Ultra‐Trace Electrolyte Additives for Ah‐Level Zinc‐Ion Batteries Through Lattice‐Matching Strategy

ABSTRACT Aqueous zinc ion batteries (AZIBs) represent a highly promising technology; however, practical deployment remains impeded by uncontrolled dendritic growth and side reactions. To address these fundamental limitations, the rational design and synthesis of a novel electrolyte additive is reported here, guided by the lattice matching principle, in which thioctic acid (TA) is covalently grafted onto an Anderson‐type polyoxometalate (POM). During electrochemical operation, TA moieties selectively adsorb onto the Zn anode surface and undergo in situ electrochemical polymerization. Due to the Zn–S interaction, Zn 2+ preferentially bind to the sulfur rich polymer chains with a periodic distance of 4.62 Å for S···S, which is perfect in agreement with the distance of zinc atoms (4.55 Å) along [10] direction within (002) crystal plane, thereby inducing the atomic level deposition of Zn 2+ . The Zn||I 2 cell exhibits outstanding longevity, retaining stable performance for more than 20 000 cycles at 10 A g −1 . Furthermore, a pouch battery with 1.6 Ah capacity retains over 99% of its initial capacity after 325 cycles. Remarkably, even at an ultralow concentration of 0.001%, the prepared electrolyte additive can enhance cycling stability. Through this work, an ultra‐trace additive‐enabled, atomic‐scale interfacial engineering paradigm for AZIBs is established.