Non‐Substituted Aromatic Pyridine N‐Oxide Additives with an Intrinsic N→O Acceptor for Ultra‐Long‐Life Zn||MnO 2 Batteries

Abstract Various organic and inorganic reagents containing N/O functional groups have been developed as additives to aqueous electrolytes (e.g., ZnSO 4 , 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‐oxide (PNO), a non‐substituted aromatic compound with a nitrogen positive charge‐induced N→O bond, is explored as ZS additives for highly durable Zn plating/stripping electrolytes (i.e., PNO/ZS). The optimized PNO 0.03 /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 ‐MnO 2 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 Zn 2+ /H 2 O donor, effectively inhibiting side reactions.