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This content will become publicly available on February 12, 2019

Title: Formation of Multilayer Graphene Domains with Strong Sulfur-Carbon Interaction and Enhanced Sulfur Reduction Zones for Lithium-Sulfur Battery Cathodes

A newly designed sulfur/graphene computational model emulates the electrochemical behavior of a Li–S battery cathode, promoting the S–C interaction through the edges of graphene sheets. A random mixture of eight-membered sulfur rings mixed with small graphene sheets is simulated at 64 wt%sulfur loading. Structural stabilization and sulfur reduction calculations are performed with classical reactive molecular dynamics. This methodology allowed the collective behavior of the sulfur and graphene structures to be accounted for. The sulfur encapsulation induces ring opening and the sulfur phase evolves into a distribution of small chain-like structures interacting with C through the graphene edges. This new arrangement of the sulfur phase not only leads to a less pronounced volume expansion during sulfur reduction but also to a different discharge voltage profile, in qualitative agreement with earlier reports on sulfur encapsulation in microporous carbon structures. The Li 2S phase grows around ensembles of parallel graphene nanosheets during sulfur reduction. No diffusion of sulfur or lithium between graphene nanosheets is observed, and extended Li 2S domains bridging the space between carbon ensembles are suppressed. The results emphasize the importance of morphology on the electrochemical performance of the composite material. Finally, the sulfur/graphene model outlined here provides new understanding ofmore » the graphene effects on the sulfur reduction behavior and the role that van der Waals interactions may play in promoting formation of multilayer graphene ensembles and small Li 2S domains during sulfur reduction.« less
Authors:
 [1] ; ORCiD logo [1]
  1. Texas A & M Univ., College Station, TX (United States). Dept. of Chemical Engineering
Publication Date:
Grant/Contract Number:
EE0008210; EE0006832
Type:
Accepted Manuscript
Journal Name:
ChemSusChem
Additional Journal Information:
Journal Volume: 11; Journal Issue: 12; Journal ID: ISSN 1864-5631
Publisher:
ChemPubSoc Europe
Research Org:
Texas A & M Univ., College Station, TX (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
Contributing Orgs:
Texas A&M High Performance Computing Center; Texas Advanced Computing Center
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; lithium-sulfur battery; carbon/sulfur cathode; molecular dynamics simulations; voltage discharge curve; molecular dynamics; multi‐layer graphene ensembles; S‐C interactions; voltage discharge profile; energy conversion
OSTI Identifier:
1460744
Alternate Identifier(s):
OSTI ID: 1426313