Optimizing carbon/carbon supercapacitors in aqueous and organic electrolytes
type: Dataset
description: The objective of this work is to improve the energy density of carbon/carbon supercapacitors. For achieving this objective, two different strategies were followed depending on the electrolyte used: i) in aqueous electrolytes, our efforts were focused on extending the operating cell voltage by using neutral alkali sulfate solutions; ii) in organic electrolyte, the target was to improve the volumetric capacitance by setting a mild activation method able to produce a porous carbon with average pore size matching the ion size, while not enlarging the pores upon porosity development. A practical cell voltage of 1.8 V has been demonstrated by implementing aqueous alkali sulfates in symmetric carbon/carbon capacitors. It has been shown that the voltage is limited by a partial destructive electro-oxidation of the positive electrode. Such irreversible electro-oxidation could be mitigated by mild chemical oxidation of the active carbon material with hydrogen peroxide; consequently, the voltage could be further expanded up to 1.9 V. Even 2.0 V could be attained after mass balancing the electrodes in order to allow them to operate in their stability window. Finally, pouch-cells with carbon coating on stainless steel current collector were realized by using 2 mol L-1 Li2SO4 as electrolyte. An exceptional cycling stability at cell voltages up to 2.1 V was obtained during 10,000 cycles. Hence, the use of alkali sulfate electrolytes is a cost-effective alternative to organic electrolytes for producing environment friendly and safe carbon/carbon supercapacitors. Dense nanoporous carbons with pores fitting the dimension of ions of the Et4NBF4/acetonitrile organic electrolyte were obtained by high pressure oxidation of non-porous carbon at low temperature, followed by a thermal desorption to remove the surface groups and unblock pore entrances. The activation mechanism consisted in drilling the narrow pores existing initially in the char. Due to the low burn-off, the density of the el…
identifier: NNT: 2013ORLE2011
issued: 2026-05-09T09:58:43.067602
language: en
modified: 2026-05-09T09:58:43.067606
contact point: Organization
  fn: CCSD
keyword: chimothechemical-sciencesother
keyword: infoeu-reposemanticsdoctoralthesis
keyword: supercapacitors
keyword: supercondensateurs
keyword: theses
landing page: https://theses.hal.science/tel-00872080

Optimizing carbon/carbon supercapacitors in aqueous and organic electrolytes
type: Distribution
format: HTML
issued: 2026-05-09T09:58:43.069395
modified: 2026-05-09T09:58:43.059524
access URL: https://theses.hal.science/tel-00872080

test_moissonnage_selune
type: Agent