Decoration of three-dimensional ZnO@Ni2P heterostructure nanoflake arrays: a novel electrode material for hybrid supercapacitors†

Abstract

The exploration of novel nanomaterials used as binder-free electrodes for constructing supercapacitors remains significant in the field of electrochemical energy storage and conversion. In this research, a novel three-dimensional ZnO@Ni₂P heterostructure nanoflake array is successfully embedded on the surface of nickel foam (ZnO@Ni₂P/NF) through an effective phosphating method followed by a hydrothermal process. The as-prepared ZnO@Ni₂P/NF electrode demonstrates an impressive specific capacity of 1482 C g⁻¹ at a current density of 1 A g⁻¹, retaining a high value of 880 C g⁻¹ even at 10 A g⁻¹. Its specific capacity is superior to that of ZnO/NF (780 C g⁻¹). Furthermore, a hybrid supercapacitor device, ZnO@Ni₂P NF//AC, is fabricated using ZnO@Ni₂P NF as the cathode and activated carbon (AC) as the anode. This device exhibits outstanding performance, achieving an impressive energy density of 102 W h kg⁻¹ with a power density of 11.6 kW kg⁻¹ at a current density of 1 A g⁻¹. Moreover, it demonstrates excellent cycling stability, retaining 88% of its capacity after 10 000 cycles at the same current density, highlighting its exceptional energy storage capabilities.