4.5 Article

TiS2-graphene heterostructures enabling polysulfide anchoring and fast electrocatalyst for lithium-sulfur batteries: A first-principles calculation

Journal

CHINESE PHYSICS B
Volume 31, Issue 4, Pages -

Publisher

IOP Publishing Ltd
DOI: 10.1088/1674-1056/ac3227

Keywords

lithium-sulfur batteries; TiS2; graphene heterostructure; anchoring material; shuttle effect

Funding

  1. National Natural Science Foundation of China [62104168, 11604235, U1510132]
  2. Beijing Institute of Technology Research Fund Program for Young Scholars
  3. Natural Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi, China [2019L0309]
  4. Natural Science Foundation of Shanxi Province, China [201901D111125, 20210302123201]
  5. Shanxi Scholarship Council of China

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A novel two-dimensional TiS2/graphene heterostructure is designed as an anchoring material for lithium-sulfur batteries to suppress the shuttle effect. Graphene improves the electronic conductivity of the sulfur cathode, while TiS2 monolayer enhances its polarity. Simulation results show that this heterostructure can effectively anchor polysulfides and catalyze fast electrochemical kinetic processes.
Lithium-sulfur batteries have attracted attention because of their high energy density. However, the shuttle effect caused by the dissolving of polysulfide in the electrolyte has greatly hindered the widespread commercial use of lithium-sulfur batteries. In this paper, a novel two-dimensional TiS2/graphene heterostructure is theoretically designed as the anchoring material for lithium-sulfur batteries to suppress the shuttle effect. This heterostructure formed by the stacking of graphene and TiS2 monolayer is the van der Waals type, which retains the intrinsic metallic electronic structure of graphene and TiS2 monolayer. Graphene improves the electronic conductivity of the sulfur cathode, and the transferred electrons from graphene enhance the polarity of the TiS2 monolayer. Simulations of the polysulfide adsorption show that the TiS2/graphene heterostructure can maintain good metallic properties and the appropriate adsorption energies of 0.98-3.72 eV, which can effectively anchor polysulfides. Charge transfer analysis suggests that further enhancement of polarity is beneficial to reduce the high proportion of van der Waals (vdW) force in the adsorption energy, thereby further enhancing the anchoring ability. Low Li2S decomposition barrier and Li-ion migration barrier imply that the heterostructure has the ability to catalyze fast electrochemical kinetic processes. Therefore, TiS2/graphene heterostructure could be an important candidate for ideal anchoring materials of lithium-sulfur batteries.

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