Multiscale Interfacial Regulation of Zn‐V2O5 Pouch Cell via Ultrathin Molecular‐Engineered Separator

Abstract Rechargeable aqueous zinc batteries (RAZBs) suffer from the structural degradation of the layered oxide cathode, parasitic side reaction on the Zn foil as well as often‐overlooked self‐discharge phenomenon at the elevated temperatures. Herein, this study presents a thin‐layer (9 µm) molecular‐engineered separator strategy to achieve the concurrent shelf life, cycling endurance, as well as the practical energy density for the RAZBs prototype. On the face‐to‐cathode side, the biphthalic anhydride is anchored onto the polyethylene separator substrate (PE) via a robotic arm‐controlled spray‐coating method, inhibiting the spontaneous vanadium dissolution and shuttle at both the dynamic cycling or static high‐temperature storage; meanwhile the 3,3′‐diamino‐4,4′‐dihydroxydiphenyl sulfone molecular tailoring on the face‐to‐anode side provides ion‐sieving capability to repel detrimental SO 4 2− , yet guiding uniform Zn 2+ influx and preferential deposits accumulation along the (002) crystallographic orientation even at the extreme deposition scenario (20 mA cm −2 , 20 mAh cm −2 ). Upon the layer‐stacked assembly of the V 2 O 5 cathode (2.0 mAh cm −2 ), molecular‐engineered separator as well as the Zn foil (20 µm), the 0.78 Ah pouch‐format prototype exhibits the superior volumetric/gravimetric energy densities of 133.3 Wh L −1 /71.4 Wh kg −1 and extreme power output (444.3 W L −1 /238.0 W kg −1 ).