Multifunctional core-shell-like nanoarchitectures for hybrid supercapacitors with high capacity and long-term cycling durability

Transition metal oxide/hydroxide with multifunctional hierarchical nanostructures has attracted widespread attention in supercapacitors (SCs) because of their large accessible surface area, high electrochemical activity and superior redox chemistry. Herein, core-shell-like copper (Cu) hydroxide nanotube arrays grafted nickel aluminum layered double hydroxide nanosheets were facilely synthesized on porous Cu foam (CH NTAs@NiAl LDH NSs) for use as an efficient battery-type electrode in hybrid SCs. With the synergistic effects of NiAl LDH NSs on well-adhered CH NTAs/CF, the core-shell-like composite (prepared for 24 h) delivered a maximum areal capacity of 334.3 µAh/cm² at a current density of 3 mA/cm² in 2 M KOH electrolyte, which is comparatively higher than other samples synthesized at different growth times. Moreover, the core-shell-like CH NTAs@NiAl LDH NSs-24 demonstrated an outstanding cycling stability of 134.3% after 10, 000 cycles. Utilizing high capacity and stability of CH NTAs@NiAl LDH NSs-24, a pouch-type hybrid SC was further assembled with core-shell-like composite as a positive electrode and reduced graphene oxide as a negative electrode with a filter paper as a separator in aqueous alkaline electrolyte. The hybrid SC showed a high areal capacity of 250 µAh/cm² at 2 mA/cm² with maximum areal energy and power densities of 181.9 µWh/cm² and 24, 991.5 µW/cm², respectively. Successfully harvesting the solar energy via solar cell panel and subsequently delivering the stored energy to switching and proximity applications also demonstrated the real-time applicability of our hybrid SCs.