Structural Investigation of Quaternary Layered Oxides upon Na-Ion Deinsertion

Abstract

Na-ion batteries are emerging alternatives to Li-ion chemistries for large-scale energy storage applications. Quaternary layered oxide Na0.76Mn0.5Ni0.3Fe0.1Mg0.1O2 offers outstanding electrochemical performance in Na-ion batteries compared to pure-phase layered oxides because of the synergistic effect of the P/O-phase mixing. The material is indeed constituted by a mixture of P3, P2, and O3 phases, and a newly identified Na-free phase, i.e., nickel magnesium oxide phase, which improves heat removal and enhances the electrochemical performance. Herein, we structurally investigate, through synchrotron-radiation X-ray diffraction, the modifications occurring after full desodiation, detailing the material structural rearrangement upon Na removal and revealing the effect of two different charging protocols, i.e., constant current (CC) and constant current–constant voltage (CCCV). While the Na-free phase is electrochemically inactive, likely helping in homogenization of the thermal gradient in the electrode during cycling, O–P intergrown phases appear during the extraction of Na ions from interslab layers, and they are dependent on the desodiation level. The application of a constant voltage step at the end of the galvanostatic charge is responsible for a shortening of the interslab distance and a significant volume contraction (−11.9%).

Tandem CO2 Valorization and Ethane Dehydrogenation: Elucidating the Nature of Highly Selective Iron Oxide Active Sites

“…The potential formation of MgO-NiO mixed oxide, suggested by the XRD (ICSD No. 13774, a = 4.19 Å, Fm 3̅ m ), was further investigated by structural modeling, , and it is in alignment with the literature. ,, …”

“…To further elucidate the origin of Fe-700 (5h) enhanced performance, XAS and XRS measurements of the fresh and used samples were conducted. 53,54 and it is in alignment with the literature. 12,55,56 According to the EXAFS data analysis (Figure S.11 and Table S.6 in the Supporting Information) and the XANES simulations reported at Ni K-edge (Figure S.10), it is reasonable to consider that the Ni atoms are homogeneously dispersed in the oxide substrate and they do not change their environment upon reaction.…”

Impact of Mg and Ti doping in O3 type NaNi1/2Mn1/2O2 on reversibility and phase transition during electrochemical Na intercalation

“…7,26,27 In our Non-sub sample, the concerned mass fraction of the NiO phase is quite small (0. 9,28 but the amounts in our Mg-substituted samples are negligibly small compared to the reported values.…”

“…However, the observed 00l reections are very broad, indicating a disordered stacking sequence of P and O e layers as stacking faults. According to previous reports, 6,28,32 we simulated XRD patterns of the stacking-faulted layered structures using the FAULTS program 18 as shown in Fig. 6b.…”

Micron-sized single-crystal cathodes for sodium-ion batteries

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