Hydrangea-like NiMoO4-Ag/rGO as Battery-type electrode for hybrid supercapacitors with superior stability.

ABSTRACT

It is a great challenge to design electrode materials with good stability and high specific capacitance for supercapacitors. Herein, a three-dimensional (3D) hydrangea-like NiMoO4 micro-architecture with Ag nanoparticles anchored on the surface has been designed by adding EDTA-2Na, which was assembled with reduced graphene oxide (rGO) and named as NiMoO4-Ag/rGO composite. Benefiting from the synergetic contributions of structural and componential properties, NiMoO4-Ag/rGO composite exhibits a high specific capacitance of 566.4 C g-1 at 1 A g-1, and great cycling performance with 90.5% capacitance retention after 1000 cycles at 10 A g-1. The NiMoO4-Ag/rGO electrode shows an enhanced cycling stability due to the two-dimensional towards two-dimensional (2D-2D) interface coupling between rGO and NiMoO4 nanosheets, and the stable 3D hydrangea-like micro-architecture. Moreover, NiMoO4-Ag/rGO with 5-15 nm pore structure and enhanced conductivity exhibits improved charge transfer and ions diffusion. Besides, NiMoO4-Ag/rGO//AC capacitor displays an outstanding energy density of 40.98 Wh kg-1 at 800 kW kg-1, and an excellent cycling performance with 73.3% capacitance retention at 10 A g-1 after 8000 cycles. The synthesis of NiMoO4-Ag/rGO composite can provide an effective strategy to solve the poor electrochemical stability and slow electron/ion transfer of NiMoO4 material as supercapacitors electrode.