H2O Activity Adjustment by Hydrogen Bonding Enables High-Performance Zn-Organic Battery

Graphical No water, no problem : The H 2 O activity in aqueous electrolyte is restrained by adding glycerol and acetonitrile into the electrolyte to form hydrogen bonds between organic solvents and H 2 O molecules, which facilities the smooth Zn deposition and alleviates Zn corrosion. Therefore, the Zn//Zn symmetrical cell cycles for over 1300 h and the Zn//FD28 full cell cycles for 9000 cycles. The advantages of low cost and high safety of zinc (Zn) metal have attracted much attention on its application in batteries, but H 2 O-induced issues of hydrogen evolution reaction (HER), Zn corrosion, and Zn dendrites formation limit the application. Here, a strategy of adjusting H 2 O activity was provided by adding glycerol (GL) and acetonitrile (AN) into aqueous electrolyte to form hydrogen bonds between organic solvents and H 2 O, which alleviated the Zn corrosion. Furthermore, molecular dynamics (MD) simulation indicated that GL could exclude H 2 O from the Zn 2+ solvation shell, thus preventing undesired HER and Zn dendrites formation. Therefore, the corresponding Zn//Zn symmetrical cell showed a ultralong lifespan (1300 h). Then, a Zn-organic battery with 3,7-dimorpholino-phenothiazin-5-ium iodide (FD28) cathode was fabricated by using such electrolyte. Interestingly, the reduced H 2 O activity also ensured the stable operation of organic cathode, and thus the full cell showed superior cycle stability for over 9000 cycles (≈1100 h), which is superior to previous reports. Moreover, such electrolyte owns novel properties of nonflammability, great weatherability, and low freezing point, thus boosting the practicality of the battery.