Projecting the Specific Energy of Rechargeable Zinc-Air Batteries

Commercial primary zinc-air batteries provide 450 Wh kg(cell)(-1) (at the cell level), but the practical specific energy of secondary zinc-air batteries remains unclear. Using a specific-energy model and data from reported zinc-air cells, we show that some rechargeable zinc-air electrode materials may already be capable of enabling system-level specific energies between 200 and 450 Wh kg(sys)(-1). These values rival best-case projections for battery packs using lithium-sulfur, lithium metal paired with layered metal oxides, or open lithium-air. By performing a sensitivity analysis on the reported specific-energy model, we show that depth of discharge, areal discharge capacity, and solid-volume fraction of the porous Zn electrode are the most important fYi parameters for increasing specific energy, rather than discharge voltage. To achieve a high specific energy, bipolar zinc-air cells need to cycle above 40% depth of discharge with areal discharge energies >100 mWh cm(geo)(-2).