Three-Dimensional CNT/Graphene–Li₂S Aerogel as Freestanding Cathode for High-Performance Li–S Batteries

Abstract

Three-dimensional (3D) CNT/graphene-Li2S (3DCG–Li2S) cathodes with 81.4 wt % record Li2S loading have been realized through solvothermal reaction and a subsequent liquid-infiltration-evaporation coating method. The highly flexible, conductive 3D mesoporous interconnected network based on two-dimensional (2D) graphene nanosheets and one-dimensional (1D) carbon nanotubes (CNTs) provides highly efficient channels for electron transfer and ionic diffusion, and leads to a low solubility of polysulfides in electrolytes in charges/discharges. Without polymeric binders or conductive additives, the freestanding 3DCG–Li2S cathode exhibits record electrochemical performances including reversible discharge capacities of 1123.6 mAh g–1 and 914.6 mAh g–1, 0.02% long-term capacity decay per cycle and a high-rate capacity of 514 mAh g–1 at 4 C. The reported 3DCG–Li2S aerogel with ultrahigh Li2S content presents promising application potentials in high-performance Li–S batteries.