A Novel Preparation Procedure of Poly(vinylidenedifluoride)-Based Gel Polymer Electrolyte for Application in Lithium-Ion Batteries

Gel-type polymer membrane electrolytes, GPEs, have attracted particular attention thanks to their low volatility, high thermal stability and safety, which make them suitable for use in lithium ion battery (LIB) technology.1 In this work we present a convenient preparation procedure of poly(vinylidene difluoride) (PVdF)-based gel polymer electrolyte. The novelty of the procedure reported is that the electrolyte is prepared under air as a dry, flexible film and directly gelled during LIB assembly. Therefore, the GPE obtained is easy to handle and suitable for roll-to-roll scaling-up and it can be efficiently used for application in LIB. The morphology and electrochemical interphase properties of the electrolyte have been investigated by scanning electron microscopy and impedance spectroscopy, respectively. Moreover, galvanostatic tests suggested good stability of the lithium electrode/gel electrolyte interface and a high lithium transference number. Finally, cycling tests of full lithium ion cell, employing the GPE, a lithium iron phosphate cathode and a graphite anode confirm the suitability of the GPE for application in stable, low cost and environmentally friendly energy storage systems.2 [1] Croce, F.; Focarete, M. L.; Hassoun, J.; Meschini, I.; Scrosati, B. A Safe, High-Rate and High-Energy Polymer Lithium-Ion Battery Based on Gelled Membranes Prepared by Electrospinning. Energ. Environ. Sci.2011, 4, 921-927. [2] Fasciani, C.; Panero, S.; Hassoun, J.; Scrosati, B. (submitted) 2015. Figure: Scanning Electron Microscopy pictures (background image) of the PVdF-gel membrane and voltage profile at 25°C of a C/GPE/LFP LIB using an activated, pre-lithiated graphite anode. Current rate: C/5; Voltage limits: 3.8 V - 2 V. Figure 1