Three-Dimensional Porous Network Electrodes with Cu(OH)₂ Nanosheet/Ni₃S₂ 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/Ni3S2 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/Ni3S2@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 Ni3S2 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/Ni3S2 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/Ni3S2@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.