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

Abstract

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.

First-principles study of catalytic mechanism of boron-doped graphene oxide on oxygen evolution reaction of lithium peroxide

“…需要探索具有高能量密度的新型动力电池 [1] . 在各 种后锂离子电池中, 如钠离子电池 [2][3][4] 、锂-硫电池 [5] 等, 能量密度高、成本低又环保的锂-氧电池被认为 有希望成为锂离子电池的替代者 [6][7][8][9] . 典型的锂-氧 电池由空气阴极(活性氧)、高能量密度的锂金属阳 极和高离子电导率的电解质组成, 通过简单的氧化…”

Two-Dimensional Transition Metal Phosphides As Cathode Additive in Robust Lithium–Sulfur Batteries

“…As shown in Figure c, charge transfer is not the only factor that determines the adsorption energy. Although there is not much difference in charge transfer between Li 2 S and the Zr 2 PS 2 (001) surface compared with other polysulfides, the short adsorption distance and bond length between Li 2 S and the Zr 2 PS 2 (001) surface (Figure S6 and Table S1) make it more difficult for Li 2 S to desorb from the Zr 2 PS 2 surface. , In addition, the internal charge loss of Li 2 S x (orange regions) leads to softening of the Li–S bond, which facilitates the conversion of Li 2 S x . Similar results were obtained for Zr 2 PTe 2 .…”