Green Synthesis of Zinc Sponge Opens Sustainable Battery Supply Chains

Scientists have devoted significant efforts highlighting the need for batteries that enable the use of sustainable energy sources such as wind and solar but have paid much less attention to the need for sustainable batteries. We seek to identify sustainable, rechargeable batteries and to create simplified, high-performance, low-cost battery electrodes. 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 lowers the cost of rechargeable Zn-sponge electrodes by 74%. We test these electrodes in Zn–air cells and demonstrate a 3,200% increase in rechargeable areal capacity over the majority of previously reported work.