Shell membrane-aided synthesis of 3D porous flower-like Co2(OH)3Cl-MnO2 hybrid composites for high performance supercapacitors

Abstract

Three-dimensional (3D) flower-like Co2(OH)3Cl-MnO2 nanostructures were fabricated inside eggshell through a facile and effective method. Inspired by semipermeable membranes, a shell membrane was selected as an interface for ion diffusion. In specific, an eggshell with shell membrane was employed as a multifunctional reactor to separate the components of the precursor solution. OH- ion diffusion was performed through porous eggshell membrane. The electrochemical measurements demonstrated that the hybrid composite achieves high capacitance 3.709 F/cm2 at 1 mA/cm2 (2061 F/g with the mass loading of 1.8 mg/cm2) and an excellent cycling stability (71% specific capacitance retained after 5000 cycle numbers), exhibiting a superior electrochemical performance compared to pure Co2(OH)3Cl or MnO2. Moreover, an asymmetric supercapacitor was assembled by Co2(OH)3Cl-MnO2-2 and activated carbon as positive and negative electrode, respectively (Co2(OH)3Cl-MnO2-2//AC ASC), which exhibits high capacitance (134.8 F/g at 0.2 A/g), excellent energy density (42.2 W h/kg at 150.3 W/kg), and remarkable cycling stability (80% capacitance retention after consecutive 5000 cycle numbers).