Organic Cocrystal Interface Engineering for Stable Aqueous Zinc‐Ion Batteries

ABSTRACT The water‐induced side reactions and sluggish ion migration kinetics of zinc metal anodes in aqueous zinc‐ion batteries (AZIBs) severely degrade the coulombic efficiency and lifespan. It is necessary to stabilize the zinc anode by constructing a functional interfacial layer. Here, organic cocrystals, self‐assembled from melamine (MA) and isophthalic acid (IPA), were introduced to form a supramolecular structure with an extensive hydrogen‐bond network between the zinc anode and the electrolyte. Both theoretical and experimental results indicate that these cocrystals can capture and isolate active water molecules from the zinc anode surface. Zinc‐affinity sites in the cocrystals, such as amino, carboxyl, and triazine groups, can enhance ion transport and promote uniform zinc deposition. It should be noted that the MA‐IPA@Zn//MA‐IPA@Zn symmetric cell remains stable and reversible for over 4200 h of plating/stripping cycles, and the MA‐IPA@Zn//NVO full cell retains 77.87% of its capacity after 2000 cycles at a current density of 4 A g ⁻¹ . Furthermore, the pouch cell cycles 200 times at 25°C and 1 A g ⁻¹ , maintaining a capacity of approximately 100 mAh g ⁻¹ with 75.9% retention. This work presents an efficient strategy of engineering organic cocrystals in AZIBs, underscoring their substantial potential for practical energy storage applications.