Nanofiller-incorporated porous polymer electrolyte for electrochemical energy storage devices

Abstract

We report the poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)-based microporous polymer membranes, prepared by phase inversion technique, incorporated with different amounts of nanosized zirconium dioxide (ZrO2) filler. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermal studies confirm the role of ZrO2 nanofiller to modify the polymer structure, pore geometry and crystallinity. The nanofillers interact with the PVdF-HFP chains via surface groups and electrostatic interactions, and their incorporation led to an increase in crystalline content of the membrane and ionic conductivity (when activated with a liquid electrolyte (LE)). A possible mechanism for the increase in crystallinity in the polymer due to interaction with nanofiller particles has also been presented. The optimized membrane has been saturated with an LE sodium perchlorate-ethylene carbonate:propylene carbonate for use as a separator/electrolyte in electrical double-layer capacitor (EDLC). The cells fabricated with the nanofiller-incorporated membrane show better performance in terms of specific electrode capacitance, specific energy and specific power (approximately 76 F g−1, approximately 20.9 Wh kg−1 and 2.62 kW kg−1) than the cells using the membrane devoid of nanofillers (approximately 61 F g−1, approximately 17.3 Wh kg−1 and approximately 3.16 kW kg−1), respectively. The EDLC shows approximately 85% retention in specific capacitance for 10,000 charge–discharge cycles.

Characterization of Local Structures of Confined Imidazolium Ionic Liquids in PVdF-co-HFP Matrices by High Pressure Infrared Spectroscopy

“…These experimental results suggest that anionic SO 2 groups and polymers may not significantly disturb each other. However, the results in Figure 1 indicate that the presence of PVdF-co-HFP disturbs the local structures of the imidazolium C–H groups in the IL cations [ 2 ].…”

“…The high safety requirements of lithium-ion batteries in mobile devices such as smartphones and other flexible electronic devices such as smartphones and other flexible electronic devices have necessitated the development of noncombustible gel-like electrolytes [ 1 , 2 , 3 , 4 ]. Polymer electrolytes, comprising a combination of flexible semi-crystalline polymer matrices and electrolytes, can separate the cathode and anode in a battery, avoid short circuits, and maintain high ion conductivity.…”

“…Flexibility of the polymers can be easily changed by adding plasticizers such as nanoparticles and ionic liquids (ILs) [ 1 , 5 ]. Researchers have discovered that PVdF-co-HFP and its mixtures hold promising applications as precursors of gas sensors [ 12 ] and can also be used in Li-ion batteries [ 1 , 4 ], dye-sensitized solar cells [ 13 ], and supercapacitors [ 2 , 6 ].…”

“…Various studies on polymer electrolytes, comprising a polymer host and an IL guest, have revealed specific properties of ion migration in the polymers [ 1 , 2 , 3 , 5 , 6 , 13 ]. Additionally, it is important to understand the interactions between the polymer backbone and the IL ions in order to design suitable polymer electrolytes that can enhance their potential applications [ 2 , 3 , 23 ]. Liang et al [ 24 ] concluded that the IL-polymer interactions mainly arise due to the associations between the positively charged ions (such as imidazolium, ammonium, and phosphonium) of the IL and the CF 2 moiety in PVdF, rather than between the anions and polymer chains.…”

“…Various studies on polymer electrolytes, comprising a polymer host and an IL guest, have revealed specific properties of ion migration in the polymers [1][2][3]5,6,13]. Additionally, it is important to understand the interactions between the polymer backbone and the IL ions in order to design suitable polymer electrolytes that can enhance their potential applications [2,3,23].…”