A π‐Conjugated Polymer Anode With Railway‐Like NH 4 + Pathways for High‐Rate Aqueous Ammonium‐Ion Batteries

ABSTRACT Aqueous ammonium‐ion batteries (AAIBs) are promising energy storage systems, while the relatively large size and tetrahedral geometry of NH 4 + present challenges for its transport within electrodes. Herein, poly(5,8‐diaza‐1,4‐naphthoquinone) (PANQ) has been synthesized to facilitate NH 4 + transport in AAIBs. The π‐conjugated PANQ possesses a rigid, linear molecular structure. The straight intermolecular slits with uniformly distributed carbonyl sites form railway‐like NH 4 + pathways, enabling rapid ion transport through the dynamic formation and disruption of hydrogen bonds. The PANQ electrode delivers a high capacity of 286.8 mAh g −1 at 1 A g −1 in a 2 mol L −1 ammonium acetate electrolyte. Thanks to the rapid NH 4 + transport pathways, the electrode displays an excellent rate capability, retaining 161.7 mAh g −1 at 80 A g −1 . Moreover, it displays exceptional cycling stability over 10 000 cycles at 20 A g −1 . The PANQ electrode was employed as the anode in a PANQ//NiCo‐LDH AAIB (NiCo‐LDH represents the Ni‐Co layered double hydroxide cathode), retaining an energy density of 25.2 Wh kg −1 even at an ultrahigh power density of 23 320.2 W kg −1 . This study provides a high‐performance electrode candidate for AAIBs and a strategy for constructing rapid ion‐transport pathways to enable efficient NH 4 + storage and superior electrochemical kinetics.