Abstract: High performance flexible lithium-sulfur flexible energy storage devices include a flexible lithium metal anode for an energy storage device comprising an electrically conducting fabric functionalised with a 3D hierarchical MnO2 nanosheet lithiophilic material; a flexible graphene/sulfur cathode protected by a FBN/G interlayer; and a flexible separator for an energy storage device, wherein the separator comprises one or more microporous films of Li ion selective permeable polyolefin material wherein at least a portion of the pores of the film are associated with nanoporous polysulfone polymer positioned between the anode and the cathode.