In-situ regulation of zinc metal surface for Dendrite-Free Zinc-ion hybrid supercapacitors

Aqueous Zn-ion hybrid supercapacitors (ZHSCs) combine the high power density of supercapacitors with the high energy density of batteries. However, the growth of dendrite and spontaneous Zn corrosion damage the service life of ZHSCs and further seriously restrict their large-scale application in energy storage fields. Herein, we study the corrosion mechanism of Zn metal in ZnSO4 solution and report a method for the modification of Zn anode with zeolitic imidazolate framework-8 (ZIF-8) layer grown in-situ. The obtained ZIF-8 layer with hydrophobicity can not only inhibit Zn corrosion and induce Zn electroplating/peeling on the Zn surface, but also promote uniform deposition of Zn during charge/discharge processes. As a result, the prepared dendrite-free Zn electrode shows low polarization (89.0 mV at 10 mA cm-2) and high cycling stability (over 800 h at 10 mA cm-2), and the developed ZHSC maintains a high capacity retention of 96% after 13,000 cycles at 5 A g-1. Furthermore, a solar power supply system is assembled by the ZHSC and monocrystalline silicon plates to certify the utility of the device, and it can light a LED successfully. This study provides a simple and inexpensive strategy to manipulate the Zn electrodeposition behavior from dendrites to non-dendritic structures, which builds a way for the development of practical ZHSCs with mild electrolytes.