Aloe vera Derived Activated High-Surface-Area Carbon for Flexible and High-Energy Supercapacitors

Abstract

Materials which possess high specific capacitance in device configuration with low cost are essential for viable application in supercapacitors. Herein, a flexible high-energy supercapacitor device was fabricated using porous activated high-surface-area carbon derived from aloe leaf (Aloe vera) as a precursor. The A. vera derived activated carbon showed mesoporous nature with high specific surface area of ∼1890 m/g. A high specific capacitance of 410 and 306 F/g was achieved in three-electrode and symmetric two-electrode system configurations in aqueous electrolyte, respectively. The fabricated all-solid-state device showed a high specific capacitance of 244 F/g with an energy density of 8.6 Wh/kg. In an ionic liquid electrolyte, the fabricated device showed a high specific capacitance of 126 F/g and a wide potential window up to 3 V, which results in a high energy density of 40 Wh/kg. Furthermore, it was observed that the activation temperature has significant role in the electrochemical performance, as the activated sample at 700 °C showed best activity than the samples activated at 600 and 800 °C. The electron microscopic images (FE-SEM and HR-TEM) confirmed the formation of pores by the chemical activation. A fabricated supercapacitor device in ionic liquid with 3 V could power up a red LED for 30 min upon charging for 20s. Also, it is shown that the operation voltage and capacitance of flexible all-solid-state symmetric supercapacitors fabricated using aloe-derived activated carbon could be easily tuned by series and parallel combinations. The performance of fabricated supercapacitor devices using A. vera derived activated carbon in all-solid-state and ionic liquid indicates their viable applications in flexible devices and energy storage.

Orange Peel Derived Activated Carbon for Fabrication of High‐Energy and High‐Rate Supercapacitors

“…Among the three electrodes, the CV profile of OPAA‐700 has shown good electrochemical response compared to OPAA‐600 and OPAA‐800 electrode. The CV profile shows a typical mirror image characteristics of rectangular shape due to the effective EDLC behaviour with faradaic humps for OPAA‐600 and OPAA‐700 electrode materials due to the pseudocapacitance influence from the hetero atom functionalities ,,,. However, the OPAA‐800 shows only EDLC response due to the reduction of functional groups at high‐temperature treatment.…”

“…The CV profile shows a typical mirror image characteristics of rectangular shape due to the effective EDLC behaviour with faradaic humps for OPAA-600 and OPAA-700 electrode materials due to the pseudocapacitance influence from the hetero atom functionalities. [9,39,44,45] However, the OPAA-800 shows only EDLC response due to the reduction of functional groups at high-temperature treatment. Based on the above observations, the OPAA-700 electrode is subjected to detailed investigation in a symmetric configuration in aqueous and ionic liquids.…”

“…Hence, the capacitance properties and performance of the supercapacitor device are varied that depend on the nature of the electrode materials. Generally, carbon‐based electrode materials like activated carbon,, carbon nano‐tube,, graphene and carbon aerogel used as an EDLC based supercapacitor due to their high specific surface area, good conductivity, and high electrochemical stability. To ameliorate the efforts for energy storage and practical potential applications of supercapacitor point of view, the EDLC materials are the best option due to their low cost and abundant in nature ,.…”

Synthesis of Boron‐Doped Graphene by Supercritical Fluid Processing and its Application in Symmetric Supercapacitors using Various Electrolytes

“…The boron presence in SBGO-(1 : 2), SBGO-(1 : 1) and SBGO-(2 : 1) is obviously notified by absorption band about 970 cm À 1 and around 1490 cm À 1 are attributed to symmetric and antisymmetric BÀ O stretching. [40] The presence of different forms of boron can be established using X-ray photoelectron spectroscopy (XPS). [39] From these results, it can be apparently inferred that boron has not only doped but also it has functionalised over the graphene network.…”

NiTe Nanorods as Electrode Material for High Performance Supercapacitor Applications

“…EDLC is based on non faradic charge reaction which does not involve the charge transfer during charge storage. Carbon based materials like graphene, carbon nanotubes and activated carbon have been extensively used for electric double layer capacitor applications . Faradic charge transfer reactions take place to store charge in pseudocapacitors.…”