Heterogeneous Electric Double Layer with Ion-Transport Pathways for Practical Zinc-Ion Batteries

Manipulating the electric double layer (EDL) structure at nanoscale remains largely underexplored yet extremely challenging for practical Ah-level aqueous zinc-ion batteries (AZIBs). Here, we construct a heterogeneous nanostructured EDL with intrinsic ion-transport pathways via cation-anion coordination strategy, which synergistically enhances the thermodynamic stability and kinetic reversibility of the Zn anode. In-situ characterizations and theoretical simulations demonstrate that the long-chain ionic additive triggers the interfacial ion rearrangement and assembly within the EDL, where hydrophobic carbon chains self-aggregate into dense apolar nanodomains, and cationic groups electrostatically attract anions and co-assemble to form interconnected polar nanodomains. This uniquely heterogeneous EDL thermodynamically confines H₂O activity and efficiently inhibits side reactions. Meanwhile, the interconnected polar ion-transport pathways accelerate Zn²⁺ migration and desolvation kinetics, achieving an ultrahigh Zn²⁺ transference number (0.89) and dendrite-free Zn deposition. Consequently, Zn//Zn cell delivers stable cycling over 1,200 h (25 mA cm^-2, 12.5 mAh cm^-2) and Zn//NVO full cell retains 100% capacity after 30,000 cycles at 5 A g^-1. Furthermore, 0.2-Ah and 1.1-Ah pouch cells exhibit stable operation for 2,500 and 257 cycles, respectively. This work establishes a new paradigm for EDL nanostructure engineering, advancing practical AZIBs.