Cation-Exchange-Induced Metal and Alloy Dual-Exsolution in Perovskite Ferrite Oxides Boosting the Performance of Li-O Battery.

A temperature-controlled cation-exchange approach is introduced to achieve a unique dual-exsolution in perovskite La Fe Co O where both CoFe alloy and Co metal are simultaneously exsolved from the parent perovskite, forming an alloy and metal co-decorated perovskite oxide. Mossbauer spectra show that cation exchange of Fe atoms in CoFe alloy and Co cations in the perovskite is the key to the co-existence of Co metal and CoFe alloy. The obtained composite exhibits an enhanced catalytic activity as Li-O battery cathode catalysts with a specific discharge capacity of 6549.7 mAh g and a cycling performance of 215 cycles without noticeable degradation. Calculations show that the combination of decorated CoFe alloy and Co metal synergistically modulated the discharge reaction pathway that improves the performance of Li-O battery.