Micro-nano structured Ni-MOFs as high-performance cathode catalyst for rechargeable Li-O₂ batteries

Rechargeable Li-O₂ batteries with high theoretical energy density urgently require efficient cathode catalysts to improve their electrochemical performance. Here we first demonstrated the application of Ni-based organic frameworks of Ni(4,4′-bipy)(H3BTC) (4,4′-bipy = 4,4′-bipyridine; H3BTC = 1,3,5-benzenetricarboxylic acid) (Ni-MOFs) as high-performance cathode catalysts for rechargeable Li-O₂ batteries. It is found that Ni-MOFs with a three-dimensional (3D) micro-nano structure, open catalytic sites and large specific surface area can guarantee the free transfer of O₂ and effective contact between the electrolyte and the catalytic sites. Preliminary testing of Ni-MOFs showed that they possess an extremely high capacity of 9000 mA h g^-1, a high round-trip efficiency of 80%, and a respectable cycling of 170 cycles without obvious voltage drop. Furthermore, plastic rechargeable Li-O₂ batteries with Ni-MOFs as the cathode catalyst have been assembled, displaying an energy density of 478 Wh kg^-1. This study leads to both fundamental and technological advances of Ni-MOFs as the cathode for rechargeable Li-O₂ batteries.