High-Rate and High-Areal-Capacity Air Cathodes with Enhanced Cycle Life Based on RuO2/MnO2 Bifunctional Electrocatalysts Supported on CNT for Pragmatic Li–O2 Batteries

Abstract

Despite their potential to provide high energy densities, lithium–oxygen (Li–O2) batteries are not yet widely used in ultrahigh energy density devices like electric vehicles, owing to various challenges, including poor cyclability, low efficiency, and poor rate capability, especially at high areal mass loading. Even the most promising Li–O2 cells are unsuitable for practical applications, owing to a limited areal mass loading below 1 mg cm–2, resulting in low areal capacity. Here, we demonstrate air cathodes of unprecedentedly high areal capacity at a high rate with sufficient cycle life for pragmatic operation of Li–O2 batteries. A separator-carbon nanotube (CNT) monolith-type cathode of massive loading is prepared to achieve high areal capacity, but the cycle life and round-trip efficiency of CNT-only separator monolith cathodes are limited. The reversible and energy-efficient operation at high areal capacity and a high rate is enabled by adopting RuO2/MnO2 solid catalysts on the CNT (RMCNT). RMCNTs sho...