Complete Decomposition of LiCO in Li-O Batteries Using Ir/BC as Noncarbon-Based Oxygen Electrode.

Instability of carbon-based oxygen electrodes and incomplete decomposition of LiCO during charge process are critical barriers for rechargeable Li-O batteries. Here we report the complete decomposition of LiCO in Li-O batteries using the ultrafine iridium-decorated boron carbide (Ir/BC) nanocomposite as a noncarbon based oxygen electrode. The systematic investigation on charging the LiCO preloaded Ir/BC electrode in an ether-based electrolyte demonstrates that the Ir/BC electrode can decompose LiCO with an efficiency close to 100% at a voltage below 4.37 V. In contrast, the bare BC without Ir electrocatalyst can only decompose 4.7% of the preloaded LiCO. Theoretical analysis indicates that the high efficiency decomposition of LiCO can be attributed to the synergistic effects of Ir and BC. Ir has a high affinity for oxygen species, which could lower the energy barrier for electrochemical oxidation of LiCO. BC exhibits much higher chemical and electrochemical stability than carbon-based electrodes and high catalytic activity for Li-O reactions. A Li-O battery using Ir/BC as the oxygen electrode material shows highly enhanced cycling stability than those using the bare BC oxygen electrode. Further development of these stable oxygen-electrodes could accelerate practical applications of Li-O batteries.