Electronic Structure and Lithium Diffusion in LiAl₂(OH)₆Cl Studied by First Principle Calculations

• Main Authors: Yueping Zhang, Xiyue Cheng, Chen Wu, Jürgen Köhler, Shuiquan Deng
• Format: Article
• Language: English
• Published: MDPI AG 2019-07-01
• Series: Molecules
• Subjects: layered double hydroxides; LiAl₂(OH)₆Cl; ab initio molecular dynamics (AIMD) simulations; superionic conductor
• Online Access: https://www.mdpi.com/1420-3049/24/14/2667

First-principles calculations based on the density functional theory (DFT) were carried out to study the atomic structure and electronic structure of LiAl₂(OH)₆Cl, the only material in the layered double hydroxide family in which delithiation was found to occur. Ab initio molecular dynamics (AIMD) simulations were used to explore the evolution of the structure of LiAl₂(OH)₆Cl during a thermally induced delithiation process. The simulations show that this process occurs due to the drastic dynamics of Li⁺ at temperatures higher than ~450 K, in which the [Al₂(OH)₆] host layers remain stable up to 1100 K. The calculated large value of the Li⁺ diffusion coefficient D, <inline-formula> <math display="inline"> <semantics> <mrow> <mo>~</mo> <mn>3.13</mn> <mo>&#215;</mo> <msup> <mrow> <mn>10</mn> </mrow> <mrow> <mo>&#8722;</mo> <mn>5</mn> </mrow> </msup> <mi>c</mi> <msup> <mi>m</mi> <mn>2</mn> </msup> <mo>/</mo> <mi>s</mi> </mrow> </semantics> </math> </inline-formula>, at 500 K and the high stability of the [Al₂(OH)₆] framework suggest a potential technical application of the partially-delithiated Li_1-xAl₂(OH)₆Cl_1-x (0 &lt; x &lt; 1) as a superionic conductor at high temperatures.