Integrated battery-capacitor storage system: polyaniline interwoven Co-ZIF-derived hollow NiCo-LDH with enhanced electrochemical properties for hybrid supercapacitors

Layered double hydroxides (LDHs) are battery-type supercapacitor electrode materials with application potential due to their abundant active metal sites and surface functional groups. The traditional LDH structure easily aggregates and collapses. In this work, a stable cobalt zeolite imidazole framework (Co-ZIF) was used as the derived template to grow LDH nanosheets in situ to increase the contact area with the electrolyte, and polyaniline (PANI) acted as a conductive bridge to provide a rapid charge transfer pathway. The fabricated NiCo-LDH@PANI hollow structure demonstrated a specific capacity of 1315 C g(-1) at 1 A g(-1) and achieved a rate capacity of 951 C g(-1) at 20 A g(-1). Furthermore, the battery-supercapacitor hybrid device (NiCo-LDH@PANI//AC) exhibited an high energy density of 66.2 W h kg(-1) at a power density of 800 W kg(-1) with 95.5% capacitance retention after 20 000 cycles.