Porous Organic Cage–Based Biomimetic Nanochannels: A Tailorable, Ion‐Sieving Interfacial Strategy for Aqueous Zinc Batteries and Beyond

Abstract Rechargeable aqueous zinc‐ion batteries (RAZBs) rely on efficient and selective cation shuttling; however, hydrated Zn 2+ causes hydrogen evolution, Zn dendrite growth, as well as cathode corrosion at high areal capacities. Inspired by cation migration through biological membranes, an interfacial strategy employing porous organic cages (POC) is developed with tunable spatial and charge properties to regulate multiscale ion diffusion in RAZBs. Zincophilic Ag sites are confined in RCC3‐type POC sub‐nanometer pores to suppress water‐induced degradation while enabling high‐flux dehydrated Zn 2+ transport via biomimetic ion pumps. This ultrathin interfacial layer (1.6 µm, ACE) facilitates dendrite‐free Zn cycling (>1300 h, 68.4% DOD at 10 mA cm −2 ). Simultaneously, a positively charged POC modification suppresses polyiodide shuttling in high‐loading I 2 cathode (2.2 mAh cm −2 ), enabling the RCC3 + /I 2 ||ACE@Zn prototype (N/P = 3.3) to achieve 71.4% self‐discharge suppression and retain 88% capacity over 1000 cycles at 1 A g −1 . Alternatively, negatively charged POC coating inhibits V 2 O 5 cathode amorphization through vanadyl species chelation while sustaining rapid Zn 2+ diffusion across the interface to bulk phase, as confirmed by operando phase/impedance tracking of RTP‐CC3 − /V 2 O 5 ||ACE@Zn pouch‐format cells (N/P = 3.9). This bioinspired ion‐sieving approach, via tailored POC chemistry, establishes a versatile interfacial paradigm, demonstrating generic applicability for high‐performance energy storage systems even beyond RAZBs.