Pressure swings assisted encapsulation of sulfur into expanded graphite as cathode for lithium-sulfur batteries

Poor electrical conductivity and the volume expansion of sulfur, shuttle effect of lithium polysulfides are key challenges for lithium-sulfur (Li–S) batteries. Due to good conductivity and adjustable pore structure, expanded graphite (EG) is considered an excellent candidate as host for sulfur. In this work, sulfur was encapsulated into the pore of Co 3 O 4 -doped expanded graphite via a pressure swing-assisted impregnation, and the surface sulfur was removed by rapid sublimation. Benefitting from the excellent electrical conductivity of expanded graphite and the chemical bonding between Co 3 O 4 and polysulfides, the shuttle effect was significantly suppressed. The prepared Co 3 O 4 -EG-S composite delivered a discharge-specific capacity of 1379 mAh g −1 at 0.1 C and 985 mAh g −1 at 1 C. After 200 cycles at 0.2 C, the capacity remained up to 661 mAh g −1 while the coulombic efficiency maintained above 98%. This work can provide an idea for restraining the shuttle effect in Li–S batteries.