In summary, an aqueous rechargeable lithium battery (ARLB) using a coated lithium metal as anode and LiMn2O4 as cathode is established. Due to the “cross-over” effect, lithium ions at the higher potential side in the aqueous electrolyte can pass through the coating and arrive at the lower potential side of lithium metal. As a result, the coated lithium metal is very stable in the aqueous electrolyte and the average output voltage of this ARLB is 4.0 V. Its energy density is 80% higher than that of conventional lithium ion batteries and much higher than practical values of Li/air. Its energy efficiency is above 95%. Its cycling behavior is also very excellent. Furthermore, its cost is low and safety including environmental safety is much high and reliable. This ARLB system opens another chemistry for the new energy industry such as electric vehicles and large-scale energy storage in smart grids.