Single-atomic tungsten-doped Co3O4 nanosheets for enhanced electrochemical kinetics in lithium–sulfur batteries

The practical application of lithium–sulfur batteries (LSBs) is severely hindered by the undesirable shuttling of lithium polysulfides (LiPSs) and sluggish redox kinetics of sulfur species. Herein, a series of ultrathin single-atomic tungsten-doped Co3O4 (Wx-Co3O4) nanosheets as catalytic additives in the sulfur cathode for LSBs are rationally designed and synthesized. Benefiting from the enhanced catalytic activity and optimized electronic structure by W doping, the Wx-Co3O4 not only reduces the shuttling of LiPSs but also decreases the energy barrier of sulfur redox reactions of sulfur species, leading to accelerated electrode kinetic. As a result, LSB cathodes with the use of 5.0 wt% W0.02-Co3O4 as the electrocatalyst show the high reversible capacities of 1217.0 and 558.6 mAh g−1 at 0.2 and 5.0 C, respectively, and maintain a high reversible capacity of 644.6 mAh g−1 at 1.0 C (1.0 C = 1675 mA g−1) after 500 cycles. With a high sulfur loading of 5.5 mg cm−2 and electrolyte–electrode ratio of 8 μLelectrolyte mgsulfur−1, the 5.0 wt% W0.02-Co3O4-based sulfur cathode also retains a high reversible areal capacity of 3.86 mAh cm−2 at 0.1 C after 50 cycles with an initial capacity retention of 84.7%.