MOF‐Derived Hollow Co 9 S 8 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⊂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 Co 9 S 8 , the as‐obtained HCSP⊂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 (≈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.