Donor-π-Acceptor Heterosystem-Functionalized Porous Hollow Carbon Microsphere for High-Performance Li-S Cathode Materials with S up to 93 wt %

Lithium-sulfur (Li-S) batteries, as a prospective energy storage system, are still plagued by many problems that prevent them from their application, especially the low content of sulfur in the cathode. Herein, a cathode material with S up to 93 wt % is designed via a hollow donor-pi-acceptor heterosystem, which combines catalytic sites, adsorption sites, and good conductivity together. Following this guidance, a hollow porous carbon sphere is prepared with CoO particles and single V atoms decorated on it (Co/V-HPCS), providing ultrahigh volumetric space for sulfur. Even the electrode made of sulfur-loaded Co/V-HPCS (Co/V-HPCS@S) has a high content of 90 wt % (sulfur content in the electrode is similar to 83.5 wt %), and the cathode exhibits an excellent discharge capacity of 575.2 mAh g(-1) under 0.2C after 100 cycles. With careful analysis by means of a high-resolution transmission electron microscope (HRTEM), the catalytic amounts of CoO particles and single V atoms loaded on the carbon shell are confirmed, which endows the material with outstanding catalytic ability to transfer sulfur and excellent adsorption of polysulfides. This concept of the cathode material increases the possibility of advanced long-life Li-S batteries with high tap density and high energy density.

Automated summary

By designing a new cathode material with high sulfur content of up to 93% for lithium-sulfur batteries, ultrahigh volumetric space for sulfur is provided, resulting in high discharge capacity and cycle stability. The material demonstrates excellent catalytic ability for sulfur transfer and adsorption of polysulfides, increasing the possibility of advanced long-life Li-S batteries with high energy density.