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Abstract: Gel polymer electrolyte (GPE) membranes based on two polymers, a copolymer of poly(vinylidene fluoride–hexafluoropropylene) (PVdF–HFP), and the poly(ethylene oxide) (PEO), together with a plasticizer, the dibutylphtalate (DBP), were elaborated in two ways. Firstly, the polymers and the plasticizer were mixed together to obtain a single membrane. Secondly, a bi-layer separator membrane was made by adjunction, through lamination, of a DBP plasticized PVdF–HFP film and a homemade DBP–PEO thin film. We report here a protocol based on a simple galvanostatic polarization of Li/GPE/Li symmetric cells as a way to rapidly screen new viable membranes. Such a procedure enables to quickly discriminate separators by leading experiments that do no not exceed 1 week compared to hundreds of days needed with classical batteries. The validity of such an approach was confirmed by investigating the performances of the membranes in Li/GPE/Li4Ti5O12 flat battery configuration. Besides, through this study we also highlighted the role of the macroscopic PEO–PVdF interface toward dendrite of bi-layered separator, while a single blended membrane does not seem to be suitable for a practical use. Post-mortem pictures and SEM investigation have confirmed this result. [Copyright &y& Elsevier]

Abstract: A new effective Gel Polymer Electrolyte membrane based on two polymers, the polyethylene oxide (PEO), a poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) copolymer and a plasticizer, the dibutylphtalate (DBP), was realized. This separator membrane was made by adjunction, through lamination, of an industrially made DBP/PVdF-HFP film and a homemade DBP/PEO thin film. Once the plasticizer was removed and the separator gelled by the electrolyte, the PEO enables the formation of a good interface with the lithium while the PVdF-HFP film brings the mechanical strength to the membrane. The electrochemical behavior of lithium batteries based on this bi-layer separator was investigated versus temperature, cycling potential and cycling rate. Owing to the promising results obtained with laboratory cells, a 1Ah prototype was successfully assembled, and its cycling and rate performances were reported. [Copyright &y& Elsevier]