Formation of Hollow Co‐Ni‐S Nanowedges Arrays via Sulfidation‐etch of ZIF‐L for Advanced Hybrid Supercapacitor

Abstract Self‐supported hollow nanoarrays with rich active sites hold great promise as binder‐free electrode for supercapacitors. In this work, the hollow Co‐Ni−S nanowedge arrays (NWAs) have been fabricated on Ni foam (NF) substrate through a facile sulfidation and etch of ZIF−L‐Co NWAs/NF. Structural evolution upon solvothermal time indicates that the formation of hollow Co‐Ni−S NWAs is mainly due to the etch of defect‐rich interior of solid ZIF−L‐Co NWAs. The unique hollow nanowedge structural and compositional advantages ensure the hollow Co‐Ni−S NWAs excellent electrochemical properties with areal capacity of 0.286 mA h cm −2 at 5 mA cm −2 , and 78% capacity retention after 2000 cycles. Moreover, the hybrid supercapacitor (HSC) of Co‐Ni−S // AC has been assembled, which illustrates good application performance. The results indicate that the Co‐Ni−S NWAs/NF is a promising binder‐free electrode for high‐performance hybrid supercapacitors.