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Yildirim H, Kinaci A, Chan MK, et al. First-Principles Analysis of Defect Thermodynamics and Ion Transport in Inorganic SEI Compounds: LiF and NaF. ACS Appl Mater Interfaces. 2015;7(34):18985-96doi: 10.1021/acsami.5b02904.
Yildirim, H., Kinaci, A., Chan, M. K., & Greeley, J. P. (2015). First-Principles Analysis of Defect Thermodynamics and Ion Transport in Inorganic SEI Compounds: LiF and NaF. ACS applied materials & interfaces, 7(34), 18985-96. https://doi.org/10.1021/acsami.5b02904
Yildirim, Handan, et al. "First-Principles Analysis of Defect Thermodynamics and Ion Transport in Inorganic SEI Compounds: LiF and NaF." ACS applied materials & interfaces vol. 7,34 (2015): 18985-96. doi: https://doi.org/10.1021/acsami.5b02904
Yildirim H, Kinaci A, Chan MK, Greeley JP. First-Principles Analysis of Defect Thermodynamics and Ion Transport in Inorganic SEI Compounds: LiF and NaF. ACS Appl Mater Interfaces. 2015 Sep 02;7(34):18985-96. doi: 10.1021/acsami.5b02904. Epub 2015 Aug 24. PMID: 26255641.
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ACS Appl Mater Interfaces. 2015 Sep 02;7(34):18985-96. doi: 10.1021/acsami.5b02904. Epub 2015 Aug 24.

First-Principles Analysis of Defect Thermodynamics and Ion Transport in Inorganic SEI Compounds: LiF and NaF.

ACS applied materials & interfaces

Handan Yildirim, Alper Kinaci, Maria K Y Chan, Jeffrey P Greeley

Affiliations

  1. School of Chemical Engineering, Purdue University , West Lafayette, Indiana 47907, United States.
  2. Center for Nanoscale Materials, Argonne National Laboratory , Argonne, Illinois 60439, United States.

PMID: 26255641 DOI: 10.1021/acsami.5b02904

Abstract

The formation mechanism and composition of the solid electrolyte interphase (SEI) in lithium ion batteries has been widely explored. However, relatively little is known about the function of the SEI as a transport medium. Such critical information is directly relevant to battery rate performance, power loss, and capacity fading. To partially bridge this gap in the case of inorganic SEI compounds, we report herein the results of first-principles calculations on the defect thermodynamics, the dominant diffusion carriers, and the diffusion pathways associated with crystalline LiF and NaF, which are stable components of the SEI in Li-ion and Na-ion batteries, respectively. The thermodynamics of common point defects are computed, and the dominant diffusion carriers are determined over a voltage range of 0-4 V, corresponding to conditions relevant to both anode and cathode SEI's. Our analyses reveal that for both compounds, vacancy defects are energetically more favorable, therefore form more readily than interstitials, due to the close-packed nature of the crystal structures. However, the vacancy concentrations are very small for the diffusion processes facilitated by defects. Ionic conductivities are calculated as a function of voltage, considering the diffusion carrier concentration and the diffusion barriers as determined by nudged elastic band calculations. These conductivities are more than ten orders of magnitude smaller in NaF than in LiF. As compared to the diffusivity of Li in other common inorganic SEI compounds, such as Li2CO3 and Li2O, the cation diffusivity in LiF and NaF is quite low, with at least three orders of magnitude lower ionic conductivities. The results quantify the extent to which fluorides pose rate limitations in Li and Na batteries.

Keywords: DFT; LiF; NaF; defect thermodynamics; diffusion; solid electrolyte interface

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