Block-copolymer-assisted one-pot synthesis of ordered mesoporous WO 3-x/carbon nanocomposites as high-rate-performance electrodes for pseudocapacitors

Changshin Jo, Jongkook Hwang, Hannah Song, Anh Ha Dao, Yong Tae Kim, Sang Hyup Lee, Seok Won Hong, Songhun Yoon, Jinwoo Lee

Research output: Contribution to journalArticle

120 Citations (Scopus)

Abstract

An ordered mesoporous tungsten-oxide/carbon (denoted as m-WO 3-x-C-s) nanocomposite is synthesized using a simple one-pot method using polystyrene-block-poly(ethylene oxide) (PS-b-PEO) as a structure-directing agent. The hydrophilic PEO block interacts with the carbon and tungsten precursors (resol polymer and WCl6), and the PS block is converted to pores after heating at 700 °C under a nitrogen flow. The m-WO 3-x-C-s nanocomposite has a high Brunauer-Emmett-Teller (BET) surface area and hexagonally ordered pores. Because of its mesoporous structure and high intrinsic density of tungsten oxide, this material exhibits a high average volumetric capacitance and gravimetric capacitance as a pseudocapacitor electrode. In comparison with reduced mesoporous tungsten oxide (denoted as m-WO3-x-h), which is synthesized by a tedious hard template approach and further reduction in a H2/N2 atmosphere, m-WO 3-x-C-s shows a high capacitance and enhanced rate performance, as confirmed by cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy. The good performance of m-WO 3-x-C-s is attributed to the high surface area arising from the mesoporous structure, the large interconnected mesopores, and the low internal resistance from the well-dispersed reduced tungsten oxide and amorphous carbon composite structure. Here, the amorphous carbon acts as an electrical pathway for effective pseudocapacitor behavior of WO3-x. An ordered mesoporous tungsten-oxide/carbon (m-WO3-x-C-s) nanocomposite is synthesized using a block-copolymer-assisted one-pot self-assembly method. As a pseudocapacitor electrode, m-WO3-x-C-s exhibits a high average volumetric capacitance of 340 F cm-3 and a gravimetric capacitance of 103 F g-1. The amorphous carbon in the m-WO3-x-C-s decreases the internal resistance of m-WO3-x-C-s electrode by facilitating electric conduction.

Original languageEnglish
Pages (from-to)3747-3754
Number of pages8
JournalAdvanced Functional Materials
Volume23
Issue number30
DOIs
Publication statusPublished - 2013 Aug 12

Keywords

  • carbon
  • electrochemical capacitors
  • mesoporous materials
  • nanocomposites
  • tungsten oxide

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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