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A room-temperature Ag 3 Ga-mediated liquid EGaSn anode with improved wettability for advanced Mg ion batteries. [Display omitted] • The room-temperature Ag 3 Ga-mediated liquid EGaSn anode was simply prepared for MIBs. • Ag 3 Ga can improve the wettability of EGaSn on the substrate and provide capacity. • ssm-Ag 3 Ga-EGaSn shows superior electrochemical performance in half and full cells. • Reaction mechanism of the Ag 3 Ga-mediated liquid EGaSn anode was unveiled. Liquid metals with a self-healing property can address the passivation issue of Mg metal and the huge volume variation problem of solid alloy-type anodes in rechargeable magnesium ion batteries (MIBs). Liquid Ga-based anodes show great potentials in MIBs, however, being operated at room temperature is a great challenge. Herein, a novel strategy is proposed to enhance the room-temperature Mg storage performance of liquid eutectic GaSn (EGaSn) alloy through constructing a bifunctional intermetallic compound (Ag 3 Ga) layer on the current collector. This Ag 3 Ga layer could greatly improve the wettability of EGaSn on the substrate in the electrolyte environment. Moreover, operando X-ray diffraction confirms that Ag 3 Ga could participate the reversible alloying/dealloying reactions during the discharge/charge processes and thus provide an extra capacity. Eventually, the Ag 3 Ga-mediated EGaSn anode exhibits outstanding electrochemical performance towards Mg storage in both half and full cells at room temperature (∼24 and 21 °C), as benchmarked with state-of-the-art anodes in MIBs. Specially, the MIBs could be stably cycled up to 600 cycles in the half cell configuration, and 100 cycles in the full cell assembly. This work provides useful information on the development of advanced anodes for MIBs. [ABSTRACT FROM AUTHOR]

A self-healing room-temperature liquid eutectic GaSn anode with improved wettability for advanced Mg ion batteries. [Display omitted] • ∙ Self-healing room-temperature liquid EGaSn anodes were simply prepared for MIBs. • ∙ The wettability of liquid EGaSn on ssm-CuGa 2 substrate was significantly improved. • ∙ The ssm-CuGa 2 -EGaSn shows greatly enhanced cycling stability and rate performance. • ∙ Reaction mechanism and self-healing feature of liquid EGaSn anodes were unveiled. Using alloy-type anodes offers an effective method to address the incompatibility issue between Mg metal anodes and conventional electrolytes and also facilitates the development of high performance magnesium ion batteries (MIBs). But the huge volume variations of alloy-type anodes during cycling impair the electrochemical performance of MIBs. Herein, a liquid eutectic GaSn (EGaSn) electrode with a low melting point (20.5 °C) and self-healing property was fabricated through simply painting onto stainless steel mesh (ssm). But the ssm-EGaSn electrode shows unsatisfactory electrochemical performance due to poor wettability of liquid EGaSn on ssm. To overcome this problem, a CuGa 2 layer was constructed to enhance the wettability of liquid EGaSn on the ssm substrate. The modified liquid EGaSn electrode delivers much better electrochemical performance (specific capacity, cycling stability and rate performance) either at ∼ 38 or 28 °C. Furthermore, operando X-ray diffraction and ex situ scanning electron microscopy were conducted to reveal the Mg storage mechanism and self-healing feature of the liquid EGaSn electrode. Noticeably, the liquid EGaSn electrode displays well compatibility with simple Mg salt electrolytes like Mg(TFSI) 2 and the full cell could display stable electrochemical behavior over dozens of cycles. [ABSTRACT FROM AUTHOR]