Quasi-solid polymer electrolytes using photo-cross-linked polymers. Lithium and divalent cation conductors and their applications

Abstract

In this report, we will present the results on the photo-cross-linked poly-(ethylene glycol) diacrylate (PEGDA) based quasi-solid, i.e. gel, polymer electrolyte systems with lithium, magnesium and zinc trifluoromethanesulfonates [triflate; M n (CF 3 SO 3 ) n ] and their preliminary applications to primary cells. The Celgard® membrane-impregnated electrolytes were prepared in the same manner as Abraham et al. [K.M. Abraham, M. Alamgir, D.K. Hoffman, J. Electrochem. Soc. 142 (1995) 683]. The precursor solutions were composed of metal triflates, ethylene carbonate, propylene carbonate, and tetraethylene glycol diacrylate. The Celgard® #3401 membrane was soaked overnight in the precursor solution, then clamped between two Pyrex glass plates and irradiated with UV light to form a gel electrolyte. The maxima of the conductivity obtained were 4.5 × 10 -4 S cm -1 at 12 mol% for LiCF 3 SO 3 , 1.7 × 10 -4 S cm -1 at 1 mol% for Mg(CF 3 SO 3 ) 2 , and 2.1 × 10 -4 S cm -1 at 4 mol% for Zn(CF 3 SO 3 ) 2 system, respectively. The Arrhenius plots of the conductivities are almost linear between 268 and 338 K with 15-25 kJ/mol of activation energy for conduction. The cell, Li|LiCF 3 SO 3 -SPE + Celgard® #3401|(CH 3 ) 4 NI 5 + acetylene black, showed 2.86 V of OCV and could discharge up to 25% with respect to the cathode active material at a discharging current of 0.075 mA/cm 2 .