Non‐Substituted Aromatic Pyridine N‐Oxide Additives with an Intrinsic N →O Acceptor for Ultra‐Long‐Life Zn||MnO2 Batteries

Various organic and inorganic reagents containing N/O functional groups have been developed as additives to aqueous electrolytes (e.g., ZnSO4, ZS) of zinc‐ion batteries (ZIBs). However, finding an additive that can significantly enhance the durability of Zn anodes by inhibiting Zn dendrites and side reactions remains a considerable challenge. Herein, pyridine N‐oxides (PNO), a non‐substituted aromatic compound with a nitrogen positive charge‐induced N→O bond, are explored as ZS additives for highly durable Zn plating/stripping electrolytes (i.e., PNO/ZS). The optimized PNO0.03/ZS mixture demonstrates exceptional stability for Zn anodes, achieving a cycle life exceeding 4200 h and a Coulombic efficiency of 99.9% at 1 mA cm‐2 and 1 mAh cm‐2. It maintains over 1000 h of life and a cumulative capacity of 2.5 Ah cm‐2, even when subjected to plating/stripping conditions intensified by a factor of 5. Importantly, it enables Zn||α‐MnO2 cells to sustain high‐current charge/discharge cycles for over 5000 cycles, retaining 80% (~125 mAh g‐1) of the initial capacity, which is the best performance reported for similar additive systems. This exceptional stability is ascribed to the highly reversible Zn anode plating/stripping, facilitated by the suitable coordination interactions between the N→O acceptor of PNO and the Zn2+/H2O donor, effectively inhibiting side reactions.