High-performance asymmetric supercapacitors based on core/shell cobalt oxide/carbon nanowire arrays with enhanced electrochemical energy storage

摘要

High-reactivity electrode materials are indispensible for developing high-performance electrochemical energy storage devices. Herein, we report self-supported core/shell Co_3O_4/C nanowire arrays by using hydrothermal synthesis and chemical vapor deposition methods. A uniform and thin carbon shell is coated on the surface of Co_3O_4 nanowire forming core/shell nanowires with diameters of ～100nm. Asymmetric supercapacitors have been assembled with the core/shell Co_3O_4/C nanowire arrays as the positive electrode and activated carbon (AC) as the negative electrode. The core/shell Co_3O_4/C nanowire arrays exhibit a specific capacity of 116 mAh g~(-1) at the working current of 100 mA (4 A g~(-1)), and a long cycle life along with ～ 92% retention after 8000 cycles at 4 A g~(-1), higher than the unmodified Co_3O_4 nanowire arrays (81 mAh g~(-1) at 4 A g~(-1)). The introduction of uniform carbon layer into the core/shell structure is favorable for the enhancement of supercapacitor due to the improved electrical conductivity and reaction kinetics.