Lee, Sungmin Huh, Sung-Ho Lee, Young-Hoon Kim, So Hee Bae, Jong-Seong Ahn, Kwang-Soon Huh, June Sung, Yung-Eun Yu, Seung-Ho 2025-06-23T05:00:11Z 2025-06-23T05:00:11Z 2025-06-23 2025-07 1385-8947 https://pubs.kist.re.kr/handle/201004/152655 Aqueous zinc metal batteries, as a post-lithium-ion technology, exhibit exceptional performance due to their nonflammability, high theoretical anode capacity (820 mAh g-1), and low redox potential (-0.762 V vs. the standard hydrogen electrode (SHE)). However, the stability of the zinc metal anode is compromised by several issues arising from the reduction of H2O, including hydrogen generation, byproduct accumulation, and zinc dendrite formation. Herein, the low concentration of caffeine electrolyte additive is introduced to 1 M ZnSO4 aqueous electrolyte. Despite the small quantity of additives, caffeine molecules adsorb onto the zinc metal anode, forming an unreactive layer that passivates the contact with reactive water molecules. Operando optical and Xray imaging confirm that the caffeine passivation layer ensures homogeneous zinc deposition. Furthermore, the caffeine-enhanced electrolyte demonstrates high stability of the zinc metal anode in both symmetric and half-cell tests. Additionally, the Zn||NVO full cell with caffeine added electrolyte maintains a higher retention rate of discharge capacity compared to the blank electrolyte condition. English Elsevier BV Exploring the effects of biomolecular additive on performance of aqueous zinc metal batteries Article 10.1016/j.cej.2025.163465 1 Chemical Engineering Journal, v.515 Chemical Engineering Journal 515 N scie scopus 001503902300011 2-s2.0-105004798790 Engineering, Environmental Engineering, Chemical Engineering Article ATOMIC CHARGES CAFFEINE Biomolecular electrolyte additives Operando optical microscopy Operando X-ray transmission microscopy Aqueous electrolytes Zinc metal anodes