Graphitic Petal Electrodes for All-Solid-State Flexible Supercapacitors

• Published in: Advanced energy materials 2014-02, Vol.4 (3), p.np-n/a
• Main Authors: Xiong, Guoping, Meng, Chuizhou, Reifenberger, Ronald G., Irazoqui, Pedro P., Fisher, Timothy S.
• Format: Article
• Language: English
• Subjects: all-solid-state materials; Capacitance; Capacitors; Density; Electrodes; energy storage; flexible supercapacitor electrodes; graphitic petals; Nanostructure; Petals; polyaniline; Polyanilines; Supercapacitors
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201300515

The charge storage characteristics of a composite nanoarchitecture with a highly functional 3D morphology are reported. The electrodes are formed by the electropolymerization of aniline monomers into a nanometer‐thick polyaniline (PANI) film that conformally coats graphitic petals (GPs) grown by microwave plasma chemical vapor deposition (MPCVD) on conductive carbon cloth (CC). The hybrid CC/GPs/PANI electrodes yield results near the theoretical maximum capacitance for PANI of 2000 F g−1 (based on PANI mass) and a large area‐normalized specific capacitance of ≈2.6 F cm−2 (equivalent to a volumetric capacitance of ≈230 F cm−3) at a low current density of 1 A g−1 (based on PANI mass). The specific capacitances remain above 1200 F g−1 (based on PANI mass) for currents up to 100 A g−1 with correspondingly high area‐normalized values. The hybrid electrodes also exhibit a high rate capability with an energy density of 110 Wh kg−1 and a maximum power density of 265 kW kg−1 at a current density of 100 A g−1. Long‐term cyclic stability is good (≈7% loss of initial capacitance after 2000 cycles), with coulombic efficiencies >99%. Moreover, prototype all‐solid‐state flexible supercapacitors fabricated from these hybrid electrodes exhibit excellent energy storage performance. Thin graphitic petals grown from carbon cloth form the basis of a flexible, solid‐state supercapacitor that employs polyaniline coating as the pseudocapacitive material. This structure exhibits very high area‐, volume‐, and mass‐based specific capacitances and energy/power densities. The cyclic stability and Coulombic efficiencies are good, and functional devices exhibit virtually no performance degradation under highly strained bent and twisted conditions.