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Title: Role of Point Defects in Spinel Mg Chalcogenide Conductors

Abstract

Close-packed chalcogenide spinels, such as MgSc2Se 4, MgIn2S 4, and MgSc2S 4, show potential as solid electrolytes in Mg batteries, but are affected by non-negligible electronic conductivity, which contributes to self-discharge when used in an electrochemical storage device. Using first-principles calculations, we evaluate the energy of point defects as a function of synthesis conditions and Fermi level to identify the origins of the undesired electronic conductivity. Our results suggest that Mg-vacancies and Mg-metal antisites (where Mg is exchanged with Sc or In) are the dominant point defects that can occur in the systems under consideration. While we find anion-excess conditions and slow cooling to likely create conditions for low electronic conductivity, the spinels are likely to exhibit significant n-type conductivity under anion-poor environments, which are often present during high-temperature synthesis. Finally, we explore extrinsic aliovalent doping to potentially mitigate the electronic conductivity in these chalcogenide spinels. Furthermore, the computational strategy is general and can be easily extended to other solid electrolytes (and electrodes) to aid the optimization of the electronic properties of the corresponding frameworks.

Authors:
ORCiD logo [1]; ORCiD logo [2];  [3];  [4];  [5]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of Bath, Bath (United Kingdom)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  3. Univ. of California, Berkeley, CA (United States)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  5. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Univ. of California, Berkeley, CA (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1476575
Grant/Contract Number:  
[AC02-05CH11231]
Resource Type:
Accepted Manuscript
Journal Name:
Chemistry of Materials
Additional Journal Information:
[ Journal Volume: 29; Journal Issue: 22; Related Information: © 2017 American Chemical Society.]; Journal ID: ISSN 0897-4756
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Canepa, Pieremanuele, Gautam, Gopalakrishnan Sai, Broberg, Danny, Bo, Shou -Hang, and Ceder, Gerbrand. Role of Point Defects in Spinel Mg Chalcogenide Conductors. United States: N. p., 2017. Web. doi:10.1021/acs.chemmater.7b02909.
Canepa, Pieremanuele, Gautam, Gopalakrishnan Sai, Broberg, Danny, Bo, Shou -Hang, & Ceder, Gerbrand. Role of Point Defects in Spinel Mg Chalcogenide Conductors. United States. doi:10.1021/acs.chemmater.7b02909.
Canepa, Pieremanuele, Gautam, Gopalakrishnan Sai, Broberg, Danny, Bo, Shou -Hang, and Ceder, Gerbrand. Thu . "Role of Point Defects in Spinel Mg Chalcogenide Conductors". United States. doi:10.1021/acs.chemmater.7b02909. https://www.osti.gov/servlets/purl/1476575.
@article{osti_1476575,
title = {Role of Point Defects in Spinel Mg Chalcogenide Conductors},
author = {Canepa, Pieremanuele and Gautam, Gopalakrishnan Sai and Broberg, Danny and Bo, Shou -Hang and Ceder, Gerbrand},
abstractNote = {Close-packed chalcogenide spinels, such as MgSc2Se4, MgIn2S4, and MgSc2S4, show potential as solid electrolytes in Mg batteries, but are affected by non-negligible electronic conductivity, which contributes to self-discharge when used in an electrochemical storage device. Using first-principles calculations, we evaluate the energy of point defects as a function of synthesis conditions and Fermi level to identify the origins of the undesired electronic conductivity. Our results suggest that Mg-vacancies and Mg-metal antisites (where Mg is exchanged with Sc or In) are the dominant point defects that can occur in the systems under consideration. While we find anion-excess conditions and slow cooling to likely create conditions for low electronic conductivity, the spinels are likely to exhibit significant n-type conductivity under anion-poor environments, which are often present during high-temperature synthesis. Finally, we explore extrinsic aliovalent doping to potentially mitigate the electronic conductivity in these chalcogenide spinels. Furthermore, the computational strategy is general and can be easily extended to other solid electrolytes (and electrodes) to aid the optimization of the electronic properties of the corresponding frameworks.},
doi = {10.1021/acs.chemmater.7b02909},
journal = {Chemistry of Materials},
number = [22],
volume = [29],
place = {United States},
year = {2017},
month = {10}
}

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