Electrodeposited Zinc-Based Films As Anodes for Aqueous Zinc Batteries

Abstract

In the past thirty years, there has been significant development in the search for alternative energy sources such as secondary battery systems. Zinc (fourth-most mined material) has attracted much attention due to its abundance, low-cost, and recyclability. More-over, as Zinc-based batteries can be manufactured with aqueous-based electrolytes, this allows for competition with Lithium-ion batteries, but with the advantage of enhanced safety. Zinc-based batteries (MnO2/Zinc) have been previously commercialized and are one of the dominant technologies in the battery market. However, the alkaline MnO2/Zinc battery is not currently considered re-chargeable due to the formation of zinc-dendrites, passivation of Zn metal, and cathode poisoning. In contrast to the alkaline system, the mild acidic system does not suffer from zinc passivation as there is negligible generation of zinc oxide/zinc hydroxide.In this work, we report a proof-of concept work where electrodeposited zinc-based anodes (zinc and copper-zinc) are used in mild aqueous zinc batteries. The study provides a comparison of commercial zinc foil, and electrodeposited zinc/copper-zinc in a mild aqueous zinc battery. Prior to this comparison, electrodeposition conditions are determined by cyclic voltammetry. The three anodes are further compared structurally through X-ray diffraction and scanning electron microscopy. Further electrochemical characterization was carried out in coin cells as symmetric/asymmetric and full cells to evaluate the feasibility of each anode. The electrodeposited zinc-based anodes exhibit low electrode polarization (~0.025V), and stable cycling performance from 0.25-10 mA cm-2 compared to commercial zinc foil. Coulombic efficiencies at 1 mA cm-2 were over 98% for the electrodeposited zinc-based materials and were maintained for over 100 cycles. Furthermore, full cells with an electrodeposited zinc and brass anode, EMD MnO2 cathode, in 1M ZnSO4 + 0.1M MnSO4 delivered capacities of 96.3, and 163 mAh g-1, respectively, at a 100 mA g− 1 compared to 92.1 mAh g-1 for commercial zinc. Lastly, the zinc-based anodes also show better rate capability at a current density of up to 3 A g-1.