Abstract
Carbon-based symmetric supercapacitors (SCs) are known for their high power density and long cyclability, making them an ideal candidate for power sources in new-generation electronic devices. To boost their electrochemical performances, deriving activated carbon doped with heteroatoms such as N, O, and S are highly desirable for increasing the specific capacitance. In this regard, activated carbon (AC) self-doped with heteroatoms is directly derived from bio-waste (lima-bean shell) using different KOH activation processes. The heteroatom-enriched AC synthesized using a pretreated carbon-to-KOH ratio of 1:2 (ONS@AC-2) shows excellent surface morphology with a large surface area of 1508 m2 g−1. As an SC electrode material, the presence of heteroatoms (N and S) reduces the interfacial charge-transfer resistance and increases the ion-accessible surface area, which inherently provides additional pseudocapacitance. The ONS@AC-2 electrode attains a maximum specific capacitance (Csp) of 342 F g−1 at a specific current of 1 Ag−1 in 1 m NaClO4 electrolyte at the wide potential window of 1.8 V. Moreover, as symmetric SCs the ONS@AC-2 electrode delivers a maximum specific capacitance (Csc) of 191 F g−1 with a maximum specific energy of 21.48 Wh kg−1 and high specific power of 14 000 W kg−1 and excellent retention of its initial capacitance (98 %) even after 10000 charge/discharge cycles. In addition, a flexible supercapacitor fabricated utilizing ONS@AC-2 electrodes and a LiCl/polyvinyl alcohol (PVA)-based polymer electrolyte shows a maximum Csc of 119 F g−1 with considerable specific energy and power.
Original language | English |
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Pages (from-to) | 669-682 |
Number of pages | 14 |
Journal | Chemistry - A European Journal |
Volume | 27 |
Issue number | 2 |
DOIs | |
State | Published - 7 Jan 2021 |
Keywords
- heteroatoms
- high specific energy
- polymer electrolytes
- porous carbon
- supercapacitors