Well-assembled nanosheets of nickel-cobalt double hydroxide flower as a reversible faradic battery-type electrode material for high-performance hybrid supercapacitor

The design and advancement of the interconnected three-dimensional (3D) porous nanoarchitecture electrode materials with fascinating electrochemical performance are in high demand for high-performance hybrid supercapacitors (HSCs). Herein, we report a facile fabrication of 3D flower-like nickel-cobalt double hydroxides (NiCoDH) architecture via a template-free hydrothermal approach. The NiCoDH flower-like architecture is composed of self-assembling and interconnecting many thin nanosheets with thicknesses ranging from 11–16 nm. The open void space and vertically oriented nanosheets in the NiCoDH flower-like architecture could shorten the pathway for the charge and electrons transport and offer abundant electroactive sites for redox reactions to enhance the electrochemical performance of the electrode material. The flower-like NiCoDH electrode material reveals a high specific capacity (Qs) of 731 C g⁻¹ at the current of 1 A g⁻¹ and retains 461 C g⁻¹ even at 20 A g⁻¹, signifying the high rate capability of the obtained electrode material. The HSC is constructed by adopting the NiCoDH and activated carbon (AC) as the positrode and negatrode, respectively. Further, the HSC supplies a Qs of 352 C g⁻¹, and it offers a high energy density of 58.30 Wh kg⁻¹ at the power density of 21.09 kW kg⁻¹ and an excellent long-term cyclic life (∼90.4% retention over 10,000 repeated GCD cycles).