Structure and Li+ Dynamics of the Single-Ion Conducting Polymer Electrolyte P(STFSI)-Ran-PEGMA

Abstract

Polymeric, solid-state, single-ion conducting electrolytes with high ionic conductivity are desired for application in high energy battery platforms. Recently, PEO-based copolymers containing the lithiated STFSI monomer have been investigated for use as single-ion conducting electrolytes in lithium batteries. These polymers exhibit wider electrochemical stability windows and sustain capacity of full cell battery cycling at higher discharge rates relative to traditional polymer electrolytes composed of PEO and a mobile, dopant salt. This presentation will report on the characterization of the morphology and dynamics of PSTFSI-ran-PEGMA copolymer electrolytes as a function of the monomer ratio (Li+ loading) and length of the polyethylene glycol comb. Structure of the electrolytes is investigated by SAXS/WAXS, SANS, and TEM. Lithium environment is examined using solid state MAS NMR spectroscopy, and ion dynamics are studied via PFG NMR spectroscopy and dielectric spectroscopy. Polymer dynamics are investigated via QENS. Together, this suite of characterization techniques reveals the structure and corresponding Li+ transport mechanisms in this family of high performing PEO-based single ion conductors.