Electrical and electrochemical studies on magnesium ion-based polymer gel electrolytes

Abstract

The development of polymer gel electrolyte system with high ionic conductivity is the main objective of polymer research. Electrochemical devices based on lithium ionconducting polymer electrolyte are not safe due to the explosive nature of lithium. An attempt has been made to synthesize magnesium ion-conducting polymeric gel electrolytes, poly (vinylidene fluoride-co-hexafluoropropylene)-propylene carbonate-magnesium perchlorate, PVdF(HFP)-PCMg(ClO 4 ) 2 using standard solution-cast techniques. The maximum room temperature ionic conductivity of the synthesized electrolyte system has been observed to be 5.0×10 −3 S cm −1 , which is quite acceptable from a device fabrication point of view. The temperature-dependent conductivity and the dielectric behavior were also analyzed. The pattern of the temperature-dependent conductivity shows the Arrhenius behavior. The dielectric constant ε r and dielectric loss ε i increases with temperature in the low-frequency region but almost negligible in the high-frequency region. This behavior can be explained on the basis of electrode polarization effects. The real part M r and imaginary part M i versus frequency indicate that the systems are predominantly ionic conductors. Further, the synthesized electrolyte materials have been checked for its suitability in energy storage devices namely redox supercapacitor with conducting polymer polypyrrole as electrode materials, and finally, it was observed that it shows good capacitive behavior in low-frequency region. Preliminary studies show that the overall capacitance of 22 mF cm −2 which is equivalent to a single electrode specific capacitance of 117 F gm −1 was observed for the above said supercapacitors.

Structural, thermal, electrical, and dielectric properties of synthesized nanocomposite solid polymer electrolytes

“…This may be due to the reduction of the flexibility and agglomeration (clustering) at high content of fumed silica nanoparticles in polymer electrolyte films. [19][20][21] The crystallinity increases, and attractive interaction between fumed silica nanoparticles and the polymer chains also increases. 22 For the sample containing 2% of fumed silica nanoparticles, increase in the T g together with the increased crystallinity can be speculated from the comparison of the XRD pattern of the samples containing no filler and 2% filler content which leads to the decrease in the conductivity.…”

“…the sample without fumed silica nanoparticles, conductivity spectra consist of low-frequency dispersive region at room temperature where the charge carriers move faster than the reversal of electric field and hence conductivity increases with frequency. 31,32 With further increase in frequency, AC conductivity spectra shows the plateau region which corresponds to the bulk conductivity of the sample. In high-frequency range, third region arises with increase in temperature, that is, decrease in the conductivity.…”

Composite Polymer Electrolyte for Highly Cyclable Room-Temperature Solid-State Magnesium Batteries

“…Although a high ionic conductivity of 8 mS cm –1 was observed in this gel polymer, no cycling data were reported. There have been other reports on polymer electrolytes based on Mg­(ClO 4 ) 2 /PVdF-HFP using conventional carbonate-based solvents such as EC and PC reporting conductivities in the range of 10 –3 S cm –1 . − Alternatively, ionic liquids such as 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITF) has also been used as the plasticizer for Mg­(ClO 4 ) 2 /PVdF-HFP-based polymer electrolytes . However, the cycling performance of such gel–polymer electrolytes against the Mg-metal anode needs improvement.…”

Structural, electrical and electrochemical studies of ionic liquid-based polymer gel electrolyte using magnesium salt for supercapacitor application

“…The choice of host polymer determines whether the gel polymer electrolyte has an excellent matrix or not. Various polymers like polyacrylonitrile (PAN) [16,17], polyethylene oxide (PEO) [18,19], polymethylmethacrylate (PMMA) [20,21], polyvinylidene fluoride (PVDF) [22] and poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) [23,24] has been used. In the present studies, PVdF-HFP has been chosen because of its strong electron-withdrawing functional groups (-C-F-), high dielectric constant ( = 8.4) which is suitable for the dissolution of magnesium salt to keep a high concentration of charge carriers.…”

“…In the present studies, PVdF-HFP has been chosen because of its strong electron-withdrawing functional groups (-C-F-), high dielectric constant ( = 8.4) which is suitable for the dissolution of magnesium salt to keep a high concentration of charge carriers. PVdF-HFP also contains more amorphous domains that are capable of trapping a large amount of liquid electrolyte and hence it is considered as one of the most promising polymer matrices for gel polymer electrolytes [24,25].…”