Carbon-Based Supercapacitors Produced by Activation of Graphene

Abstract

Supercapacitors, also called ultracapacitors or electrochemical capacitors, store electrical charge on high-surface-area conducting materials. Their widespread use is limited by their low energy storage density and relatively high effective series resistance. Using chemical activation of exfoliated graphite oxide, we synthesized a porous carbon with a Brunauer-Emmett-Teller surface area of up to 3100 square meters per gram, a high electrical conductivity, and a low oxygen and hydrogen content. This sp(2)-bonded carbon has a continuous three-dimensional network of highly curved, atom-thick walls that form primarily 0.6- to 5-nanometer-width pores. Two-electrode supercapacitor cells constructed with this carbon yielded high values of gravimetric capacitance and energy density with organic and ionic liquid electrolytes. The processes used to make this carbon are readily scalable to industrial levels.

Laminated Hybrid Junction of Sulfur‐Doped TiO2 and a Carbon Substrate Derived from Ti3C2 MXenes: Toward Highly Visible Light‐Driven Photocatalytic Hydrogen Evolution

“…More interestingly, the EPR intensity of LDC‐S‐TiO 2 /C is further slightly improved. Considering that the carbon can be easily oxidized by O 2 , the enhanced V O • concentration is mainly attributed to the oxidation of carbon, which is consistent with the Raman spectra 33. Furthermore, the charge‐transfer efficiency was investigated using electrochemical impedance spectroscopy (EIS) and transient photocurrent density (TPC) response measurements, respectively.…”

Paper‐Based Electrodes for Flexible Energy Storage Devices

“…Compared with other materials, graphene has unique 2D structure, high electronic mobility (15000 cm 2 V −1 s −1 ),103, 104 exceptional electric (10 6 S m −1 )105 and thermal (5300 W m −1 K −1 )106 conductivities, excellent optical transmittance (97.7% in visible region),107 good mechanical strength (tensile strength 130 GPa and stiffness 1.5 × 10 8 psi)108 and ultrahigh surface area (≈2630 m 2 g −1 ) 109. Its extraordinarily high surface area enables its high electric double‐layer capacitance as high as 550 F g −1 if the entire surface area can be fully utilized 102…”

Sodium‐Ion Batteries: Improving the Rate Capability of 3D Interconnected Carbon Nanofibers Thin Film by Boron, Nitrogen Dual‐Doping

“…And the pronounced hysteresis loop reveal more developed mesopores. A growing number of mesopores are displayed in the pore size distribution curves of all samples as the amount of NH 4 HB 4 O 7 · H 2 O increases as a result of harsher activation resulting in relatively larger pores 39. The Brunauer–Emmett–Teller (BET) specific surface area is 741 m 2 g −1 for CNFs, 1280 m 2 g −1 for BN‐CNFs‐1, 1585 m 2 g −1 for BN‐CNFs, and 1556 m 2 g −1 for BN‐CNFs‐2, respectively.…”