Electroactive Ultra-Thin rGO-Enriched FeMoO4 Nanotubes and MnO2 Nanorods as Electrodes for High-Performance All-Solid-State Asymmetric Supercapacitors

Kugalur Shanmugam Ranjith; Ganji Seeta Rama Raju; Nilesh R Chodankar; Seyed Majid Ghoreishian; Cheol Hwan Kwak; Yun Suk Huh; Young-Kyu Han

doi:10.3390/nano10020289

Electroactive Ultra-Thin rGO-Enriched FeMoO₄ Nanotubes and MnO₂ Nanorods as Electrodes for High-Performance All-Solid-State Asymmetric Supercapacitors

Nanomaterials (Basel). 2020 Feb 9;10(2):289. doi: 10.3390/nano10020289.

Authors

Kugalur Shanmugam Ranjith¹, Ganji Seeta Rama Raju¹, Nilesh R Chodankar¹, Seyed Majid Ghoreishian², Cheol Hwan Kwak², Yun Suk Huh², Young-Kyu Han¹

Affiliations

¹ Department of Energy and Material Engineering, Dongguk University-Seoul, Seoul 04620, Korea.
² Department of Biological Engineering, Inha University, Incheon 22212, Korea.

Abstract

A flexible asymmetric supercapacitor (ASC) with high electrochemical performance was constructed using reduced graphene oxide (rGO)-wrapped redox-active metal oxide-based negative and positive electrodes. Thin layered rGO functionality on the positive and the negative electrode surfaces has promoted the feasible surface-active sites and enhances the electrochemical response with a wide operating voltage window. Herein we report the controlled growth of rGO-wrapped tubular FeMoO₄ nanofibers (NFs) via electrospinning followed by surface functionalization as a negative electrode. The tubular structure offers the ultrathin-layer decoration of rGO inside and outside of the tubular walls with uniform wrapping. The rGO-wrapped tubular FeMoO₄ NF electrode exhibited a high specific capacitance of 135.2 F g^-1 in Na₂SO₄ neutral electrolyte with an excellent rate capability and cycling stability (96.45% in 5000 cycles) at high current density. Meanwhile, the hydrothermally synthesized binder-free rGO/MnO₂ nanorods on carbon cloth (rGO-MnO₂@CC) were selected as cathode materials due to their high capacitance and high conductivity. Moreover, the ASC device was fabricated using rGO-wrapped FeMoO₄ on carbon cloth (rGO-FeMoO₄@CC) as the negative electrode and rGO-MnO₂@CC as the positive electrode (rGO-FeMoO₄@CC/rGO-MnO₂@CC). The rationally designed ASC device delivered an excellent energy density of 38.8 W h kg^-1 with a wide operating voltage window of 0.0-1.8 V. The hybrid ASC showed excellent cycling stability of 93.37% capacitance retention for 5000 cycles. Thus, the developed rGO-wrapped FeMoO₄ nanotubes and MnO₂ nanorods are promising hybrid electrode materials for the development of wide-potential ASCs with high energy and power density.

Keywords: FeMoO4 nanotubes; MnO2-rGO; asymmetric supercapacitors; electrospinning; rGO wrapping.