Unveiling Structural Disorders in Honeycomb Layered Oxide: Na2Ni2TeO6

Abstract

<b>Honeycomb layered oxides have garnered tremendous research interest in a wide swath of disciplines owing to not only the myriad physicochemical properties they exhibit, but also due to their rich crystal structural versatility. Herein, a comprehensive crystallographic study of a sodium-based Na<sub>2</sub>Ni<sub>2</sub>TeO<sub>6</sub> honeycomb layered oxide has been performed using atomic-resolution transmission electron microscopy, elucidating a plethora of atomic arrangement (stacking) disorders in the pristine material. Stacking disorders in the arrangement honeycomb metal slab layers (stacking faults) occur predominantly perpendicular to the slabs with long-range coherence length and enlisting dislocations in some domains. Moreover, the periodic arrangement of the distribution of alkali atoms is altered by the occurrence of stacking faults. The multitude of disorders innate in Na<sub>2</sub>Ni<sub>2</sub>TeO<sub>6</sub> envisage broad implications in the material functionalities of related honeycomb layered oxide materials and will bolster renewed interest in their material science.</b>

Sintering temperature dependency on sodium‐ion conductivity for Na2Zn2TeO6 solid electrolyte

“…σ total shows the maximum (=4.0 × 10 −4 S cm −1 ) in the samples sintered at 750℃, which is 100℃ lower than the condition in previous works 6−11 . Such low sintering temperature compared to other Na‐based oxide solid electrolytes could be useful for co‐sintering with electrode active materials with similar layered structure for fabricating oxide‐based all‐solid‐state SiBs 19−24 . Even for the sample sintered at the lowest temperature of 650℃, σ total = 2 × 10 −4 S cm −1 was obtained.…”

“…In the previous works, sintering temperatures of NZTO were commonly set to 850–900℃ 6–11 . However, this sintering temperature may be still high not only for the Na volatilization in the precursor, 10,11 but also for co‐sintering with electrode active materials with similar layered structure for fabricating oxide‐based solid‐state Na batteries 19–24 . In this study, we investigated the sintering temperature dependency on the properties of NZTO.…”

Unraveling diffusion kinetics of honeycomb structured Na$_2$Ni$_2$TeO$_6$ as a high-potential and stable electrode for sodium-ion batteries

“…Grundish et al found that the electrochemical reactivity in Na 3 Ni 1.5 TeO 6 cathode is mainly due to the Ni 2+/3+ redox couple as well as small contribution from Ni 3+/4+ [29]. The splitting in some of the oxidation/reduction peaks observed in the CV curves manifests the presence of different sodium ion disordering in the layered structure [36,37,61]. The appearance of the minor redox peaks can be attributed to the phase transformations during Na + (de)intercalation reactions [38].…”

Stacking Disorders in MixedAlkali Honeycomb Layered Oxide NaKNi2TeO6 and Feasibility for Mixed-Cation Transport

“…Further, SAED patterns taken along the [100] and [11 ̅ 0] zone axes (Figures 7d and 7e) evidence streaks reminiscent of the modulation in the Na arrangement in Na-rich phase (Na2Ni2TeO6). 57 Whilst only Na-rich phases are observed in TEM measurements, ex situ XRD measurements of discharged electrodes (Supplementary Figure S24) reveal K-rich and mixed alkali phases with Narich phase being predominant. These results reveal that there is a propensity of NaKNi2TeO6 to predominantly reinsert Na ions when cycled in NaK cells.…”