Building vertically-structured, high-performance electrodes by interlayer-confined reactions in accordion-like, chemically expanded graphite

Abstract

Graphene has attracted major interests as electrode materials for energy storage applications. However, the major limitation of using blade- or spin-coated graphene films for fabricating electrode is that the basal plane of the flat-lying graphene is orthogonal to the direction of charge transport, causing sluggish charge transfer kinetics for the coated graphene film. Here we propose a general, scalable strategy to prepare vertically-structured hybrid electrodes using accordion-like, chemically expanded graphite (CEG). The coated CEG rods possess two-dimensional (2D) interlayer galleries that are vertically aligned with respect to the substrate because of their large length-diameter ratio, which facilitates high-efficiency ion transport. Due to its excellent wettability and high electrochemical surface areas, these interlayer galleries allow a high loading of redox-active (RA) materials, including metal (Pt), metal hydroxide (Ni(OH)2, Fe2O3 and MnO2) or metal dichalcogenide (MoS2). As an example, Ni(OH)2-infiltrated CEG shows excellent rate-performance and long-term cycling stability when used as electrochemical electrodes in lithium-ion batteries and supercapacitors.