Coo@Coal-Ldh Nanobouquet Arrays for High Performance Pesudocapacitors

Abstract

CoO and CoAl layered double hydroxide (CoAl-LDH) are both promising active electrode materials for pesudocapacitors. It is of great significance to ingrate the advantages of both materials and design ingenious electrode structure to achieve high electrochemical performance. Herein, 3D core-shell CoO@CoAl-LDH nanobouquet arrays on Ni foam were fabricated via two-step hydrothermal growth methods, where CoAl-LDH nanoflakes regularly grew on the surface of CoO nanosheets. The composite exhibits superior capacitance (2031.2 F/g at 1 A/g) and desirable cycling stability (88.2% after 5000 cycles at 16 A/g). An asymmetric supercapacitor (ASC) device is also assembled by using as-systhesized CoO@CoAl-LDH composite as positive electrode and activated carbon (AC) as negative electrode. The electrochemical test of ASCs provides a specific capacitance of 195.6 F/g at 1 A/g and remains approximately 85% of capacitance 85.0% after 5000 cycles. The ASCs display a high energy density of 69.55 Wh/kg at a high power density of 800 W/kg and remains 29.2 Wh/kg even at a higher power density of 12800W/kg. The electrochemical mechanism was discussed. This work offers a meaningful perspective to explore the possibility of supercapacitor application of LDH-based materials.

Keywords: Supercapacitor, 3D Nanobouquet Arrays, CoO, Cobalt-Aluminum layered double hydroxide