Free-standing graphene@carbon hollow sphere confining high-loading sulfur cathode for high-performance lithium–sulfur batteries

Practical applications of lithium–sulfur batteries are not satisfactory due to the poor conductivity, large volume expansion, dissolution of polysulfides, low sulfur content, and sulfur loading. Herein, free-standing graphene@carbon hollow sphere confining sulfur composite (G@C-HS@S) was prepared by ice template technology and vacuum immersion method for high-loading Li–S batteries. Ice template technology was used to adjust the vertical pore structure of the free-standing G@C-HS gel, allowing for easier ion transport. A three-dimensional G@C-HS framework with physical confinement improves the conductivity of cathode and inhibits the loss of sulfur and polysulfide, in which C-HS also greatly alleviates the volume expansion of sulfur. Sulfur is ingeniously encapsulated into G@C-HS framework by vacuum immersion method, achieving a high sulfur content of 81% and a high sulfur loading of 7.29 mg cm⁻². Benefiting from the above synergistic effects, G@C-HS@S delivers a specific capacity of 1187 mAh g⁻¹ at 0.1 C, a superior rate capability of 643 mAh g⁻¹ at 10 C, and an excellent cycle life of 61.8% after 700 cycles. The above results provide an effective route for high-performance Li–S batteries.