Superior iodine reservoirs in phenazine−embedded heteronetworks for high areal capacity and anti−freezing zinc–iodine batteries

The advent of wearable electronics has highlighted the potential of flexible zinc−iodine (Zn–I2) batteries thanks to high theoretical capacity, affordability, and operational security. However, challenges impede their areal capacity, lifespan and low temperature adaptability. Herein, phytic acid doped polyaniline (PANI) array was integrated with multi–walled carbon nanotubes (CNTs) through scalable freeze−spraying technique to construct 3D heteronetworks as porous host cathode for superior iodine reservoir, more clearly, featuring hierarchical mesopores (1−100 nm), substantial mass loading (12 mg cm−2), and an enhanced specific surface area (57.2 m2 g−1). The systematic experiments and density functional theory (DFT) calculations together reveal that the synergistic combination of oriented nanofibers of PANI with phenazine segments and conductive CNTs can provide sufficient physicochemical confinement to suppress polyiodide migration. Meanwhile, the usage of water−in−salt (WIS) electrolyte can further inhibit the migration of polyiodide ion, and enable excellent reaction kinetics and low temperature adaptability. Thanks to the mechanically interlocked heteronetworks with rapid charge transfer, the fabricated Zn–I2 battery can reach a record capacity of 8.5 mAh cm−2, and extraordinary cumulative capacity of 4.779 Ah cm−2 in 1000 cycles. Furthermore, the assembled flexible battery exhibits an impressive capacity of 4.75 mAh cm−2 and retains 83.8 % of initial capacity after 5000 cycles. Notably, the device also demonstrates a capacity of 4 mAh cm−2 at −20 °C, low self−discharge behavior, and excellent flexibility. This work underscores the potential of efficiently constructing mesoporous heteroarchitecture to achieve advanced Zn–I2 batteries. [Display omitted] •3D hierarchical mesoporous heteronetworks were prepared by scalable freeze−spraying method.•CNTs provides elastic and conductive channels for enhanced stability and charge transfer.•Polyaniline with phenazine segments provides enhanced physicochemical adsorption of polyiodide.•Water in salt electrolyte with reduced water molecule ensures the long lifespan and low–temperature tolerance.•Delivering a record areal capacity of 8.5 mA h cm−2 in aqueous electrolyte, and 4.75 mA h cm−2 for flexible Zn–I2 battery.