PNNL

Abstract

Poly(ethylene) oxide (PEO)-based solid electrolytes show limited applications in lithium metal batteries because of their low ionic conductivity and lithium-ion transference number. Herein, we report a solid-state PEO-deep eutectic solvent (DES) electrolyte by simply introducing N, N-dimethylmethanesulfonamide into PEO-lithium bis(trifluoromethane)sulfonimide (LiTFSI) matrix to in situ form PEO-DES systems via a facile solution casting method. Such PEO-DES electrolyte achieved an improved ionic conductivity and enhanced lithium-ion transference number compared with PEO-LiTFSI owing to the significantly reduced crystallinity of PEO and decoupled Li+ cations from the ether oxygens in PEO chains. Moreover, the PEO-DES exhibited good compatibility with Li metal, higher oxidation stability, and stable cyclability of Li plating/stripping with uniform Li deposition. The Li|LiFePO4 cell with PEO-DES electrolyte delivered a high reversible capacity of 168 mAh g?1 under 0.2 C and good rate capability under various C-rates at 60 ?C.