Characterization of fibrous gel polymer electrolyte for lithium polymer batteries with enhanced electrochemical properties

This study highlights physical properties that are associated with the electrochemical properties of lithium batteries. Although the electrochemical properties of electrospun gel polymer electrolytes (GPEs) have been studied and understood in great detail, the physical properties of GPEs, such as ion interaction and phase transformation, have largely been ignored. A nano-fibrous poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) polymer matrix for GPEs was prepared by electrospinning. The ionic conductivity of the GPE was approximately 2.7 x 10(-3) S cm(-1) at 30 degrees C. The phase transition of the PVdF-HFP matrix as well as interaction between solvent or cation and polymer matrix or anion was investigated by Raman spectroscopy. Interaction between PF6- anion and PVdF-HFP matrix and phase transformation of the polymer matrix were confirmed. The LiFePO4/GPE/Li cell showed high discharge capacities of 134.6 mAh g(-1), 131.3 mAh g(-1), and 113.5 mAh g(-1) at high current densities of 1 C, 2 C, and 3 C, respectively. Moreover, this cell exhibited excellent cycle stability with high capacity retention. In particular, this nano-fibrous GPE is suitable for application in polymer batteries and is promising as a polymer electrolyte for scaled-up lithium batteries. (C) 2016 Elsevier B.V. All rights reserved.