High performance rechargeable aqueous zinc-iodine batteries via a double iodine species fixation strategy with mesoporous carbon and modified separator.

With the increasing requirement for high capacity energy storage systems, a large amount of recent work has focused on the development of zinc-iodine batteries (ZIBs) on account of high energy density, fast redox kinetics, and excellent reversibility. Nevertheless, low electron conductivity, the shuttle effect, and highly soluble iodine species (I, I, and I) have impeded their widespread application. In this study, metal organic framework-5 (MOF-5)-derived mesoporous carbon (MPC) loaded iodine (MPC/I) cathode and the single-sided ketjen black modified cotton fiber (KB@CF) separator are designed to solve the problems mentioned above. That is, the double fixation strategy using MPC and KB@CF separators for iodine species suppresses the shuttle effect. Therefore, the ZIBs constructed with the MPC/I cathode and the KB@CF separator can exhibit excellent electrochemical performance. At the current density of 0.1 A g, a high discharge specific capacity of 137 mAh g is still available after 300 cycles. Meanwhile, it exhibits a low capacity decay rate at long cycling (0.030% per cycle over 2000 cycles).