Achieving stable zinc metal anode by eliminating the surface heterogeneity

Abstract

Aqueous zinc-ion batteries (AZIBs) are regarded as one of the promising alternatives for lithium-ion batteries in large-scale energy storage systems. However, the further development of AZIBs is limited by the challenges related to the heterogeneity of zinc anode, which arises from the harmful micro-regions and the accumulation of corrosion products. We employ a simple and effective molecular self-assembly method to modify the anode with a homogeneous (Octadecanethiol) ODT molecular layer through the combination of zinc and sulfhydryl (-SH) groups. The molecular-scale modification method can precisely repair the harmful micro-regions and ensure the homogeneity of the surface. In addition, the hydrophobic alkyl chains of the ODT molecules inhibit the corrosion reaction, thus avoiding the enhancement of heterogeneity due to the accumulation of corrosion products. Theoretical calculations and simulations show that this homogeneous molecular layer effectively eliminates the surface heterogeneity and thus has a profound impact on the deposition process. Benefiting from above, all the ODT-Zn symmetrical batteries can cycle at 5 mA cm−2 for more than 1000 h. The full battery using MnO2 cathode can cycle for more than 1000 times with a capacity retention rate is 90 %.