First Principles Study of TiS2/Graphene Heterojunction as Cathode Material for Sodium–Sulfur Batteries

Abstract

Rechargeable batteries are an indispensable part of the development of environmental sustainability, high capacity and excellent conductivity are essential for optimal energy storage. Sodium–sulfur (Na─S) batteries are recognized as promising options for stationary energy storage solutions, which can be attributed to their high theoretical energy density and cost advantages. Additionally, 2D XS₂@graphene heterojunction is considered an excellent host material for batteries. Using the first-principles calculations, a novel 2D TiS₂/graphene heterojunction have been theoretically investigated as an anchoring material for sodium–sulfur batteries to mitigate the shuttle effect. First, the composite structure is created by depositing a TiS₂ layer onto a single layer of graphene retains its inherent metallic character. Furthermore, the calculated results show that the TiS₂/graphene heterojunction exhibits adsorption energy of 1.3 eV for long-chain sodium polysulfides while maintaining its metallic properties, effectively anchoring polysulfides and inhibiting the shuttle effect. Moreover, a low diffusion barrier (0.31 eV) for Na ion diffusion shows that this heterojunction can enhance electrochemical processes. TiS₂/graphene heterojunction may be the candidate for ideal anchoring materials in sodium–sulfur batteries.