*2.3.3 Electrolyte*

ILs have also been used as solvents in extraction processes or as electrolytes. Polymer electrolytes comprising IL [emim][Tf2N] and soluble SPI showed a high ionic conductivity and reliable mechanical strength, suitable for HPP actuators [106]. Gel polymer electrolytes (GPEs) [107–109] and solid polymer electrolytes [110–114] have been widely reported. A series of GPEs were prepared using the electrospun membranes of poly(vinylidene fluoride-cohexafluoropropylene) [P(VdF-co-HFP)] incorporating ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethylsulphonyl)imide in the presence of lithium bis(trifluoromethylsulphonyl)imide (LiTf2N) [115]. An IL-GPE containing semicrystal PVDF, amorphous polyvinyl acetate (PVAc) and ionic conductive [bmim] [BF4] was prepared via the solution-casting method for solid supercapacitors [116]. A PVDF-HFP/PMMA-blended microporous gel polymer electrolyte incorporating [bmim][BF4] was fabricated for lithium-ion batteries [117]. Solid polymer electrolytes using poly(vinylidene-fluoridetrifluoroethylene) and N,N,N-trimethyl-N-(2-hydroxyethyl) ammonium bis(trifluoromethylsulphonyl)imide ([N1112(OH)] [Tf2N]) IL were fabricated for energy storage applications [118]. PI/IL composite membranes for fuel cells operating at high temperatures were prepared by impregnating a porous Matrimid® membrane with protic ILs: 1-*n*-methyl-imidazolium dibutylphosphate ([C1im][DBP]), 1-*n*-butylimidazolium dibutyl-phosphate ([C4im][DBP]) and 1-*n*-butylimidazolium bis(2-ethylhexyl)phosphate ([C4im] [BEHP]). The electrolyte membranes were used as a proton-exchange membrane fuel cell (PEMFC) [119]. An IL-polymer electrolyte film based on a low-viscosity IL (1-ethyl-3-methylimidazolium dicyanamide) incorporated into a polymer matrix

**111**

**Figure 9.**

*HFP polymer electrolyte film (maximum conductivity).*

*Progress in Ionic Liquids as Reaction Media, Monomers and Additives in High-Performance…*

**Figure 9** [120]. Quasi-solid-state electrolytes (QSEs) consisting of IL-LiTf2Nfumed silica nanoparticles were prepared for use in bulk-type all-solid-state cell

(PVDF-HFP) was prepared, exhibiting liquid-like conductivity, and the maximum

Carbon nanotubes (CNTs) consist of rolled-up graphene sheets and can be used as electronic, conductive and reinforcing fillers for polymer composites. MWCNTs possess a nanoscale diameter, a high aspect ratio, excellent mechanical properties, and good electrical conductivity. In recent years, MWCNTs have gained considerable interests of scientists and engineers, especially in polymer composites containing HPPs and ILs. A PI composite film comprising finely IL-dispersed MWCNTs in IL was obtained with a high shielding effectiveness (SE) for use in the packaging of a 2.5-Gbps plastic transceiver module with numerous applications in fibre to the home lightwave transmission systems [122]. PEI NCs consisting of bucky gels of industrial-grade MWCNTs and [bmim][PF6] were prepared; they are suitable for the aerospace and electronics industries, as shown in **Figure 10** [123]. Some PI and PEI NCs consisting of MWCNTs and polymerised ILs (PILs) were prepared, exhibiting differential function [124, 125]. The crystal structure of PVDF was modified by utilising the long alkyl chains of [C16mim][Br] and IL-modified MWCNTs, and the crystallisation kinetics of the composites was investigated [126, 127]. A series of PVDF composites with 'bucky gels' of MWNTs and ILs were obtained by simple melt compounding. According to the DSC and XRD results, the addition of ILs in the composites changed the crystallinity and crystal form of the PVDF [128]. PTFT and PVDF as the components of NCs containing HPP and ILs have received increasingly more attention. The nanomaterials with a nanoscale structure were prepared using pyridinium, imidazolium and phosphonium ILs as new synthetic building blocks in a PTFT. The cation-anion combination and functionalisation of ILs affect the ionic networks and nanostructures of materials [129, 130]. These nanomaterials show optimised thermal and mechanical properties and have numerous potential applications such as supercritical CO2 [131]. PVDF/IL/GraNCs were fabricated via the solution casting of PVDF with graphene (Gra) modified with a long alkyl chain IL [C16mim][Br], exhibiting a low loss tangent and low conductivity in the PVDF/ionic liquid-modified graphene

*Photograph of (a) assemble DSSC and (b) I-V characteristics of DSSC comprising IL-incorporated PVDF-*

S/cm, as shown in

*DOI: http://dx.doi.org/10.5772/intechopen.86472*

*2.3.4 Nanocomposite*

conductivity of PVDF-HFP + 25 wt% IL was as high as 10<sup>−</sup><sup>3</sup>

configuration lithium-sulphur rechargeable batteries [121].

## *Progress in Ionic Liquids as Reaction Media, Monomers and Additives in High-Performance… DOI: http://dx.doi.org/10.5772/intechopen.86472*

(PVDF-HFP) was prepared, exhibiting liquid-like conductivity, and the maximum conductivity of PVDF-HFP + 25 wt% IL was as high as 10<sup>−</sup><sup>3</sup> S/cm, as shown in **Figure 9** [120]. Quasi-solid-state electrolytes (QSEs) consisting of IL-LiTf2Nfumed silica nanoparticles were prepared for use in bulk-type all-solid-state cell configuration lithium-sulphur rechargeable batteries [121].

## *2.3.4 Nanocomposite*

*Solvents, Ionic Liquids and Solvent Effects*

[bmim][PF6] were also obtained by spraying a suspension dispersion with an encapsulation capacity of 29% [102]. PSF microcapsules have practical use such as the removal of caprolactam from water [103]. PEEK microcapsules containing trihexyl(tetradecyl) phosphonium chloride IL was obtained in *N*,*N*-dimethylformamide (DMF) as the dispersing phase and dodecane [104]. PTFE microcapsules containing [hmim][Tf2N]

*Optical microscopic images and composition of organic phase is PSF: dichloromethane (DCM): [bmim] PF6 = 5 g: 80 ml: 3 g; continuous phase is 0.1 wt% gelatin solution; inner size of nozzle: 0.6 mm, IL microcapsules, flow rate of continuous phases (CP): 30 ml/min; and flow rate of droplet phases (DP):* 

ILs have also been used as solvents in extraction processes or as electrolytes.

Polymer electrolytes comprising IL [emim][Tf2N] and soluble SPI showed a high ionic conductivity and reliable mechanical strength, suitable for HPP actuators [106]. Gel polymer electrolytes (GPEs) [107–109] and solid polymer electrolytes [110–114] have been widely reported. A series of GPEs were prepared using the electrospun membranes of poly(vinylidene fluoride-cohexafluoropropylene) [P(VdF-co-HFP)] incorporating ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethylsulphonyl)imide in the presence of lithium bis(trifluoromethylsulphonyl)imide (LiTf2N) [115]. An IL-GPE containing semicrystal PVDF, amorphous polyvinyl acetate (PVAc) and ionic conductive [bmim] [BF4] was prepared via the solution-casting method for solid supercapacitors [116]. A PVDF-HFP/PMMA-blended microporous gel polymer electrolyte incorporating [bmim][BF4] was fabricated for lithium-ion batteries [117]. Solid polymer electrolytes using poly(vinylidene-fluoridetrifluoroethylene) and N,N,N-trimethyl-N-(2-hydroxyethyl) ammonium bis(trifluoromethylsulphonyl)imide ([N1112(OH)] [Tf2N]) IL were fabricated for energy storage applications [118]. PI/IL composite membranes for fuel cells operating at high temperatures were prepared by impregnating a porous Matrimid® membrane with protic ILs: 1-*n*-methyl-imidazolium dibutylphosphate ([C1im][DBP]), 1-*n*-butylimidazolium dibutyl-phosphate ([C4im][DBP]) and 1-*n*-butylimidazolium bis(2-ethylhexyl)phosphate ([C4im] [BEHP]). The electrolyte membranes were used as a proton-exchange membrane fuel cell (PEMFC) [119]. An IL-polymer electrolyte film based on a low-viscosity IL (1-ethyl-3-methylimidazolium dicyanamide) incorporated into a polymer matrix

IL lubricant with small sizes (below 10 μm) have been reported [105].

**110**

*2.3.3 Electrolyte*

**Figure 8.**

*125 μl/min.*

Carbon nanotubes (CNTs) consist of rolled-up graphene sheets and can be used as electronic, conductive and reinforcing fillers for polymer composites. MWCNTs possess a nanoscale diameter, a high aspect ratio, excellent mechanical properties, and good electrical conductivity. In recent years, MWCNTs have gained considerable interests of scientists and engineers, especially in polymer composites containing HPPs and ILs. A PI composite film comprising finely IL-dispersed MWCNTs in IL was obtained with a high shielding effectiveness (SE) for use in the packaging of a 2.5-Gbps plastic transceiver module with numerous applications in fibre to the home lightwave transmission systems [122]. PEI NCs consisting of bucky gels of industrial-grade MWCNTs and [bmim][PF6] were prepared; they are suitable for the aerospace and electronics industries, as shown in **Figure 10** [123]. Some PI and PEI NCs consisting of MWCNTs and polymerised ILs (PILs) were prepared, exhibiting differential function [124, 125].

The crystal structure of PVDF was modified by utilising the long alkyl chains of [C16mim][Br] and IL-modified MWCNTs, and the crystallisation kinetics of the composites was investigated [126, 127]. A series of PVDF composites with 'bucky gels' of MWNTs and ILs were obtained by simple melt compounding. According to the DSC and XRD results, the addition of ILs in the composites changed the crystallinity and crystal form of the PVDF [128]. PTFT and PVDF as the components of NCs containing HPP and ILs have received increasingly more attention. The nanomaterials with a nanoscale structure were prepared using pyridinium, imidazolium and phosphonium ILs as new synthetic building blocks in a PTFT. The cation-anion combination and functionalisation of ILs affect the ionic networks and nanostructures of materials [129, 130]. These nanomaterials show optimised thermal and mechanical properties and have numerous potential applications such as supercritical CO2 [131]. PVDF/IL/GraNCs were fabricated via the solution casting of PVDF with graphene (Gra) modified with a long alkyl chain IL [C16mim][Br], exhibiting a low loss tangent and low conductivity in the PVDF/ionic liquid-modified graphene

#### **Figure 9.**

*Photograph of (a) assemble DSSC and (b) I-V characteristics of DSSC comprising IL-incorporated PVDF-HFP polymer electrolyte film (maximum conductivity).*

**Figure 10.**

*Processing of PEI/bucky gel nanocomposites; the obtained composites had good toughness as the film could be curved adequately without any damage.*

(GIL) composites [132, 133]. NCs, based on a homopolymer PVDF and IL, were fabricated, and the preparation process opens up a new synthesis route for nanostructured polymer composites. Dielectric NCs based on PVDF, conductive carbon black (CB) and IL 1-vinyl-3-ethylimidazolium tetrafluoroborate [VEIM][BF4] were prepared via melt blending and electron beam irradiation (EBI) methods [134].

A nanostructured PAI was prepared in TBAB as a green medium by the step polymerisation reaction of 4,4′-methylenebis(3-chloro-2,6-diethyl trimellitimidobenzene) with 3,5-diamino-*N*-(4-hydroxy-phenyl)benzamide. Then, amino acid-functionalised multiwalled carbon nanotubes (f-MWCNTs)/PAI NCs were prepared by a solution mixing method [30].
