We explore the influence of coverage percentage of the sulfur electrode on the cycle performance of lithium-sulfur batteries. Four sulfur electrodes covered with composite films made of carbon (BP2000), nano-Al2O3 and polytetrafluoroethylene (PTFE) with different exposure are prepared and tested in lithium-sulfur batteries. The results display that both the capacity retention and coulombic efficiency are improved with the increase of surface coverage percentage among which the cell with the completely sealed sulfur electrode exhibits the best cycle performance. The discharge capacity of the sealed sulfur electrode is ca. 800 mAh g−1 after 1000 cycles at 2 C with capacity retention over 77%. The ex-situ field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), Ultraviolet–Visible spectroscopy (UV) and nitrogen sorption measurements reveal that the sealed structure with narrow and irregular interstitials effectively suppresses the diffusion of soluble polysulfides out of the embraced environment with virtually no effect on lithium ion conduction. The present study demonstrates the effectiveness of the sealed structure for achieving robust electrochemical performance of lithium-sulfur batteries.