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Research paper thumbnail of Atomistic simulation studies of lithiated and sodiated TiO2 nanoarchitectures

Bulletin of the American Physical Society, 2017

Research paper thumbnail of Simulated synthesis and structure of LixTiO2 nanosheets as anode material for lithium ion batteries

Optical Materials, 2020

Nano-architectured Li x TiO 2 are promising as anode electrode materials for lithium rechargeable... more Nano-architectured Li x TiO 2 are promising as anode electrode materials for lithium rechargeable batteries due to their ability to accommodate and transport lithium atoms at low and elevated temperatures. In the current study, lithiated nanosheets with concentrations, Li 0. 03 TiO 2 and Li 0. 07 TiO 2 , were crystallised from amorphous precursors at 2000K, using large scale molecular dynamics (MD) simulation method, which was followed by a cooling process towards 0 K. The cooled nanosheets, Li 0. 03 TiO 2 and Li 0. 07 TiO 2 , were subsequently heated at temperature intervals of 100 K from 100 K to 500 K with a Nose-Hoover thermostat. The calculated Ti-O radial distribution functions (RDFs), were used to confirm the extent of crystallisation after cooling. The simulated X-ray diffraction (XRD) spectra, at low (0 K) and high (500 K) temperatures, exhibit peaks associated with both rutile and brookite polymorphs. Microstructural features also depicted diffusion pathways with rutile and brookite character, consistent with XRD results. These results confirm that the Li 0. 03 TiO 2 and Li 0. 07 TiO 2 nanosheets are good candidates for anode materials in lithium ion batteries (LIB), since they can contain and transport lithium ions well, even under higher temperature conditions.

Research paper thumbnail of Amorphisation and recrystallisation study of lithium intercalation into TiO2 nano-architecture

IOP Conference Series: Materials Science and Engineering, 2017

View the article online for updates and enhancements. You may also like Recrystallisation before ... more View the article online for updates and enhancements. You may also like Recrystallisation before austenitization for improved microstructure and properties in automotive steel sheets with high product of strength and elongation Fei Huang, Heng Zhang, Jialin Qi et al.-Recovery and recrystallisation in mechanically alloyed and annealed, legacy, FeCrAlY ODS alloy precursor powders K Dawson, A Rao, G J Tatlock et al.-A physically-based constitutive model and processing map of as-cast 30Cr2Ni4MoV low-pressure rotor steel Y Xu, Y X Jiao, J S Liu et al.

Research paper thumbnail of Structure of Surface Entrance Sites for Li Intercalation into TiO2Nanoparticles, Nanosheets, and Mesoporous Architectures with Application for Li-Ion Batteries

The Journal of Physical Chemistry C, 2016

The version in the Kent Academic Repository may differ from the final published version. Users ar... more The version in the Kent Academic Repository may differ from the final published version. Users are advised to check http://kar.kent.ac.uk for the status of the paper. Users should always cite the published version of record.

Research paper thumbnail of Molecular dynamics simulations of spinels: LiMn2O4 and Li4Mn5O12 at high temperatures

IOP Conference Series: Materials Science and Engineering, 2015

Energy storage technologies are critical in addressing the global challenge of clean sustainable ... more Energy storage technologies are critical in addressing the global challenge of clean sustainable energy. Spinel lithium manganates have attracted attention due to their electrochemical properties and also as promising cathode materials for lithium-ion batteries. The current study focused on the effects of high temperatures on the materials, in order to understand the sustainability in cases where the battery heats up to high temperature and analysis of lithium diffusion aids in terms of intercalation host compatibility. It is also essential to understand the high temperature behaviour and lithium ion host capability of these materials in order to perform the armorphization and recrystalization of spinel nano-architectures. Molecular dynamics simulations carried out to predict high temperature behaviour of the spinel systems. The NVE ensemble was employed, in the range 300-3000K. The melting temperature, lithium-ion diffusion and structural behaviour were monitored in both supercell systems. LiMn 2 O 4 indicated a diffusion rate that increased rapidly above 1500K, just before melting (~1700K) and reached its maximum diffusion at 2.756  10-7 cm 2 s-1 before it decreased. Li 4 Mn 5 O 12 indicated an exponential increase above 700K reaching 8.303  10-7 cm 2 s-1 at 2000K and allowing lithium intercalation even above its melting point of around 1300K. This indicated better structural stability of Li 4 Mn 5 O 12 and capability to host lithium ions at very high temperatures (up to 3000 K) compared to LiMn 2 O 4 .

Research paper thumbnail of Atomistic simulation studies of nanostructured Li2MnO3

The structures of the lithium-rich layered materials are basically derived from the layered rock-... more The structures of the lithium-rich layered materials are basically derived from the layered rock-salt a-NaFeO2 type structure with space group R-3m. Nano-sized crystalline cathode material, Li2MnO3, was prepared by single step hydrothermal reaction [1]. The prepared materials delivered a high electrochemical reversible capacity charged/discharged between 2.0-4.3V, which indicates their promising future potential. In the current study simulated amorphisation recrystallisation method [2] is used to nucleate and crystallise ternary a nanoparticle of Li2MnO3, which is an end member compound of composites. The generated structure is characterized and the Li layer is found to accommodate some Mn ions. The latter is explained in terms of heats of formation deduced from DFT calculations. Microstructural features and transport properties are presented and a possible origin of the electrochemical activity is discussed. [1]

Research paper thumbnail of Atomistic Simulation Studies of the Bulk Lithiated TiO2

ABSTRACT TiO2 has been confirmed as a safe anode material in lithium ion batteries due to its hig... more ABSTRACT TiO2 has been confirmed as a safe anode material in lithium ion batteries due to its higher Li-insertion potential, (1.5V) in comparison with commercialised carbon anode materials. In the current study, amorphisation recrystallization method is used to produce bulk TiO2 with a brookite structure and lithium is inserted at different concentrations. In accordance with pair distribution function experiments [1], it is found that lithiation tends to amorphise the structures. Simulated X-ray diffraction patterns are produced from such structures and compared with the experimental XRDs. Microstructures of TiO2 are generated and are found to be highly twinned hence forming straight and zigzag tunnels. The microstructures of lithiated TiO2 display limited twinning and tunnels with less pathways available for lithium transport. The microstructures are compared with those of nanostructural TiO2 and suggestions for the preference of the latter in anodes are put forward. [4pt] [1] D. Dambournet, K. W. Chapman, M.V. Koudriachova, P.J. Chupas, I. Belharouak, and K. Amine, Inorg. Chem. 2011, 50, 5855--5857.

Research paper thumbnail of Studies of the location of precious metals in nanocrystalline titanium dioxide using XRD and XANES

Physica Status Solidi (c), 2007

Au, Ag, Pt and Pd doped TiO 2 nanocrystals were prepared using sol-gel routes. X-ray Near Edge St... more Au, Ag, Pt and Pd doped TiO 2 nanocrystals were prepared using sol-gel routes. X-ray Near Edge Structure (XANES) was used to study the location of these precious metal dopants in nanocrystalline TiO 2. The effects of these dopants on the phase transformation and grain growth were investigated using X-ray diffraction (XRD). Two dopant concentrations i.e. 1 and 5% were studied and similar results were found. Silver and Palladium initially form oxides but annealing at high temperatures converts them to metals. Gold and and silver do not affect the anatase-rutile transformation temperature whereas palladium and platinum do.

Research paper thumbnail of Atomistic simulation studies of lithiated and sodiated TiO2 nanoarchitectures

Bulletin of the American Physical Society, 2017

Research paper thumbnail of Simulated synthesis and structure of LixTiO2 nanosheets as anode material for lithium ion batteries

Optical Materials, 2020

Nano-architectured Li x TiO 2 are promising as anode electrode materials for lithium rechargeable... more Nano-architectured Li x TiO 2 are promising as anode electrode materials for lithium rechargeable batteries due to their ability to accommodate and transport lithium atoms at low and elevated temperatures. In the current study, lithiated nanosheets with concentrations, Li 0. 03 TiO 2 and Li 0. 07 TiO 2 , were crystallised from amorphous precursors at 2000K, using large scale molecular dynamics (MD) simulation method, which was followed by a cooling process towards 0 K. The cooled nanosheets, Li 0. 03 TiO 2 and Li 0. 07 TiO 2 , were subsequently heated at temperature intervals of 100 K from 100 K to 500 K with a Nose-Hoover thermostat. The calculated Ti-O radial distribution functions (RDFs), were used to confirm the extent of crystallisation after cooling. The simulated X-ray diffraction (XRD) spectra, at low (0 K) and high (500 K) temperatures, exhibit peaks associated with both rutile and brookite polymorphs. Microstructural features also depicted diffusion pathways with rutile and brookite character, consistent with XRD results. These results confirm that the Li 0. 03 TiO 2 and Li 0. 07 TiO 2 nanosheets are good candidates for anode materials in lithium ion batteries (LIB), since they can contain and transport lithium ions well, even under higher temperature conditions.

Research paper thumbnail of Amorphisation and recrystallisation study of lithium intercalation into TiO2 nano-architecture

IOP Conference Series: Materials Science and Engineering, 2017

View the article online for updates and enhancements. You may also like Recrystallisation before ... more View the article online for updates and enhancements. You may also like Recrystallisation before austenitization for improved microstructure and properties in automotive steel sheets with high product of strength and elongation Fei Huang, Heng Zhang, Jialin Qi et al.-Recovery and recrystallisation in mechanically alloyed and annealed, legacy, FeCrAlY ODS alloy precursor powders K Dawson, A Rao, G J Tatlock et al.-A physically-based constitutive model and processing map of as-cast 30Cr2Ni4MoV low-pressure rotor steel Y Xu, Y X Jiao, J S Liu et al.

Research paper thumbnail of Structure of Surface Entrance Sites for Li Intercalation into TiO2Nanoparticles, Nanosheets, and Mesoporous Architectures with Application for Li-Ion Batteries

The Journal of Physical Chemistry C, 2016

The version in the Kent Academic Repository may differ from the final published version. Users ar... more The version in the Kent Academic Repository may differ from the final published version. Users are advised to check http://kar.kent.ac.uk for the status of the paper. Users should always cite the published version of record.

Research paper thumbnail of Molecular dynamics simulations of spinels: LiMn2O4 and Li4Mn5O12 at high temperatures

IOP Conference Series: Materials Science and Engineering, 2015

Energy storage technologies are critical in addressing the global challenge of clean sustainable ... more Energy storage technologies are critical in addressing the global challenge of clean sustainable energy. Spinel lithium manganates have attracted attention due to their electrochemical properties and also as promising cathode materials for lithium-ion batteries. The current study focused on the effects of high temperatures on the materials, in order to understand the sustainability in cases where the battery heats up to high temperature and analysis of lithium diffusion aids in terms of intercalation host compatibility. It is also essential to understand the high temperature behaviour and lithium ion host capability of these materials in order to perform the armorphization and recrystalization of spinel nano-architectures. Molecular dynamics simulations carried out to predict high temperature behaviour of the spinel systems. The NVE ensemble was employed, in the range 300-3000K. The melting temperature, lithium-ion diffusion and structural behaviour were monitored in both supercell systems. LiMn 2 O 4 indicated a diffusion rate that increased rapidly above 1500K, just before melting (~1700K) and reached its maximum diffusion at 2.756  10-7 cm 2 s-1 before it decreased. Li 4 Mn 5 O 12 indicated an exponential increase above 700K reaching 8.303  10-7 cm 2 s-1 at 2000K and allowing lithium intercalation even above its melting point of around 1300K. This indicated better structural stability of Li 4 Mn 5 O 12 and capability to host lithium ions at very high temperatures (up to 3000 K) compared to LiMn 2 O 4 .

Research paper thumbnail of Atomistic simulation studies of nanostructured Li2MnO3

The structures of the lithium-rich layered materials are basically derived from the layered rock-... more The structures of the lithium-rich layered materials are basically derived from the layered rock-salt a-NaFeO2 type structure with space group R-3m. Nano-sized crystalline cathode material, Li2MnO3, was prepared by single step hydrothermal reaction [1]. The prepared materials delivered a high electrochemical reversible capacity charged/discharged between 2.0-4.3V, which indicates their promising future potential. In the current study simulated amorphisation recrystallisation method [2] is used to nucleate and crystallise ternary a nanoparticle of Li2MnO3, which is an end member compound of composites. The generated structure is characterized and the Li layer is found to accommodate some Mn ions. The latter is explained in terms of heats of formation deduced from DFT calculations. Microstructural features and transport properties are presented and a possible origin of the electrochemical activity is discussed. [1]

Research paper thumbnail of Atomistic Simulation Studies of the Bulk Lithiated TiO2

ABSTRACT TiO2 has been confirmed as a safe anode material in lithium ion batteries due to its hig... more ABSTRACT TiO2 has been confirmed as a safe anode material in lithium ion batteries due to its higher Li-insertion potential, (1.5V) in comparison with commercialised carbon anode materials. In the current study, amorphisation recrystallization method is used to produce bulk TiO2 with a brookite structure and lithium is inserted at different concentrations. In accordance with pair distribution function experiments [1], it is found that lithiation tends to amorphise the structures. Simulated X-ray diffraction patterns are produced from such structures and compared with the experimental XRDs. Microstructures of TiO2 are generated and are found to be highly twinned hence forming straight and zigzag tunnels. The microstructures of lithiated TiO2 display limited twinning and tunnels with less pathways available for lithium transport. The microstructures are compared with those of nanostructural TiO2 and suggestions for the preference of the latter in anodes are put forward. [4pt] [1] D. Dambournet, K. W. Chapman, M.V. Koudriachova, P.J. Chupas, I. Belharouak, and K. Amine, Inorg. Chem. 2011, 50, 5855--5857.

Research paper thumbnail of Studies of the location of precious metals in nanocrystalline titanium dioxide using XRD and XANES

Physica Status Solidi (c), 2007

Au, Ag, Pt and Pd doped TiO 2 nanocrystals were prepared using sol-gel routes. X-ray Near Edge St... more Au, Ag, Pt and Pd doped TiO 2 nanocrystals were prepared using sol-gel routes. X-ray Near Edge Structure (XANES) was used to study the location of these precious metal dopants in nanocrystalline TiO 2. The effects of these dopants on the phase transformation and grain growth were investigated using X-ray diffraction (XRD). Two dopant concentrations i.e. 1 and 5% were studied and similar results were found. Silver and Palladium initially form oxides but annealing at high temperatures converts them to metals. Gold and and silver do not affect the anatase-rutile transformation temperature whereas palladium and platinum do.