Hydrogen-substituted graphdiyne/graphene as an sp/sp2 hybridized carbon interlayer for lithium–sulfur batteries

Abstract

To overcome the shuttle effect in lithium–sulfur (Li–S) batteries, an sp/sp² hybridized all-carbon interlayer by coating graphene (Gra) and hydrogen-substituted graphdiyne (HsGDY) with a specific surface area as high as 2184 m² g⁻¹ on a cathode is designed and prepared. The two-dimensional network and rich pore structure of HsGDY can enable the fast physical adsorption of lithium polysulfides (LiPSs). In situ Raman spectroscopy and ex situ X-ray photoelectron spectroscopy (XPS) combined with density functional theory (DFT) computations confirm that the acetylenic bonds in HsGDY can trap the Li⁺ of LiPSs owing to the strong adsorption of Li⁺ by acetylenic active sites. The strong physical adsorption and chemical anchoring of LiPSs by the HsGDY materials promote the conversion reaction of LiPSs to further mitigate the shuttling problem. As a result, Li–S batteries integrated with the all-carbon interlayers exhibit excellent cycling stability during long-term cycling with an attenuation rate of 0.089% per cycle at 1 C over 500 cycles.