Formation of a CoMn-Layered Double Hydroxide/Graphite Supercapacitor by a Single Electrochemical Step

Atanu Roy, Theresa Schoetz, Leo W. Gordon, Hung Ju Yen, Qingli Hao, Daniel Mandler*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

Hybrid electric storage systems that combine capacitive and faradaic materials need to be well designed to benefit from the advantages of batteries and supercapacitors. The ultimate capacitive material is graphite (GR), yet high capacitance is usually not achieved due to restacking of its sheets. Therefore, an appealing approach to achieve high power and energy systems is to embed a faradaic 2D material in between the graphite sheets. Here, a simple one-step approach was developed, whereby a faradaic material [layered double hydroxide (LDH)] was electrochemically formed inside electrochemically exfoliated graphite. Specifically, GR was exfoliated under negative potentials by CoII and, in the presence of MnII, formed GR-CoMn-LDH, which exhibited a high areal capacitance and energy density. The high areal capacitance was attributed to the exfoliation of the graphite at very negative potentials to form a 3D foam-like structure driven by hydrogen evolution as well as the deposition of CoMn-LDH due to hydroxide ion generation inside the GR sheets. The ratio between the CoII and MnII in the CoMn-LDH was optimized and analyzed, and the electrochemical performance was studied. Analysis of a cross-section of the GR-CoMn-LDH confirmed the deposition of LDH inside the GR layers. The areal capacitance of the electrode was 186 mF cm−2 at a scan rate of 2 mV s−1. Finally, an asymmetric supercapacitor was assembled with GR-CoMn-LDH and exfoliated graphite as the positive and negative electrodes, respectively, yielding an energy density of 96.1 μWh cm−3 and a power density of 5 mW cm−3.

Original languageAmerican English
Article numbere202201418
JournalChemSusChem
Volume15
Issue number21
DOIs
StatePublished - 8 Nov 2022

Bibliographical note

Publisher Copyright:
© 2022 The Authors. ChemSusChem published by Wiley-VCH GmbH.

Keywords

  • electrochemistry
  • electrodeposition
  • graphene
  • layered double hydroxides
  • supercapacitors

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