Low-cost green synthesis of zinc sponge for rechargeable, sustainable batteries

Policy makers and consumers push for sustainable batteries that rely on abundant, recyclable materials with accessible, stable supply chains. Growing concerns over lithium-ion battery safety, recyclability, and reliance on shrinking cobalt reserves prompt efforts to advance alternative chemistries. To identify promising candidates, we review supply-risk data and the abundance of battery-relevant elements in the Earth's upper continental crust. We find that of the rechargeable-battery chemistries that rely on abundant low-risk elements, zinc (Zn) batteries, namely Zn–MnO2 and Zn–air, are the lowest cost and most energy dense. Guided by this analysis, we advance Zn batteries by reporting a green synthesis that dramatically lowers the cost and boosts the performance of rechargeable Zn-sponge electrodes. We test these electrode architectures in Zn–air cells and demonstrate a 3200% increase in rechargeable areal capacity over the majority of previously reported studies.