Intercalation processes and diffusion paths of lithium ions in spinel-type structuredLi1+xTi2O4: Density functional theory

Abstract

Intercalation processes and corresponding diffusion paths of Li ions into spinel-type structured Li 1+x Ti 2 O 4 ͑0 ഛ x ഛ 0.375͒ are systematically studied by means of periodic density functional theory calculations for different compositions and arrangements. An analysis of the site preference for intercalation processes is carried out, while energy barriers for the diffusion paths have been computed in detail. Our results indicate that the Li insertion is thermodynamically favorable at octahedral sites 16c in the studied composition range, and Li migration from tetrahedral sites 8a to octahedral sites 16c stabilizes the structure and becomes favorable for compositions x ജ 0.25. Diffusion paths from less stable arrangements involving Li migrations between tetrahedral and octahedral sites exhibit the lowest energy barrier since the corresponding trajectories and energy profiles take place across a triangle made by three neighboring oxygen anions without structural modification. Theoretical and experimental diffusion coefficients are in reasonable agreement.

Alkali Metal Cation and Proton Conductors: Relationships between Composition, Crystal Structure, and Properties

“…The hopping rate, in turn, may be translated into the jump diffusion coefficient that directly affects ionic conductivity properties: [109], and Li x WO 3 [110], have demonstrated good agreement with the experimental values obtained using impedance spectroscopy or nuclear magnetic resonance (NMR). In order to model dynamic behavior on the atomic level, special techniques were developed that now constitute the molecular dynamics (MD) branch of computer simulations.…”

Li-ion diffusion inLi4Ti5O12andLiTi2O4

“…This is because the Li + ions must diffuse across these interfaces during each charge and discharge cycle. However, prior to studying Li-diffusion across the interfaces, it is important to first understand the behavior in each individual component, particularly for Li 4 Ti 5 O 12 , since there are no reliable measurements of the Li + ions diffusion coefficient (D Li ) in this compound [10][11][12][13][14].…”

Multiple-Stripe Lithiation Mechanism of IndividualSnO2Nanowires in a Flooding Geometry

“…Understanding the atomic scale lithiation process is the key to unfold the operation mechanism of LIBs, thus providing the critical science for designing better LIBs [1,2]. Although lithiation has been investigated extensively by theoretical simulation over a wide range of electrode materials [3][4][5][6][7][8][9][10][11][12][13][14], there is lack of direct experimental evidence and fundamental understanding on the initiation and evolution of the atomic scale lithiation mechanisms [15,16]. We have demonstrated very recently that it is possible to study the lithiation process at an atomic scale and in real time by transmission electron microscopy (TEM) [17].…”