In Situ Electropolymerization‐Induced Interfacial Electrostatic Regulation Enables Dendrite‐Free Aluminum Anodes for Ultralong‐Life Rechargeable Aluminum Batteries

ABSTRACT Rechargeable aluminum batteries (RABs) have attracted considerable attention for large‐scale energy storage owing to their safety, low‐cost, and high energy density. Nevertheless, their cycling life is severely compromised by the corrosive nature of ionic liquid electrolytes and dendrite growth, particularly under high current densities. Herein, we propose an in situ electropolymerization strategy to fabricate a protective polymeric membrane on the Al anode from functional ionic liquid monomers, 1‐butyl‐3‐vinylimidazolium chloride (BVIMCl). The in situ‐formed polymeric membrane can not only serve as a physical barrier that effectively suppresses anode corrosion but also homogenizes the interfacial electric field through electrostatic attraction. This dual functionality guides the ordered migration of Al 2 Cl 7 − anions and promotes a uniform ion flux, enabling highly reversible Al plating/stripping and dendrite‐free Al deposition. Consequently, the Al/Al symmetric cell delivers stable cycling for over 1000 h at 5 mA cm − 2 and 5 mAh cm − 2 , achieving a high critical current density of 8.5 mA cm − 2 . More remarkably, the Al/Graphite full cell demonstrates an ultralong lifespan of over 80 000 cycles at 5 A g − 1 . This work not only provides a facile and scalable strategy for stabilizing Al anodes but also establishes polymer‐mediated interface engineering as a promising paradigm for developing high‐performance RABs.