A “skeleton/skin” strategy for preparing ultrathin free-standing single-walled carbon nanotube/polyaniline films for high performance supercapacitor electrodes

Abstract

One of the most critical aspects in the preparation of single-walled carbon nanotubes (SWCNTs)/ conducting polymer hybrid electrodes is to improve the energy density without seriously deteriorating their high power capability. Here, we report a ''skeleton/skin'' strategy for the preparation of freestanding, thin and flexible SWCNT/polyaniline (PANI) hybrid films by a simple in situ electrochemical polymerization method using directly grown SWCNT films with a continuous reticulate structure as template. In situ electrochemical polymerization can achieve effective deposition of PANI onto the surface of SWCNT bundles in the films and control the morphology and microstructure of the SWCNT/PANI hybrid films. In a SWCNT/PANI hybrid film, the directly grown SWCNT film with continuous reticulate architecture acts as the skeleton and PANI layers act as the skin. This unique continuous ''skeleton/skin'' structure ensures that these hybrid films have much higher conductivity compared to SWCNT/PANI composite films based on post-deposition SWCNT films. Flexible supercapacitors have been fabricated using the SWCNT/PANI hybrid films as both electrodes and charge collectors without metallic current collectors. High energy and power densities (131 W h kg À1 and 62.5 kW kg À1 , respectively) have been achieved for the optimized assembly. The high electrical conductivity and flexibility, in combination with continuous porous architecture, suggests that the asprepared ultrathin free-standing SWCNT/PANI hybrid films have significant potential as promising electrode materials for thin, lightweight and flexible energy storage devices with high performance. Broader contextThe hybrid electrodes of SWCNT/conducting polymer display high energy density due to pseudocapacitance originating from the conducting polymer. However, their power density is dramatically reduced in comparison with pure SWCNT-based electrodes, due to the poor electrical conductivity of PANI layers and overlapped PANI-PANI contact. Therefore, one of the most critical aspects in the development of SWCNT/conducting polymer supercapacitors is to optimize the energy density without deteriorating their high power capability as these two parameters determine concomitantly the ultimate performance of the supercapacitor. In this work, we report a ''skeleton/skin'' strategy to prepare free-standing, thin and flexible SWCNT/PANI hybrid films by a simple in situ electrochemical polymerization method using directly grown SWCNT films with continuous reticulate structure as template. The high electrical conductivity and flexibility, in combination with continuous porous architecture, suggest that as-prepared ultrathin freestanding SWCNT/PANI hybrid films have significant potential as promising electrode materials for thin, lightweight and flexible energy storage devices with high performance. The flexible supercapacitors based on the SWCNT/PANI hybrid films achieve high energy and power densities. 8726

Microwave-Assisted Oxidation of Electrospun Turbostratic Carbon Nanofibers for Tailoring Energy Storage Capabilities

“…Nonetheless, carbon electrodes are still the most popular choice to date for use in commercial supercapacitor devices due to their ease of synthesis, low cost, and exceptional chemical and electrochemical stability. [48][49][50] Metal oxides (e.g., RuO 2 , [51,52] MnO 2 [53,54] ) and electroactive polymers (e.g., polyaniline, [55,56] polyvinylferrocene) [57,58] exhibit pseudocapacitive characteristics, and have been shown to deliver remarkably higher capacitance values than those of carbon materials possessing only DL capacitances. However, several challenges still remain -the high cost of Ru-based oxides may prohibit them from use in practical applications, while the cycling instability and the poor rate performance of Mn-based oxides and electroactive polymers remain critical issues that require careful examination.…”

Recent advances in conjugated polymer energy storage

“…3 Conductive papers made from composites of polymer with graphene or carbon nanotubes are promising flexible electrodes. 131,133,157,207 Zhao et al 208 report a compressible electrode made of a composite of ''graphene foam'' and polypyrrole. Cellulose is another popular flexible substrate due to its industrial importance, high surface area, and economic sources such as bacteria or wood.…”

Recent advances in flexible supercapacitors based on carbon nanotubes and graphene

“…Approaches including CVD/floating catalyst CVD [41][42][43][44][45][46][47], vacuum filtration [48][49][50][51][52], interfacial reaction [53,54], and printing [55] have been developed to fabricate CNT films for use in flexible supercapacitor applications.…”