Ultrafast rechargeable room-temperature solid-state sodium ion battery based on graphene-based liquid alloy

Abstract

Solid state sodium ion batteries have attracted great attentions due to its high safety and high energy density. However, the poor wettability between sodium and solid electrolytes (point-contact) seriously limits its application at room temperature. Here, we use a graphene-based Na-K alloy instead of pure sodium as anode to improve the wettability, which allows the batteries to be operated with ultrahigh rate capability at room temperature. The reduced interfacial resistance and accelerated charge transfer kinetics between alloy anode and NASICON electrolyte (face-contact) made the batteries stable cycle more than 220 hours with a small voltage hysteresis at a high current density of 25 mA cm-2 at room temperature, even increased the current density to 65 mA cm-2, the batteries can still operate well. These results proved that the feasibility of using liquid alloy in room-temperature solid-state sodium ion batteries. This work will pave the way for the development of high-rate, dendrite-free and long-life solid-state sodium ion batteries.