Nature of the “Z”-phase in layered Na-ion battery cathodes

Somerville, James; Sobkowiak, Adam; Tapia‐Ruiz, Nuria; Billaud, Juliette; Lozano, J.; House, Robert A.; Gallington, Leighanne C.; Ericsson, Tore; Häggström, Lennart; Roberts, Matthew; Maitra, Urmimala; Bruce, Peter G.

doi:10.1039/c8ee02991a

Cited by 196 publications

(209 citation statements)

References 40 publications

Supporting

Mentioning

177

Contrasting

Unclassified

Order By: Relevance

“…This observation is in good agreement with previously reported Mg‐doped Na 3 Ni 2 SbO 6 , where a smooth phase transition between the initial O′3 and desodiated P′3 phases resulted in improved rate performance . On the other hand, the broadened reflections observed in this study might be attributable to a number of stacking‐fault phases which have been reported before in similar materials . Although the exact mass ratios of O′3, P′3, and other minor phases such as the O1 phase for each compound at the end of charge and discharge are not clearly identified, the results from a series of profile matches for the charged samples, using the most distinctive reflections obtained from ex‐situ XRD measurements, match well with the theoretically calculated structures within a small range of experimental error (∼2 %).…”

Section: Resultssupporting

confidence: 93%

Effects of Mn‐Doping on the Structural and Electrochemical Properties of Na₃Ni₂SbO₆ for Sodium‐Ion Battery.

Kee

Put

Dimov

et al. 2020

Batteries & Supercaps

View full text Add to dashboard Cite

Recently, layered O'3-Na 3 Ni 2 SbO 6 has been investigated as a unique cathode material for Na-ion batteries due to the good electrochemical performance via O'3-P'3 phase transitions in the voltage range between 2.0 and 4.0 V vs Na + /Na. However, at present it is not well understood whether transition metal doping of the pristine structure could improve the phase transition kinetics during charge/discharge. In this study, we synthesized Mn-doped Na 3 Ni 2-x Mn x SbO 6 (x = 0, 0.25, 0.5) layered oxides and investigated their feasibility as cathode materials for Na-ion batteries using ex-situ X-ray diffraction (XRD) coupled with DFT calculations. The results show that light Mn doping (x = 0.25) energetically enhances the O'3-P'3 phase transition kinetics with smaller unit-cell-volume changes. However, the heavily doped (x = 0.5) sample suffers from large polarization, which could be attributable to the reduced two-phase reaction range and a large unit-cell-volume change upon sodium extraction.[a] Dr.

show abstract

Section: Resultssupporting

confidence: 93%

Effects of Mn‐Doping on the Structural and Electrochemical Properties of Na₃Ni₂SbO₆ for Sodium‐Ion Battery.

Kee

Put

Dimov

et al. 2020

Batteries & Supercaps

View full text Add to dashboard Cite

show abstract

“…The capacity in the sloping region might be contributed by conventional formal oxidation of Ru 4+ partially to Ru 5+ , while the high‐voltage plateau can be associated to a discrete structure rearrangement revealed below by operando XRD analysis of the first cycle. [ 17 ] More intriguingly, an interesting potential plateau appears at around 3.0 V upon discharge, which is maintained during subsequent cycles. More clearly, the corresponding d Q /d V curves of 10th and 20th cycles both show two pair of reversible peaks.…”

Section: Figurementioning

confidence: 99%

Stabilizing Reversible Oxygen Redox Chemistry in Layered Oxides for Sodium‐Ion Batteries

Cao

Qiao

et al. 2020

Advanced Energy Materials

108

123

View full text Add to dashboard Cite

premise of guaranteeing electrochemical stability upon cycling. [2] Not rigidly limited to conventional redox reactions based on transition metal (TM) centers, redox activity centered at the oxide anions is emergently viewed as a promising strategy to effectively increase the energy density of SIBs. [3] When conventional cationic and novel anionic activities are triggered simultaneously, several cathodes delivering boosted capacities break the shackle of reversible TM redox couples. [4] As a representative example, Mn-based layered cathodes Na x [M y Mn 1−y ]O 2 (M = Li, Mg and Zn) deliver considerable capacity in the initial discharge process by employing the Mn-based and oxygen-related redox reactions simultaneously. [5] Based on the experience of Li-rich layered cathode materials, the utilization of these attractive anionic redox capacities would accompany harmful irreversible processes induced by excessive oxygen oxidation during charging process. [6] More importantly, irreversible lattice oxygen loss inevitably triggers deleterious migration of TM and structural distortion upon cycling, resulting in capacity decay, fading of the output potential and sluggish kinetics. [7] Therefore, the foremost challenge would focus on not only triggering unconventional anionic redox capacity but also stabilizing reversible these oxygen-related reactions. [5d,8] However, puzzled by foggy charge compensation mechanism between TM based and oxygenrelated redox processes, it is difficult to identify the reversible and irreversible anionic redox reactions. [9] Specifically, based on typically obtained "S-shape" discharge voltage profiles, no distinct boundary between TM and oxygen reduction reactions can be observed. [5b,10] More importantly, despite the existence of undesirable lattice oxygen loss during charging, high discharge capacities can still be obtained, which are actually caused by a reduction of TM couples beyond the pristine state. [9,11] In this case, comprehensive and in-depth characterizations including the valence change of TM and oxygen, O 2 evolution, surface/ bulk oxygen states, among others, are required to make a clear assignment of TM-based and oxygen-related redox capacity, which is essentially helpful for the development of anionic redox activity and inform subsequent materials selection. [3c,5a,12] Furthermore, in sodium-ion batteries, the trigger of anionic redox reactions is typically by the introduction of NaOM configuration, in which M is defined as the Li, Na, Mg and Zn within TM layer. [4c,5a,8,12c,13] Meanwhile, the Tarascon group has proved that lowering the energy of the transition metal d Triggering oxygen-related activity is demonstrated as a promising strategy to effectively boost energy density of layered cathodes for sodium-ion batteries. However, irreversible lattice oxygen loss will induce detrimental structure distortion, resulting in voltage decay and cycle degradation. Herein, a layered structure P2-type Na 0.66 Li 0.22 Ru 0.78 O 2 cathode is designed, delivering reversible ...

show abstract

“…[12,14] Very recently, Somerville et al investigated the structural evolution of P2-type layered Na2/3Ni1/6Mn1/2Fe1/3O2 (33% Fe in the TM layer), and observed that in the high-voltage phase, prismatic and octahedral Na coexist. [15] In this work, the unusual phase observed at the very high state of charge in layered Na compounds is investigated. We provide a comprehensive perspective on the phase transitions in O3-NaTi0.25Fe0.25Co0.25Ni0.25O2, a compound which shows high energy density and good cycle life.…”

Section: Introductionmentioning

confidence: 99%

“…We also relate our findings to other work on layered Na oxides that contain a certain concentration of Jahn-Teller ions, where the intergrowth of different stackings is also observed. [11][12][13]15] We propose a mechanism that may promote structural stability at high state of charge, potentially leading to better understanding of high voltage stability of Na-ion batteries.…”

Section: Introductionmentioning

confidence: 99%

Direct Observation of Alternating Octahedral and Prismatic Sodium Layers in O3‐Type Transition Metal Oxides

Kim

Kwon

Yang

et al. 2020

Advanced Energy Materials

View full text Add to dashboard Cite

The oxygen stacking of O3-type layered sodium transition metal oxides (O3-NaTMO2) changes dynamically upon topotactic Na extraction and reinsertion. While the phase transition from octahedral to prismatic Na coordination that occurs at intermediate desodiation by TM slab gliding is well understood, the structural evolution at high desodiation, crucial to achieve high reversible capacity, remains mostly uncharted. In this work, the phase transitions of O3-type layered NaTMO2 at high voltage are investigated by combining experimental and computational approaches. We directly observe an OP2-type phase that consists of alternating octahedral and prismatic Na layers by in situ X-ray diffraction and high-resolution scanning transmission electron microscopy. The origin of this peculiar phase is explained by atomic interactions involving Jahn-Teller active Fe 4+ and distortion tolerant Ti 4+ that stabilize the local Na environment. We also rationalize the path-dependent desodiation and resodiation pathways in this material through the different kinetics of the prismatic and octahedral layers, presenting a comprehensive picture about the structural stability of the layered materials upon Na intercalation.

show abstract

Nature of the “Z”-phase in layered Na-ion battery cathodes

Abstract: In this article, the nature of the “Z”-phase, which forms on charging many P2-type compounds to high voltages, is probed.

Cited by 196 publications

References 40 publications

Effects of Mn‐Doping on the Structural and Electrochemical Properties of Na₃Ni₂SbO₆ for Sodium‐Ion Battery.

Effects of Mn‐Doping on the Structural and Electrochemical Properties of Na₃Ni₂SbO₆ for Sodium‐Ion Battery.

Stabilizing Reversible Oxygen Redox Chemistry in Layered Oxides for Sodium‐Ion Batteries

Direct Observation of Alternating Octahedral and Prismatic Sodium Layers in O3‐Type Transition Metal Oxides

Contact Info

Product

Resources

About

Nature of the “Z”-phase in layered Na-ion battery cathodes

Abstract: In this article, the nature of the “Z”-phase, which forms on charging many P2-type compounds to high voltages, is probed.

Cited by 196 publications

References 40 publications

Effects of Mn‐Doping on the Structural and Electrochemical Properties of Na3Ni2SbO6 for Sodium‐Ion Battery.

Effects of Mn‐Doping on the Structural and Electrochemical Properties of Na3Ni2SbO6 for Sodium‐Ion Battery.

Stabilizing Reversible Oxygen Redox Chemistry in Layered Oxides for Sodium‐Ion Batteries

Direct Observation of Alternating Octahedral and Prismatic Sodium Layers in O3‐Type Transition Metal Oxides

Contact Info

Product

Resources

About

Effects of Mn‐Doping on the Structural and Electrochemical Properties of Na₃Ni₂SbO₆ for Sodium‐Ion Battery.

Effects of Mn‐Doping on the Structural and Electrochemical Properties of Na₃Ni₂SbO₆ for Sodium‐Ion Battery.