Design and synthesis of efficient cathode materials for high-performance lithium-sulfur batteriesCopyright: Z.Li
Lithium-sulfur batteries have been considered one of the most promising candidates for the next-generation battery system because of high energy density, low cost, and environmental friendliness. However, several problems have restricted the development of lithium-sulfur batteries for commercialization. The principle issue is the intrinsic insulating nature of sulfur, leading to an increase in internal resistance of the battery. Another issue is the diffusion of sulfur intermediates into the electrolyte, decreasing the active mass utilization. The third problem lies in the volumetric variation of the sulfur cathode upon cycling, which pulverizes the cathode. Considerable efforts have been devoted to solving these problems. An attempt to encapsulate sulfur in conductive carbon materials can enhance the electrical conductivity and prohibit the diffusion of polysulfides. On the other hand, non-polar carbon materials as physical barriers fail to effectively anchor polysulfides. Inorganic compounds like metal oxides and sulfides etc. can form strong chemical interactions with polysulfides, which could be the superior sulfur host materials. Therefore, the rational design of sulfur host materials with high conductivity and a strong affinity for polysulfides should be developed to overcome these conundrums, achieving superior capacity and durable cycling stability.
In this PhD project, the focus is on the rational design and synthesis of hollow nanocage composites (see Figure) for enhancing the conductivity of cathodes and efficiently anchoring polysulfides. The synergetic effect of the hollow nanocage composites facilitates redox kinetics of the electrode and significantly inhibits the diffusion of polysulfides.