Atomic-scale unveiling of multiphase evolution during hydrated Zn-ion insertion in vanadium oxide

Abstract

An initial crystalline phase can transform into another phases as cations are electrochemically inserted into its lattice. Precise identification of phase evolution at an atomic level during transformation is thus the very first step to comprehensively understand the cation insertion behavior and subsequently achieve much higher storage capacity in rechargeable cells, although it is sometimes challenging. By intensively using atomic-column-resolved scanning transmission electron microscopy, we directly visualize the simultaneous intercalation of both H2O and Zn during discharge of Zn ions into a V2O5 cathode with an aqueous electrolyte. In particular, when further Zn insertion proceeds, multiple intermediate phases, which are not identified by a macroscopic powder diffraction method, are clearly imaged at an atomic scale, showing structurally topotactic correlation between the phases. The findings in this work suggest that smooth multiphase evolution with a low transition barrier is significantly related to the high capacity of oxide cathodes for aqueous rechargeable cells, where the crystal structure of cathode materials after discharge differs from the initial crystalline state in general.

Revisiting the Chevrel Phase: Impact of Dispersion Corrections on the Properties of Mo6S8 for Cathode Applications**

“…[17] Multiple cathode materials have been proposed for Mg batteries such as spinels, [11,12,[18][19][20][21] V 2 O 5 [22][23][24][25] or the chevrel phase (CP) [13][14][15][16] which are often also used for other multivalent charge carriers such as Zn 2 + . [26,27] However, only in the CP the issues of sluggish insertion kinetics and low reversibility are solved more or less satisfactorily. [13][14][15][16] The CP was first discovered in 1973 by Chevrel et al and the corresponding structure is depicted in Figure 1.…”

Comparison of Fe-enhanced oxygen evolution electrocatalysis in amorphous and crystalline nickel oxides to evaluate the structural contribution

“…To scrutinize the surface structure at atomic resolution, we utilized annular bright-field (ABF) STEM. 44–48 Fig. 6 shows three sets of atomic-scale STEM images for the surface region from the pristine (Fig.…”

Local-electrostatics-induced oxygen octahedral distortion in perovskite oxides and insight into the structure of Ruddlesden–Popper phases

“…To visualize the position of light-element anions, we utilized the annular bright-field (ABF) mode in STEM 22 – 29 . All the ABF images acquired from the fault region in the five perovskites are provided in Fig.…”