Investigation of electrical and electrochemical properties of PVDF-based polymer electrolytes

A study has been made of the electrical and electrochemical characteristics of polyvinylidene fluoride (PVDF)-based polymer electrolytes. The room-temperature ionic conductivity of PVDF increases by up to four orders of magnitude on addition of trifluoromethane sulfone (LiCF3SO3), and a further increase is observed with the incorporation of an ethylene carbonate (EC) plasticizer. The conductive behavior of the electrolytes over a wide temperature range (−100 to 100 °C) is examined. An electrochemical cell has been fabricated using the film that gives the highest ionic conductivity at room temperature. The discharge characteristics of cells stored/heated at different temperatures have been studied in the 4.2–2.5 V voltage range. A greater discharge capacity is delivered on heating. In general, the discharge capacity and the capacity retention increase with the increase in temperature. This can be attributed to a reduction in the interfacial resistance due to an improvement in the electrolyteelectrode interfacial adhesion.