Construction of Double-Shell Basic Cobalt/Nickel Carbonate Microspheres via MOFs Etching Strategy for Boosting Aqueous Supercapacitor Performances

Recently, the anion-functioned or anion-doped Co/Ni hydroxide materials have attracted widespread concern in the scientific field due to their dramatically enhanced performances in energy storage and conversion application. Herein, we reported effective metal–organic frameworks (MOFs) etching strategy to construct the MOFs derived cobalt–nickel hydroxide carbonate (CNHC) double-shell microspheres for boosted supercapacitor performance. The etching process is driven by the CO32– and OH– anions via the hydrolysis of urea, and the organic ligand in MOFs is gradually substituted by the CO32– and OH– anions to form the thermodynamically stable Co/Ni(CO3)x(OH)y phase. Then, the hierarchical double-shell structure constructed by a self-supported Co/Ni(CO3)x(OH)y nanosheet is accessed by the Ostwald ripening process, which provides abundant channels and abundant accessible active centers for enhanced electrochemical reaction kinetics. The optimized CNHC-12h electrode demonstrates a high specific capacitance of 1233.6 F g–1 at 1 A g–1 and outstanding rate performance of 80% when the current density is expanded ten times. In addition, the hybrid supercapacitor device assembled by CNHC-12h//AC achieves the high energy density of 41.8 Wh kg–1 at the power density of 0.8 kW kg–1 and can operate the thermometer normally for 20 min with 5 s charging time. The construction of MOFs derived basic carbonate materials will provide a possibility to synthesize high capacitance performance anions-functioned hydroxide electrode materials for energy storage devices and practical application.