An All-Solid-State Sodium–Sulfur Battery Using a Sulfur/Carbonized Polyacrylonitrile Composite Cathode

An all-solid-state sodium–sulfur (Na–S) battery using a S/CPAN (carbonized polyacrylonitrile) composite cathode and poly(ethylene oxide) (PEO) electrolyte was prepared and tested at 60 °C. The S/CPAN composites was synthesized by heating a mixture of S and PAN at 600 °C. The solid polymer electrolytes consisted of PEO, NaFSI, and different amounts nano-TiO2. Moreover, the PEO–NaFSI–1% TiO2 electrolyte was chosen to be the electrolyte in all-solid-state Na–S battery due to its high ionic conductivity (4.89 × 10–4 S cm–2 at 60 °C) as well as outstanding electrochemical and thermal stability. The specific capacity of the S/CPAN composite cathode material can be 252 mAh g–1 (713 mAh g–1sulfur) at the second cycle, and it still remains 251 mAh g–1 (710 mAh g–1sulfur) after 100 cycles with a Coulombic efficiency near 100%.