Evaluating silicene as a potential cathode host to immobilize polysulfides in lithiumsulfur batteries
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2016 Informa UK Limited, trading as Taylor & Francis Group. The internal shuttle effect caused by polysulfides dissolution and migration negatively impacts lithiumsulfur battery performance. In this work, a mesoscale simulation strategy, which involves atomistic calculation and coarse-grained molecular modeling, is employed to evaluate silicene as a potential cathode host material to immobilize polysulfides. Adsorption energies of insoluble polysulfides (Li 2 S x with x = 1, 2) and soluble polysulfide Li 2 S 4 on pristine and doped silicene sheets are calculated. Results show that the adsorption is thermodynamically favorable and N-doped silicene is helpful in trapping intermediate discharge products, Li 2 S 2 and Li 2 S 4 . The dissociation and reduction of long-chain polysulfides to short-chain polysulfides are observed. Electronic structure analysis shows that Li 2 S x molecules interact with silicene via strong chemical bonds. The atomistic structure evolution of Li 2 S layer formation on silicene is also investigated in this study. It is found that Li 2 S (110) layer forms first, and then, it is converted to Li 2 S (111) layer by introducing more Li 2 S molecules to the substrate. Li 2 S (111)/silicene interfacial structure is thermodynamically stable, and the interaction is dominated by LiSi bonds. A coarse-grained model is developed to study and compare the growth of Li 2 S on silicene and graphene. Li 2 S-induced surface coverage is faster on silicene than on graphene, which indicates that a silicene-based cathode host will experience more acute surface passivation, which will adversely affect cathode performance.
Journal of Coordination Chemistry
author list (cited authors)
Liu, Z., Balbuena, P. B., & Mukherjee, P. P.
complete list of authors
Liu, Zhixiao||Balbuena, Perla B||Mukherjee, Partha P