Room Temperature Synthesis of Vertically Aligned Amorphous Ultrathin NiCo-LDH Nanosheets Bifunctional Flexible Supercapacitor Electrodes

Abstract

Developing a simple scalable method to fabricate electrodes with high capacity and wide voltage range is desired for the real use of electrochemical supercapacitors. Herein, we synthesized amorphous NiCo-LDH nanosheets vertically aligned on activated carbon cloth substrate, which was in situ transformed from Co-metal–organic framework materials nano-columns by a simple ion exchange process at room temperature. Due to the amorphous and vertically aligned ultrathin structure of NiCo-LDH, the NiCo-LDH/activated carbon cloth composites present high areal capacities of 3770 and 1480 mF cm−2 as cathode and anode at 2 mA cm−2, and 79.5% and 80% capacity have been preserved at 50 mA cm−2. In the meantime, they all showed excellent cycling performance with negligible change after >10 000 cycles. By fabricating them into an asymmetric supercapacitor, the device achieves high energy densities (5.61 mWh cm−2 and 0.352 mW cm−3). This work provides an innovative strategy for simplifying the design of supercapacitors as well as providing a new understanding of improving the rate capabilities/cycling stability of NiCo-LDH materials.