Binder-free S-FCNF composite films with sulfur coated uniformly on the surface of FCNFs were used as cathodes for lithium–sulfur batteries. Such cathodes have both high sulfur content (78 wt%) and large areal mass loading (8 mg cm⁻²), and they can deliver a high areal specific capacity of 1.87 mA h cm⁻² (234 mA h g_electrode⁻¹) after 100 cycles at 0.1 C.