After two decades of development, lithium ion batteries are approaching their theoretical energy density limit and unable to satisfy the demand of society with the consumption of fossil fuels and the increase of electric vehicles. It is very important for researchers to look for replaceable green new energy sources. Among all the batteries, lithium-sulfur batteries are one of the most promising alternatives to lithium-ion batteries as the next generation of electrochemical energy storage systems, due to their advantages of non-toxicity, low materials cost, high energy density and so on. Tremendous attentions have been paid on lithium-sulfur batteries by researchers. They are very promising to be commercialized. As a vital part of cathode electrode, the host materials of sulfur usually have a strong impact on the cycle life, cycle stability, energy density and Coulombic efficiency of lithium-sulfur batteries. However, there are many problems to increasingly hamper their applications, such as the lower conductivity of sulfur, shuttle effect, the lower-loading of sulfur, huge volumetric expansion, complex internal reaction mechanism and so forth. It is becoming more and more important to design a variety of host materials with high specific surface area, superior conductivity and more active site to load sulfur, in purpose of improving the integral performance in lithium-sulfur batteries. In response to these problems, researchers have designed various materials for loading sulfur, such as carbon-based composite materials, metal oxide-based composite materials and polymer-based composite materials. Researchers make great efforts and put a premium on carbon materials especially, due to their advantages of low density, large specific surface, good conductivity, diverse structure, easy to process and produce, low cost and so on. Therefore, researchers have also implemented carbon materials of different structures such as one-dimensional, two-dimensional and three-dimensional for sulfur loading, which has effectively improved the cycle life, cycle stability and coulombic efficiency of lithium-sulfur batteries. Although researchers have made great contributions in terms of cycle life, etc., the loading of sulfur is limited, resulting in a low energy density of the entire battery. From a commercial point of view, researchers are not only improving their performance, but also constantly increase the sulfur loading to achieve higher energy density, which is closer to commercial requirements. This review summarized the progress in four aspects: First, the recent development history of lithium-sulfur batteries was briefly introduced. Next, we insighted the reaction mechanism and challenges that may exist in lithium-sulfur batteries; Then, unremitting efforts to improve the performance and sulfur loading were summarized and introduce the important influence of areal sulfur loading, areal specific capacity and Electrolyte/sulfur ratio for the whole cell. Finally, the perspective of lithium-sulfur batteries is simply proposed. © 2019, Materials Review Magazine. All right reserved.
