Edge‐Enriched, Porous Carbon‐Based, High Energy Density Supercapacitors for Hybrid Electric Vehicles

Abstract

Supercapacitors can store and deliver energy by a simple charge separation, and thus they could be an attractive option to meet transient high energy density in operating fuel cells and in electric and hybrid electric vehicles. To achieve such requirements, intensive studies have been carried out to improve the volumetric capacitance in supercapacitors using various types and forms of carbons including carbon nanotubes and graphenes. However, conventional porous carbons are not suitable for use as electrode material in supercapacitors for such high energy density applications. Here, we show that edge-enriched porous carbons are the best electrode material for high energy density supercapacitors to be used in vehicles as an auxiliary powertrain. Molten potassium hydroxide penetrates well-aligned graphene layers vertically and consequently generates both suitable pores that are easily accessible to the electrolyte and a large fraction of electrochemically active edge sites. We expect that our findings will motivate further research related to energy storage devices and also environmentally friendly electric vehicles.

Engineering the Pores of Biomass‐Derived Carbon: Insights for Achieving Ultrahigh Stability at High Power in High‐Energy Supercapacitors

“…In addition to the textural properties, the surface functionalities and heteroatoms present in the carbon also govern EDLC performance, particularly at higher currents, by improving the wettability of carbon by the electrolyte and reducing the electrode–electrolyte interfacial resistance . The X‐ray photoelectron spectroscopy (XPS) spectrum in Figure S4 reveals the presence of a C 1s spectrum with a major C−C bond signal at around 284.8 eV, which confirmed the highly carbonaceous nature of all samples .…”

“…In addition to the textural properties, the surface functionalities and heteroatoms presenti nt he carbon also govern EDLC performance, particularly at higher currents, by improving the wettability of carbon by the electrolyte and reducing the electrode-electrolyte interfacial resistance. [46][47][48] The X-ray photoelectrons pectroscopy (XPS) spectrum in Figure S4 reveals the presence of aC1s spectrumw ith am ajor CÀCb ond signal at around2 84.8 eV,w hich confirmed the highly carbonaceous nature of all samples. [11,22] Samples CDC-1 and CDC-3 showed al ow C/O ratio, which indicatedt he presenceo fl arge number of oxygen-containing functional groups.Ahigh C/O ratio in CDC-2 indicated its highly carbonaceousn ature and the presence of av ery low quantity of oxygen functional groups.…”

“…The high‐resolution P 2p spectrum of CDC‐3 shows a major peak at around 133 eV, which corresponds to P−C bonds and confirms the successful incorporation of phosphorous atoms into the carbon framework. The percentage of phosphorous was calculated to be 3.04 at %, which is much higher than earlier reports, and this strategy greatly reduces the need for a second treatment for heteroatom doping . The presence of P atoms in the carbon framework can increase the active sites for ionic adsorption and also facilitates the adsorption of ions from the electrolyte .…”

“…The percentage of phosphorous was calculated to be 3.04 at %, which is much highert han earlier reports, and this strategy greatly reduces the need for as econd treatment for heteroatom doping. [48,49] The presence of Pa toms in the carbon framework can increaset he actives ites for ionic adsorption anda lso facilitates the adsorption of ions from the electrolyte. [50] Ah igh rate performance can be achieved despite poor textural properties.…”

Effect of the Size and Position of Ion-Accessible Nanoholes on the Specific Capacitance of Single-Walled Carbon Nanohorns for Supercapacitor Applications

“…1 With regard to porous carbons traditionally used as electrode materials for commercial supercapacitors, tuning the ion-accessible pore size and maximizing the ion-accessible surface area are considered as the most effective approaches to achieve high-energy-density supercapacitors. 2,3 Recently, single-wall nanocarbons have been actively studied as alternative electrode materials for supercapacitors owing to their nanoporous characteristics and relatively high electrical conductivity.…”