surfinpy: A Surface Phase Diagram Generator

Dual-ion Li-Mg batteries offer a potential route to cells that combine desirable properties of both single-ion species. To maximize the energy density of a dual-ion battery, we propose a strategy for achieving simultaneous intercalation of both ionic species, by chemically modifying the intercalation host material to produce a second, complementary, class of insertion sites. We show that donor-doping of anatase TiO 2 to form large numbers of cationic vacancies allows the complementary insertion of Li + and Mg 2+ in a dual-ion cell with a net increase in cell energy density, due to a combination of an increased reversible capacity, an increased operating voltage, and a reduced polarization. By tuning the lithium concentration in the electrolyte, we achieve full utilization of the Ti 4+ /Ti 3+ redox couple with excellent cyclability and rate capability. We conclude that native interstitial sites preferentially accommodate Li + ions, while Mg 2+ ions occupy single-vacancy sites. We also predict a narrow range of electrochemical conditions where adjacent vacancy pairs preferentially accommodate one ion of each species, i.e., a [Li Ti +Mg Ti ] configuration. These results demonstrate the implementation of additional host sites such as cationic sites as an effective approach to increase the energy density in dual-ion batteries.

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“…6. The data analysis scripts use the Python packages numpy, [54,55] snakemake, [56] surfinpy, [57] and vasppy. [58]…”

Section: Resultsmentioning

confidence: 99%

Exploiting cationic vacancies for increased energy densities in dual-ion batteries

Koketsu

Morgan

et al. 2020

Energy Storage Materials

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“…Analysis was conducted using the surfinpy code. 50 Wulff constructions were generated using the pymatgen code 51 and all figures were drawn using VESTA. 52…”

Section: Surface Energies and Thermodynamic Frameworkmentioning

confidence: 99%

Influence of Carbon Dioxide on the Energetics of Cerium Oxide Surfaces and Nanoparticle Morphology

Symington¹,

Harker²,

Storr³

et al. 2020

Preprint

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Many nanoparticles show enhanced catalytic activity on particular surfaces. Hence, a key challenge is to identify strategies to control the expression of such surfaces and to avoid their disappearance over time. Here, we use density functional theory to explore the adsorption of carbon dioxide on the surfaces of Cerium oxide (CeO2), and its relationship with the resulting nanoparticle morphology under conditions of pressure and temperature. CeO2 is an important solid electrolyte in fuel cells, a catalyst, and enzyme mimetic agent in biomedicine, and has been shown to interact strongly with CO2. We demonstrate that the adsorption of CO2 as a carbonate ion is energetically favorable on the {111}, {110} and {100} surfaces of CeO2, and that the strength of this interaction is morphology and surface stoichiometry dependent. By predicting the surface stability as a function of temperature and pressure, we built surface phase diagrams and predict the surface dependent desorption temperatures of CO2. These temperatures of desorption follow the order {100} > {110} > {111} and are higher for surfaces containing oxygen vacancies compared to stoichiometric surfaces, indicating that surface oxidation processes can reduce the stability of surface carbonate groups. Finally, we propose a thermodynamic strategy to predict the evolution of nanoparticle morphology in the presence of CO2 as the external conditions of temperature and pressure change. We show that there is a thermodynamic driving force dependent on CO2 adsorption that should be considered when selecting nanoparticle morphologies in catalytic applications.

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“…Phase diagrams were generated and analysis was conducted using the surfinpy code. 35 Wulff constructions were generated using pymatgen 36 and all figures were drawn using VESTA. 37…”

Section: Surface Modelsmentioning

confidence: 99%

“…ARS, MM, SM, JMF and DS performed the calculations, ARS analysed the DFT data and developed the surfinpy code, 35 DS analysed the MD data, SCP and MM designed the study and ARS wrote the paper with contributions from all authors.…”

Section: Author Contributionsmentioning

confidence: 99%

Strongly Bound Surface Water Affects the Shape Evolution of Cerium Oxide Nanoparticles

Symington

Molinari²,

Moxon³

et al. 2019

Preprint

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The surface structure and composition of functional materials are well known to be critically important factors controlling the surface reactivity. However, when doped the surface composition will change and the challenge is to identify its impact on important surface processes and nanoparticle morphologies. We have begun to address this by using a combination of density functional theory and potential-based methods to investigate the effect of surface dopants on water adsorption and morphology of the technologically important material, CeO 2 , which finds application as electrolyte in SOFCs, catalyst in soot combustion, and enzyme mimetic agent in biomedicine. We show that by mapping CeO 2 surface phase diagrams we can predict nanoparticle morphologies as a function of dopant, temperature and water partial pressure. Our results show that a low temperature, un-doped CeO 2 nanocubes with active {100} surface sites are thermodynamically stable. But at the typical high temperature operating conditions favours polyhedra where {100} surfaces are replaced by less active {111} surfaces by surface ion migration. However, on doping with trivalent cations, such as Gd 3+ , will increase binding of water on the {100} surfaces and hence act to preserve the cuboidal architecture, by capping the active surfaces. As surfaces tend to be decorated by impurities and dopants it is clear that their role should receive more attention and the approach we describe can be routinely applied to nanomaterials, morphologies and associated active/inactive surfaces.

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surfinpy: A Surface Phase Diagram Generator

Cited by 14 publications

References 5 publications

Exploiting cationic vacancies for increased energy densities in dual-ion batteries

Exploiting cationic vacancies for increased energy densities in dual-ion batteries

Influence of Carbon Dioxide on the Energetics of Cerium Oxide Surfaces and Nanoparticle Morphology

Strongly Bound Surface Water Affects the Shape Evolution of Cerium Oxide Nanoparticles

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