Perovskite Cathodes for Aqueous and Organic Iodine Batteries Operating Under One and Two Electrons Redox Modes

Although conversion-type iodine-based batteries are considered promising for energy storage systems, stable electrode materials are scarce, especially for high-performance multi-electron reactions. The use of tin-based iodine-rich 2D Dion-Jacobson (DJ) ODASnI₄ (ODA: 1,8-octanediamine) perovskite materials as cathode materials for iodine-based batteries is suggested. As a proof of concept, organic lithium-perovskite and aqueous zinc-perovskite batteries are fabricated and they can be operated based on the conventional one-electron and advanced two-electron transfer modes. The active elemental iodine in the perovskite cathode provides capacity through a reversible I^- /I⁺ redox pair conversion at full depth, and the rapid electron injection/extraction leads to excellent reaction kinetics. Consequently, high discharge plateaus (1.71 V vs Zn²⁺ /Zn; 3.41 V vs Li⁺ /Li), large capacity (421 mAh g^-1 _I ), and a low decay rate (1.74 mV mAh^-1 g^-1 _I ) are achieved for lithium and zinc ion batteries, respectively. This study demonstrates the promising potential of perovskite materials for high-performance metal-iodine batteries. Their reactions based on the two-electron transfer mechanism shed light on similar battery systems aiming for decent operational stability and high energy density.