Thermal Behaviors And Ionic Conductivity Of Composite Enr-50-Based Polymer Electrolytes
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Date
2013-02
Authors
Tan, Wei Leng
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
The synthesis of polymer electrolytes (PEs) and composite polymer electrolytes
(CPEs) using epoxidized natural rubber (ENR-50) as the host matrix and magnetite
(Fe3O4) nanoparticles as the inorganic filler was carried out. These were characterized
by FTIR, SEM/X-mapping, TEM, XRD, DSC, TGA and EIS. The influence of lithium
salt, LiX (where X = BF4
-, I-, CF3SO3
-, COOCF3
- and ClO4
-) with various anions and
iodide salt, MI (where M = Li+, Na+, K+ and Ag+) with different cations on the properties
and degradation of PEs was investigated. This was followed by the study of the
simultaneous presence of Fe3O4 nanoparticles in various LiX-ENR-50 PE systems. The
study on sole Fe3O4/ENR-50 composites was also performed for comparison purposes.
The trend in thermal stability and ionic conductivity of LiX-ENR-50 PEs is in the order of
LiBF4 >> LiCF3SO3 ~ LiCOOCF3 > LiI >> LiClO4. The LiClO4 hardly dissociates and
formed LiClO4 aggregates within the ENR-50 matrix that resulted in a PE with low
thermal stability and low ionic conductivity. The LiCF3SO3, LiCOOCF3 and LiI exert
moderate interactions with the ENR-50 and their respective PEs exhibit moderate ionic
conductivity and thermal property. The occurrence of epoxide ring opening and
complexation or cross-linking reactions in and between the ENR-50 chains that involve
BF4
- ions have produced a LiBF4-ENR-50 PE with superior thermal stability and ionic
conductivity as compared to other LiX-ENR-50 PEs studied in this work. The
impedance properties of MI-ENR-50 PEs are closely related to the solubility, interaction
and the outcome morphology of MI salt in the ENR-50. The solubility of MI salt in the
ENR-50 follows the decreasing trend of LiI > NaI > KI > AgI. In PEs, the LiI mostly
exists in ions and the Li+ are pseudo-crosslinked with the epoxide in the ENR-50
chains. Other MI salts are hardly dissociated in the ENR-50 which exert weak or no
chemical interaction with the ENR-50. The thermal stability of ENR-50 in PEs is
dependant on the type of metal in the MI salt. The alkali metal like Li, Na and K does
not greatly influence the stability of ENR-50. Nonetheless, the presence of AgI
destabilizes the ENR-50 in PE. The degradation of ENR-50 in LiClO4-, NaI- and KIENR-
50 PE is similar to purified ENR-50 due to weak salt-ENR-50 interaction. It
initiates with first-order reaction (F1) followed by 3-dimensional diffusion control (D3)
reaction. The presence of other salts in PE caused the degradation of ENR-50 to follow
only a D3 type model.
Description
Keywords
Thermal Behaviors And Ionic Conductivity , Enr-50-Based Polymer Electrolytes