Electrochemical De-/Intercalation of Silver for Ag[sub 2]NiO[sub 2] and AgNiO[sub 2]

Liu, Xiao Xia; Oberndorfer, C. P. M.; Jansen, Martin

doi:10.1149/1.2798983

Cited by 5 publications

(1 citation statement)

References 22 publications

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“…It could be investigated by looking at a system in which that coupling could be modified without modifying the intralayer exchange integrals. AgNiO 2 is a rare example of a delafossite having two polymorphs whose synthesis is feasible, 30 and therefore the ideal candidate for further studies seems to be the 3R-AgNiO 2 polytype. The only difference between the latter and 2H-AgNiO 2 is the way the NiO 2 layers are stacked on top of each other.…”

Section: Discussionmentioning

confidence: 99%

Charge disproportionation and collinear magnetic order in the frustrated triangular antiferromagnetAgNiO2

et al. 2008

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We report a high-resolution neutron diffraction study of the crystal and magnetic structure of the orbitally degenerate frustrated metallic magnet AgNiO 2 . At high temperatures the structure is hexagonal with a single crystallographic Ni site, low-spin Ni 3+ with spin 1/2 and twofold orbital degeneracy, arranged in an antiferromagnetic triangular lattice with frustrated spin and orbital order. A structural transition occurs upon cooling below 365 K to a tripled hexagonal unit cell containing three crystallographically distinct Ni sites with expanded and contracted NiO 6 octahedra, naturally explained by spontaneous charge order on the Ni triangular layers. No Jahn-Teller distortions occur, suggesting that charge order occurs in order to lift the orbital degeneracy. Symmetry analysis of the inferred Ni charge order pattern and the observed oxygen displacement pattern suggests that the transition could be mediated by charge fluctuations at the Ni sites coupled to a soft oxygen optical phonon breathing mode. At low temperatures the electron-rich Ni sublattice ͑assigned to a valence close to Ni 2+ with S =1͒ orders magnetically into a collinear stripe structure of ferromagnetic rows ordered antiferromagnetically in the triangular planes. We discuss the stability of this uncommon spin order pattern in the context of an easy-axis triangular antiferromagnet with additional weak second-neighbor interactions and interlayer couplings.

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Section: Discussionmentioning

confidence: 99%

Charge disproportionation and collinear magnetic order in the frustrated triangular antiferromagnetAgNiO2

et al. 2008

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Recent Advances toward Achieving High‐Performance Carbon‐Fiber Materials for Supercapacitors

et al. 2017

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State-of-the-art energy storage devices are highly attractive for the ever-worsening energy depletion and environmental deterioration. Among various candidates, supercapacitors (SCs) have been considered among the most promising energy storage devices. As key factors for the development of SCs, the electrode materials have been widely exploited, and great achievements have been made. Among these materials, carbonfiber materials, such as carbon nanofibers (CNFs), carbon cloths (CCs), and carbon fiber papers (CFPs), are considered as promising candidates for electrodes and supports/current collectors for other electrode materials, owing to their special physical/chemical properties and structures. This Minireview aims to provide an overview of recent advances and technologies to improve the electrochemical performance of these carbon-fiber materials and their composite electrodes. We also briefly outline the current challenges and perspectives for the development of these carbon-fiber materials and carbon-fiberbased composite electrode materials.[a] Dr.

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Towards more Durable Electrochemical Capacitors by Elucidating the Ageing Mechanisms under Different Testing Procedures

Fic

Frąckowiak

et al. 2018

ChemElectroChem

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Electrical double‐layer capacitors (EDLCs) commonly denoted supercapacitors are rechargeable energy storage devices with excellent power and energy delivery metrics intermediate to conventional capacitors and batteries. High‐voltage aqueous electrolyte based EDLCs are particularly attractive due to their high‐power capability, facile production, and environmental advantages. EDLCs should last for thousands of cycles and evaluation of future cell chemistries require long‐term and costly galvanostatic cycling. Voltage holding tests have been proposed to shorten evaluation time by accelerating cell degradation processes. Whether voltage holding can replace cycling completely remains undemonstrated. In this work, a systematic investigation of the influence of testing procedure on cell performance is presented. The state‐of‐the‐art post‐mortem and operando experimental techniques are implemented to elucidate ageing mechanisms and kinetics inside EDLC cells under different testing procedures. Carbon corrosion occurring on the positively polarized electrode leads to the lower active surface area and higher oxygen content. On the contrary, an increase of surface area and micropore volume are observed on the negatively polarized electrode. Repeated galvanostatic cycles at U <1.6 V appears to facilitate the depletion of oxygen species on the positively polarized electrode in comparison with voltage holding, which indicates a more complex degradation mechanism during cycling. Caution is advised when comparing results from different test procedures.

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Electrochemical De-/Intercalation of Silver for Ag[sub 2]NiO[sub 2] and AgNiO[sub 2]

Cited by 5 publications

References 22 publications

Charge disproportionation and collinear magnetic order in the frustrated triangular antiferromagnetAgNiO2

Charge disproportionation and collinear magnetic order in the frustrated triangular antiferromagnetAgNiO2

Recent Advances toward Achieving High‐Performance Carbon‐Fiber Materials for Supercapacitors

Towards more Durable Electrochemical Capacitors by Elucidating the Ageing Mechanisms under Different Testing Procedures

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