The development of rechargeable aluminum-ion batteries (AIBs) has recently attracted much scientific attention due to the low cost and high specific capacity of Al. Most efforts are being concentrated on enhancing the specific charge capacity of active materials for the positive electrode, while other important issues for commercial deployment of this technology have often been overlooked. The aim of this frontier article is not to systematically review the recent advances in the literature, but to bring under the spotlight the critical aspects requiring intensive research activity for paving the way toward the commercialization of AIBs. After a brief revision of the fundaments of an Al-ion battery, the discussion is classified into 5 sections: energy density, specific power, cost, cycle life and safety. Finally, a performance comparison among Al-ion, Li-ion and lead-acid battery technologies on the basis of these 5 primary parameters summarizes the strengths and limitations of Al-ion batteries.