Co3O4 nanocage derived from metal-organic frameworks: An excellent cathode catalyst for rechargeable Li-O2 battery

Rechargeable non-aqueous Li-O2 battery is regarded as one of the most promising energy-storage technologies on account of its high energy density. It is believed that the rational design of three-dimensional (3D) architecture for catalyst is a key factor for the remarkable performance. Metal-organic frameworks (MOFs) derived materials possess excellent architecture, which is beneficial for Li-O2 batteries. In this work, ZIF-67 is used as precursor template and calcinated under different temperature to produce Co3O4 crystals. When the anneal treatment is under 350 °C, the derived Co3O4 nanocage holds the most complete skeleton, which provides better charge transfer ability as well as O2 and Li+ diffusion. Meanwhile, the Co3O4 nanocage owns more oxygen vacancies, offering more active sites. With the synergistic effect of nanocage structure and active sites, the Co3O4 nanocage stably delivers a large specific capacity of 15,500 mAh·g-1 as well as a long cycle-life of 132 cycles at limited discharge capacity of 1,000 mAh·g-1 under discharge/charge current density of 0.5 A·g-1. [graphic not available: see fulltext]