Highly Porous Carbon with Graphene Nanoplatelet Microstructure Derived from Biomass Waste for High‐Performance Supercapacitors in Universal Electrolyte

Abstract

Highly porous carbon (3047 m2 g−1) with a graphene nanoplatelet microstructure is obtained by using a biomass waste as a new carbon source. Introducing high‐energy ball milling treatment during the synthesis procedure can greatly improve the surface wettability of carbon and ensure the homogenously contact between carbon and KOH, thus leading to high reactivity of the KOH activation. The highly efficient activation endows this carbon with favorable features for supercapacitors, such as high surface area with coexistence of rich micropores and mesopores, unique graphene nanoplatelet microstructure with good conductivity and many capacitive active sites. The as‐prepared carbon exhibits high specific capacitances of 329 and 311 F g−1 in 2 m KOH and 1 m H2SO4 electrolyte at 1.0 A g−1, respectively. In 1 m TEABF4/AN electrolyte, a high working voltage of 3 V and excellent rate performance can be obtained based on a two‐electrode full cell. The energy density of the carbon/carbon symmetric capacitor reaches 49.5 W h kg−1 and the extreme power density can reach 10.8 kW kg−1. The results suggest this biomass‐waste‐derived carbon can serve as a low‐cost and high‐performance electrode material for supercapacitors with universal electrolytes.

Multidimensional Co‐Exfoliated Activated Graphene‐Based Carbon Hybrid for Supercapacitor Electrode

“…It is important to note that the slightly lower capacitance retention (≈98%) is observed after the initial 1000 cycles and then started to increase after about 2000 cycles. The initial capacitance decrease maybe ascribed to the existence of heteroatoms, such as oxygen, as confirmed by XPS, which can lead to the pseudocapacitance, and, after a few cycles, fades away after all the heteroatoms have been exhausted . The further increase in the capacitance might be due to the complete wetting of the electrode with the KOH electrolyte.…”

Redox‐Mediator‐Enhanced Electrochemical Capacitors: Recent Advances and Future Perspectives

“…The emerging redox‐active electrolytes are prepared by dissolving redox mediators in the inert electrolyte, thus endowing the electrolyte with the fascinating ability to store energy . Carbon‐based electrodes are widely used in active electrolytes because of their high surface area, good conductivity, superior stability, excellent chemical inertness, and low cost . Redox mediators are reduced and oxidized at the solid–electrolyte interface, which provides additional pseudocapacitance while retaining the EDL capacitance of carbon materials (Figure d).…”

“…[24] Carbon-based electrodes are widely used in active electrolytes because of their high surfacea rea, good conductivity,s uperior stability, excellent chemical inertness, and low cost. [12,[25][26][27] Redox mediators are reduced and oxidized atthe solid-electrolyte interface, which provides additional pseudocapacitance while retaining the EDL capacitance of carbon materials (Figure 1d). Specifically,t his method turns inert electrolytes into fascinating liquid fuels with little effect on weighta nd volume of devices.…”

Cost‐efficient magnetic nanoporous carbon derived from citrus peel for the selective adsorption of seven insecticides

“…However, these carbon materials were extremely reliant on fossil fuel‐based precursors and harsh or energy intensive synthetic conditions, some synthetic process would use toxic reagents, which were costly and harmful to the environment . Recently, nanoporous carbons derived from biomass sources have inspired more research interest due to the advantages of abundant, sustainable, relatively low cost, large specific surface area, and high affinity to some organic compounds . Just because of these excellent characteristics, they have been developed as good electric supercapacitors , catalysts , and adsorbents .…”

“…A large amount of citrus peel waste is generally dumped into landfill or disposed of in the ocean. Some compounds such as sugars and large specific surface area, and high affinity to some organic compounds [10,11]. Just because of these excellent characteristics, they have been developed as good electric supercapacitors [12], catalysts [13], and adsorbents [14].…”