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

Li–O₂ 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–O₂ 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-MnO₂ (5–10 nm) decorated with small-sized IrO₂ (around 5 nm). The superior catalytic activity of IrO₂/MnO₂ enables conformal growth of amorphous Li₂O₂ on the 2D IrO₂/MnO₂ nanosheets at high current density, leading to significantly enhanced Li₂O₂ formation/decomposition kinetics. As a result, Li–O₂ cells with the IrO₂/MnO₂ 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 IrO₂/MnO₂ makes it a promising catalyst for high-performance Li–O₂ cells.