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.