Electrodeposited coral-like bimetallic NiCo-MOFs on Ni foam as binder-free electrodes for high performance all solid-state asymmetric supercapacitors

The rational design of electrode materials is greatly significant for improving the performance of the super-capacitor. In this work, high mass loading coral-like bimetallic nickel/cobalt-based metal-organic frameworks are in-situ constructed on cobalt-modified nickel foam (NiCo-MOFs/NF) via a facile cathodic electrodeposition process as binder-free electrodes for supercapacitors. Such electrodes with optimized Ni/Co molar ratios, high specific surface area and unique hierarchical structure with open channels provide abundant reaction active sites and fast ion transfer kinetics, and the three-dimensional porous Ni foam (NF) offers successive pathways for fast electron transportation. As a result, an ultrahigh areal specific capacitance of over 9300 mF cm-2 with a high-capacity retention of over 87% is achieved at 10 mA cm-2. And the NiCo-MOFs/NF with Ni/Co molar ratio of 1:3 presents a favorable stability of retaining its 73% original specific capacitance after a long-term cycling of 10,000 cycles. Moreover, the assembled all solid-state asymmetric supercapacitors (ASSCs) device performs an energy density of 617.2 mWh cm-2 at a power density of 7506.9 mW cm-2.