Synchronously manipulating Zn2+ transfer and hydrogen/oxygen evolution kinetics in MXene host electrodes toward symmetric Zn-ions micro-supercapacitor with enhanced areal energy density

Zhiqian Cao, Jimin Fu, Mingzai Wu, Tao Hua, Haibo Hu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

Abstract

Sluggish divalent charges (e.g., Zn2+) diffusion within MXene host electrodes due to the larger sizes and stronger coulomb interactions compared to those of dominant univalent charges is an essential issue in developing MXene-based microsupercapacitors (MSCs) of higher theoretical energy densities. Herein, MXene/bacterial cellulose fiber (BCF) hybrid films with effectively expanded interlayer spacing between re-stacked few-layered MXene sheets via homogeneous intercalation of BCF nanospacer were designed and prepared. The electrochemical testing and molecular dynamics simulation demonstrated the consequently widened ions-transport-channels between few-layered MXene sheets can effectively reduce the diffusion barrier of Zn2+ within the MXene/BCF host electrodes compared to pure MXene film electrodes without BCF nanospacer. Further in-situ Raman and ex-situ XPS spectroscopy characterizations suggest: the consequently accelerated Zn2+ diffusion involved adsorption/desorption featured charge storage, and followed electrochemical reaction of Zn2+ with oxygen terminal groups on the MXene flakes induced additional pseudocapacitance within the MXene/BCF host electrodes simultaneously contribute to the acquired superior areal capacitance of the fabricated symmetrical aqueous Zn-ions MSCs (ZMSCs) based on the MXene/BCF host electrodes and Zn(CF3SO3)2/polyacrylamide hydrogel electrolyte. Meanwhile, combined with doubled voltage window (1.2 V) benefiting from the cocurrently suppressed kinetics of hydrogen/oxygen evolution within the MXene/BCF host electrodes, a tremendously increased areal energy density (34.0 μWh cm−2) in comparison with that employing conventional H2SO4/polyacrylamide hydrogel electrolyte (0.6 V/8.6 μWh cm−2) is finally realized. The work demonstrates a simple and effective strategy to synchronously boost bivalent Zn2+ diffusion and depress hydrogen/oxygen evolution within MXene host electrodes toward symmetric ZMSCs of high areal energy density.

Original languageEnglish
Pages (from-to)10-21
Number of pages12
JournalEnergy Storage Materials
Volume40
DOIs
Publication statusPublished - Sep 2021

Keywords

  • Hydrogen/oxygen evolution kinetics
  • Molecular dynamics
  • MXene
  • Zn-ions micro-supercapacitors
  • Zn transfer kinetics

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)
  • Energy Engineering and Power Technology

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