Achieving ion accessibility within graphene films by carbon nanofiber intercalation for high mass loading electrodes in supercapacitors

Abstract Achieving high specific surface area and ion accessibility in graphene-based electrodes with a high mass loading for supercapacitors poses a significant challenge because strong π-π stacking of graphene sheets often blocks the access of electrolyte ions to active sites. Herein, we report a novel protocol to prepare free-standing laminated graphene/carbon nanofiber films as high areal mass-loading electrodes through a layer-by-layer electrospinning technique. The unique laminated structure of graphene/carbon nanofiber thin films can enhance electrolyte penetration and increase transportations of ions/electrons. The symmetric supercapacitors (SCs) using the as-obtained graphene/carbon nanofiber films as electrodes reach areal specific capacitance of 1536 mF cm−2 at a current density of 1 mA cm−2. Most importantly, the areal energy density of the SCs can reach 0.22 mWh cm−2 at a power density of 1 mW cm−2 with a high areal mass loading of 24 mg cm−2. The exceptional electrochemical properties of the laminated graphene/carbon nanofiber films render them promising materials for electrodes in SCs.