H2 O Activity Adjustment by Hydrogen Bonding Enables High-Performance Zn-Organic Battery.

Abstract

The advantages of low cost and high safety of zinc (Zn) metal have attracted much attention on its application in batteries, but H2 O-induced issues of hydrogen evolution reaction (HER), Zn corrosion, and Zn dendrites formation limit the application. Here, a strategy of adjusting H2 O activity was provided by adding glycerol (GL) and acetonitrile (AN) into aqueous electrolyte to form hydrogen bonds between organic solvents and H2 O, which alleviated the Zn corrosion. Furthermore, molecular dynamics (MD) simulation indicated that GL could exclude H2 O from the Zn2+ 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 H2 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.