Trace amounts of fluorinated surfactant additives enable high performance zinc-ion batteries

Abstract

Aqueous zinc-ion batteries are promising alternatives to lithium-ion batteries for grid-scale energy storage. However, the practical application of AZIBs is challenged by side reactions and unsatisfactory performance. A new electrolyte additive is reported that can inhibit side reactions on the Zn anode and enlarge the working potential window of aqueous electrolytes. Trace amounts of perfluorooctanoic acid (PFOA) is capable of facilitating long-term reversible Zn deposition in AZIBs due to C-F chains ordered orientation absorbing on the electrode surface. The molecular dynamics results show that the as-formed electronegative absorbing layer act as a zincophilic layer to regulate the ions in the electrolyte. The electrolyte with PFOA additive enables a long lifespan of the Zn anode for >2000 hours. Also, the PFOA additive is used at one of the lowest amounts of reported additives in AZIBs. This strategy provides a simple and low-cost method to tackle common issues in AZIBs. Owing to C-F chains ordered orientation absorbing on the electrode surface, ultralow quantities of perfluorooctanoic acid (PFOA) additive (0.25 mM) in AZIBs is capable of enlarging working window to 2.1 V and facilitating long-term reversible Zn deposition (2200 hours), a high rate performance (153 mAh g −1 at 5 A −1 ) is achieved in Zn||Na 0.65 Mn 2 O 4 cells.