Ragone plots for the reported energy densities for the representative state-of-the-art Zn-air and Zn-ion batteries including liquid and solid electrolytes. The theoretical limit of cell energy and the year 2030 cell energy target for the United States, Department of Energy (US DOE) are shown. Two black dotted lines display the boundaries of 60% and 5% depth of discharge (DOD). Square and circle symbols correspond to the reported values from zinc-air and zinc-ion batteries, respectively, and the filled color reflects the number of operating cycles. TheEgis the reported gravimetric energy density. Please see the Experimental Section and Tables1and S1,Supporting Information for more details about specific energy and cell parameters. The dotted lines in (b), (c), (d), and (e) show the optimal values for ultrahigh energy densities with long cycle life.
