Three-functional ether-based co-solvents for suppressing water-induced parasitic reactions in aqueous Zn-ion batteries

Despite the high safety and low cost of aqueous Zn batteries, water-induced parasitic reactions severely restrict their stability. Herein, a three-functional ether-based co-solvent, tetraglyme (G4), has been rationally designed to decrease the reactivity of water on the basis of disclosing the functioning mechanism of a set of ethers. It is found that ether co-solvents can (i) reduce the number of coordinated H2O, (ii) interrupt the hydrogen-bonding networks of water, and (iii) isolate water adsorption on Zn anodes, thus reducing water decomposition and stabilizing Zn anodes. Furthermore, this synergistic effect would be intensified once incorporating multiple ether groups in the ether molecular skeleton. As a result, the designed G4-based hybrid electrolyte enables the Zn||Zn cell to stably cycle for 1000 h at 5 mA cm−2 with 5 mAh cm−2 and the polyaniline/carbon felt-based full cell to gain a 94% capacity retention over 1500 cycles at 0.5 A g−1. Our findings will shed light on the rational design of effective co-solvents for inhibiting water-related parasitic reactions in aqueous batteries.