Zinc-dual-halide complexes suppressing polyhalide formation for rechargeable aqueous zinc–halogen batteries

Abstract

Aqueous zinc–halogen batteries suffer from poor coulombic efficiency and short cycle life owing to the formation and dissolution of polyhalides in electrolytes. Herein, we apply a zinc-dual-halide complex strategy to confine free halides and suppress polyhalide formation. The high stabilities of zinc-dual-halide complexes are identified to be essential for effective confinement. The resulting Zn–Br₂ and Zn–I₂ cells deliver excellent rate capability and cycling stability, as well as high coulombic efficiency and energy efficiency.