Electrochemical performance of polymer electrolytes based on Poly(vinyl alcohol)/Poly(acrylic acid) blend and Pyrrolidinium ionic liquid for lithium rechargeable batteries. (20th June 2017)

• Record Type: Journal Article
• Authors: Thayumanasundaram, Savitha; Rangasamy, Vijay Shankar; Seo, Jin Won; Locquet, Jean-Pierre
• Is Part Of: Electrochimica acta. Volume 240(2017)
• Page Start: 371
• Page End: 378
• Publication Date: 2017-06-20
• Subjects: Pyrrolidinium ionic liquid -- lithium transference number -- polymer electrolyte -- LiFePO4 -- PVA; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2017.04.107
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: Polymer electrolytes offer the most promising solution to address the all-solid-state battery requirements such as flexibility, leak-proof packing and easy processing. In this study, a polymer blend of 25 mol% poly(acrylic acid) (PAA) and 75 mol% poly(vinyl alcohol) (PVA) was optimized based on its thermal, mechanical and structural properties. The ionic liquid (IL) electrolyte, 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYRTFSI) with 0.2 m lithium bis(trifluoromethansulfonyl)imide (LiTFSI), was added to the polymer blend in different molar ratios. A maximum ionic conductivity of 1 mS cm −1 is observed at 90 °C in the membrane with 70 mol% IL. Cyclic voltammetry of the polymer electrolytes shows peaks corresponding to lithium stripping (+0.25 V vs. Li + /Li) and deposition (−0.3 V vs. Li + /Li) processes indicating the occurrence of a highly reversible redox process. The electrochemical stability window of these polymer electrolytes, as determined by linear sweep voltammetry, extends up to 5 V, suggesting that these electrolytes could be suitable for batteries that use high voltage cathode materials. A lithium transference number (tLi+ ) of 0.4 was determined for the polymer electrolytes by using chronoamperometry and impedance measurements. Galvanostatic charge-discharge studies of the polymer electrolytes in a lithium half-cell with LiCoO2 (LCO) as cathode delivers a capacity of about 100 mAh g −1 at 60 °C. Coin-type half-cell with LiFePO4 (LFP) cathode and the polymer electrolyte containing 70 mol% IL delivered a capacity of 172 mAh g −1 . Interestingly, the LFP/polymer composite cathode (LFP-C) delivers a higher capacity (215 mAh g −1 at 60 °C) than the pristine LiFePO4 cathode.