Supersonically sprayed self-aligned rGO nanosheets and ZnO/ZnMn2O4 nanowires for high-energy and high-power-density supercapacitors

Chanwoo Park, Edmund Samuel, Byeong Yeop Kim, Seongpil An, Hae Seok Lee, Sam S. Yoon

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


Core-shell-type bimetallic oxide and carbon composites comprising zinc oxide (ZnO) nanospheres and zinc manganese oxide (ZnMn2O4) nanowires were produced by a hydrothermal method, and supersonically sprayed together with reduced graphene oxide (rGO) nanosheets onto Ni foil to fabricate flexible supercapacitors. The supersonic impact facilitated the exfoliation of the rGO nanosheets, thereby increasing the surface area and adhesion of the composite particles to the substrate. The rGO nanosheets were vertically aligned during the supersonic impact and formed localized zones, enabling optimal accommodation of the ZnO/ZnMn2O4 particles. This localization, with the addition of rGO, reduced the agglomeration of ZnO/ZnMn2O4 particles. The molar concentration of MnSO4 used in the synthesis of ZnO/ZnMn2O4 was varied from 0.05 to 0.15 mol/L to determine the optimal MnSO4 concentration that would result in the highest energy storage capacitance. The unique nanostructure of ZnO/ZnMn2O4 and the self-alignment of rGO sheets facilitated a favorable environment for high energy storage capability with a specific capacitance of 276.3 mF⋅cm−2 at a current density of 0.5 mA⋅cm−2 and an energy density of 98.2 µWh⋅cm−2 at a power density of 1600 µW⋅cm−2. The width of the potential window was increased to 1.2 V, implying a significant increase in the energy storage capability of the supercapacitor. Capacitance retention of 88% was achieved after 10,000 charge/discharge cycles for the supercapacitor fabricated using an optimal MnSO4 concentration (0.10 mol/L) during the composite synthesis.

Original languageEnglish
Pages (from-to)193-204
Number of pages12
JournalJournal of Materials Science and Technology
Publication statusPublished - 2023 Feb 20

Bibliographical note

Funding Information:
This work was financially supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (Nos. NRF-2020R1A5A1018153 , NRF-2021R1A2C2010530 , and 2020K1A3A1A74114847 ). This research was also supported by Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (No. HI21C0049010021 ).

Publisher Copyright:
© 2022


  • Hydrothermal method
  • Supercapacitor
  • Supersonic spraying
  • ZnO/ZnMnO nanowires
  • rGO nanosheets

ASJC Scopus subject areas

  • Ceramics and Composites
  • Mechanics of Materials
  • Mechanical Engineering
  • Polymers and Plastics
  • Metals and Alloys
  • Materials Chemistry


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