CoOOH-hierarchical porous carbon-sulfur as an excellent cathode for Li-S batteries

The “shuttle effect”, tardy reaction kinetics and volume change of sulfur cathode limit the wide application of Li-S batteries (LSBs). In this work, a composite of flower-like CoOOH decorating hierarchical porous carbon (CoOOH-HPC) was successfully synthesized and utilized as a sulfur host for LSBs. SEM and TEM images exhibited that the flower-like CoOOH formed by nanosheets was uniformly dispersed on the hierarchical porous carbon which was constructed by carbon spheres and nanotubes. Nitrogen adsorption/desorption isotherm and pore size distribution revealed that the ultrahigh specific surface area and suitable uniform mesopores of the CoOOH-HPC. Benefitting from the perfect combination of CoOOH and HPC, the CoOOH-HPC/S electrode delivered satisfactory electrochemical performance. It remained a discharge capacity of 550.9 mA h g−1 after 270 cycles at 0.5 C, with a low capacity decay rate of 0.017 % per cycle and a stable coulombic efficiency (over 96 %). Besides, the CoOOH-HPC/S electrode with a high sulfur loading of 2.8 mg cm−2 can demonstrate a discharge capacity of 357.91 mA h g−1 after 500 cycles, with the capacity decay rate of 0.08 % per cycle. This work provided a new method for preparing a variety of metal-based compound decorative hierarchical porous carbon composites, which can be used in LSBs and other energy storage and conversion devices.