Facilely synthesized honeycomb-like NiCo2O4 nanoflakes with an increased content of oxygen vacancies as an efficient cathode catalyst for Li-O2 batteries

•Honeycomb-like NiCo2O4 nanoflakes are successfully synthesized by electrochemical deposition and subsequent heat treatment.•NiCo2O4/CC benefits from a vital synergistic effect of Co and Ni and has abundant oxygen vacancies.•The NiCo2O4/CC electrode delivers a long lifetime of 102 cycles.•The NiCo2O4/CC electrodes deliver high discharge capacities of 8388 and 5238 mA h g−1 at 200 and 400 mA g−1, respectively. The development of high energy density Li-O2 batteries is restricted by the sluggish kinetics of both the oxygen reduction reaction and the oxygen evolution reaction, and developing an efficient cathode catalyst is the key to resolving this issue. In present study, interconnected honeycomb-like NiCo2O4 nanoflakes are synthesized by facile electrochemical deposition on carbon cloth (CC) and subsequent heat treatment. Compared with NiO and Co3O4, suitably sized NiCo2O4 nanoflakes benefit from a vital synergistic effect of components Co and Ni and are expected to show superior OER/ORR performance. The presence of redox couples Co3+/Co2+ and Ni2+/Ni3+ and abundant oxygen vacancies in NiCo2O4 allow Li-O2 batteries deliver satisfactory cycle durability and high discharge/recharge capacities. Li-O2 batteries that use the NiCo2O4/CC cathodes exhibit high specific discharge capacities of 8388 mA h g−1 and 5238 mA h g−1 at 200 mA g−1 and 400 mA g−1, respectively, and deliver a long lifetime of 102 cycles with a capacity limit of 500 mA h g−1 at 340 mA g−1, thereby suggesting that honeycomb-like NiCo2O4 nanoflakes are a promising cathode catalyst.