A 3D stable and highly conductive scaffold with carbon nanotubes/carbon fiber as electrode for lithium sulfur batteries

•A freestanding thin-film composite with carbon nanotubes/carbon fiber is prepared by CVD method.•A binder-free cathode is fabricated by S-CNTs/CF composite for lithium sulfur battery.•Cycle life is improved by establishing a stable conductive and high porous electrode. A freestanding thin-film composite with carbon nanotubes/carbon fiber modified by sulfur (S-CNTs/CF) has been fabricated by chemical vapor deposition (CVD) method as the binder-free cathode for lithium sulfur battery. This porous electronic conductor with 3D structure improved the electrochemical performance of the cathodes by simultaneously increasing porosity of material and changing conductive pathway. Electrochemical test results showed that the discharge specific capacity of S-CNTs/CF positive electrode decreased slightly from initial 1213.6 mAh g−1(Sulfur) to 798.4 mAh g−1(Sulfur) after 55 cycles. Comparing with powder cathode, the electrochemical performance of S-CNTs/CF cell is improved significantly. It proves that establishing a sulfur electrode with stable conductive and high porous structure provide a promising way to improve the cycle life.