Metal-organic framework-derived hollow CoS nanobox for high performance electrochemical energy storage

In this work, hollow CoS nanobox (noted as HCSN) have been successfully synthesized via annealing and hydrothermal process from zeolitic imidazolate framework (ZIF-67) template. When tested as positive electrode materials in alkaline aqueous electrolyte, it shows high specific capacitance of 720 F g −1 at a current density of 1 A g −1 , good rate capability (82.1%) and good cycling stability with 86.4% capacitance retention over 10,000 cycles at 10 A g −1 . To further demonstrate the advantages of our ZIF-67 derived materials, asymmetric energy storage device was assembled (HCSN//NC), where the as-prepared HCSN was employed as the anode and ZIF-67-derived nanoporous carbon (noted as NC) as the cathode. This device achieves high energy density (80 Wh kg −1 at a specific power density of 882 W kg −1 ), good rate capability (53.3 Wh kg −1 even at a specific power density of 7.9 kW kg −1 ) and long-term stability up to 10,000 cycles. More importantly, it could simultaneously light up 12 LEDs in parallel, demonstrating its potential in practical applications.