Electrostatic shielding chemistry enabling reversible four-electron aqueous zinc-iodine batteries.

A divalent organic cation-mediated electrolyte provides stronger confinement of polyiodide species and interhalogen intermediates than its monovalent analogue, promoting reversible Br--assisted four-electron iodine redox while suppressing side reactions and regulating Zn deposition. Consequently, aqueous Zn-I2 batteries exhibit high capacity, enhanced rate capability and stable cycling over 2500 cycles.