Enhanced Cycling Performance of All-Solid-State Li-S Battery Enabled by PVP-Blended PEO-Based Double-Layer Electrolyte

Graphical PEO-based Double-layer solid electrolyte was fabricated through casting method. PVP distributed into PEO layer contacting with cathode promotes the dissolution of lithium salts and forms lithium bonds with (LiPSs). The double-layer solid electrolytes can ameliorate the shuttle effect of LiPSs better than pure PEO electrolytes. Despite the high specific capacity of Li−S battery, shuttle effect of lithium polysulfides (LiPSs) and safety issue pose a great challenge to realize its commercial application. Replacing liquid electrolyte with poly (ethylene oxide) (PEO) -based solid-state electrolyte is considered as a promising method to boost the safety, but the shuttle effect of LiPSs cannot be completely eliminated. In this work, a new kind of double-layer PEO-based polymer electrolyte is designed to restrict the LiPSs. The layer next to cathode consists of PEO and poly(vinylpyrrolidone) (PVP). The other layer consists of PEO. PVP with abundant of amide groups has been proved to have strong affinity to LiPSs. The strong interaction between LiPSs and carbonyl groups in amide is verified by Attenuated Total Reflection-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy tests. As a result, the assembled Li−S battery exhibits a specific capacity of 1100 mAh g −1 and capacity retention of 347 mAh g −1 after 200 cycles at 60 °C and 0.05 C, while the capacity retention of the battery without PVP-blended PEO electrolyte remains only 27 % at the same conditions.