The Stabilization Effect of CO₂ in Lithium-Oxygen/CO₂ Batteries

The lithium (Li)-air battery has an ultrahigh theoretical specific energy, however, even in pure oxygen (O₂ ), the vulnerability of conventional organic electrolytes and carbon cathodes towards reaction intermediates, especially O₂ ^- , and corrosive oxidation and crack/pulverization of Li metal anode lead to poor cycling stability of the Li-air battery. Even worse, the water and/or CO₂ in air bring parasitic reactions and safety issues. Therefore, applying such systems in open-air environment is challenging. Herein, contrary to previous assertions, we have found that CO₂ can improve the stability of both anode and electrolyte, and a high-performance rechargeable Li-O₂ /CO₂ battery is developed. The CO₂ not only facilitates the in situ formation of a passivated protective Li₂ CO₃ film on the Li anode, but also restrains side reactions involving electrolyte and cathode by capturing O₂ ^- . Moreover, the Pd/CNT catalyst in the cathode can extend the battery lifespan by effectively tuning the product morphology and catalyzing the decomposition of Li₂ CO₃ . The Li-O₂ /CO₂ battery achieves a full discharge capacity of 6628 mAh g^-1 and a long life of 715 cycles, which is even better than those of pure Li-O₂ batteries.