Synthesis of Double-Shell SnO₂@C Hollow Nanospheres as Sulfur/Sulfide Cages for Lithium–Sulfur Batteries

Double-shell SnO 2 @C hollow nanospheres were synthesized by a template method, and then the sulfur was loaded to form a cathode material of S/SnO 2 @C composite. In Li–S batteries, it delivered a high initial specific capacity of 1473.1 mAh/g at a current density of 200 mA/g, and the capacity retention was even up to 95.7% over 100 cycles at 3200 mA/g, i.e., a capacity fade rate of only 0.043% per cycle. These good electrochemical performances should be attributed to the SnO 2 @C hollow nanospheres. They can enhance the electronic conductivity by the outside carbon shell, and confine the lithium polysulfides by S–Sn–O and S–C chemical bonds to suppress the shuttle effect. Besides, the hollow nanospheres can readily accommodate the sulfur/sulfides to prevent the electrical/mechanical failure of the cathode, instead of their agglomeration on the external surface of SnO 2 @C.