Establishing Ohmic contact with ultra-thin semiconductor layer through magnetron sputtering for dendrite-free Zn metal batteries

Abstract

The improvement in reversibility and kinetics for Zn metal anodes is crucial to facilitate the further application of aqueous zinc ion batteries. However, the abnormal surface-caused dendrites and parasitic reactions significantly impede the commercial application. Herein, we established Ohmic contact by fabricating an ultrathin semiconductor ZnTe (∼150 nm) layer on the Zn surface via magnetron sputtering to form an electron enrichment region for zinc ions attraction. Particularly, the ZnTe with a higher work function than that of Zn could render a spontaneous electron transfer from Zn to ZnTe, accelerating the zinc ions diffusion, and repelling water and negative sulfate radicals. As a result, the ultrathin ZnTe layer decreases the nucleation and deposition barrier of Zn leading to homogeneous deposition, and restrains the Zn from corrosion and hydrogen evolution reaction. The ZnTe-modified symmetric cells can stably cycle for over 2,400 h and 1,100 h at current density 1 mA cm−2 with area capacity of 1 mAh cm−2 and 5 mAh cm−2, respectively. The full cell matched with CaV8O20·nH2O shows a 63 % capacity retention after 3,000 cycles at 3 A/g. Our work demonstrates that the construction of Ohmic contact could be an effective way to obtain highly reversible Zn anodes and promote the development of aqueous zinc ions batteries.