Hierarchical mesoporous flower-like ZnCo 2O 4@NiO nanoflakes grown on nickel foam as high-performance electrodes for supercapacitors

摘要

Herein, mesoporous ZnCo2O4@NiO nanoflakes grown on a nickel foam conductive substrate are prepared through a simple hydrothermal method combined with environmentally friendly chemical bath deposition method. The as-synthesized three-dimensional nanoflakes used as a binder-free supercapacitor electrode possess high specific surface area and shorten the ions and electron diffusion path. Electrochemical measurements indicate that ZnCo2O4@NiO (M3) nanoflakes deliver an ultrahigh specific capacitance of 2797?F?g?1at a current density of 1?A?g?1, and 2287.2?F?g?1at 10?A?g?1, even 1079.2?F?g?1at 40?A?g?1, respectively, revealing a remarkably improved rate performance. Moreover, the ZnCo2O4@NiO (M3) composite electrode exhibits superior cycling stability with ～100% initial capacitance retention at the current density of 30?A?g?1after 3000 cycles, and the coulombic efficiency remains over 97%. The first principle calculation shows that strong chemical bonds are formed between Ni (Co) and O species at the interface, which is favorable for the stabilization of the composite, resulting in a smaller interfacial polarization. The results indicate that ZnCo2O4@NiO with excellent electrochemical properties can be considered as a promising candidate for high-performance supercapacitors, and the facile architectural design strategy offers new insights in opportunities to exhibit promising potential in the field of the energy storage conversion applications.