The Stabilization Effect of CO 2 in Lithium–Oxygen/CO 2 Batteries

The lithium (Li)–air battery has an ultrahigh theoretical specific energy, however, even in pure oxygen (O 2 ), the vulnerability of conventional organic electrolytes and carbon cathodes towards reaction intermediates, especially O 2 − , 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 CO 2 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 CO 2 can improve the stability of both anode and electrolyte, and a high‐performance rechargeable Li–O 2 /CO 2 battery is developed. The CO 2 not only facilitates the in situ formation of a passivated protective Li 2 CO 3 film on the Li anode, but also restrains side reactions involving electrolyte and cathode by capturing O 2 − . Moreover, the Pd/CNT catalyst in the cathode can extend the battery lifespan by effectively tuning the product morphology and catalyzing the decomposition of Li 2 CO 3 . The Li–O 2 /CO 2 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–O 2 batteries.