Rapid in situ growth of beta-Ni(OH)(2) nanosheet arrays on nickel foam as an integrated electrode for supercapacitors exhibiting high energy density

摘要

Ni(OH)(2) has been widely investigated as a prospective electrode material because of its high theoretical capacitance and relatively low cost. However its synthesis usually needs a complex and lengthy process, and a binder is generally used for fabricating Ni(OH)(2) based electrodes. In this work, a self-supporting binder-free beta-Ni(OH)(2)@nickel foam (NF) integrated electrode was prepared by the in situ growth of beta-Ni(OH)(2) on NF using a rapid and facile approach. This approach consists of two processing steps: (1) the pre-treatment of NF with an acid and (2) the quick in situ electrochemical synthesis of beta-Ni(OH)(2) on the NF in the KOH electrolyte within half a minute under an applied voltage. The beta-Ni(OH)(2)@NF integrated electrode possesses a three-dimensional network structure of nanosheet arrays and exhibits excellent electrochemical performance. Its areal capacity is 3.68 mA h cm(-2) at a current density of 2 mA cm(-2), and the capacity can retain 115.8% of its initial value even after 2000 cycles at a current density of 15 mA cm(-2). Moreover, the as-assembled beta-Ni(OH)(2)@NF//activated carbon (AC) asymmetric supercapacitor (ASC) exhibits a high energy density of 74.2 W h kg(-1) with a power density of 776.9 W kg(-1) and excellent cycling stability (89.9% retained after 10000 cycles). This work provides an efficient, facile and economic method for fabricating Ni(OH)(2) based integrated electrodes for high-performance supercapacitors.