In situ construction of organic anion-enriched interface achieves ultra-long life aqueous zinc-ion battery

Abstract

Aqueous zinc-ion batteries (AZIBs) are significantly limited in their long-term cyclability due to the growth of zinc dendrite and rampant side reactions. Herein, acesulfame (ACE) was introduced as an electrolyte additive to address these issues. Specifically, the organic anions in ACE contain functional groups that interact with Zn metal, resulting in forming an organic anion-enriched interface in situ on the Zn metal surface. Such an interface not only replaces the originally adsorbed H2O molecules, constructing a H2O-poor electrical double layer (EDL) that inhibits both HER and zinc corrosion, but also modulates Zn2+ diffusion through the ACE− anion's donor atoms bonding with Zn2+ to facilitate the even nucleation of Zn2+. Beyond that, this organic anion-enriched interface layer can be reduced to generate a rich ZnS solid electrolyte interphase (SEI) during electrochemical cycling, which further inhibits side reactions and the random growth of zinc dendrite. Consequently, the Zn||Zn symmetric cell with ACE additive delivers a remarkable lifespan of over 4600 h at 1 mA cm−2 and 1 mAh cm−2. Even under a high depth of discharge (DOD) of 50 %, the Zn||Zn symmetric cell maintains a longevity of 270 h. Besides, ACE improves the self-discharge performance and cycling stability of Zn||MnO2 battery, further attesting to its potential in future aqueous zinc-based devices. This endeavor sheds new light on addressing the challenges of zinc dendritic growth and rampant side reactions, thereby hastening the commercial viability of AZIBs.