A holistic analysis of adsorption energies, charge transfer, and structural changes has been employed to highlight the variations in adsorption mechanisms upon changing the surface type and the adsorption site.
Carbon materials have widely been used to enhance the performance of a plethora of supercapacitor electrode materials. In this regard, it is crucial to identify carbon materials that function over a wide pH range while enjoying a wide potential window. Herein, the DFT calculations were used to elucidate the electronic performance of C 76 and the C 76 /electrolyte interface. The electronic investigation revealed the nature of the conductivity and charge storage mechanism of C 76 based on the bandgap and quantum capacitance calculations. Also, the electrochemical and electronic properties of fullerene C 76 have been extensively investigated over a wide pH range; acidic H 2 SO 4 , basic KOH, and neutral Na 2 SO 4 . The results showed a promising performance in the three electrolytes. Moreover, C 76 electrodes exhibited a potential window of 1.9 V in Na 2 SO 4 electrolyte, resulting in capacitances of 171 F/g and 142 F/g at a scan rate of 1 mV/s in the positive and negative potential windows, respectively. The material showed a pseudocapacitance performance of 65 % in Na 2 SO 4 electrolyte in the positive potential window. We believe higher fullerenes provide a new class of materials for developing versatile supercapacitor devices for efficient energy storage.Laboratory is highly appreciated. We also acknowledge Bibliotheca Alexandrina HPC for allowing us to use the HPC resources.
Identifying the proper carbon material
is one of the key requirements
in developing high-performance supercapacitor electrodes. Carbon nanotubes
(CNTs), graphene nanoplatelets (GNPs), and graphite (Gr) are commonly
used carbon allotropes for supercapacitor applications. The performance
of those materials depends on the electrolyte used and the operating
potential window. However, those parameters have rarely been investigated
and explained. Herein, we present a roadmap for the proper selection
of carbon materials in supercapacitor applications via the investigation
of the behavior of CNTs, GNPs, and Gr in different electrolytes using
both electrochemical and computational tools. The charge storage mechanism
was found to be electrolyte-dependent. In terms of the operating potential
window, the best performance was obtained upon the use of a Na2SO4 electrolyte, which enabled a potential window
of −1 to 0.9, while in terms of capacitance, the positive electrodes
in a H2SO4 electrolyte exhibited the highest
capacitance. H2SO4 enabled keto–enol
tautomerism in the positive potential window and can enlarge the potential
window to 1 V. Quantum capacitance calculations helped to identify
the reasons behind the obtained different performances in the negative
and positive potential windows. For example, upon the identification
of the proper electrolyte and potential window, it was possible to
obtain a capacitance as high as 453.60 F/g at 5 mV/s in a potential
window of 1 V for CNTs, which are much higher than those reported
in the literature. Moreover, the guidelines were successfully used
to develop a symmetric device that delivers a specific energy of 23.3
Wh/kg and a specific power of 475 W/kg with a stability of 97.8% after
5000 cycles over a potential window of 1.9 V, which are much higher
than those reported for CNTs-based symmetric devices.
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