Room-Temperature Liquid-Metal Coated Zn Electrode for Long Life Cycle Aqueous Rechargeable Zn-Ion Batteries

Aqueous rechargeable zinc-ion batteries (ARZIBs) are potential candidates for grid-scale energy storage applications. In addition to its reversible chemistry in aqueous electrolytes, Zn metal is stable in water and air. However, there are critical challenges, such as non-uniform plating, hydrogen evolution, corrosion, and the formation of a passivation layer, which must be addressed before practical applications. In this study, the surface of Zn metal was coated with room-temperature bulk liquid-metal and liquid-metal nanoparticles to facilitate the uniform plating of Zn–ions during cycling. A simple probe ultrasonication method was used to prepare the liquid-metal nanoparticles, and a nanoparticle suspension film was formed through spin coating. At an areal capacity and current density of 0.5 mAh cm−2 and 0.5 mA cm−2, respectively, symmetric cells composed of bare Zn metal electrodes were prone to short-circuiting after ~45 h of deposition/striping cycles. However, under the same operating conditions, symmetric cells employing the room-temperature liquid-metal-coated electrodes operated stably for more than 500 h. Compared to the symmetric cell with bare Zn, the symmetric cell with the bulk liquid-metal coated electrode exhibited a significant reduction in the initial nucleation barrier, with respective values of 113.2 and 10.1 mV. Electrochemical characterization of practical full cells also showed significant improvements in the capacity and cycling performance derived from the room-temperature liquid-metal coating.