Two-dimensional IrO2/MnO2 enabling conformal growth of amorphous Li2O2 for high-performance Li–O2 batteries

Li–O 2 cells have attracted a worldwide attention due to their extremely high energy density compared with current Li-ion batteries. However, great challenges must to be overcome to realize full charge and discharge of Li–O 2 cells at high rates over a wide electrochemical window. Herein, we propose a unique design of binder-free catalytic cathode composed of two-dimensional (2D), few-layered δ-MnO 2 (5–10 nm) decorated with small-sized IrO 2 (around 5 nm). The superior catalytic activity of IrO 2 /MnO 2 enables conformal growth of amorphous Li 2 O 2 on the 2D IrO 2 /MnO 2 nanosheets at high current density, leading to significantly enhanced Li 2 O 2 formation/decomposition kinetics. As a result, Li–O 2 cells with the IrO 2 /MnO 2 catalyst exhibit high capacity (16370 mAh g −1 at 200 mA g −1 ), superior rate capability (2315 mAh g −1 at 1600 mA g −1 ) and high-rate cycling stability (312 cycles at 1600 mA g −1 ) between 2.2 and 4.3 V. Even over a wider voltage window of 2–4.4 V, the cell can sustain 247 cycles at 1600 mA g −1 in a full charge/discharge mode. The superior catalytic activity of IrO 2 /MnO 2 makes it a promising catalyst for high-performance Li–O 2 cells.