Extended iodine chemistry: Toward high-energy-density aqueous zinc-ion batteries

Aqueous zinc-ion batteries are appealing owing to their high safety and low cost; however, the low energy density hinders their wide applications. Recently in Nature Communications, Liang and coworkers reported a Zn-I₂ battery that enables a reversible four-electron I⁻/I₂/I⁺ conversion, which exhibits high voltage and capacity, high energy density, and excellent cycling performance.