efficiency are shown in Figure S2a. In the discharge reaction, the cell exhibits two plateaus at ∼1.6 and 0.8 V, the former of which corresponds to the Li + insertion ( y 1 ) into the initially vacant octahedral 4 a and 12 d sites, while the latter corresponds to further Li + insertion ( y 2 ) accompanied by the movement of Zn 2+ ions ( p ) from the tetrahedral to octahedral sites. , These electrochemical reactions are represented by for the plateau at ∼1.6 V and for the plateau at ∼0.8 V, where tet and oct mean tetrahedral and octahedral sites, respectively.…”

“…The LZTO samples with x = 0.125, 0.25, 0.375, and 0.5 were synthesized by a conventional solid-state reaction technique as previously reported. , Reagent-grade LiOH·H 2 O (98.0 wt %), ZnO (99.0 wt %), and TiO 2 (98.5 wt %) powders (FUJIFILM Wako Pure Chemical) were mixed at a stoichiometric ratio and then pressed into a pellet with a thickness of ∼5 mm and diameter of 23 mm. Each pellet was calcined at 750 °C for 12 h in air after preheating at 400 °C for 12 h in air.…”

“…In the discharge reaction, the cell exhibits two plateaus at ∼1.6 and 0.8 V, the former of which corresponds to the Li + insertion (y 1 ) into the initially vacant octahedral 4a and 12d sites, while the latter corresponds to further Li + insertion (y 2 ) accompanied by the movement of Zn 2+ ions (p) from the tetrahedral to octahedral sites. 17,18 These electrochemical reactions are represented by…”