Preparation and electrochemical performance of PPyNTs/NiCo-LDH for asymmetric supercapacitors

Abstract

Supercapacitors possess remarkable benefits in terms of electrochemical energy storage, whereas the inherent defects, such as suboptimal power density, limit commercial employment. Here, NiCo double hydroxide (NiCo-LDH) nanosheets with ZIF-67 as the precursor were fabricated and anchored on the surface of polypyrrole nanotubes (PPyNTs) to prepare composite electrode materials (PPyNTs/NiCo-LDH). Electrochemical test results show that the electrode material possesses 1802 F g−1 specific capacitance under a 1 A g-1 current density. Furthermore, it shows a retention of 50.2 % for capacitance after 5000 cycles with 10 A g-1 current density. To examine the practical performance of the materials, aqueous asymmetric supercapacitors PPyNTs/NiCo-LDH//AC were assembled, with up to 115 F g−1 specific capacitance at 1 A g-1 under a stabilized output voltage of 1.5 V, and possessing a high energy density of 35.94 Wh kg−1 at a power density of 760.2 W kg−1. Meanwhile, the capacitance retention of 65.3 % after 5000 cycles.