Abstract:

Using the tetrachloro-p-benzoquinone (TCQ) monomer, poly(benzoquinonyl sulfide) (PBQS) was synthesized by a simple polycondensation reaction. The influence of the molar ratio of S to Na₂S on the electrochemical performance of a PBQS anode was assessed by changing the amount of S added. The results showed that the electrochemical performance of PBQS strongly depended on the molar ratio of S to Na₂S. When the molar ratio of S to Na₂S was 0.4, two Cl were replaced by S, and PBQS with a stable structure was obtained. The discharge capacity of PBQS exceeded 140 mAh·g^-1. At the same time, PBQS displayed satisfactory rate capability and excellent cyclability. Conversely, when the molar ratio of S to Na₂S was decreased to 0.25, Cl was not substituted completely and the polymerization degree was low. Upon increasing the molar ratio of S to Na₂S to 0.7, an unstable S-S bond may form in the polymer. The above two factors degraded the electrode performance of these materials.

Key words: Aqueous lithium-ion battery, Polycondensation, Poly(benzoquinonyl sulfide), Mole ratio of S to Na₂S, Electrochemical performance