Aqueous Zinc–Organoiodine Battery with High Kinetics and Dense Cathodes

As a promising candidate for sustainable and safe energy storage systems, aqueous zinc-ion batteries have garnered significant attention. Even though organic compounds have advantages, their limited electronic conductivity, solubility of redox intermediates, and low utilization of active groups limit the practical applicability. Here, through the innovative design of a charge-transfer complex between phenazine (PNZ) and iodine (I₂), PNZ-I₂ exhibits greatly improved conductivity, enabling fast reaction kinetics and dense cathodes with a mass loading of nearly 60 mg·cm^-2. The formation of N-H···I hydrogen bonds reduces the solubility of intermediates, leading to exceptional long-term cycling stability. At a high current density of 3.0 A·g^-1, the battery retains 92% of its capacity after 4500 cycles. A record-stable aqueous (1.1 Ah) AZIB maintains 70% capacity retention after 700 cycles. The recyclability of PNZ-I₂ after cycling in batteries and low cost are directly related to renewable energy and transformative energy technologies.