Electrochemical deposition of honeycomb magnetite on partially exfoliated graphite as anode for capacitive applications

Abstract

Abstract Research on anode materials with high capacitive performance is lagging behind that of cathode materials, which has severely hindered the development of high-efficient energy storage devices. Compared with other anode materials, Fe 3 O 4 exhibits highly desirable advantages due to its low cost, high theoretical capacity and preferable electronic conductivity of ∼10 2 S cm −1 . Herein, hierarchical honeycomb Fe 3 O 4 is integrated on functionalized exfoliated graphite through electrochemical deposition and the following chemical conversion. The hierarchical honeycomb Fe 3 O 4 is constructed by the oxide nanorods, which are assembled by a number of nanoparticles. This unique porous structure not only ensures fast ion diffusion in the electrode, but also provides large amount of active sites for electrochemical reactions. The exfoliated graphene atop the graphite base can act as 3D conductive scaffold to facilitate the electron transport of the electrode. Therefore, FEG/Fe 3 O 4 exhibits large specific capacitances of 327 F g −1 @1 A g −1 and 275 F g −1 @10 A g −1 . Good cycling stability is also achieved due to the flexibility of the graphene substrate. The assembled asymmetric device using FEG/Fe 3 O 4 as anode can deliver a high energy density of 54 Wh kg −1 .