Nowadays, lithium-ion batteries are widely used in portable devices because of their high energy density. Lithium-sulfur batteries with sulfur or sulfur-containing compounds as cathode materials have been attracting much attention because of its highly theoretical specific capacity (1675 mAh/g). However, there are two main technical challenges of lithium-sulfur batteries, i.e., the poor conductivity of elemental sulfur and the suoluble nature of polysulfide in electrolyte, can greatly result in the loss of active material. In this respect, we focus on designing and preparing the cathode material in a simpler manner. Concerning the existing problems, we prepared a petal-shaped SnS₂ / S composites. The first step is to synthesize a semiconductor SnS₂ with petal-like structure by hydrothermal method. The synthesized material was served as a support of elemental sulfur. Since SnS₂ itself has certain electrical conductivity and specific capacity, it can improve the conductivity of the cathode by blending with elemental sulfur. Small molecular sulfur was supported onto the petal-shaped structure of SnS2 by vacuum sublimation method in the second step.  The prepared petaloid SnS2/S composite was applied as cathode materials for lithium-sulfur batteries. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were conducted to characterize the structure and morphology of the hydrothermal reaction products SnS2 and petal-shaped SnS2/S composites. We also conducted Charge-discharge tests, cyclic voltammetry and AC impedance spectroscopy analysis to examine the electrochemical performance of coin cell batteries with pure sulfur, petal-shaped SnS2 and petal-shaped SnS2 /S composites as cathode material. The results showed that the initial discharge specific capacity of the composites cathode reached 598 mAh/g, and after 100 cycles, the specific capacity remained 464 mAh/g with a coulombic efficiency about 94%, which revealed the superior cyclic ability compared with pure sulfur cathode under the same conditions.

Presenter：Prof  Yuezhong Meng