Interfacial Modification of a Zn Anode by Amorphous Se toward Long-Life and Hydrogen Evolution-Free Aqueous Rechargeable Batteries

Abstract

The Zn anode in rechargeable aqueous Zn-ion batteries suffers from hydrogen gas evolution and dendrite growth, which are critical issues that make the battery impractical. Here, the Zn anode performance is greatly improved by coating an amorphous selenium overlayer with a simple chemical bath reaction process. The reduction of SeO 3 2− ions by the Zn metal leads to the formation of an amorphous Se layer, and the optimal reaction time that determines the thickness of the Se coating as well as the Zn anode performance is found to be 2 h. The symmetric cell using Zn@Se exhibits improved rate performance and an ultralong cycle life of 4500 h after being tested at 1 mA cm −2 and 1 mAh cm −2 , respectively. Compared to the bare Zn anode, the Zn@Se anode leads to a larger Zn 2+ transference number and reduced charge transfer resistance. The button-type MnO 2 ∥Zn@Se full cell exhibits higher capacity and a much longer cycle life compared to the counterpart using a bare Zn anode. Also, pouch-type MnO 2 ∥Zn@Se full cells with a high capacity of 9.7 mAh cm −2 are made to demonstrate the inhibition of hydrogen evolution and practical applications. It is found that the in situ formation of an amorphous ZnO nanosheet network induced by the amorphous Se overlayer plays a key role in enhancing the Zn anode performance.

New insights into the charge storage chemistry of polymer cathodes in aqueous Zn batteries

“…The amorphous Se protective layer, which can efficiently suppress the corrosion of Zn and H 2 evolution, was deposited onto the Zn foil through a chemical bath reaction process, as reported in our previous work. 16 In this work, the prohibition of H 2 in the beaker-based cell was further confirmed by our gas chromatography measurement (Fig. S2†).…”