Unraveling the Role of Oxides in Electrochemical Performance of Activated Carbons for High Voltage Symmetric Electric Double‐Layer Capacitors

Abstract

Having control over the architecture of functional materials to maximize their exposed surface area and the working potential window is critical yet challenging for surface‐sensitive applications, including energy storage and environmental remediation. Herein, a sustainable and green strategy is established to fabricate activated carbon (AC) materials with designed microstructures including stratified architecture comprising stacked nanosheets with a surface area of 1743 m2 g−1 and 3D scaffold with homogeneously distributed surface nanoholes with surface area as high as 2120 m2 g−1. An optimized pathway toward the fabrication of symmetric supercapacitors (SCs), highlighting impacts of AC precursors, activation process, and oxide nanostructures on electrochemical behaviors of the resultant ACs, is also offered. The representative symmetric two‐ and three‐electrode electric double‐layer capacitor (EDLC) configuration cells are fabricated using coffee‐ and textile‐derived ACs with high gravimetric capacitances of 377 and 356 F g−1, respectively. Coffee‐derived AC exhibits excellent capacitance retention of 93% after ≈18 000 cycles under a remarkable potential window of 2.7 V in aqueous media. The findings broaden the current understanding on the optimization of electrochemical behavior of ACs using structural and morphological modifications, while uncovering the impacts of oxides on improving both energy density and cycling stability of AC‐based SCs.

Keywords

• highly stable electric double-layer capacitors
• hybrid porous activated carbons
• nanoperforated carbon sheets
• oxide-embedded activated carbons
• symmetric supercapacitor devices
• value-added microrecycling