Li/O-2 batteries are a breakthrough in battery technology for powering long-range electric vehicles. The viability of high efficiency, rechargeable Li/O-2 battery is demonstrated by the use of catalyst-free mesomacroporous carbon cathode and N-butyl-N-methyl pyrrolidinium bis(trifluoromethanesulfonyl)imide ionic liquid-based electrolyte. The carbon electrode, obtained by a simple, low-cost template method, features a high specific capacity of 2500 mAh g(-1) at 2.6 V vs. Li+/Li and, more importantly, a recharge potential lower than 3.8 V vs Li+/Li that prevents secondary reactions in the ionic liquid detrimental for battery rechargeability and makes it possible to reach a recharge efficiency of 90%. (C) 2012 Elsevier B.V. All rights reserved.