Electrodeposition of Ni(OH)<sub>2</sub> Nanosheets on Activated Carbon-NiO Composites for Supercapacitor Applications
Wencheng Yang, Jianbo Zhang, Lu Liu, Mengchen Pei, Huiyong Chen, Xiaoxun Ma
Abstract
The growing electric automobile and portable electronics industries have stimulated increasing demand and boosted the consumption of high-performance energy storage materials. Herein, a precipitation-pyrolysis method was used to synthesize activated carbon (AC) supported NiO composites that serve as a substrate for the formation of Ni(OH) 2 nanosheets (with a thickness of 13–20 nm) by electrodeposition for supercapacitor electrodes. It was found that pretreatment of the AC (or using graphite or another AC as an alternative) greatly affected the as-prepared electrode performance. The well-designed AC-NiO/Ni(OH) 2 composite exhibits a high specific capacity of 748.8 C/g at 1 A/g and good cyclic stability (with a capacity retention ratio of 87.6% after 5000 charge–discharge cycles) in a three-electrode system, thanks to the unique structure and components involving a porous carbon skeleton, Ni 0 and NiO species, and Ni(OH) 2 nanosheets. The assembled asymmetric capacitor possesses a potential window of 1.45 V, an energy density of 30.0 Wh/kg at a power density of 145 W/kg (or 15.5 Wh/kg at 2000 W/kg), and good cyclic stability (with a capacity retention ratio of 92.6% after 5000 charge–discharge cycles at 2 A/g). The presented work provides a potential pathway for the rational design of high-performance electrode materials for electrochemical capacitors and/or energy storage devices.