Recycling decoration wastes toward a high-performance porous carbon membrane electrode for supercapacitive energy storage devices

Abstract

Using discarded wastes as carbon precursors to prepare high value-added carbon electrode materials for supercapacitors (SCs) can not only enrich the selection of precursors to reduce the cost but also alleviate the environmental pressure on recovering these wastes. Herein, a porous carbon membrane (DWCM) was fabricated by direct carbonization of decoration waste using KOH as an activator and employed as a binder-free self-supported electrode for aqueous SC. The DWCM electrode features a large specific surface area (917 m² g⁻¹) and high porosity (0.5 cm³ g⁻¹) and thus exhibits superior electrolyte wettability. Moreover, the DWCM electrode possesses excellent structural integrity and mechanical strength, providing continuous 3D networks for rapid electron transfer. Attributing to the above structural merits, the best DWCM-1-1000 electrode even with a weight of ∼30 mg exhibits the highest specific capacitance (C_s) (areal capacitance, C_a) of 338.2 F g⁻¹ (10.6 F cm⁻²) at 0.5 A g⁻¹ in a three-electrode system in 6 M KOH. An assembled symmetric SC using two DWCM-1-1000 electrodes can stably operate at a potential window of 0–1.4 V showing a high C_s (C_a) of 138.3 F g⁻¹ (8.9 F cm⁻²) at 0.2 A g⁻¹. Notably, this SC shows excellent cycling stability (98% capacitance retention and 100% coulombic efficiency after 20 000 cycles) and presents a maximum energy density of 9.7 Wh kg⁻¹ at a power density of 139.6 W kg⁻¹. Also, it is found that reducing the thickness of the electrode will further improve the capacitive performance of the DWCM-based SC device. This work opens a new route of using decoration waste to develop high-performance self-supported porous carbon membranes for practical energy storage.