Study of Carbamate‐Modified Disiloxane in Porous PVDF‐HFP Membranes: New Electrolytes/Separators for Lithium‐Ion Batteries

Abstract

A gel electrolyte membrane is obtained through the absorption of a carbamate-modified liquid disiloxane-containing lithium bis(trifluoromethane)sulfonimide (LiTFSI) by using macroporous poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) membranes. The porous membranes are prepared by means of a phase inversion technique. The resulting gel electrolyte membrane is studied by using differential scanning calorimetry, Fourier-transform infrared (FTIR) spectroscopy, and microscope mapping through coherent anti-Stokes Raman scattering (CARS) confocal microscopy and impedance spectroscopy. The ionic conductivity of the gel electrolyte is 10(-4) S cm(-1) at 20 °C. FTIR spectroscopy reveals interactions between LiTFSI and the carbonyl moiety of the disiloxane. No interactions between LiTFSI and PVDF-HFP or between disiloxane and PVDF-HFP are detected by FTIR spectroscopy. Furthermore, the distribution of the α and β/γ phases of PVDF-HFP and the homogeneous distribution of disiloxane/LiTFSI in the gel electrolyte membranes are examined by FTIR mapping. CARS confocal microscopy is used to image the three-dimensional interconnectivity, which reveals a reticulated structure of macrovoids in the porous PVDF-HFP framework. Owing to properties such as electrochemical and thermal stability of the disiloxane-based liquid electrolyte and the mechanical stability of the porous PVDF-HFP membrane, the gel electrolyte membranes presented herein are promising candidates for applications as electrolytes/separators in lithium-ion batteries.

Solid polymer electrolytes based on lithium bis(trifluoromethanesulfonyl)imide/poly(vinylidene fluoride -co-hexafluoropropylene) for safer rechargeable lithium-ion batteries

“…This fact is also confirmed by the bands in the region 1380 to 1420 cm -1 corresponding to the vibrations of the CH2 group, which also show shape changes and intensity variations. Further, figure 3a) also show the vibrations peaks for LiTFSI at 842 and 1357 cm -1 that correspond to N-CO-O symmetric stretching and asymmetric SO2 stretching modes, respectively [41,42].…”

Organosilicon‐Based Functional Electrolytes for High‐Performance Lithium Batteries

“…To improve the performances of GPEs, organosilicon compounds like siloxane, [ 171,172 ] polysiloxane, [ 173,174 ] and POSS [ 100,175–177 ] have been employed as alternative components for GPEs due to their wider electrochemical window, flexibility, better thermal, and electrochemical stability. Taking POSS as an example, POSS has been introduced into various polymer matrixes as a functional organic–inorganic hybrid nanofiller.…”

Recent Advances in Poly(vinylidene fluoride) and Its Copolymers for Lithium-Ion Battery Separators

“…For PVDF-HFP electrospun membranes, it has been demonstrated that a single layer membrane shows good porosity and uptake value, but that the mechanical stability is negatively affected, with the viscosity of the solution playing an important role [ 44 ]. Also, a novel gel electrolyte was developed based on PVDF-HFP by the addition of disiloxane into the electrolyte solution [ 42 ], leading to a thermally stable separator that is not flammable, thus contributing to safer lithium ion batteries [ 45 ]. It this sense, ionic liquids have also been used in electrolyte solutions, improving both safety and the ionic conductivity of the membranes [ 43 ].…”