Highly efficient electro-optically tunable smart-supercapacitors using an oxygen-excess nanograin tungsten oxide thin film

Akbar I. Inamdar, Jongmin Kim, Yongcheol Jo, Hyeonseok Woo, Sangeun Cho, Sambhaji M. Pawar, Seongwoo Lee, Jayavant L. Gunjakar, Yuljae Cho, Bo Hou, Seung Nam Cha, Jungwon Kwak, Youngsin Park, Hyungsang Kim, Hyunsik Im

Research output: Contribution to journalArticlepeer-review

107 Scopus citations

Abstract

A smart supercapacitor shares the same electrochemical processes as a conventional energy storage device while also having electrochromic functionality. The smart supercapacitor device can sense the energy storage level, which it displays in a visually discernible manner, providing increased convenience in everyday applications. Here, we report an electro-optically tunable smart supercapacitor based on an oxygen-rich nanograin WO3 electrode. The nanostructured WO3 electrode is dark blue in color in the charged state and becomes transparent in its discharged state with a high optical modulation of 82%. The supercapacitor has a specific capacitance of 228 F g−1 at 0.25 Ag−1 with a large potential window (1.4 V). It is highly durable, exhibits good electrochemical stability over 2000 cycles, retains 75% of its initial capacitance, and exhibits high coloration efficiency (~170 cm2/C). The excellent electrochromic and electrochemical supercapacitor properties of the electrode is due to the synergetic effect between nanograin morphology and excess oxygen. A smart-supercapacitor fabricated with an oxygen-rich nanograin WO3 electrode exhibits a superb combination of energy storage and highly-efficient electrochromic features in one device that can monitor the energy storage level through visible changes in color.

Original languageEnglish
Pages (from-to)78-85
Number of pages8
JournalSolar Energy Materials and Solar Cells
Volume166
DOIs
StatePublished - 1 Jul 2017

Keywords

  • Electrochromism
  • Multi-functional electrode
  • Nanograin
  • Oxygen-excess tungsten oxide
  • Supercapacitor

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