Bilateral Stabilization Enabled by Electrostatic Interaction Within Zwitterionic Additives Toward Long‐Life Aqueous Zinc Iodine Batteries

ABSTRACT Aqueous zinc‐iodine (Zn‐I 2 ) batteries are promising energy storage devices due to their low cost and high safety. However, their widespread application is hindered by hydrogen evolution reactions (HER), Zn dendritic growth, and polyiodide shuttle. To solve these issues, zwitterionic choline alfoscerate (CAF) is used as a multi‐functional electrolyte additive to stabilize the Zn anode and I 2 cathode simultaneously based on electrostatic interactions, thus extending the cycling life of the Zn‐I 2 battery. At the I 2 cathode, the [─N(CH 3 ) 3 ] + functional groups in CAF electrostatically capture I 3 – with a high adsorption energy of −0.59 eV, thus inhibiting the polyiodide shuttle. Concurrently, the [─(PO 4 )─] − groups in CAF adsorbed at the Zn interface reversibly capture H + and dynamically neutralize OH − , maintaining a stable local pH and thus depressing the HER. The H 2 evolution rate in the CAF‐modified electrolyte decreases to 31.53 µmol h −1 cm −2 , representing a 1.77‐fold reduction compared to that in the baseline electrolyte. Additionally, these phosphate groups serve as zincophilic sites that promote homogeneous Zn 2+ deposition, avoiding dendrite formation. Benefiting from this dual‐electrode stabilization, a Zn‐I 2 full cell paired with a high‐mass‐loading I 2 cathode (13.2 mg cm −2 ) cycles stably for over 15 000 cycles at 2 A g −1 .