High Sodium Ion Mobility of PEO-NaTFSI-Na3Zr2Si2PO_(12) Composite Solid Electrolyte for All-Solid-State Na-S Battery

摘要

A composite solid electrolyte based on PEO-NaTFSI (polyethylene oxide-sodium bis(trifluoromethanesulfonyl)imide) and Na3Zr2Si2PO_(12) is fabricated for all-solid-state NaS battery (ASSB). When the molar ratio of EO (ethylene oxide of PEO) to Na~+ (sodium ion of NaTFSI) is 20 and the amount of Na3Zr2Si2PO_(12) is 30wt%, a highest ionic conductivity of 3.14× 10~(-4) Scm~(-1) and the sodium ion transference number of 0.66 are achieved at 60°C. Harnessing the electrolyte's improved sodium ion transport abilities enables ASSB's assembled with a sulfur cathode and sodium metal anode to exhibit highly reversible current-rates and capacity retention. At 0.2 C and 60°C, the battery delivers a superior discharge capacity of 1110.0 mAhg~(-1) in the first cycle and maintains 666.8 mAhg~(-1) after 60 cycles with a stable Coulombic efficiency near 100%.