In-situ synthesis of hierarchical Mn-decorated NiCo_2S_4 nanosheet arrays on Ni foam as binder-free electrodes for high-performance supercapacitors

摘要

In this paper, novel hierarchical Mn-decorated NiCo_2S_4 nanosheet arrays on Ni foam have been synthesized by a facile multi-step hydrothermal method and directly used as binder-free electrodes for supercapacitors. The vertically aligned NiCo_2S_4 nanosheet arrays on Ni foam act as not only a good pseudocapacitive material but also a conductive scaffold that can be uniformly decorated by ultrathin and interconnected chiffon-like nanoflakes of MnS_2. This unique architecture with a highly specific surface area and fast transfer channels for electron and ion can employ many independent nanospaces to participate in electrochemical reaction. The optimized Mn-decorated NiCo_2S_4 nanosheet arrays electrode represents an impressive areal capacitance of 4.6 F cm~(−2) at 2 mA cm~(−2) and good cycling stability (87.3% of the areal capacitance can be maintained after 2000 cycles at 10 mA cm~(−2)), indicating the great potential of this hybrid hierarchical nanostructure as a promising candidate for high-performance supercapacitors.