E01-JEM ARM 200CF
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Yiding
Jiao
,
Liqun
Kang
,
Jasper
Berry-Gair
,
Kit
Mccoll
,
Jianwei
Li
,
Haobo
Dong
,
Hao
Jiang
,
Ryan
Wang
,
Furio
Corà
,
Dan J. L.
Brett
,
Guanjie
He
,
Ivan
Parkin
Diamond Proposal Number(s):
[24450]
Open Access
Abstract: The primary issue faced by MnO2 cathode materials for aqueous Zn-ion batteries (AZIBs) is the occurrence of structural transformations during cycling, resulting in unstable capacity output. Pre-intercalating closely bonded ions into the MnO2 structures has been demonstrated as an effective approach to combat this. However, mechanisms of the pre-intercalation remain unclear. Herein, two distinct δ-MnO2 (K0.28MnO2·0.1H2O and K0.21MnO2·0.1H2O) are prepared with varying amounts of pre-intercalated K+ and applied as cathodes for AZIBs. The as-prepared K0.28MnO2·0.1H2O cathodes exhibit relatively high specific capacity (300 mA h g−1 at 100 mA g−1), satisfactory rate performance (35% capacity recovery at 5 A g−1) and competent cyclability (ca. 95% capacity retention after 1000 cycles at 2 A g−1), while inferior cyclability and rate performance are observed in K0.21MnO2·0.1H2O. A stable δ-MnO2 phase is observed upon cycling, with the reversible deposition of Zn4SO4(OH)6·5H2O (ZSH), ion migration between electrodes and synchronous transition of Mn valence states. This work firstly and systematically reveals the role of the pre-intercalated ions via density functional theory simulations and show that above a threshold K/Mn ratio of ca. 0.26, the K ions suppress structural transformations by stabilizing the δ phase. To demonstrate its commercial potential, AZIBs with high-loading active materials are fabricated, which deliver adequate energy and power densities compared with most commercial devices.
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Nov 2020
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B18-Core EXAFS
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Ian D.
Johnson
,
Gene
Nolis
,
Kit
Mccoll
,
Yimin A.
Wu
,
Daisy
Thornton
,
Linhua
Hu
,
Hyun Deog
Yoo
,
John W.
Freeland
,
Furio
Corà
,
Jeremy K.
Cockcroft
,
Ivan P.
Parkin
,
Robert F.
Klie
,
Jordi
Cabana
,
Jawwad A.
Darr
Diamond Proposal Number(s):
[14239]
Abstract: While commercial Li-ion batteries offer the highest energy densities of current rechargeable battery technologies, their energy storage limit has almost been achieved. Therefore, there is considerable interest in Mg batteries, which could offer increased energy densities in comparison to Li-ion batteries if a high-voltage electrode material, such as a transition-metal oxide, can be developed. However, there are currently very few oxide materials which have demonstrated reversible and efficient Mg2+ insertion and extraction at high voltages; this is thought to be due to poor Mg2+ diffusion kinetics within the oxide structural framework. Herein, the authors provide conclusive evidence of electrochemical insertion of Mg2+ into the tetragonal tungsten bronze V4Nb18O55, with a maximum reversible electrochemical capacity of 75 mA h g–1, which corresponds to a magnesiated composition of Mg4V4Nb18O55. Experimental electrochemical magnesiation/demagnesiation revealed a large voltage hysteresis with charge/discharge (1.12 V vs Mg/Mg2+); when magnesiation is limited to a composition of Mg2V4Nb18O55, this hysteresis can be reduced to only 0.5 V. Hybrid-exchange density functional theory (DFT) calculations suggest that a limited number of Mg sites are accessible via low-energy diffusion pathways, but that larger kinetic barriers need to be overcome to access the entire structure. The reversible Mg2+ intercalation involved concurrent V and Nb redox activity and changes in crystal structure, as confirmed by an array of complementary methods, including powder X-ray diffraction, X-ray absorption spectroscopy, and energy-dispersive X-ray spectroscopy. Consequently, it can be concluded that the tetragonal tungsten bronzes show promise as intercalation electrode materials for Mg batteries.
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Jul 2020
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
E01-JEM ARM 200CF
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Jianwei
Li
,
Kit
Mccoll
,
Xuekun
Lu
,
Sanjay
Sathasivam
,
Haobo
Dong
,
Liqun
Kang
,
Zhuangnan
Li
,
Siyu
Zhao
,
Andreas G.
Kafizas
,
Ryan
Wang
,
Dan J. L.
Brett
,
Paul R.
Shearing
,
Furio
Corà
,
Guanjie
He
,
Claire J.
Carmalt
,
Ivan P.
Parkin
Diamond Proposal Number(s):
[24197, 22572]
Abstract: Cost‐effective and environment‐friendly aqueous zinc‐ion batteries (AZIBs) exhibit tremendous potential for application in grid‐scale energy storage systems but are limited by suitable cathode materials. Hydrated vanadium bronzes have gained significant attention for AZIBs and can be produced with a range of different pre‐intercalated ions, allowing their properties to be optimized. However, gaining a detailed understanding of the energy storage mechanisms within these cathode materials remains a great challenge due to their complex crystallographic frameworks, limiting rational design from the perspective of enhanced Zn2+ diffusion over multiple length scales. Herein, a new class of hydrated porous δ‐Ni0.25V2O5.nH2O nanoribbons for use as an AZIB cathode is reported. The cathode delivers reversibility showing 402 mAh g−1 at 0.2 A g−1 and a capacity retention of 98% over 1200 cycles at 5 A g−1. A detailed investigation using experimental and computational approaches reveal that the host “δ” vanadate lattice has favorable Zn2+ diffusion properties, arising from the atomic‐level structure of the well‐defined lattice channels. Furthermore, the microstructure of the as‐prepared cathodes is examined using multi‐length scale X‐ray computed tomography for the first time in AZIBs and the effective diffusion coefficient is obtained by image‐based modeling, illustrating favorable porosity and satisfactory tortuosity.
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Feb 2020
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[12336, 17193]
Abstract: Phonon-glass electron-crystal (PGEC) behaviour is realised in La0.5Na0.5Ti1–xNbxO3 thermoelectric oxides. The vibrational disorder imposed by the presence of both La3+ and Na+ cations on the A site of the ABO3 perovskite oxide La0.5Na0.5TiO3 produces a phonon-glass with a thermal conductivity, κ, 80% lower than that of SrTiO3 at room temperature. Unlike other state-of-the-art thermoelectric oxides, where there is strong coupling of κ to the electronic power factor, the electronic transport of these materials can be optimised independently of the thermal transport through cation substitution at the octahedral B site. The low κ of the phonon-glass parent is retained across the La0.5Na0.5Ti1–xNbxO3 series without disrupting the electronic conductivity, affording PGEC behaviour in oxides.
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Aug 2017
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I11-High Resolution Powder Diffraction
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Hongjun J.
Niu
,
Michael J.
Pitcher
,
Alex J.
Corkett
,
Sanliang
Ling
,
Pranab
Mandal
,
Marco
Zanella
,
Karl
Dawson
,
Plamen
Stamenov
,
Dmitry
Batuk
,
Artem M.
Abakumov
,
Craig L.
Bull
,
Ronald I
Smith
,
Claire A.
Murray
,
Sarah J.
Day
,
Ben
Slater
,
Furio
Cora
,
John B.
Claridge
,
Matthew J.
Rosseinsky
Diamond Proposal Number(s):
[12336]
Abstract: The polar corundum structure type offers a route to new room temperature multiferroic materials, as the partial LiNbO3-type cation ordering that breaks inversion symmetry may be combined with long range magnetic ordering of high spin d5 cations above room temperature in the AFeO3 system. We report the synthesis of a polar corundum GaFeO3 by a high-pressure high-temperature route and demonstrate that its polarity arises from partial LiNbO3-type cation ordering by complementary use of neutron, X-ray and electron diffraction methods. In-situ neutron diffraction shows that the polar corundum forms directly from AlFeO3-type GaFeO3 under the synthesis conditions. The A3+/Fe3+ cations are shown to be more ordered in polar corundum GaFeO3 than in isostructural ScFeO3. This is explained by DFT calculations that indicate that the extent of ordering is dependent on the configurational entropy available to each system at the very different synthesis temperatures required to form their corundum structures. Polar corundum GaFeO3 exhibits weak ferromagnetism at room temperature that arises from its Fe2O3-like magnetic ordering, which persists to a temperature of 408 K. We demonstrate that the polarity and magnetisation are coupled in this system, with a measured linear magnetoelectric coupling coefficient of 0.057 ps/m. Such coupling is a prerequisite for potential applications of polar corundum materials in multiferroic/magnetoelectric devices.
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Dec 2016
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B18-Core EXAFS
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Ian D.
Johnson
,
Mechthild
Lübke
,
On Ying
Wu
,
Neel M.
Makwana
,
Glen
Smales
,
Husn
Islam
,
Rashmi Y.
Dedigama
,
Robert I.
Gruar
,
Christopher
Tighe
,
David O.
Scanlon
,
Furio
Corà
,
Dan J.l.
Brett
,
Paul
Shearing
,
Jawwad
Darr
Diamond Proposal Number(s):
[12093]
Abstract: A high performance vanadium-doped LiFePO4 (LFP) electrode is synthesized using a continuous hydrothermal method at a production rate of 6 kg per day. The supercritical water reagent rapidly generates core/shell nanoparticles with a thin, continuous carbon coating on the surface of LFP, which aids electron transport dynamics across the particle surface. Vanadium dopant concentration has a profound effect on the performance of LFP, where the composition LiFe0.95V0.05PO4, achieves a specific discharge capacity which is among the highest in the comparable literature (119 mA h g−1 at a discharge rate of 1500 mA g−1). Additionally, a combination of X-ray absorption spectroscopy analysis and hybrid-exchange density functional theory, suggest that vanadium ions replace both phosphorous and iron in the structure, thereby facilitating Li+ diffusion due to Li+ vacancy generation and changes in the crystal structure.
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Jan 2016
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I15-Extreme Conditions
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Open Access
Abstract: The compression of the layered carbon nitride C6N9H3·HCl was studied experimentally and with density functional theory (DFT) methods. This material has a polytriazine imide structure with Cl− ions contained within C12N12 voids in the layers. The data indicate the onset of layer buckling accompanied by movement of the Cl− ions out of the planes beginning above 10–20 GPa followed by an abrupt change in the diffraction pattern and c axis spacing associated with formation of a new interlayer bonded phase. The transition pressure is calculated to be 47 GPa for the ideal structures. The new material has mixed sp2–sp3 hybridization among the C and N atoms and it provides the first example of a pillared-layered carbon nitride material that combines the functional properties of the graphitic-like form with improved mechanical strength. Similar behavior is predicted to occur for Cl-free structures at lower pressures.
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Jul 2013
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I11-High Resolution Powder Diffraction
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Man-Rong
Li
,
Umut
Adem
,
Sean R. C.
Mcmitchell
,
Zhongling
Xu
,
Chris I.
Thomas
,
John E.
Warren
,
Duong V.
Giap
,
Hongjun
Niu
,
Xinming
Wan
,
Robert G.
Palgrave
,
Florian
Schiffmann
,
Furio
Cora
,
Ben
Slater
,
Tim L.
Burnett
,
Markys G.
Cain
,
Artem M.
Abakumov
,
Gustaaf
Van Tendeloo
,
Michael F.
Thomas
,
Matthew J.
Rosseinsky
,
John B.
Claridge
Open Access
Abstract: Combining long-range magnetic order with polarity in the same structure is a prerequisite for the design of (magnetoelectric) multiferroic materials. There are now several demonstrated strategies to achieve this goal, but retaining magnetic order above room temperature remains a difficult target. Iron oxides in the +3 oxidation state have high magnetic ordering temperatures due to the size of the coupled moments. Here we prepare and characterize ScFeO3 (SFO), which under pressure and in strain-stabilized thin films adopts a polar variant of the corundum structure, one of the archetypal binary oxide structures. Polar corundum ScFeO3 has a weak ferromagnetic ground state below 356 K—this is in contrast to the purely antiferromagnetic ground state adopted by the well-studied ferroelectric BiFeO3.
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Feb 2012
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I19-Small Molecule Single Crystal Diffraction
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James T. A.
Jones
,
Tom
Hasell
,
Xiaofeng
Wu
,
John
Bacsa
,
Kim E.
Jelfs
,
Marc
Schmidtmann
,
Samantha Y.
Chong
,
Dave J.
Adams
,
Abbie
Trewin
,
Florian
Schiffman
,
Furio
Cora
,
Ben
Slater
,
Alexander
Steiner
,
Graeme M.
Day
,
Andrew I.
Cooper
Diamond Proposal Number(s):
[7036]
Abstract: Nanoporous molecular frameworks are important in applications such as separation, storage and catalysis. Empirical rules exist for their assembly but it is still challenging to place and segregate functionality in three-dimensional porous solids in a predictable way. Indeed, recent studies of mixed crystalline frameworks suggest a preference for the statistical distribution of functionalities throughout the pores rather than, for example, the functional group localization found in the reactive sites of enzymes. This is a potential limitations for 'one-pot' chemical syntheses of porous frameworks from simple starting materials. An alternative strategy is to prepare porous solids from synthetically preorganized molecular pores. In principle, functional organic pore modules could be covalently prefabricated and then assembled to produce materials with specific properties. However, this vision of mix-and-match assembly is far from being realized, not least because of the challenge in reliably predicting three-dimensional structures for molecular crystals, which lack the strong directional bonding found in networks. Here we show that highly porous crystalline solids can be produced by mixing different organic cage modules that self-assemble by means of chiral recognition. The structures of the resulting materials can be predicted computationally, allowing in silico materials design strategies. The constituent pore modules are synthesized in high yields on gram scales in a one-step reaction. Assembly of the porous co-crystals is as simple as combining the modules in solution and removing the solvent. In some cases, the chiral recognition between modules can be exploited to produce porous organic nanoparticles. We show that the method is valid for four different cage modules and can in principle be generalized in a computationally predictable manner based on a lock-and-key assembly between modules.
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Jun 2011
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I15-Extreme Conditions
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Abstract: Synchrotron x-ray diffraction and Raman scattering data supported by ab initio calculations are reported for the dense tetrahedrally bonded phase (C2N3H) with a defective wurtzite (dwur) structure synthesized by laser heating from dicyandiamide (C2N4H4) at high pressure in a diamond anvil cell. This work confirms the structure deduced in previous work from electron diffraction experiments. The phase (Cmc21) is recoverable to ambient conditions. The ambient pressure volume (V0=137.9 Å3) and bulk modulus (K0=258±21 GPa) are in excellent agreement with density functional calculations (V0=134.7 Å3; K0=270 GPa). The calculated Raman frequencies and pressure shifts are also in good agreement with experiment. Ammonia (P212121) was identified among the reaction products as expected from the synthesis reaction.
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Sep 2009
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