Hollow carbon spheres with TiO2 encapsulated sulfur and polysulfides for long-cycle lithium-sulfur batteries

HC-TiO 2 /S composite (Hollow carbon spheres with TiO 2 in or out the carbon spheres encapsulates sulfur and polysulfides) is successfully prepared in our study. The hollow carbon spheres own good electrical conductivity and hollow volume, which can remedy the defect of nonconductive sulfur species and restrain the volumetric expansion of sulfur, respectively. And the TiO 2 has strong interaction with sulfur species and polysulfides, which can suppress the diffusion of polysulfide intermediates. TGA indicates that the HC-TiO 2 can be loaded with 67   wt% sulfur. Based on the synergistic effect of hollow carbon spheres and nano TiO 2 , the HC-TiO 2 /S cathode can deliver a discharge specific capacity of 671   mAh/g at 1   C (1   C   =   1672   mA/g) after 300 cycles, together with the capacity retention of 93%.