A High-Performance Quasi-Solid-State Aqueous Zinc–Dual Halogen Battery

Aqueous zinc-based batteries are promising candidates for the grid-scale energy storage owing to their nonflammability, ecofriendliness, and low cost. Nevertheless, their practical applications are hindered by the relatively low capacity and energy density. Herein, we develop a quasi-solid-state aqueous zinc-dual halogen battery composed of freestanding carbon cloth-iodine cathode and in situ prepared concentrated aqueous gel electrolyte. The freestanding composite cathode and aqueous gel electrolyte can afford iodine source and bromide ions, respectively, thus activating the I-/I0/I+ reaction by forming [IBr2]- interhalogen. Furthermore, the conversion reaction of Br-/Br0 in [IBr2]- interhalogen is stimulated due to the catalytic effect of iodine. Therefore, this rationally designed aqueous dual halogen conversion chemistry enables three successive redox reactions (i.e., I-/I0, I0/I+, and Br-/Br0). Additionally, the LiNO3 additive and acrylamide (AM)-based polymer matrix not only stabilizes the anode/electrolyte interface but also restrains the side reactions and dissolution/diffusion of active species. Consequently, the as-assembled aqueous zinc-dual halogen battery exhibits high areal capacity and energy density.