Cobalt embedded in porous carbon fiber membranes for high-performance lithium-sulfur batteries

Lithium-sulfur (Li–S) batteries have received quite significant attention rooted from its ultra-high energy density. Nevertheless, the shuttle effect of dissoluble sulfurous intermediates is the primary obstacle which hinders their practical application. Herein, a porous carbon fiber membrane embedded with cobalt nanoparticles (Co–PCNF) was prepared by electrostatic spinning, then the active material was firmly fixed between the two layers of Co–PCNF to form a unique sandwich structure. With this strategy, an aluminum foil current collector can be replaced by the Co–PCNF sandwich structure, which is helpful to improve the energy density of Li–S battery as well as coordinate the volume change of sulfur in the process of charge and discharge, what's more, the shuttle effect is significantly inhibited. Results show that the as-assembled battery delivers an initial discharge specific capacities of 1013.3 mAh g−1 and 933.4 mAh g−1 at 0.5C and 1C, together with the decay rate of only 0.04% and 0.08% per cycle over 500 cycles, respectively. Moreover, the larger sulfur load (2.2 mg cm−2) still has the discharge specific capacity of 1009.8 mAh g−1 after 150 cycles at 0.2C. This Co–PCNF sandwich electrode may provide a new idea for the structural design for Li–S batteries. A porous carbon fiber membranes embedded with cobalt nanoparticles (Co–PCNF) was prepared by electrospinning, then the mixture of sulfur powder and Ketjen Black (KB) was firmly fixed between the two layers of carbon fiber membrane to form a unique sandwich structure, by which aluminum foil current collector can be replaced. The results show that this kind of Co–PCNF sandwich structure electrode is helpful to improve the energy density of lithium-sulfur battery and coordinate the volume change of sulfur in the process of charge and discharge, what's more, the shuttle effect is significantly inhibited, thus showing excellent electrochemical performance. [Display omitted] •A porous carbon fiber membrane embedded with cobalt nanoparticles (Co–PCNF) was prepared by electrospinning.•The electrode forms a unique sandwich structure.•The structural characteristics of the Co–PCNF sandwich electrode was explored.•Co-PCNF sandwich electrode can effectively inhibit the shuttle effect of polysulfide.