Research Progress of Sulfur/Carbon Composite Cathode Materials and the Corresponding Safe Electrolytes for Advanced Li-S Batteries

Abstract

Lithium-sulfur (Li-S) battery is one of the most promising secondary batteries for its high energy density, high natural abundance and environment friendly nature of sulfur. However, the commercial application of Li-S battery faces some technical obstacles, such as low cycling stability resulted from the shuttle effect of polysulfides, low electrical conductivity of sulfur and volume expansion during charge/discharge process. Furthermore, due to the flammability of organic solvents in liquid electrolytes, the continuous formation of lithium dendrites and the low ignition temperature of carbon–sulfur mixtures, safety of Li-S batteries has become another critical issue to be solved. In recent years, many different strategies have been put forward to improve the electrochemical performance and safety of Li-S batteries, containing the development of carbon/sulfur composite cathodes, design of flame retardant electrolytes and protection of negative electrodes. In this review, the recent progress of sulfur/carbon composite cathode materials for Li-S battery is first introduced. Then the evaluation methods and latest development of high-safety electrolytes toward advanced Li-S batteries are summarized. Finally, the development trends of Li-S battery are forecasted.