Aqueous asymmetric supercapacitors (ASCs) have been recently designed to improve energy storage density due to their large operation voltage and low cost. However, most reported ASCs (particularly for cobalt/nickel-based materials) always deviate from ideal capacitive behavior. In the present work, Co (OH) 2 nanosheets arrays (NAs) are directly loaded on Ni mesh (Co(OH)(2) NAs@Ni) via electrodeposition, while coral-like carbon nanotubes (CNTs) are successfully grown on Ni mesh (CNTs@Ni) through chemical vapor deposition (CVD). Using Co(OH)(2) NAs@Ni as positive electrode and CNTs@Ni as negative electrode, a novel ASC has been successfully fabricated. Due to the merits of in-situ growth for active materials, the highly-conductive Ni mesh current collector and the positive synergistic effect between the positive and negative electrodes, our Co(OH)(2) NAs@Ni//CNTs@Ni ASC exhibits excellent capacitive behavior, which is quite similar to RuO2 center dot xH(2)O-based supercapacitors. Notably, even when the scan rate rise up to 1 V s(-1), the CV curve of the ASC device can still retains an inspiring quasi-rectangle shape from 0 to 1.5 V. Furthermore, the ASC demonstrates a high energy density of 19 Wh kg(-1) at 113 W kg(-1). More impressively, an ultra-high power density of 45 kW kg(-1) is achieved at an energy density of 12.5 Wh kg(-1). Besides, the Co(OH)(2) NAs@Ni//CNTs@Ni ASC also presents long-term cycling stability (with only 4% capacitance loss after 7000 cycles). (C) 2015 Elsevier Ltd. All rights reserved.