Enhancing energy storage by constructing poly(3,4-ethylenedioxythiophene)-encapsulated iron oxide/carbon nanotubes composites

Nanocomposites consisting of conducting polymers and metal oxide are promising material in electrochemical energy storage. The design of nanostructure is regarded as an efficient strategy to improve electron and ion transfer. However, the construction of nanocomposites usually needs multistep reaction. Herein, a poly(3,4-ethylenedioxythiophene)-encapsulated iron oxide/carbon nanotube nanocomposite (Fe₂O₃/CNTs@PEDOT) is demonstrated as an efficient anode for aqueous supercapacitors. The Fe₂O₃/CNTs nanocomposite is firstly constructed by a rapid combustion strategy, which provided electrode a good hydrophilic ability. The PEDOT is further in situ constructed on the surface of Fe₂O₃/CNTs by an electrochemical polymerization process for enhancing the cycling stability. The Fe₂O₃/CNTs@PEDOT electrode delivers an enhanced ions transfer and stability during the charge/discharge process. In 1 M Na₂SO₄, such Fe₂O₃/CNTs@PEDOT-180 s electrode delivers a specific capacitance of 1014 mF cm⁻² at 2 mA cm⁻² and retains 89.7% of initial capacitance at 20 mA cm⁻² after 3000 cycles, which is superior than that of the Fe₂O₃/CNTs electrode (79.2%). The asymmetric aqueous supercapacitor consisted of Fe₂O₃/CNTs@PEDOT and MnO₂/CC electrodes with an operating potential of 2.0 V reaches a high areal energy density of 0.207 mWh cm⁻² at a power density of 2.0 mW cm⁻².

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