Stable Sn@Cu foam enables long cycling life of zinc metal anode for aqueous zinc batteries

Aqueous zinc batteries (AZBs) hold great promise for advancing applications in next-generation energy storage devices because of their high safety, high energy density, and low cost. However, zinc metal anodes have greatly impeded the application in AZBs due to their poor cycle performance. Short lifespan, which is caused by dendritic growth, deformation, corrosion, and competing hydrogen evolution, is very tricky. Herein, a stable Sn@Cu foam, prepared by plating tin on copper foam, is reported as the substrate of Zn anodes. We evaluate the quality of plating tin layers, which are prepared by using different tin salt solutions, and Na2SnO3 solution is eventually selected. Electrochemical tests show that Sn@Cu foam can not only inherit the merits of Cu foam but also suppress hydrogen evolution reaction and lower the initial heterogeneous nucleation barrier of deposited Zn. Moreover, in situ observation by optical microscope demonstrates that Zn dendrite growth on Sn layer is suppressed during the plating-stripping process. As a result, a compact Zn layer on Sn@Cu foam is obtained (Zn/Sn@Cu foam), symmetrical cells display superior cycling life of 1800 h at 1 mA cm(-2) for 1 mAh cm(-2), and full cells with VO2 cathode deliver remarkably better cycling stability and longer lifespan.

Automated summary

This study reports a stable Sn@Cu foam prepared by plating tin on copper foam as a substrate for zinc anodes. The Sn@Cu foam not only inherits the advantages of the copper foam but also suppresses hydrogen evolution reaction and lowers the initial heterogeneous nucleation barrier of deposited zinc. In situ observation confirms the suppression of zinc dendrite growth on the Sn layer. As a result, a compact zinc layer on Sn@Cu foam is obtained, which exhibits a longer cycling life and better cycling stability.