In Situ Fabricated Poly(1,8‐naphthalenediamine)/Active Carbon Composite Cathodes for Aqueous Zinc‐Ion Batteries with High Active Sites Utilization and Ultralong Life Span of 50 000 Cycles

Abstract Polymers with redox activity are one type of promising candidates of cathode materials for aqueous Zn‐ion batteries due to their potential low‐cost, high safe, and renewable features. Unfortunately, suboptimal polymer electrode structure often results in unsatisfactory electrochemical performance. Herein, poly(1,8‐diaminonaphthalene)/active carbon composite electrodes are prepared via nanoconfined in situ electropolymerization within porous active carbon, which have ultrahigh specific surface area (1035.0 m² g⁻¹) and unique nano‐porous structure, thereby highly enhancing the utilization of the active site up to 91.6%. The as‐prepared cathodes deliver ultrahigh reversible capacity of 479.5 mAh g⁻¹, ultrafast rate capability of up to 60 A g⁻¹ and an ultralong life span of 50,000 cycles. Storage mechanism investigation indicates that the cathode material involves a bipolar‐type behavior. These encouraging results demonstrate that nanoconfined in situ electropolymerization in active carbon is a brand‐new strategy for the design of advanced polymer electrodes for high‐performance aqueous Zn‐organic batteries.