MOF-Derived Hollow Co9S8 Nanoparticles Embedded in Graphitic Carbon Nanocages with Superior Li-Ion Storage

Novel electrode materials consisting of hollow cobalt sulfide nanoparticles embedded in graphitic carbon nanocages (HCSP subset of GCC) are facilely synthesized by a top-down route applying room-temperature synthesized Co-based zeolitic imidazolate framework (ZIF-67) as the template. Owing to the good mechanical flexibility and pronounced structure stability of carbon nanocages-encapsulated Co9S8, the as-obtained HCSP subset of GCC exhibit superior Li-ion storage. Working in the voltage of 1.0-3.0 V, they display a very high energy density (707 Wh kg(-1)), superior rate capability (reversible capabilities of 536, 489, 438, 393, 345, and 278 mA h g(-1) at 0.2, 0.5, 1, 2, 5, and 10C, respectively), and stable cycling performance (approximate to 26% capacity loss after long 150 cycles at 1C with a capacity retention of 365 mA h g(-1)). When the work voltage is extended into 0.01-3.0 V, a higher stable capacity of 1600 mA h g(-1) at a current density of 100 mA g(-1) is still achieved.