Wednesday, 4 October 2017
Prince George's Exhibit Hall D/E (Gaylord National Resort and Convention Center)
For a brand-new electrode material with transition metal-free and high electrochemical performance for Li-ion battery (LIB), graphene and disulfide-based framework was designed and synthesized by hybridizing graphene and organic compounds. For the designing of the material, we focused on the four important electrochemical properties: specific capacity, potential sensitiveness, cyclic stability and high Li+/e- mobility. As a result, graphene framework with a layered structure constructed by the formation of disulfide bonds between terminal dithiol organic linker molecules and thiol-functionalized graphene sheets. The organic linker molecules play a role as pillars which maintains the framework structure and prevents restacking of graphene sheets. Various types of dithiol organics were investigated as linker components in GSF for evaluating the effect of its length or structure on electrochemical properties. As a result, distinctive electrochemical performance among the synthesized materials was observed depending on current density, implies the involvement of multiple Li-incorporation mechanisms. Based on the differential analyses and electrochemical impedance spectroscopy (EIS), the linker-dependent Li storage mechanism in GSFs was suggested. Also, reversible breakage-formation of disulfide bond within GSF was proved by ex-situ XPS analysis with varied state of charge (SOC), which represents self-healing functionality of the material. The GSF proposed in this study could be a promising electrode material for transition metal-free, low cost and high performance energy storage system.