Amorphous nickel cobalt oxides as highly efficient catalytic cathodes for rechargeable Li–O2 batteries

Abstract

Although it is well acknowledged that regulating the adsorption behavior of oxygen-containing intermediates can prompt the reaction kinetics of lithium–oxygen batteries, its implementation still suffers from lacking a practical strategy. The amorphization strategy has great potential for custom-tuning surface engineering due to the induced atomic disorder possessing unique electronic structures and abundant defect sites. In this work, amorphous NiCo2O4 nanosheets (a-NiCo2O4 NSs) are reported for high-performance lithium–oxygen batteries by modulating the electron density around metal sites. The Li–O2 batteries with a-NiCo2O4 NSs deliver an overpotential as low as 0.74 V with an ultralong lifetime of over 1000 h. Theoretical calculations reveal that the enhanced binding energy of the LiO2 intermediate is stemmed from d-band center upshifting, mediated by atomic disordering, which consequently yields low oxygen evolution-reaction and oxygen-reduction-reaction overpotentials. More importantly, the amorphization strategy can be utilized as a general approach toward other materials, such as cobalt oxide and nickel oxide.