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Monday, March 11

Design and synthesis of a crystalline LiPON electrolyte

Natalie Holzwarth, Wake Forrect University, Winston-Salem
Center for Nanophase Materials Sciences/ Nanomaterials Theory Institute Seminar
3:00 PM — 4:00 PM, Central Laboratory and Office Building (SNS), Building 8600, Room C-250
Contact: Paul Kent (kentpr@ornl.gov), 865.574.4845

Abstract

In the course of a computation study of the broad class of lithium phosphorus oxy-nitride materials of interest for solid electrolyte applications, Du and Holzwarth,[2] recently predicted a stable crystalline material with the stoichiometry Li_2PO_2N. This talk reports the experimental preparation of the material using high temperature solid state synthesis and reports the results of experimental and calculational characterization studies. The so-named SD-Li_2PO_2N crystal structure is similar to that of Li2SiO3, having the orthorhombic space group Cmc2_1. It's structure is similar but not identical to the predicted structure, and is characterized by parallel arrangements of anionic phosphorus oxy-nitride chains having planar P-N-P-N backbones. Nitrogen 2p ϖ states contribute to the strong bonding and to the chemical and thermal stablility of the material in air up to 600°C and in vacuum up to 1050°C. The measured Arrhenius activation energy for ionic conductivity is 0.6 eV which is comparable to computed vacancy migration energies in the presence of a significant population of Li^+ ion vacancies.


[1] Keerthi Senevirathne, Cynthia S. Day, Michael D. Gross, and N. A. W. Holzwarth, Solid State Ionics 233 95-101 (2013) [2] Y. A. Du and N. A. W. Holzwarth, Phys. Rev. B 81 184106 (2010).

This work was supported by the Wake Forest University Center for Energy, Environment, and Sustainability, and by NSF grants DMR-1105485 and MRI-1040264.