Genetics of superionic conductivity in lithium lanthanum titanates

Jay, Eleanor E.; Rushton, Michael; Chroneos, Alexander; Grimes, Robin W.; Kilner, John A.

doi:10.1039/c4cp04834b

Cited by 87 publications

(73 citation statements)

References 38 publications

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“…Here we have employed the full charge ionic model with the calculations in the dilute limit. These are sufficient and will correctly calculate trends in energies, however, defect energies are bound to be overestimated 44,45 .…”

Section: Resultsmentioning

confidence: 99%

Defects, Dopants and Sodium Mobility in Na2MnSiO4

Kuganathan

Chroneos

2018

Sci Rep

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Sodium manganese orthosilicate, Na2MnSiO4, is a promising positive electrode material in rechargeable sodium ion batteries. Atomistic scale simulations are used to study the defects, doping behaviour and sodium migration paths in Na2MnSiO4. The most favourable intrinsic defect type is the cation anti-site (0.44 eV/defect), in which, Na and Mn exchange their positions. The second most favourable defect energy process is found to be the Na Frenkel (1.60 eV/defect) indicating that Na diffusion is assisted by the formation of Na vacancies via the vacancy mechanism. Long range sodium paths via vacancy mechanism were constructed and it is confirmed that the lowest activation energy (0.81 eV) migration path is three dimensional with zig-zag pattern. Subvalent doping by Al on the Si site is energetically favourable suggesting that this defect engineering stratergy to increase the Na content in Na2MnSiO4 warrants experimental verification.

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Section: Resultsmentioning

confidence: 99%

Defects, Dopants and Sodium Mobility in Na2MnSiO4

Kuganathan

Chroneos

2018

Sci Rep

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“…Within each domain there are well‐defined La‐rich and La‐poor layers, but the orientation of each domain varies randomly. For all three configurations, the simulation box contains 160 256 atoms (11 008 Li, 18 176 La, 32 768 Ti, and 98 304 O), and the interatomic interactions were described by a Buckingham‐type potential . Although the simple pair interatomic potential may not be able to accurately describe all the properties of (Li 0.33 La 0.56 )TiO 3 , this model does effectively isolate the effects of domain size, and thus is a legitimate one to study the phenomenon of interest.…”

Section: Resultsmentioning

confidence: 99%

Mesoscopic Framework Enables Facile Ionic Transport in Solid Electrolytes for Li Batteries

Cheng

Chen

et al. 2016

Advanced Energy Materials

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Li‐ion‐conducting solid electrolytes can simultaneously overcome two grand challenges for Li‐ion batteries: the severe safety concerns that limit the large‐scale application and the poor electrolyte stability that forbids the use of high‐voltage cathodes. Nevertheless, the ionic conductivity of solid electrolytes is typically low, compromising the battery performances. Precisely determining the ionic transport mechanism(s) is a prerequisite for the rational design of highly conductive solid electrolytes. For decades, the research on this subject has primarily focused on the atomic and microscopic scales, where the main features of interest are unit cells and microstructures, respectively. Here, it is shown that the largely overlooked mesoscopic scale lying between these extremes could be the key to fast ionic conduction. In a prototype system, (Li0.33La0.56)TiO3, a mesoscopic framework is revealed for the first time by state‐of‐the‐art scanning transmission electron microscopy. Corroborated by theoretical calculations and impedance measurements, it is demonstrated that such a unique configuration maximizes the number of percolation directions and thus most effectively improves the ionic conductivity. This discovery reconciles the long‐standing structure–property inconsistency in (Li0.33La0.56)TiO3 and also identifies mesoscopic ordering as a promising general strategy for optimizing Li+ conduction.

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“…20,21 A recent computational study suggests that, in the case where there is not significant ordering of the A-site cations in layers normal to the c-axis, lithium ions could also diffuse along c-axis, which is in better agreement with experimental conductivity results. 146 The bottleneck size can be increased by using large rare-earth or alkaline-earth metal ions in the A site, which can lead to significant increases in the ionic conductivity. A systematic increase in the bulk ionic conductivity at 400 K and lowered activation energy correlates with increasing rare-earth metal ion size (Sm 3+ < Nd 3+ < Pr 3+ < La 3+ ).…”

Section: Perovskitementioning

confidence: 99%

Inorganic Solid-State Electrolytes for Lithium Batteries: Mechanisms and Properties Governing Ion Conduction

Bachman¹,

Muy²,

Grimaud³

et al. 2015

Chem. Rev.

2,054

1,656

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This Review is focused on ion-transport mechanisms and fundamental properties of solid-state electrolytes to be used in electrochemical energy-storage systems. Properties of the migrating species significantly affecting diffusion, including the valency and ionic radius, are discussed. The natures of the ligand and metal composing the skeleton of the host framework are analyzed and shown to have large impacts on the performance of solid-state electrolytes. A comprehensive identification of the candidate migrating species and structures is carried out. Not only the bulk properties of the conductors are explored, but the concept of tuning the conductivity through interfacial effects-specifically controlling grain boundaries and strain at the interfaces-is introduced. High-frequency dielectric constants and frequencies of low-energy optical phonons are shown as examples of properties that correlate with activation energy across many classes of ionic conductors. Experimental studies and theoretical results are discussed in parallel to give a pathway for further improvement of solid-state electrolytes. Through this discussion, the present Review aims to provide insight into the physical parameters affecting the diffusion process, to allow for more efficient and target-oriented research on improving solid-state ion conductors.

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Genetics of superionic conductivity in lithium lanthanum titanates

Cited by 87 publications

References 38 publications

Defects, Dopants and Sodium Mobility in Na2MnSiO4

Defects, Dopants and Sodium Mobility in Na2MnSiO4

Mesoscopic Framework Enables Facile Ionic Transport in Solid Electrolytes for Li Batteries

Inorganic Solid-State Electrolytes for Lithium Batteries: Mechanisms and Properties Governing Ion Conduction

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