Rational design of hierarchical hollow-core dual-shell amorphous 3D nanospheres as an effective electrode material for hybrid supercapacitors†

Abstract

Extensive research in energy storage has aimed to develop materials with exceptional morphological and electrochemical characteristics. In this report, we synthesized novel cobalt copper zinc (CCZ) nanospheres with a multilayered core–shell structure using a simple hydrothermal process, followed by low-temperature wet chemical synthesis. By optimizing the reaction time, we developed three-dimensional hierarchical CCZ nanospheres with a core–shell structure and hollow interior. The optimized CCZ-8 (8 h) hollow-core single-shell nanospheres exhibited an impressive areal capacity of 53.7 μA h cm⁻² (29.8 mA h g⁻¹). To further enhance performance, the CCZ-8 material underwent wet chemical treatment using an ionic solution at low temperature, transforming it into Ni@CCZ-8 hollow-core dual-shell nanospheres. This modification significantly increased the areal capacity to 124.46 μA h cm⁻² (76.06 mA h g⁻¹), with a cycling stability of 87.4% over 20 000 charge/discharge cycles. For validation, Ni@CCZ-8/Ni foam was used as a positive electrode in a pouch-type hybrid supercapacitor (HSC). The HSC achieved a peak energy density of 100.77 μW h cm⁻² (25.58 W h kg⁻¹) and a maximum power density of 7500 μW h cm⁻² (1923.07 W h kg⁻¹) with robust cycling stability. The HSC's performance was demonstrated by powering radio-remote-operated electronics and other real-time applications. This study not only advances nanomaterial-based energy storage devices but also highlights their practical potential in real-world applications.