Plant root cell-inspired interphase layer for practical aqueous zinc-iodine batteries with super-high areal capacity and long lifespan

Abstract

Aqueous zinc-iodine batteries are of considerable interest for stationary energy storage because of safety and cost-effectiveness. Nonetheless, the unstable Zn anode/electrolyte interface and shuttling of polyiodides during cycling have hinered their progress. Herein, these two issues are synergistically addressed by designing a plant root cell-inspired Ti2O(PO4)2·2H2O/ι-Carrageenan (TOP/Carra) interphase layer on metallic Zn surface. The outer flexible Carra polymer with abundant -SO3- groups, functions similarly to the epidermis of plant roots, dynamically absorbing Zn2+ cations and repelling detrimental SO42- and I3- anions through electrostatic interactions. Furthermore, the inner robust TOP nanorods, with high Zn2+ ion diffusion coefficients, serve as vascular tissues, facilitating homogenous Zn2+ ion flux through rapid one-dimension ion diffusion channels. Based on the stabilized Zn anode interphasial chemistry, the Zn@TOP/Carra electrode exhibits highly reversible Zn deposition behavior with suppressed interfacial parasitic side reactions. Consequently, the Zn@TOP/Carra electrode demonstrates an outstanding lifespan of over 6000 hours and enables the operation of Zn@TOP/Carra||I2 full battery at an ultra-high areal capacity of 5.77 mAh cm-2 after 4500 cycles, which is one of the best high-areal-capacity cycling stabilities to date. Most importantly, the resulting high-energy Ah-level pouch cell (1.05 Ah) also delivers competitive capacity retention of 80% after 500 cycles, demonstrating the potential for practical applications.