A promising metal–air secondary battery based on aluminium–oxygen couple is described. In this paper, we observed that an aluminium–air battery employing EMImCl, AlCl3 room temperature ionic liquid (RTIL) as electrolyte and aluminium as negative electrode, has an exceptional reduced self-discharged rate. Due to its new and innovative type of electrolyte, this aluminium–air battery can support relatively high current densities (up to 0.6 mA cm−2) and an average voltage of 0.6–0.8 V. Such batteries may find immediate applications, as they can provide an internal, built-in autonomous and self-sustained energy source.