Rational design of epoxy functionalized ionic liquids electrolyte additive for hydrogen-free and dendrite-free aqueous zinc batteries.

Despite the high safety and low cost associated with aqueous Zn-ion batteries (ZIBs), uncontrolled Zn dendrite growth and parasitic reactions induced by water significantly diminish their stability. Herein, a new epoxy functionalized ionic liquid, 4-methyl-4-glycidylmorpholin bis[(trifluoromethyl)sulfonyl]imide (MGM[TFSI]), has been developed to mitigate water reactivity for stable ZIBs. It was found that the MGM cation disrupts the hydrogen bond network of water, hindering its adsorption on Zn anodes, thereby suppressing water decomposition and enhancing anode stability. Additionally, preferential adsorption of MGM cations on the Zn anode surface mitigates tip effects, suppresses dendrite growth, and promotes the formation of a ZnF solid electrolyte interphase layer, effectively isolating the anode from the bulk electrolyte. As a result, benefiting from the well-designed MGM-based electrolyte, Zn//Zn cells achieve significantly enhanced cycling stability, lasting over 2000 h at 1 mA cm with 1 mAh cm. Furthermore, Zn//MnO full cells deliver remarkable stability, retaining approximately 89 % of their initial capacity after 3000 cycles at 5 A/g. This work proposes that the MGM[TFSI] additive can effectively regulate the interfacial chemistry of the Zn anode, providing an opportunity to design advanced electrolytes for highly reversible ZIBs and beyond.