25) as salt. SEM analysis suggests the uniform surface and morphology was
unaltered with cylindrical particles. The ionic conductivity was 10 wt. % MIL-53
(Al) content for EO:Li ratio of 15:1 with value 1.62 Â 10
À5 S cm
À1 (at 30
C) and
9.71 Â 10
À4 S cm
À1 (at 80
C). This was also further supported by the lowering of
phase transition temperature from 56.9
C to 50.3
C with the addition of MIL-53
(Al); and this enhances the amorphous content and hence the improved conductivity.
The Li
+ transference number was increased from 0.252 to 0.343 with MIL-53(Al)
addition and may be due to the formation of the metal–organic framework which
enhances the ion mobility. Then the zeta electric potential measurement shows the
pH is about 7, and it indicates that the MIL-53(Al) particles have strong Lewis acidic
properties. This helps in the salt dissociation, while anion is coordinated with the
Lewis acidic surface of the nanoparticle. The overall effect is the disruption of the
crystalline nature and improved ionic conductivity. The electrochemical stability
window of the polymer electrolyte was 5.31 V at 80
C and 5.10 V at 120
C with
nanoparticle and is larger than the nanoparticle-free system which shows 5.15 V at
80
C and 4.99 V at 120
C (Fig. 8.9d). The thermal stability analysis evidences the
thermal stability of about 200
C with the first degradation beginning from 195
C
(decomposition of PEO) followed by degradation at 375
C (decomposition of
LiTFSI) (Shodai et al. 1994). Also, the mechanical properties were enhanced with
nanoparticle addition and may be due to the formation of crossing-linking centers for
PEO. Then the cyclic performance of the solid-state battery (LiFePO4–PEO–MIL53(Al)-LiTFSI–Li) was tested, and the initial discharge capacity was 127.1 mAhg
À1
(at 5 C and 80
C) and 136.4 mA h g
À1 at 120
C. After 300 cycles, the discharge
capacity was 116.0 mAh g
À1 at 80
C and 129.2 mAh g
À1 at 120
C. Even after
14 cycles, the retention ratios of 52.4% and 61.3%, respectively, were achieved at
80
C and 120
C.
Vignabooran et al. (2014) reported the preparation of the composite polymer
electrolyte based on PEO-LiTf-EC-TiO 2 . The purpose of this research was to study
the combined effect of the plasticizer and the nanofiller, as both influence the
polymer matrix in a different manner. The highest ionic conductivity was
4.9 Â 10
À5 S cm
À1 for the 10 wt. % TiO 2 (at 30
C, E a ¼ 78.8 kJ/mol) and was
attributed to the Lewis acid–base character of the nanofiller surface. The nanofiller
surface can affect in two ways: one is a reduction of the polymer recrystallization
tendency and another is an increase of salt dissociation or lowering in ion pairing.
Both simultaneously support the fast ion migration. Further addition of the EC
increases the conductivity up to 1.6 Â 10
À4 S cm
À1 for the 50 wt. % EC
(at 30
C, E a ¼ 57.5 kJ/mol). Further, DSC analysis supports the enhancement in
the conductivity as both glass transition temperature (À46
C to À50
C) and the
melting temperature (60
C to 50
C) show a decrease in the signal temperature with
addition of the EC in TiO 2 -based polymer matrix.
Another report by Klongkan et al. (Klongkan and Pumchusak 2015) investigated
the effect of PEG–DOP plasticizer and Al 2 O 3 nanofiller on the PEO–LiCF 3 SO 3 -
based polymer matrix. DSC spectra shows the decrease of the crystallinity from
37.31% (PEO-15 wt.%LiCF 3 SO 3 ) to 23.11% (PEO-15 wt.% LiCF 3 SO 3 -20 wt.%
DOP) and 18.61% (PEO-15 wt.% LiCF 3 SO 3 -20 wt.%Al 2 O 3 ). The decrease in
8 Polymer Nanocomposites: Synthesis and Characterization
287
unaltered with cylindrical particles. The ionic conductivity was 10 wt. % MIL-53
(Al) content for EO:Li ratio of 15:1 with value 1.62 Â 10
À5 S cm
À1 (at 30
C) and
9.71 Â 10
À4 S cm
À1 (at 80
C). This was also further supported by the lowering of
phase transition temperature from 56.9
C to 50.3
C with the addition of MIL-53
(Al); and this enhances the amorphous content and hence the improved conductivity.
The Li
+ transference number was increased from 0.252 to 0.343 with MIL-53(Al)
addition and may be due to the formation of the metal–organic framework which
enhances the ion mobility. Then the zeta electric potential measurement shows the
pH is about 7, and it indicates that the MIL-53(Al) particles have strong Lewis acidic
properties. This helps in the salt dissociation, while anion is coordinated with the
Lewis acidic surface of the nanoparticle. The overall effect is the disruption of the
crystalline nature and improved ionic conductivity. The electrochemical stability
window of the polymer electrolyte was 5.31 V at 80
C and 5.10 V at 120
C with
nanoparticle and is larger than the nanoparticle-free system which shows 5.15 V at
80
C and 4.99 V at 120
C (Fig. 8.9d). The thermal stability analysis evidences the
thermal stability of about 200
C with the first degradation beginning from 195
C
(decomposition of PEO) followed by degradation at 375
C (decomposition of
LiTFSI) (Shodai et al. 1994). Also, the mechanical properties were enhanced with
nanoparticle addition and may be due to the formation of crossing-linking centers for
PEO. Then the cyclic performance of the solid-state battery (LiFePO4–PEO–MIL53(Al)-LiTFSI–Li) was tested, and the initial discharge capacity was 127.1 mAhg
À1
(at 5 C and 80
C) and 136.4 mA h g
À1 at 120
C. After 300 cycles, the discharge
capacity was 116.0 mAh g
À1 at 80
C and 129.2 mAh g
À1 at 120
C. Even after
14 cycles, the retention ratios of 52.4% and 61.3%, respectively, were achieved at
80
C and 120
C.
Vignabooran et al. (2014) reported the preparation of the composite polymer
electrolyte based on PEO-LiTf-EC-TiO 2 . The purpose of this research was to study
the combined effect of the plasticizer and the nanofiller, as both influence the
polymer matrix in a different manner. The highest ionic conductivity was
4.9 Â 10
À5 S cm
À1 for the 10 wt. % TiO 2 (at 30
C, E a ¼ 78.8 kJ/mol) and was
attributed to the Lewis acid–base character of the nanofiller surface. The nanofiller
surface can affect in two ways: one is a reduction of the polymer recrystallization
tendency and another is an increase of salt dissociation or lowering in ion pairing.
Both simultaneously support the fast ion migration. Further addition of the EC
increases the conductivity up to 1.6 Â 10
À4 S cm
À1 for the 50 wt. % EC
(at 30
C, E a ¼ 57.5 kJ/mol). Further, DSC analysis supports the enhancement in
the conductivity as both glass transition temperature (À46
C to À50
C) and the
melting temperature (60
C to 50
C) show a decrease in the signal temperature with
addition of the EC in TiO 2 -based polymer matrix.
Another report by Klongkan et al. (Klongkan and Pumchusak 2015) investigated
the effect of PEG–DOP plasticizer and Al 2 O 3 nanofiller on the PEO–LiCF 3 SO 3 -
based polymer matrix. DSC spectra shows the decrease of the crystallinity from
37.31% (PEO-15 wt.%LiCF 3 SO 3 ) to 23.11% (PEO-15 wt.% LiCF 3 SO 3 -20 wt.%
DOP) and 18.61% (PEO-15 wt.% LiCF 3 SO 3 -20 wt.%Al 2 O 3 ). The decrease in
8 Polymer Nanocomposites: Synthesis and Characterization
287