Iodide Anion Anchoring by Silver Nanoparticles Enables Shuttle-Free Zinc-Iodine Batteries

Zinc-iodine (Zn-I₂) batteries are gaining popularity due to cost-effectiveness and ease of manufacturing. However, challenges like the polyiodide shuttle effect, sluggish conversion kinetics, and Zn dendrite growth hinder their practical application. Herein, we reported to design 'ship-in-bottle' structured polyiodide electrocatalyst to simultaneously prevent the shuttle effect and promote the catalytic conversion of polyiodides. The implanted ultrafine Ag nanoparticles inside the carbonaceous framework can offer potent active centres to confine the I^- and facilitate the I^-/I₂ conversion through the adsorption of I^- by forming AgI. Meanwhile, the generated AgI further contributes to anchoring the polyiodides, effectively suppressing its shuttle effect. The strong hybridization between Ag d orbitals and iodine p orbitals enables efficient charge transfer during conversion. Therefore, the Zn-I₂ battery exhibits high discharge capacity over 200 mAh g^-1, excellent rate capability up to 10 A g^-1, and long-term cycling stability (30 000 cycles at 6 A g^-1). The practicality is also validated via pouch cell with impressive energy density of 180 Wh kg^-1 based on the cathode and excellent cycling stability over 500 cycles, enlightening the material engineering for catalyst design towards rapid polyiodide conversion. Our findings offer valuable guidance for the development of high-performance Zn-I₂ batteries.