(435h) Novel PEO-Based Composite Solid Electrolytes for All-Solid-State Li-S Battery

Polymer solid electrolytes (SPEs) were investigated for several decades due to their good compatibility with electrodes. However, there are still several key requirements for solid polymer electrolytes including higher ionic conductivity, excellent solubility to the conductive lithium salt, and good interface stability against the Li anode. In our work, we found that transition metal carbides (NiNbCeC) over mesoporous silica (SBA-15) can be filled into the Polyethylene Oxide (PEO) matrix to form composite solid electrolytes which can greatly improve the ionic conductivity of PEO. Then, a series of transition metal carbides with different mass ratios of Cerium (5%, 10%, and 20%) was used in fabricating all-solid-state Li-S cells (ASSLi-S). The different mass ratios of Cerium improve the ionic conductivity of the composite solid electrolytes significantly and result in decreasing the impedance of the solid electrolytes from 13345 ohms (20% Ce) to 8000 ohms (10% Ce) to 1765 ohms (5%). A high initial specific capacity at 0.1C and reversible specific capacity after 8 cycles are 1644 and 1254 mAh/g, 1311 and 1198 mAh/g, 1317 mAh/g and 544 mAh/g for 5% Ce, 10%, and 20%, respectively at room temperature. Long-term cycling testing of ASSLi-S cells was conducted at 1C and the cell with 5% Ce solid electrolytes deliver an initial specific capacity of 525 mAh/g and 332 mAh/g after 150 cycles. The SEM characterization was used for the volume change of the solid electrolyte layer and elemental distribution of solid electrolyte materials by cross-section view. XRD was utilized to study the crystallinity of composite solid electrolytes.