Template-Induced Ni(OH)₂ Nanosheet-Constructed Hierarchically Porous Aerogel Boosts Superior Specific Capacitance and Rate Performance for Supercapacitors

Hierarchically porous materials are promising electrode materials for supercapacitors due to their high surface area and large amounts of interconnected active sites. As a three-dimensional (3D) porous material, aerogels can further increase the exposure of active sites and improve the ion transport by constructing hierarchically porous structures. Herein, a kind of 3D hierarchically porous Ni(OH) 2 aerogel (HP-NiA) constructed by a template-directed Ni(OH) 2 nanosheet can be obtained via combining the sol–gel method and template-etching method, in which the controllable pore size was achieved via using the mesoporous silica-KIT-6 and silicon template KH570 as sacrificial templates. The microporous cavities are interconnected with mesopores and macropores, which enable full contact of active sites with electrolytes and facilitate quick transport of ions. Benefiting from the hierarchically porous structure and the high active specific surface area (1577.5 cm 2 ), the amorphous HP-NiAs exhibit ultrahigh specific capacitance (5578 F/g at 1 A/g), excellent rate performance (3698 F/g at 20 A/g), and superior cycling stability (72.5% capacitance retention after 10,000 cycles), which are superior to the state-of-the-art supercapacitor electrode materials. This work highlights the importance of the rational design on the hierarchical structure and provides a feasible strategy to construct hierarchical porous materials for energy-storage applications.