A Co-Doped MnO₂ Catalyst for Li-CO₂ Batteries with Low Overpotential and Ultrahigh Cyclability

Li-CO₂ batteries can not only capture CO₂ to solve the greenhouse effect but also serve as next-generation energy storage devices on the merits of economical, environmentally-friendly, and sustainable aspects. However, these batteries are suffering from two main drawbacks: high overpotential and poor cyclability, severely postponing the acceleration of their applications. Herein, a new Co-doped alpha-MnO₂ nanowire catalyst is prepared for rechargeable Li-CO₂ batteries, which exhibits a high capacity (8160 mA h g^-1 at a current density of 100 mA g^-1 ), a low overpotential (≈0.73 V), and an ultrahigh cyclability (over 500 cycles at a current density of 100 mA g^-1 ), exceeding those of Li-CO₂ batteries reported so far. The reaction mechanisms are interpreted depending on in situ experimental observations in combination with density functional theory calculations. The outstanding electrochemical properties are mostly associated with a high conductivity, a large fraction of hierarchical channels, and a unique Co interstitial doping, which might be of benefit for the diffusion of CO₂ , the reversibility of Li₂ CO₃ products, and the prohibition of side reactions between electrolyte and electrode. These results shed light on both CO₂ fixation and new Li-CO₂ batteries for energy storage.