Stable Interface between a NaCl-AlCl₃ Melt and a Liquid Ga Negative Electrode for a Long-Life Stationary Al-Ion Energy Storage Battery

Intermediate temperature NaCl-AlCl₃-based Al-ion batteries are considered as a promising stationary energy storage system due to their low cost, high safety, etc. However, such a cheap electrolyte has a critical feature, i.e., strong corrosion, which results in the short cycle life of the conventional Al-metal anode and also limits the development of the NaCl-AlCl₃-based Al-ion batteries. A noncorrosive electrolyte may be a good choice for addressing the above challenge, while it is difficult to obtain the electrolyte that has advantages of both noncorrosion and low cost. Therefore, here, we report a Ga-metal anode in the affordable NaCl-AlCl₃ electrolyte for constructing a long-life stationary Al-ion energy storage system. This featured liquid metal anode shows good alloying and dealloying processes between metallic Ga and Al, as well as renders superior stability of the interface between the electrolyte and the anode (e.g., smoothly running for over 580 h at 2 mA cm^-2). No-corrosion and no-pulverization problems appear in this novel liquid/liquid interface. Those advantages demonstrate that the liquid Ga-metal anode has a great promise for the improvement of the NaCl-AlCl₃-based Al-ion batteries for large-scale stationary energy storage applications.