Self-supporting electrode for flexible supercapacitors: NiCo-layered double hydroxide derived from metal organic frameworks wrapped on graphene/polyaniline nanotubes@cotton cloth

Nowadays, constructing hetero-structure materials is an efficacious procedure to uplift the electrochemical performance of layered double hydroxide (LDH) materials. The logical design of such elegant nanostructures is still challenging. Herein, NiCo-LDH nanosheets derived from Co-ZIF grown on graphene/polyaniline nanotube (G/PANI-NT)@cotton cloth (CC) was synthesized by a facile and novel two-step strategy for supercapacitors. Such hetero-structures give a 30.63 m2 g−1 surface area and more subjected electrochemical active sites. The supercapacitor performance results exhibit that the NiCo-LDH/G/[email protected] electrode has the best supercapacitor performance when it is used as a pseudocapacitor. By the ratio of Ni/Co = 2:1 in the precursor solution, the electrode shows an areal specific capacitance of 88.15 mF cm−2 at a current density of 0.075 mA cm−2. The electrochemical performance of the electrodes was perused using a redox-additive electrolyte. The electrochemical performance of the NiCo-LDH/G/[email protected] electrode was amended using K2S2O8 in a 3 M KOH solution. Considerably, the areal specific capacitance of NiCo-LDH/G/[email protected] (181.17 mF cm−2) increased to 431.30 mF cm−2, by changing the K2S2O8 concentration in KOH solution at a current density of 0.075 mA cm−2. Long-term stability test demonstrates that 84.05 % of the original capacitance remains after 10,000 cycles at the current density of 0.2 mA cm−2. The results indicate that NiCo-LDH/G/[email protected] will be an appropriate candidate for high-performance supercapacitors. The NiCo-LDH/G/[email protected]//NiCo-LDH/G/[email protected] flexible solid-state supercapacitor was assembled with the PVA/KOH gel electrolyte.