Abstract
Supercapacitors are considered to be the most promising approach to meet the pressing requirements for energy storage devices. The electrode materials for supercapacitors have close relationship with their electrochemical properties and thus become the key point to improve their energy storage efficiency. Herein, by using poly (vinylidene fluoride-co-hexafluoropropylene) and ionic liquid as the dual templates, polyacrylonitrile as the carbon precursor, a flake-like carbon material was prepared by a direct carbonization method. In this method, poly (vinylidene fluoride-co-hexafluoropropylene) worked as the separator for the formation of isolated carbon flakes while aggregated ionic liquid worked as the pore template. The obtained carbon flakes exhibited a specific capacitance of 170 F/g at 0.1 A/g, a high energy density of 12.2 Wh/kg and a high power density of 5 kW/kg at the current of 10 A/g. It also maintained a high capacitance retention capability with almost no declination after 500 charge-discharge cycles. The ionic liquid directed method developed here also provided a new idea for the preparation of hierarchically porous carbon nanomaterials.
Highlights
A great attention has been focused on the application of meso and microporous carbons as electrode materials for supercapacitors due to their remarkable properties including easy processability, environmental friendness, and high chemical stability in acidic or basic solutions as well as high performance ability in a wide range of temperatures[1,2]
The suggested formation mechanism was as below: since poly-(vinylidene fluoride) (PVDF)-HFP and PAN were of different miscibility with ionic liquid (IL), the composite film was separated into two phases after being dried at 80 °C
PVDF-HFP greatly shrinked into small carbon dots while PAN/IL was carbonized into mesoporous carbon flakes (Fig. 2)
Summary
Electrode material received: 31 March 2015 accepted: 16 November 2015 Published: 10 December 2015. We proposed the direct carbonization route to prepare mesoporous carbon nanoflakes by using polyacrylonitrile (PAN) as the carbon precursor, and using poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and ionic liquid (IL) as dual templates. In this method, PVDF-HFP worked as the separator for the formation of isolated carbon flakes while IL worked as the pore template. PVDF-HFP worked as the separator for the formation of isolated carbon flakes while IL worked as the pore template Their electrochemical capacitive properties, including specific capacitance, rate performance and cycling stability, were studied. Thermogravimetric analysis (TGA) was conducted using asystem under dry air with a heating rate of 10 °C min−1
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