ИСТИНА

Power sources that utilize the reaction of lithium and oxygen have become a great challenge since first works in 1996 [1]. Today lithium‐air batteries (LAB) attract new wave of attention due to its promise to provide more than 1 kWh/kg and skyrocketing expansion of electric vehicle market [2]. However practical use of LAB is limited by low round‐trip efficiency associated with slow kinetics of oxygen reduction on discharge, oxygen evolution on charge and variety of side reactions. Nowadays researcher efforts are focused on different carbon electrode materials. Rather contradictory data on recharge efficiency and cycleablity of a battery with carbon electrode were published last year [3]. In general, the lack of rechargebility is associated with Li2CO3 byproduct formation. It appears at the cathode due to lithium superoxide (electrochemical intermediate) or peroxide (discharge product) reactions with the carbon (electrode material). Advanced operando analysis of the processes at the cathode is highly useful in order to resolve such situations and facilitate the search of proper electrode materials. Using operando high pressure XPS experiments we show that superoxide radicals generated at the cathode during discharge react with carbon that contains activated double bonds or aromatics to form epoxy groups and carbonates, which limits the rechargeability of Li−O2 cells [4]. Carbon materials with a low amount of functional groups and defects demonstrate better stability and does not react with Li2O2 thus keeping the carbon will‐o’‐the‐wisp lit for lithium−air batteries. 1. J. Electrochem Soc – 143,1(1996) 2. J Phys Chem Let 1,14 (2010) 3. Science 337, 563 (2012) 4. Nano Lett 130904111116007(2013)