Ab-Initio Study of Li-Ion Electrolyte Li2(OH)Cl

Wednesday, 4 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)
J. D. Howard (Wake Forest University), Z. D. Hood (Georgia Institute of Technology, Oak Ridge National Laboratory), and N. A. W. Holzwarth (Wake Forest University)
The material Li2(OH)Cl is experimentally found to exist in two phases, a poor Li-ion conducting orthorhombic phase (T<312K) and a fast Li-ion conducting disordered cubic phase (T>312K). Recently experiments report the high temperature phase cycled in a symmetric cell with lithium electrodes with the apparent creation of a stabilizing solid electrolyte interphase layer[1]. Li2(OH)Cl is related to a variety of other materials that have been studied for their Li-ion electrolyte properties, Li2+x(OH1-x)Cl, Li2(OH)Br, and Li2(OH)1-xFxCl.[2][3]

We report the results of a combined computational and experimental study of the structural and ion migration properties of this material as a function of temperature. Using first principles methods to calculate the idealized static structures together with estimations of the phonon free energies in the quasi-harmonic approximation, the simulations predict several phases at low temperature including tetragonal and orthorhombic structures. The predicted orthorhombic phases are similar to experimental X-ray analysis performed at temperatures 15 K < T < 300 K as well as with literature reports,[1][2] while the tetragonal phase may be difficult to experimentally realize. Additionally, the disordered cubic phase was investigated using first-principles molecular dynamics to determine the lithium tracer diffusion and several order parameters in the temperature range of ~350-650 K.

[1] Hood, Z. D., Wang, H., Pandian , A. S., Keum, J. K. and Liang, C. J. Am. Chem. Soc. 138 1768-1771 (2016).

[2] Schwering G., Hönnerscheid, A., van Wüllen, L., and Jansen, M., CHEMPHYSCHEM, 4, 343-348 (2003).

[3] Li, Y., Zhou, W., Xin, S., Li, S., Zhu, J., Lü, X., Cui, Z., Jia, Q., Zhou, J., Zhao, Y., Goodenough, J.B.,. Angewandte Chemie International Edition, 9965–9968 (2016).


Jason Howard was supported by NSF grant DMR-1507942. Computations were performed on
the Wake Forest University DEAC cluster, a centrally managed resource with support provided in part by the University. A portion of this research was supported by the Center for Nanophase Materials Sciences at Oak Ridge National Laboratory, which is a U.S. Department of Energy (DOE) Office of Science User Facility. Zachary Hood was supported by a Graduate Research Fellowship award from the National Science Foundation (DGE-1148903) and the Georgia Tech-ORNL Fellowship.