Towards three-dimensional hierarchical ZnO nanofiber@Ni(OH)2 nanoflake core–shell heterostructures for high-performance asymmetric supercapacitors

Abstract

The design and synthesis of unique core–shell heterostructures for high-performance supercapacitors have exerted a tremendous fascination and have recently attracted intensive attention. In this paper, a three-dimensional ZnO@Ni(OH)₂ core–shell heterostructure is controllably synthesized through an electrospinning method combined with a hydrothermal approach. The as-prepared ZnO@Ni(OH)₂ heterostructures are investigated for their use as electrodes for supercapacitors, which exhibit excellent electrochemical performances such as ultrahigh specific capacitance (2218 F g⁻¹ at 2 mV s⁻¹) and superior rate capability even at a high scan rate. Moreover, the assembled asymmetric supercapacitor with the as-obtained ZnO@Ni(OH)₂ hybrid as the positive electrode and the porous carbon microfibers as the negative electrode yields a high energy density of 57.6 W h kg⁻¹ with a power density of 129.7 W kg⁻¹. Hence, the ZnO@Ni(OH)₂ hybrid holds great promise for high-performance energy storage applications.