Conductive carbon materials have been widely used as framework materials for electrodes. Spiral carbon nanotubes (SCNTs) with excellent physical and chemical properties can be used in lithium–sulfur (LiS) batteries. Here, a novel type of planar double-layer structure cathode was designed by introducing SCNTs. Sulfur, activated carbon (AC), and SCNTs were used to fabricate the S/AC/SCNT and S/AC/SCNT–AC planar double-layer structure cathodes. The initial discharge capacity of the batteries with the S/AC/SCNT and S/AC/SCNT–AC cathodes reached 1016 mAh g−1 and 946 mAh g−1 at 0.2 C, respectively. This result indicates that SCNTs play a major role given their excellent conductivity and insertion throughout the cathodes, which can provide an efficient charge transfer path for active materials. Moreover, the S/AC/SCNT–AC cathode exhibits long cycle stability with a capacity decay rate of only 0.11% per cycle at 0.5 C. Therefore, the introduction of SCNTs to a planar double-layer cathode is an efficient method for increasing the conductivity and bound polysulfide amount of LiS batteries.