Hierarchical CuO nanosheets encasing nanorods via a singular potential-cycling activation: Innovations in supercapacitor energy density and longevity

Copper oxides (CuO), by virtue of their exceptional electrical conductivity, benign environmental profile, and economic viability, have emerged as indispensable constituents in the design and development of binder-free electrodes for advanced supercapacitor systems. The ongoing quest for the synthesis of CuO nanomaterials through gentle yet economically feasible methodologies held considerable promise for broadening their applicability within the domain of energy storage devices. In this investigation, a novel architectural innovation was achieved through the integration of carbon nanotubes (CNTs) within the framework of an in-situ electrooxidation process, culminating in the formation of a distinctive CuO-CNT nanorod configuration. Subsequent to this fabrication, the electrode material was subjected to an extensive cyclic voltammetry (CV) activation for 2000 cycles, which precipitated a profound morphological evolution. This process resulted in the emergence of 2D hierarchical nanosheet arrays enveloping 1D nanorods, a configuration herein designated as CuO-CNT-2000. This meticulously engineered lamellar structure conferred upon the material an extraordinary specific surface area, quantified at 219.6 m 2 g⁻ 1 , and an impressive specific capacitance of 709.1 F g⁻ 1 . Moreover, the asymmetric supercapacitor (ASC) assembled utilizing this advanced material exhibited a remarkable energy density, measured at 38.09 Wh kg⁻ 1 . Notably, even after enduring 60,000 charge-discharge cycles, the device demonstrated a retention of 82.36 % of its initial energy density, coupled with a Coulombic efficiency of 99.43 %, thus attesting to its superior electrochemical stability and longevity. The efficacy of the CV activation technique in facilitating significant morphological refinement, augmenting the specific surface area, and enhancing the electrochemical performance of the material suggests a broad applicability of this method to a diverse array of other electrode materials, potentially revolutionizing the design and fabrication of next-generation energy storage systems.