Vertically aligned sulfur-graphene nanowalls on substrates for ultrafast lithium-sulfur batteries.

Abstract

Although lithium-sulfur batteries have gained great interest owing to their high energy density, they lack suitable electrodes capable of rapid charging and discharging to enable a high power density critical for wide applications. Here, we demonstrate a simply electrochemical assembly strategy to achieve vertically aligned sulfur-graphene (S-G) nanowall onto electrically conductive substrates. Remarkably, in each individual S-G nanowalls, sulfur nanoparticles are homogeneously anchored in between of graphene layers and ordered graphene arrays arrange perpendicularly to the substrates, which are favorable for the fast diffusions of both lithium and electron. Moreover, the hierarchical and porous structures facilate the effective accommodation of the volume change of sulfur. As a consequence, a high reversible capacity of 1261 mAh g(-1) in the first cycle and over 1210 mAh g(-1) after 120 cycles with excellent cyclability and high-rate performance (over 400 mAh g(-1) at 8C, 13.36 A g(-1)) are achieved with these S-G nanowalls as cathodes for lithium-sulfur batteries, providing the best reported rate performance for sulfur-graphene cathodes to date.