Graphene-coated plastic film as current collector for lithium/sulfur batteries

► A metal free cathode of sulfurized polyacrylonitrile is attempted. ► Using graphene coated polyethylene terephthalate film as current collector. ► 110 mAh prototype lithium sulfur cells are assembled with energy density of 452 Wh kg−1. ► The capacity retention is 96.8% after 30 cycles at 100% depth of discharge. ► The self-discharge is less than 1% after 30 days of storage at room temperature.