PNNL

Abstract

Incomplete decomposition of Li2CO3 during charge process is a critical barrier for rechargeable Li-O2 batteries. Here we report complete decomposition of Li2CO3 in Li-O2 batteries using ultrafine iridium-decorated boron carbide (Ir/B4C) nanocomposite as oxygen electrode. The systematic investigation on charging the Li2CO3 preloaded Ir/B4C electrode in an ether-based electrolyte demonstrates that Ir/B4C electrode can decompose Li2CO3 with an efficiency close to 100% at below 4.37 V. In contrast, the bare B4C without Ir electrocatalyst can only decompose 4.7% of preloaded Li2CO3. The reaction mechanism of Li2CO3 decomposition in the presence of Ir/B4C electrocatalyst has been further investigated. A Li-O2 battery using Ir/B4C as oxygen electrode material shows highly enhanced cycling stability than that using bare B4C oxygen electrode. These results clearly demonstrate that Ir/B4C is an effecitive oxygen electrode amterial to completely decompose Li2CO3 at relatively low charge voltages and is of significant importance in improving the cycle performanc of aprotic Li-O2 batteries.