Synthesis of Polypyrrole-Intercalated Layered Manganese Oxide Nanocomposite by a Delamination∕Reassembling Method and Its Electrochemical Capacitance Performance

Abstract

A polypyrrole-intercalated layered manganese oxide nanocomposite ͑PPy-MnO 2 ͒ has been synthesized by a delamination/ reassembling process. X-ray diffraction analysis shows that the basal spacing of the PPy-MnO 2 nanocomposite is 1.38 nm. The room-temperature conductivity of the PPy-MnO 2 nanocomposite is found to be 1.3 ϫ 10 −1 S/cm, which is 4-5 orders of magnitude higher than that of the pristine manganese oxide ͑6.1 ϫ 10 −6 S/cm͒. The improved specific capacitance of the PPy-MnO 2 nanocomposite ͑290 F/g͒ compared with that of the pristine manganese oxide ͑221 F/g͒ is attributed to a combination of the conductivity effect and the high specific capacitance of PPy. © 2009 The Electrochemical Society. ͓DOI: 10.1149/1.3082015͔ All rights reserved.Manuscript submitted September 29, 2008; revised manuscript received January 15, 2009. Published February 17, 2009 Electrochemical capacitors ͑or supercapacitors͒ are chargestorage devices which possess high power density, excellent reversibility, and long cycle life compared with batteries.1-4 Depending on their charge-storage mechanism, electrochemical capacitors are divided into electric double-layer capacitors ͑EDLCs͒ and pseudocapacitors. The energy-storage mechanism of EDLCs relies on the separation of charges at the interface between an electrode and an electrolyte. Various carbonaceous materials ranging from amorphous carbons to carbon nanotubes have been used as electrode materials in EDLCs.2 In the case of pseudocapacitors, a faradaic process occurs in addition to a simple charge separation. Numerous metal oxides and conducting polymers have demonstrated qualifications as electrode materials for pseudocapacitors. Among these materials, hydrated ruthenium oxide exhibits remarkably high specific capacitance, as high as 1300 F/g, and excellent reversibility. 5,6 However, the high cost and the toxicity to the environment have limited its wide application. Therefore, much research interest has focused on other transition metal oxides. In this respect, manganese oxide is one of the most attractive candidates for electrochemical capacitor electrode materials because of its environmental friendliness and low cost.7-9 However, manganese oxide exhibits inferior specific capacitance and electrical conductivity to ruthenium oxide. Polypyrrole ͑PPy͒, as a kind of conducting polymer, has advantageous properties with respect to low cost, high conductivity, and high doping/ dedoping rate during charge/discharge. [10][11][12][13][14][15] However, it exhibits the disadvantage of a low cycle life because swelling and shrinkage may occur during doping/dedoping processes, thus leading to mechanical degradation of the electrodes and fading of electrochemical performance. 16,17 A combination of manganese oxide and conducting polymer appears interesting for supercapacitor electrodes. The resulting composite is expected to possess synergic properties from both components, such as enhancement in electrical conductivity or electrochemical cycling stability. Recently, Sivakkumar et al. pr...

Development of redox deposition of birnessite-type MnO2 on activated carbon as high-performance electrode for hybrid supercapacitors

“…However, MnO 2 shows a low electrical conductivity (10 À5 to 10 À6 S cm À1 ) [37]. High conductive materials such as activated carbon were combined with MnO 2 to improve the electrical conductivity of MnO 2 -based electrodes [38,39].…”

Synthesis of mesoporous polythiophene/MnO2 nanocomposite and its enhanced pseudocapacitive properties

“…However, the relatively low electrical conductivities of pristine manganese oxides, to a great extent, limit their high-rate performances [20,21]. The intrinsic manganese oxides are generally decorated with conducting agents, such as carbons and conducting polymers, in order to enhance their electrical conductivities [22][23][24][25][26][27][28][29]. In particular, good electrical conductivities and fast electrochemical doping/undoping redox kinetics of conducting polymers make them potential alternative electrode materials for high-rate SCs [30].…”

“…These demerits of conducting polymers restrain their practical applications in SCs. A general strategy to overcome the above drawbacks is to introduce conducting polymers into the matrix of other active electrode materials [22,24,26,27,29,[31][32][33][34][35][36]. The corresponding composites, such as manganese oxide/conducting polymer and carbon nanotube/conducting polymer, are expected to convey enhanced electrochemical properties if each component can retain its merits and both individuals can compensate their shortcomings synergistically.…”

“…And some synthesis routes required expensive templates and tedious post-treatments [24]. Challenges still exist in facile synthesis and fundamental understanding of exact function of each component, although researches on manganese oxide/conducting polymer composite for advanced SC materials have emerged [22,[24][25][26][27]29,[33][34][35][36][37].…”

Morphological characterization and impedance spectroscopy study of porous 3D carbons based on graphene foam-PVA/phenol-formaldehyde resin composite as an electrode material for supercapacitors

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