Molecular structure-controlled synthesis of sulfur-containing polymers for rechargeable Li–S batteries

Abstract

Lithium–sulfur (Li–S) batteries are considered a superior candidate for next-generation batteries because of their high theoretical energy density, low cost and environmentally friendly nature. However, the shuttle effect caused by the high solubility of lithium polysulfides severely destroys the cycling life of these batteries, resulting in serious capacity deterioration. In recent years, many efforts have been made to improving the performance of Li–S batteries by designing the molecular structure and morphology of their electrodes, electrolytes, binders, and separators, as well as lithium electrode protection for trapping polysulfides to inhibit the shuttle effect, thus improving their cycling stability. In this review, we aim to present a comprehensive review of the current research activities focused on the molecular structure-controlled synthesis of sulfur-containing polymer cathode materials to improve the electrochemical performance of Li–S batteries. We begin with a brief introduction on the molecular structure characteristics of organosulfur with sulfur chains as the main framework, followed by a discussion of its synthetic methods and electrochemical activities. We then focus on the design strategy and molecular structure characteristics of sulfur-containing polymers based on carbon chains as their main skeleton, which are grafted by polymeric sulfur chains. Next, we discuss a series of principles and methods for regulating the molecular structure of sulfur-containing polymers with organic frameworks. Finally, some existing problems and future development trends of sulfur-containing polymers in Li–S systems are discussed.