A Particle‐Level Dual‐Polymer Interphase for Coupled Interfacial and Contact Stabilization of Zinc Metal Powder Anodes in Aqueous Zinc‐Ion Batteries

ABSTRACT Zinc metal powder (ZnMP) anodes offer a practical strategy for aqueous zinc‐ion batteries (AZIBs). However, the curved and discontinuous ZnMP surfaces enlarge the Zn/electrolyte interface, accelerating hydrogen evolution and surface corrosion. Point contacts and limited electronic pathways further cause nonuniform current distribution and Zn 2+ flux, leading to uneven Zn deposition and contact loss. Here, a dual‐polymer interphase composed of carboxymethyl cellulose (CMC) and poly(acrylic acid) (PAA) on ZnMP (C/P@ZnMP) is reported. The CMC matrix regulates the local aqueous environment and suppresses water‐related interfacial degradation, while PAA provides abundant carboxyl/carboxylate sites with relatively high Zn 2+ affinity. Their integration balances PAA‐derived Zn 2+ affinity with CMC‐mediated interfacial stabilization and limits byproduct accumulation. The hydrophilic C/P interphase improves electrolyte infiltration into the particulate ZnMP electrode, helping alleviate electrical contact loss within the powder framework. C/P@ZnMP enables stable Zn plating/stripping for over 1500 h at 2 mA cm −2 and 1 mAh cm −2 . The C/P@ZnMP‖V 2 O 5 coin cell retains 85.5% of its initial capacity after 1000 cycles at 5 A g −1 , and the 4 × 3 cm 2 C/P@ZnMP‖V 2 O 5 pouch cell retains 89.2% of its initial capacity after 1000 cycles at 0.5 A g −1 , demonstrating the potential of dual‐polymer interphase engineering for practical ZnMP‐based AZIBs.