Hierarchical CuO@ZnCo–OH core-shell heterostructure on copper foam as three-dimensional binder-free electrodes for high performance asymmetric supercapacitors

Abstract Rational architecture design and ingenious electrochemical performance optimization are highly desirable in developing high-performance asymmetric supercapacitors. Herein, a facile electrodeposition strategy is adopted to construct the hierarchical core-shell architecture of binary transitional metal hydroxide nanosheets anchored on copper foam ( CF) supported three-dimensional (3D) CuO scaffolds. The synergistic contributions from different electro-active components are maximized by the heterostructures construction and components optimization. As a result, the 3D binder-free electrode of CF supported CuO@Zn1Co2-OH core-shell heterostructure achieve a high areal capacitance of 2.634 F cm−2 at 5 mA cm−2, enhanced rate performance (71.6% retention at 30 mA cm−2), and long durability (99.1% after 4000 cycles). Additionally, a CuO@Zn1Co2–OH//LSDC (loofah sponge derived carbon) asymmetric supercapacitor (ASC) is assembled with an operating voltage of 1.5 V. The ASC device delivers a maximum energy density of 0.21 mW h cm−2 (22.10 W h kg−1) at a power density of 4.08 mW cm−2 (434 W kg−1), and exceptional cycling stability (91.7% of capacitance retention after 4000 cycles). Of practical importance, this work broadens our horizons in fabricating novel hierarchical core-shell heterostructures for next-generation electrochemical energy-storage technologies.