Vibrational, electrical, and ion transport properties of PVA-LiClO4-sulfolane electrolyte with high cationic conductivity

Novel solid polymer electrolytes, poly(vinylalcohol)-lithium perchlorate (PVA-LiClO4) and PVA-LiClO4-sulfolane are prepared by solvent casting method. The experimental results show that sulfolane addition enhances the ionic conductivity of PVA-LiClO4 complex by three orders. The maximum ionic conductivity of 1.14 ± 0.20 × 10−2 S cm−1 is achieved for 10 mol% sulfolane-added electrolyte at ambient temperature. Polymer-salt-plasticizer interactions are analyzed through attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Lithium ion transference number is found by AC impedance spectroscopy combined with DC potentiostatic measurements. The results confirm that sulfolane improves the Li+ transference number of PVA-LiClO4 complex to 0.77 from 0.40. The electrochemical stability window of electrolytes is determined by cyclic voltammetry (CV). The broad electrochemical stability window of 5.45 V vs. lithium is obtained for maximum conducting electrolyte. All-solid-state cell is fabricated using maximum conducting electrolyte, and electrochemical impedance study is carried out. It reveals that electrolyte interfacial resistance with Li electrode is very low. The use of PVA-LiClO4-sulfolane as a viable electrolyte material for high-voltage lithium ion batteries is ensured.