ZnO/ZnS Core-Shell Nanowires Arrays on Ni Foam Prepared by Atomic Layer Deposition for High Performance Supercapacitors

Abstract

Nowadays, a great of attention has been paid to the rational design and fabrication of unique core-shell heterostructures for high performance supercapacitor electrodes. In this work, unique ZnO@ZnS core-shell nanowires (NWs) arrays on nickel foam are successfully prepared by combination of hydrothermal process and atomic layer deposition (ALD). Due to ALD's perfect 3D conformality, ALD ZnS nanofilm can be deposited uniformly and seamlessly on the backbone of ZnO NWs arrays. The ZnO@ZnS/Ni can be directly used as a binder-free supercapacitor electrode with excellent electrochemical performance. This unique electrode exhibits high specific capacitance of 227.0 F g−1 at the current density of 1.28 A g−1, which is much larger than that of commercial ZnS powders. More importantly, this unique core-shell electrode shows great rate capacity. 87.3% of capacitance can be remained when increasing the current density from 1.28 to 12.80 A g−1. Furthermore, this hierarchical structure shows ultrastable cycling ability, as no capacity fading is observed even after 20000 cycles of charge-discharge at high current of 12.80 A g−1. These results indicate that ALD is a powerful and promising technology to design and fabricate unique nanostructured electrode for high-performance supercapacitor applications.