Stabilized Lithium-Sulfur Batteries by Covalently Binding Sulfur onto the Thiol-Terminated Polymeric Matrices

Despite the low competitive cost and high theoretical capacity of lithium-sulfur battery, its practical application is severely hindered by fast capacity fading and limited capacity retention mainly caused by the polysulfide dissolution problem. Here, this paper reports a new strategy of using thiol-terminated polymeric matrices to prevent polysulfide dissolution, which exhibits an initial capacity of 829.1 mAh g^-1 , and the exceptionally stable capacity retention of ≈84% at 1 C after 200 cycles, and excellent cycling stability with a low mean decay rate of 0.048% after 600 cycles. Significantly, in situ UV/vis spectroscopy analysis of the electrolyte upon battery cycling is performed to verify the function of preventing polysulfide dissolution by means of strongly anchoring discharge products of lithium sulphides. Moreover, density functional theory calculations reveal that the breakage of the linear sulfur chains results in the less soluble short-chain polysulfides due to the formation of the covalently crosslinked discharge products, which avoids the production of soluble long-chain polysulfide and minimizes the shuttle effect. These results exhibit an alternative for the stabilization of the electrochemical performance of lithium-sulfur batteries.