Template growth of porous graphene microspheres on layered double oxide catalysts and their applications in lithium-sulfur batteries

The wise integration of individual two-dimensional graphene nanosheets into three-dimensional (3D) macroscopic architectures is essential for full exploration of their potential applications in electrochemical energy storage. Graphene microspheres (GMSs) with hierarchical porous architectures and high 3D electrical conductivities are highly expected to be the host carbon to accommodate sulfur cathode for lithium-sulfur batteries. Herein we reported the direct synthesis of GMSs assembled by 3D interconnected graphene with hierarchical pores by template chemical vapor deposition (CVD) on layered double oxide (LDO) microspheres. The LDO templates were derived from conformally calcined layered double hydroxide microspheres produced by spray drying. After methane-CVD, graphene was catalytically grown on LDO templates. Subsequent routine chemical etching of the LDO templates enabled as-obtained GMSs with a large diameter of ca. 11 mu m and a high surface area of 1275 m(2) g(-1). The GMS was employed as carbon scaffold to accommodate sulfur for rechargeable lithium-sulfur batteries. An initial areal discharge capacity of 2.67 mAh cm(-2) was obtained at a current density of 0.83 mA cm(-2) on flexible GMS paper electrode with an areal sulfur loading of 2.5 mg cm(-2). (C) 2015 Elsevier Ltd. All rights reserved.