Defects, Diffusion, and Dopants in Li2Ti6O13: Atomistic Simulation Study

Lithium zirconate is a candidate material in the design of electrochemical devices and tritium breeding blankets. Here we employ an atomistic simulation based on the classical pair-wise potentials to examine the defect energetics, diffusion of Li-ions, and solution of dopants. The Li-Frenkel is the lowest defect energy process. The Li-Zr anti-site defect cluster energy is slightly higher than the Li-Frenkel. The Li-ion diffuses along the c axis with an activation energy of 0.55 eV agreeing with experimental values. The most favorable isovalent dopants on the Li and Zr sites were Na and Ti respectively. The formation of additional Li in this material can be processed by doping of Ga on the Zr site. Incorporation of Li was studied using density functional theory simulation. Li incorporation is exoergic with respect to isolated gas phase Li. Furthermore, the semiconducting nature of LZO turns metallic upon Li incorporation.

Download Full-text

Na-ion diffusion in a NASICON-type solid electrolyte: a density functional study

Physical Chemistry Chemical Physics ◽

10.1039/c6cp05164b ◽

2016 ◽

Vol 18 (39) ◽

pp. 27226-27231 ◽

Cited By ~ 13

Author(s):

Kieu My Bui ◽

Van An Dinh ◽

Susumu Okada ◽

Takahisa Ohno

Keyword(s):

Density Functional Theory ◽

Solid Electrolyte ◽

Electronic Structures ◽

Density Functional ◽

Diffusion Mechanism ◽

Functional Study ◽

Ion Diffusion ◽

Functional Theory ◽

Density Functional Study ◽

Nasicon Type

Based on density functional theory, we have systematically studied the crystal and electronic structures, and the diffusion mechanism of the NASICON-type solid electrolyte Na3Zr2Si2PO12.

Download Full-text

Defect, Diffusion and Dopant Properties of NaNiO2: Atomistic Simulation Study

Energies ◽

10.3390/en12163094 ◽

2019 ◽

Vol 12 (16) ◽

pp. 3094 ◽

Cited By ~ 8

Author(s):

Ruwani Kaushalya ◽

Poobalasuntharam Iyngaran ◽

Navaratnarajah Kuganathan ◽

Alexander Chroneos

Keyword(s):

Atomistic Simulation ◽

High Capacity ◽

Sodium Ion ◽

Intrinsic Defect ◽

Sodium Ion Batteries ◽

Ion Diffusion ◽

Defect Diffusion ◽

Simulation Techniques ◽

Defect Process ◽

Isovalent Dopant

Sodium nickelate, NaNiO2, is a candidate cathode material for sodium ion batteries due to its high volumetric and gravimetric energy density. The use of atomistic simulation techniques allows the examination of the defect energetics, Na-ion diffusion and dopant properties within the crystal. Here, we show that the lowest energy intrinsic defect process is the Na-Ni anti-site. The Na Frenkel, which introduces Na vacancies in the lattice, is found to be the second most favourable defect process and this process is higher in energy only by 0.16 eV than the anti-site defect. Favourable Na-ion diffusion barrier of 0.67 eV in the ab plane indicates that the Na-ion diffusion in this material is relatively fast. Favourable divalent dopant on the Ni site is Co2+ that increases additional Na, leading to high capacity. The formation of Na vacancies can be facilitated by doping Ti4+ on the Ni site. The promising isovalent dopant on the Ni site is Ga3+.

Download Full-text

Evidence for a Solid-Electrolyte Inductive Effect in Superionic Conductors

10.26434/chemrxiv.13075745 ◽

2020 ◽

Author(s):

Sean Culver ◽

Alex Squires ◽

Nicolo Minafra ◽

Callum Armstrong ◽

Thorben Krauskopf ◽

...

Keyword(s):

Solid Electrolyte ◽

Solid Electrolytes ◽

Density Functional ◽

Inductive Effect ◽

Ionic Conductivities ◽

Lithium Ion ◽

Density Functional Theory Calculations ◽

Ion Diffusion ◽

Functional Theory ◽

Li Ion

Identifying and optimizing highly-conducting lithium-ion solid electrolytes is a critical step towards the realization of commercial all–solid-state lithium-ion batteries. Strategies to enhance ionic conductivities in solid electrolytes typically focus on the effects of modifying their crystal structures or of tuning mobile-ion stoichiometries. A less-explored approach is to modulate the chemical-bonding interactions within a material to promote fast lithium-ion diffusion. Recently, the idea of a solid-electrolyte inductive effect was proposed, whereby changes in bonding within the solid-electrolyte host-framework modify the potential-energy landscape for the mobile ions, resulting in an enhanced ionic conductivity. This concept has since been invoked to explain anomalous conductivity trends in a number of solid electrolytes. Direct evidence for a solid-electrolyte inductive effect, however, is lacking—in part because of the challenge of quantifying changes in local bonding interactions within a solid-electrolyte host-framework. <a></a><a>Here, we consider the evidence for a solid-electrolyte inductive effect in the archetypal superionic lithium-ion conductor Li10Ge1−xSnxP2S12, using Rietveld refinements against high-resolution temperature-dependent neutron-diffraction data, Raman spectroscopy, and density functional theory calculations.</a> Substituting Ge for Sn weakens the {Ge,Sn}–S bonding interactions and increases the charge-density associated with the S2- ions. This charge redistribution modifies the Li+ substructure causing Li+ ions to bind more strongly to the host-framework S anions; which in turn modulates the Li-ion potential-energy surface, increasing local barriers for Li-ion diffusion. Each of these effects is consistent with the predictions of the solid-electrolyte inductive effect model. Density functional theory calculations further predict that this inductive effect occurs even in the absence of changes to the host-framework geometry due to Ge → Sn substitution. These results provide direct evidence in support of a measurable solid-electrolyte inductive effect and demonstrate its application as a practical strategy for tuning ionic conductivities in superionic lithium-ion conductors.

Download Full-text

Nanometer-size Na cluster formation in micropore of hard carbon as origin of higher-capacity Na-ion battery

npj Computational Materials ◽

10.1038/s41524-021-00515-7 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Yong Youn ◽

Bo Gao ◽

Azusa Kamiyama ◽

Kei Kubota ◽

Shinichi Komaba ◽

...

Keyword(s):

Density Functional ◽

Cluster Formation ◽

High Capacity ◽

Density Functional Theory Calculations ◽

High Energy ◽

High Energy Density ◽

Hard Carbon ◽

Functional Theory ◽

Nanometer Size ◽

Li Ion

AbstractDevelopment of high-energy-density anode is crucial for practical application of Na-ion battery as a post Li-ion battery. Hard carbon (HC), though a promising anode candidate, still has bottlenecks of insufficient capacity and unclear microscopic picture. Usage of the micropore has been recently discussed, however, the underlying sodiation mechanism is still controversial. Herein we examined the origin for the high-capacity sodiation of HC, based on density functional theory calculations. We demonstrated that nanometer-size Na cluster with 3–6 layers is energetically stable between two sheets of graphene, a model micropore, in addition to the adsorption and intercalation mechanisms. The finding well explains the extended capacity over typical 300 mAhg−1, up to 478 mAhg−1 recently found in the MgO-templated HC. We also clarified that the MgO-template can produce suitable nanometer-size micropores with slightly defective graphitic domains in HC. The present study considerably promotes the atomistic theory of sodiation mechanism and complicated HC science.

Download Full-text

Evidence for a Solid-Electrolyte Inductive Effect in Superionic Conductors

10.26434/chemrxiv.13075745.v1 ◽

2020 ◽

Author(s):

Sean Culver ◽

Alex Squires ◽

Nicolo Minafra ◽

Callum Armstrong ◽

Thorben Krauskopf ◽

...

Keyword(s):

Solid Electrolyte ◽

Solid Electrolytes ◽

Density Functional ◽

Inductive Effect ◽

Ionic Conductivities ◽

Lithium Ion ◽

Density Functional Theory Calculations ◽

Ion Diffusion ◽

Functional Theory ◽

Li Ion

Identifying and optimizing highly-conducting lithium-ion solid electrolytes is a critical step towards the realization of commercial all–solid-state lithium-ion batteries. Strategies to enhance ionic conductivities in solid electrolytes typically focus on the effects of modifying their crystal structures or of tuning mobile-ion stoichiometries. A less-explored approach is to modulate the chemical-bonding interactions within a material to promote fast lithium-ion diffusion. Recently, the idea of a solid-electrolyte inductive effect was proposed, whereby changes in bonding within the solid-electrolyte host-framework modify the potential-energy landscape for the mobile ions, resulting in an enhanced ionic conductivity. This concept has since been invoked to explain anomalous conductivity trends in a number of solid electrolytes. Direct evidence for a solid-electrolyte inductive effect, however, is lacking—in part because of the challenge of quantifying changes in local bonding interactions within a solid-electrolyte host-framework. <a></a><a>Here, we consider the evidence for a solid-electrolyte inductive effect in the archetypal superionic lithium-ion conductor Li10Ge1−xSnxP2S12, using Rietveld refinements against high-resolution temperature-dependent neutron-diffraction data, Raman spectroscopy, and density functional theory calculations.</a> Substituting Ge for Sn weakens the {Ge,Sn}–S bonding interactions and increases the charge-density associated with the S2- ions. This charge redistribution modifies the Li+ substructure causing Li+ ions to bind more strongly to the host-framework S anions; which in turn modulates the Li-ion potential-energy surface, increasing local barriers for Li-ion diffusion. Each of these effects is consistent with the predictions of the solid-electrolyte inductive effect model. Density functional theory calculations further predict that this inductive effect occurs even in the absence of changes to the host-framework geometry due to Ge → Sn substitution. These results provide direct evidence in support of a measurable solid-electrolyte inductive effect and demonstrate its application as a practical strategy for tuning ionic conductivities in superionic lithium-ion conductors.

Download Full-text

Defects and Dopants in CaFeSi2O6: Classical and DFT Simulations

Energies ◽

10.3390/en13051285 ◽

2020 ◽

Vol 13 (5) ◽

pp. 1285 ◽

Cited By ~ 3

Author(s):

Navaratnarajah Kuganathan ◽

Alexander Chroneos

Keyword(s):

Electronic Structures ◽

Density Functional ◽

Electrode Materials ◽

Ion Diffusion ◽

Reaction Energy ◽

Functional Theory ◽

Ion Migration ◽

Process Formation ◽

Calculated Activation Energy ◽

Calculated Activation

Calcium (Ca)-bearing minerals are of interest for the design of electrode materials required for rechargeable Ca-ion batteries. Here we use classical simulations to examine defect, dopant and transport properties of CaFeSi2O6. The formation of Ca-iron (Fe) anti-site defects is found to be the lowest energy process (0.42 eV/defect). The Oxygen and Calcium Frenkel energies are 2.87 eV/defect and 4.96 eV/defect respectively suggesting that these defects are not significant especially the Ca Frenkel. Reaction energy for the loss of CaO via CaO Schottky is 2.97 eV/defect suggesting that this process requires moderate temperature. Calculated activation energy of Ca-ion migration in this material is high (>4 eV), inferring very slow ionic conductivity. However, we suggest a strategy to introduce additional Ca2+ ions in the lattice by doping trivalent dopants on the Si site in order to enhance the capacity and ion diffusion and it is calculated that Al3+ is the favourable dopant for this process. Formation of Ca vacancies required for the CaO Schottky can be facilitated by doping of gallium (Ga) on the Fe site. The electronic structures of favourable dopants were calculated using density functional theory (DFT).

Download Full-text

Density functional theory prediction of Mg3N2 as a high-performance anode material for Li-ion batteries

Physical Chemistry Chemical Physics ◽

10.1039/c8cp07398h ◽

2019 ◽

Vol 21 (13) ◽

pp. 7053-7060 ◽

Cited By ~ 4

Author(s):

Lixin Xiong ◽

Junping Hu ◽

Sicheng Yu ◽

Musheng Wu ◽

Bo Xu ◽

...

Keyword(s):

Density Functional Theory ◽

Anode Material ◽

High Performance ◽

Density Functional ◽

High Capacity ◽

Li Ion Batteries ◽

Functional Theory ◽

2D Material ◽

Li Ion

We predict that a novel graphene-like 2D material (g-Mg3N2) can serve as a LIB anode with super high capacity.

Download Full-text

Comparative Studies on Monolayer and Bilayer Phosphorous as the Anodes of Li Ion Battery

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.896.61 ◽

2021 ◽

Vol 896 ◽

pp. 61-66

Author(s):

Yuan Yuan

Keyword(s):

Density Functional ◽

Open Circuit ◽

Binding Energies ◽

Li Ion Battery ◽

Ion Diffusion ◽

Functional Theory ◽

2D Material ◽

Li Ion ◽

Open Circuit Voltages ◽

Current Report

Recently, two-dimensional (2D) material developed rapidly and provided a wide application on the anode of the batteries, reducing the adverse effect of traditional ion batteries such as low capacity, short cycle life, slow charging and poor safety mainly coming from the use of graphite anode. The current report investigates the anode performances of phosphorus, a new 2D material in electrochemistry field, with monolayer and bilayer structure for Li ion batterys (LIBs) through density functional theory (DFT) calculations and gives a comparison on the Li ion valences, binding energies and open-circuit voltages between the two structures. The results indicate that bilayer phosphorus perform better as a novel anode due to the stronger adhesion to Li and lower barrier for ion diffusion. Furthermore, our research results illustrate a broad application prospect on the new anode inventions as well as reducing useless consumption on the batteries by the practice of bilayer phosphorus anode.

Download Full-text

Studies on the Performance of Two Dimensional AlSi as the Anodes of Li Ion Battery

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.324.109 ◽

2021 ◽

Vol 324 ◽

pp. 109-115

Author(s):

Shuai Hao

Keyword(s):

Density Functional ◽

Open Circuit ◽

Binding Energies ◽

Two Dimensional ◽

Ion Diffusion ◽

Functional Theory ◽

Charging Rate ◽

Li Ion ◽

Open Circuit Voltages ◽

Current Report

Recently, two-dimensional (2D) materials have been rapidly developed and they provided a wide application on the anode of the batteries, reducing the adverse effect of traditional ion batteries including low capacity, short cycle life, low charging rate and poor safety mainly coming from the use of graphite anode. The current report investigates the anode performances of AlSi, a new 2D material exfoliated from NaAlSi, for Li ion batterys (LIBs) through density functional theory (DFT) calculations and gives quantitative discussions on the Li ion valences, binding energies and open-circuit voltages of 2D AlSi anode. The results indicate that 2D AlSi performs great as a novel anode due to the moderate adhesion to Li and low barrier for ion diffusion. Furthermore, our research results illustrate a broad application prospect on the new anode inventions as well as reducing useless consumption on the batteries by the practice of AlSi anode.

Download Full-text