A metal-free battery is of great practical significance in terms of high energy density, low cost, high safety, eco-friendly and sustainability. Here a metal-free cathode, using graphene-coated polyethylene terephthalate (G-PET) film (Commercial-Off-The-Shelf) as current collector and sulfurized polyacrylonitrile (SPAN) as active material, is aiming at low cost and high energy density battery. 110 mAh prototype lithium sulfur cells are assembled using SPAN/G-PET cathode, showing energy density of 452 Wh kg−1 excluding the weight of package and capacity retention of 96.8% after 30 cycles at 100% depth of discharge. The self-discharge characteristics of prototype cells are tested. After 30 days of storage at room temperature, the discharge capacity has decreased less than 1%, indicative of low self-discharge of the SPAN-based Li/S batteries. This paper shows that G-PET can be a potential promising current collector for lithium ion batteries.