Liquefaction electrochemistry evolving liquid-gas conversion to liquid-liquid modes of zinc||chlorine batteries.

The chlorine-based batteries exhibit persistent issues with the evolution of toxic gaseous chlorine at ambient temperatures, which severely compromise conversion reversibility, cycling stability, and corrode vital battery components, despite their promising capacity and voltage. Here, we propose the coordination-locked liquefaction electrochemistry mediated by ionic liquid for constructing energetic aqueous zinc||chlorine batteries based on liquid-liquid modes. The amphiphilic ionic liquid nanoclusters optimize the halogen conversion mechanism, Zn redox, and electrolyte stability. Consequently, the zinc||chlorine battery shows long-term durability with 0.0017% capacity fade per cycle over 10000 cycles at 10.0 A g-1, a large capacity of 541.9 mAh g-1Cl at 1.0 A g-1, and a high discharge voltage plateau of 1.78 V at 1.0 A g-1. The activated one-step liquid-liquid conversion modes eliminate gas formation, corrosion, and the need for non-standard components. The synergistic interplay of multifaceted spectroscopy and computational modeling uncovers the halogen redox mechanism and the mass-charge transfer process. Furthermore, the universality and efficiency of the emergent redox electrochemistry are verified across zinc||iodine and zinc||bromine batteries, spanning conventional two-electron and frontier four-electron transfer mechanisms. This work unlocks halogen electrochemistry and establishes a transformative blueprint for designing high-performance halogen batteries.