In-situ grown vanadium nitride coated with thin layer of nitrogen-doped carbon as a highly durable binder-free cathode for Li–O2 batteries

Abstract

The Li–O2 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–O2 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–O2 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.