So, a recent report by Liu et al. (2017) investigated the effect of alignment of the
nanowire (LLTO; Li 0.33 La 0.557 TiO 3 ) in the three orientations (0
Æ 5
, 45
Æ 9
, and
90
Æ 8
) w.r.t of electrodes in a PAN–LiClO 4 - based polymer matrix. SEM analysis
depicts that the NW are well embedded in the polymer matrix with an average
spacing of 5 μm (Fig. 8.23e–g). The ionic conductivity of randomly aligned NW was
5.40 Â 10
À6 S cm
À1 and is higher than when dispersed with the nanoparticle.
Further, when the NW were aligned with 0
o orientation, then conductivity was
increased to 6.05 Â 10
À5 S cm
À1 .
This enhancement in the conductivity may be due to the absence of the crossing
junctions as in the nanoparticle and aligned NW. For orientation, angle 45
conductivity decreases to 2.24 Â 10
À5 S cm
À1 and is due to more continuous length along
electrodes as compared to the 0
. While for the 90
orientation, the conductivity was
1.78 Â 10
À7 S cm
À1 and is due to the parallel alignment of NW with electrodes.
Also, the electronic conductivity was of the order of 10
À11 S cm
À1 and is negligible
as compared to the ionic conductivity. The dispersion of the nanowire may also
increase the polymer chain segmental motion, and that was evidenced by the
increased Li
+ transference number from 0.27 to 0.42. Further, the faster relaxation
was confirmed by plotting the imaginary part of impedance, and peak shifts toward
high-frequency evidence the same. To further verify the experimental conductivity
data simulation using the COMSOL Multiphysics (COMSOL), numerical analysis
of the current distribution was performed and is in good agreement with
experimental data.
Another report by Zhang et al. (2011) demonstrates the synthetization of the
composite gel polymer electrolytes by adding SiO 2 nanowires into a P(VDF–HFP)
matrix. FESEM analysis concludes that the synthesized nanowires are flexible and of
high purity with the diameter and length of the SiO 2 as <50 nm and $1 μm,
respectively. FTIR was performed to check the nanorod formation, and it shows
the main absorption band asymmetric bending mode of –Si–O–Si, symmetric
bending mode of –Si–O–Si, bending mode of –O–Si–O, and the bending mode of
the –Si–OH. FESEM analysis of the composite matrix suggests the effective role in
modifying the surface morphology of pure polymer which is favorable for cation
transport. Also, the presence of pores suggests the absorption of more electrolyte and
hence the more ionic conductivity. FTIR spectrum confirms the interaction between
the Si atoms of SiO 2 and F atoms of P(VDF–HFP) chain which helps in ion
migration. TGA plot reveals the improved thermal stability (427
C) as compared
to the pure polymer (384
C) and is due to the interaction between the host polymer
matrix and the Si nanowire. Further, DSC analysis shows the reduction in the
crystallinity on the addition of nanowire and may be due to the lowering of polymer
chain reorganization tendency and enhanced amorphous content. The stress–strain
curve shows increased tensile strength from 18.3 MPa (zero % nanowire) to
27.3 MPa for composite polymer electrolyte with 10 wt. % nanowire and is owing
to the interaction between the polymer matrix and SiO 2 nanowire. This may be due
to the increased chain flexibility on the addition of nanowire which makes it capable
to bear high stress and is in agreement with the FTIR. The ionic conductivity was
increased by one order and is 1.08 Â 10
À3 S cm
À1 (at 30
C) and may be due to the
306
A. Arya and A. L. Sharma
nanowire (LLTO; Li 0.33 La 0.557 TiO 3 ) in the three orientations (0
Æ 5
, 45
Æ 9
, and
90
Æ 8
) w.r.t of electrodes in a PAN–LiClO 4 - based polymer matrix. SEM analysis
depicts that the NW are well embedded in the polymer matrix with an average
spacing of 5 μm (Fig. 8.23e–g). The ionic conductivity of randomly aligned NW was
5.40 Â 10
À6 S cm
À1 and is higher than when dispersed with the nanoparticle.
Further, when the NW were aligned with 0
o orientation, then conductivity was
increased to 6.05 Â 10
À5 S cm
À1 .
This enhancement in the conductivity may be due to the absence of the crossing
junctions as in the nanoparticle and aligned NW. For orientation, angle 45
conductivity decreases to 2.24 Â 10
À5 S cm
À1 and is due to more continuous length along
electrodes as compared to the 0
. While for the 90
orientation, the conductivity was
1.78 Â 10
À7 S cm
À1 and is due to the parallel alignment of NW with electrodes.
Also, the electronic conductivity was of the order of 10
À11 S cm
À1 and is negligible
as compared to the ionic conductivity. The dispersion of the nanowire may also
increase the polymer chain segmental motion, and that was evidenced by the
increased Li
+ transference number from 0.27 to 0.42. Further, the faster relaxation
was confirmed by plotting the imaginary part of impedance, and peak shifts toward
high-frequency evidence the same. To further verify the experimental conductivity
data simulation using the COMSOL Multiphysics (COMSOL), numerical analysis
of the current distribution was performed and is in good agreement with
experimental data.
Another report by Zhang et al. (2011) demonstrates the synthetization of the
composite gel polymer electrolytes by adding SiO 2 nanowires into a P(VDF–HFP)
matrix. FESEM analysis concludes that the synthesized nanowires are flexible and of
high purity with the diameter and length of the SiO 2 as <50 nm and $1 μm,
respectively. FTIR was performed to check the nanorod formation, and it shows
the main absorption band asymmetric bending mode of –Si–O–Si, symmetric
bending mode of –Si–O–Si, bending mode of –O–Si–O, and the bending mode of
the –Si–OH. FESEM analysis of the composite matrix suggests the effective role in
modifying the surface morphology of pure polymer which is favorable for cation
transport. Also, the presence of pores suggests the absorption of more electrolyte and
hence the more ionic conductivity. FTIR spectrum confirms the interaction between
the Si atoms of SiO 2 and F atoms of P(VDF–HFP) chain which helps in ion
migration. TGA plot reveals the improved thermal stability (427
C) as compared
to the pure polymer (384
C) and is due to the interaction between the host polymer
matrix and the Si nanowire. Further, DSC analysis shows the reduction in the
crystallinity on the addition of nanowire and may be due to the lowering of polymer
chain reorganization tendency and enhanced amorphous content. The stress–strain
curve shows increased tensile strength from 18.3 MPa (zero % nanowire) to
27.3 MPa for composite polymer electrolyte with 10 wt. % nanowire and is owing
to the interaction between the polymer matrix and SiO 2 nanowire. This may be due
to the increased chain flexibility on the addition of nanowire which makes it capable
to bear high stress and is in agreement with the FTIR. The ionic conductivity was
increased by one order and is 1.08 Â 10
À3 S cm
À1 (at 30
C) and may be due to the
306
A. Arya and A. L. Sharma