Electrospun N-Doped Hierarchical Porous Carbon Nanofiber with Improved Degree of Graphitization for High-Performance Lithium Ion Capacitor
Graphical Highly graphitized : A highly graphitized activated carbon nanofiber (a-PANF) has been obtained by a bottom-up synthesis involving electrospinning of polyacrylonitrile followed by calcination and chemical activation (see figure). The product has a hierarchical porous structure and abundant N-heteroatom doping. The lithium-ion capacitor (LIC) has been regarded as a promising device that combines the merits of lithium-ion batteries and supercapacitors, and that meets the requirements for both high energy and high power density. The development of advanced electrode materials is the key requirement. Herein, we report the bottom-up synthesis of activated carbon nanofiber (a-PANF) with a hierarchical porous structure and a high degree of graphitization. Electrospinning has been employed to prepare an interconnected fiber network with macropores, and ferric acetylacetonate has been introduced as both a mesopore-creating agent and a graphitic catalyst to increase the degree of graphitization. Furthermore, chemical activation enlarges the specific surface area by producing abundant micropores. Half-cell evaluation of the as-prepared a-PANF gave a discharge capacity of 80 mA h g −1 at 0.1 A g −1 within 2–4.5 V and no capacity fading after 1000 cycles at 2 A g −1 , which represents a significant improvement compared to conventional activated carbon (AC). Furthermore, an as-assembled LIC with a-PANF cathode and Fe 3 O 4 anode showed a superior energy density of 124.6 W h kg −1 at a specific power of 93.8 W kg −1 , which remained at 103.7 W h kg −1 at 4687.5 W kg −1 . This indicates promising application potential of a-PANF as an electrode material for efficient energy storage systems.
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