A metal-air battery is disclosed in one embodiment of the invention as including a cathode to reduce oxygen molecules and an alkali-metal-containing anode to oxidize the alkali metal (e.g., Li, Na, and K) contained therein to produce alkali-metal ions. An aqueous catholyte is placed in ionic communication with the cathode to store reaction products generated by reacting the alkali-metal ions with the oxygen containing anions. These reaction products are stored as solutes dissolved in the aqueous catholyte. An ion-selective membrane is interposed between the alkali-metal containing anode and the aqueous catholyte. The ion-selective membrane is designed to be conductive to the alkali-metal ions while being impermeable to the aqueous catholyte.