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The Li–O 2 battery is one of the most promising next-generation energy storage systems due to its super-high theoretical energy density. However, its further development is impeded by the current cathode system, which exhibits low energy efficiency and poor cycling stability. Herein, we report a composite of vanadium nitride coated with nitrogen-doped carbon nanoribbons grown in situ on carbon paper (denoted as VN@C) as a novel binder-free cathode for Li–O 2 batteries. We find that the nitrogen-doped carbon coating can significantly improve the stability of VN and enhance the composite's ORR/OER activities. The Li–O 2 batteries with our optimal VN@C-850 cathodes achieve an initial discharge capacity of 8269 mA h g−1, a discharge-charge voltage gap of 0.88 V, and considerable cycling stability for 183 cycles with a cut-off capacity of 1000 mA h g−1, compared with 2027 mA h g−1, 1.21 V, and 12 cycles with uncoated VN cathodes. • In situ grown VN coated with N -doped carbon cathode was fabricated. • The cathode exhibited high capacity and excellent cyclability in Li–O 2 battery. • It is found that the synergetic effects between VN and N -doped carbon is existed. [ABSTRACT FROM AUTHOR]

Highly effective cathode materials are critical to improve existing Li–O 2 batteries. In this paper, we report a free-standing Co 3 O 4 @NiCo 2 O 4 sheet array cathode, which is prepared by in-situ growing an array of sword-like cobalt-based metal-organic framework (Co-MOF) sheets on a carbon cloth (CC) substrate, followed by impregnated with nickel nitrate solution and pyrolyzed in air flow. The Co 3 O 4 @NiCo 2 O 4 /CC cathode exhibits excellent ORR/OER bifunctional activity and high cathodic performance in a Li–O 2 battery, achieving a specific capacity of 10645 mAh g−1 and a stability of 225 cycles. We suggest the high performance of our cathode can be ascribed to its well-defined 3D sheet array structure, which can facilitate O 2 diffusion and electrolyte impregnation, provide sufficient space for the discharge products, and the synergistic effect between Co 3 O 4 and NiCo 2 O 4. This work provides an effective method for the rational design of electrode composition and structure. Image 1 • A sword-like Co 3 O 4 @NiCo 2 O 4 nanosheet array cathode for Li–O 2 battery is prepared. • The cathode exhibited enhanced bifunctional OER/ORR activities in Li–O 2 batteries. • The high performance can be ascribed to its hybrid and array structure. • A high specific capacity of 10645 mAh g−1 with stability of 225 cycles is achieved. [ABSTRACT FROM AUTHOR]