Fluorinated carbon as high-performance cathode for aqueous zinc primary batteries

Fluorinated carbon (CF) has been extensively served as promising positive electrode material for lithium primary batteries due to its high energy density. However, there are comparatively far less reports about the use of CF on other battery systems, let alone on the research of aqueous batteries. Herein in this study, we employed CF as the cathode active for aqueous zinc batteries for the first time and systematically investigated its electrochemical behavior under a series of aqueous zinc-ion electrolytes. As is discovered that the F/C ratio (the x value in CF) of CF have significant effects on the electrochemical performance of aqueous Zn/CF batteries. Specifically, CF_0.85 exhibits excellent electrochemical property with delivering a remarkable discharge capacity of 503 mA h g^-1 and energy density of 388 W h kg^-1 (at a current rate of 30 mA g^-1 under temperature of 25 °C), much better than several other CF electrode with F/C ratio of 0.70, 0.95, and 1.10, respectively. Besides, it also exhibits decent temperature performance with discharge capacities of 550 mA h g^-1 at 50 °C and 460 mA h g^-1 at 0 °C under current density of 30 mA g^-1. Furthermore, the electrochemical discharge mechanism based on conversion reaction was further uncovered by applying XPS, XRD, SEM and EDS elemental analysis characterization techniques. In conclusion, these results demonstrate the potential application value of CF in aqueous zinc primary batteries.