A novel rechargeable potassium–sulfur battery based on liquid alloy anode.

Highlights • Injecting liquid KNa alloy into sandwich-like carbon felt at room temperature. • Synthesizing nano-scale SPAN via a one-step facile solid state reaction. • The new battery presents good cycle stability (capacity retention 95.5%/100 cycles). Abstract Considering high earth abundance and low cost of potassium resource, potassium ion batteries are very promising candidates for energy storage devices due to its similar electrochemical performance to lithium ion batteries and more negative potential than sodium anode. K–Na alloy extending from 41.8 to 90.8 wt% potassium is liquid at ambient temperature. It was used as anode for a rechargeable potassium–sulfur battery in this work because of its high capacity and dendrite-free when charging and discharging. Sulfurized polyacrylonitrile (SPAN) nanocomposites were synthesized and adopted as cathode in the novel battery within good performance. The novel battery presented better cycling stability than K–SPAN battery. We obtained a highly reversible capacity of 513 mAh g−1 and excellent cycling performance of 490 mAh g−1 retention after 100 cycles at a current density of 35 mA g−1, in addition the coulombic efficiency approximately approached to 100% in successive cycles. [ABSTRACT FROM AUTHOR]