Three-Dimensional Porous Network Electrodes with Cu(OH) 2 Nanosheet/Ni 3 S 2 Nanowire 2D/1D Heterostructures for Remarkably Cycle-Stable Supercapacitors.

Developing advanced electrode materials with highly improved charge and mass transfer is critical to obtain high specific capacities and long-term cycle life for energy storage. Herein, three-dimensionally (3D) porous network electrodes with Cu(OH) 2 nanosheets/Ni 3 S 2 nanowire 2D/1D heterostructures are rationally fabricated. Different from traditional surface deposition, the 1D/2D heterostructure network is obtained by in situ hydrothermal chemical etching of the surface layer of nickel foam (NF) ligaments. The Cu(OH) 2 /Ni 3 S 2 @NF electrode delivers a high specific capacity (1855 F g -1 at 2 mA cm -2 ) together with a remarkable stability. The capacity retention of the electrode is over 110% after 35,000 charge/discharge cycles at 20 mA cm -2 . The improved performance is attributed to the enhanced electron transfer between 1D Ni 3 S 2 and 2D Cu(OH) 2 , highly accessible sites of 3D network for electrolyte ions, and strong mechanical bonding and good electrical connection between Cu(OH) 2 /Ni 3 S 2 active materials and the conductive NF. Especially, the unique 1D/2D heterostructure alleviates structural pulverization during the ion insertion/desertion process. A symmetric device applying the Cu(OH) 2 /Ni 3 S 2 @NF electrode exhibits a remarkable cycling stability with the capacitance retention maintaining over 98% after 30,000 cycles at 50 mA cm -2 . Therefore, the outstanding performance promises the architectural 1D/2D heterostructure to offer potential applications in future electrochemical energy storage.