Enabling high-areal-capacity zinc-iodine batteries: Constructing high-density microporous carbon framework with large surface area

The aqueous zinc-iodine batteries hold great potential for next-generation energy storage device owing to their exceptional advantages in cost-effectiveness and intrinsic safety. However, the iodine loading is below 2 mg cm−2 in most of the reported aqueous zinc-iodine batteries, resulting in a low practical energy density, which is still the key challenge in implementing their practical applications. Herein, the hierarchical porous carbon with high-density microporous was successfully prepared by a sample one-step alkali activation strategy using 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) as carbon source. The resultant product possesses a large specific surface area (2693 m2 g−1), a typical three-dimensional framework comprised of high-density microporous (Vmicropore = 0.77 cm3 g−1) with suitable pore size distribution, together with an appropriate oxygen doping. Benefiting from the efficient physical adsorption of high-density micropores, the iodine electrode demonstrated low polarization, high iodine utilization and excellent electrochemical stability. The assembled Zn-I2 battery exhibited high discharge capacity (140.7 mAh g−1 at 0.1 A g−1) and capacity retention (∼ 90% retention upon 6000 cycles). Most importantly, ultra-high area capacity of 2.89 mAh cm−2 can be obtained with a loading of 24 mg cm−2 electrode, showing superior application potential.