LAUSR

Abstract The present article entails the effect of chain lengths or number of carbons (n) of dinitrile plasticizers (NC-(CH2)n-CN) in ionic conductivity and electrochemical stability of polymer electrolyte membranes (PEM) containing poly(ethylene glycol diacrylate) (PEGDA) precursor and lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) salt. Ternary phase diagrams of PEGDA, dinitrile plasticizers/ionizers such as succinonitrile (SCN, n = 2), glutaronitrile (GLN, n = 3), and adiponitrile (ADN, n = 4) plasticizers, and LiTFSI salt blends were established to provide guidance for photo-curing the amorphous PEM mixtures. The resulting photo-cured PEM networks exhibited very high room-temperature ionic conductivity at the level of 10−3 S/cm. Among them, the GLN-plasticized PEM revealed the highest ionic conductivity (∼2.3 × 10−3 S/cm) with a very wide working temperature window from −80 °C to 60 °C. The electrochemical stability of these dinitrile-plasticized PEM networks was evaluated in half-cell configurations (viz., Li4Ti5O12/PEM/Li and LiFePO4/PEM/Li) using Li4Ti5O12 (LTO) and LiFePO4 (LFP) electrodes by means of potentiostat for cyclic voltammetry and galvanostatic charge-discharge cycling. The effect of chain lengths of the dinitrile plasticizers on the electrochemical performance of the PEM network is discussed.