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Title: Revealing Charge Transport Mechanisms in Li 2 S 2 for Li–Sulfur Batteries

Besides lithium sulfide (Li 2S), lithium persulfide (Li 2S 2) is another solid discharge product in lithium-sulfur (Li-S) batteries. Revealing the charge transport mechanism in the discharge products is important for developing an effective strategy to improve the performance of Li-S batteries. Li 2S 2 cannot transport free electrons due to its wide bandgap between the valence band maximum (VBM) and conduction band minimum (VBM). However, electron polarons (p -) and hole polarons (p +) can appear in solid Li 2S 2 due to the unique molecular orbital structure of the S 2 2- anion. The thermodynamic and kinetic properties of native defects are investigated. It is found that negatively charged Li vacancies (V Li-) and p + are the main native defects with a low formation energy of 0.77 eV. The predominant charge carrier is p + because p + has a high mobility. Thus, the electronic conductivity related to p + diffusion is dependent on temperature, and high temperatures are preferred to increase the conductivity.
Authors:
 [1] ; ORCiD logo [1] ; ORCiD logo [1]
  1. Texas A & M Univ., College Station, TX (United States). Dept. of Mechanical Engineering and Dept. of Chemical Engineering
Publication Date:
Grant/Contract Number:
EE0006832
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry Letters
Additional Journal Information:
Journal Volume: 8; Journal Issue: 7; Journal ID: ISSN 1948-7185
Publisher:
American Chemical Society
Research Org:
Texas A & M Univ., College Station, TX (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; 36 MATERIALS SCIENCE
OSTI Identifier:
1430632