Vanadium disulfide-coated carbon nanotube film as an interlayer for high-performance lithium‑sulfur batteries

Abstract

Owing to the “shuttle effect” and slow solid–solid reaction of Li2S2–Li2S, the capacity of lithium‑sulfur batteries cannot be fully actualized, and the capacity loss is rapid. To address this issue, in this study, a vanadium disulfide-coated carbon nanotube film (VS2@CNTF), fabricated using floating catalyst chemical vapor deposition following a hydrothermal reaction, was adopted as the interlayer in the sulfur cathode. The initial discharge capacity of the Li-S battery with the VS2@CNTF interlayer was 1432.9 mA·h·g−1 at 0.2 C, which was 85.6% of the theoretical capacity of sulfur. Even at a sulfur loading of 3.6 mg cm−2, the Li-S battery with a VS2@CNTF interlayer demonstrated a discharge capacity of 970.6 mA·h·g−1 after 200 cycles at 1 C. This outstanding performance of the sulfur cathode is partially attributed to the three-dimensional electrical conductive networks formed by the ultra-long intertwined carbon nanotubes, which facilitate the effective adsorption of lithium polysulfides by the VS2@CNTF interlayer, inhibiting the “shuttle effect.” Furthermore, VS2@CNTF catalyzed the solid–solid reaction of Li2S2–Li2S to accelerate the reaction kinetics, thereby enhancing the rate performance.