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are scrutinized for potential replacement of fossil fuels, new conductive ma-
terialshavecometotheforefrontofthisresearcharea.
Solid-state materials with high conductivity for ions such as Li
+
are essen-
tial for the development of more efficient Li ion batteries with higher energy
densities. The solid electrolytes [e.g., poly(ethylene oxide), (PEO)] that trans-
port Li
+
in the current generation of Li batteries arguably play the most crucial
role in dictating overall battery performance. In a similar vane, materials with
high proton conductivity are essential for the development of high efficiency
fuel cells for electrical power generation [76]. Additionally, the development of
more efficient electrical storage devices with higher energy density, lower over-
all mass, and higher amperage output is the current focus of ion-conductive
materials research [75]. Furthermore, the miniaturization of electronic devices
to smaller and smaller dimensions requires specialized electrically conductive
materials to meet new high performance requirements.
Nanostructured LLC systems offer potential advantages over conventional
non-ordered, ion-conducting materials such as amorphous non-charged PEO
polymers, and non-coordinating charged polymers such as Nafion. LLC sys-
tems made from surfactant molecules containing the same types of ion-
transporting units, as found in PEO and Nafion, have uniform nanoscale
domains that run through the bulk materials which can be interconnected or
continuous in 1, 2, or 3 dimensions depending on the LLC phase. This unique
feature of LLC phases can potentially afford superior transport of ions and
better bulk ionic conductivity, compared to amorphous polymers, so long as
the solvent, used in LLC formation, is conducive to good ion transport and
stability. Similarly, if the ordered LLC domains contain electrically conduct-
ing materials such as metals, semiconductors, or conjugated polymers, then
new composite materials, with anisotropic and perhaps enhanced bulk elec-
trical conductivity may be obtained. Functional LLC systems have already
made an impact in the design of new ion- and electrically conductive organic
materials.
3.1
LLCPhasesasIonConductors
Although a substantial number of functionalized thermotropic LC systems
have been designed and investigated as anisotropic ion-conducting materi-
als [18, 19, 21, 78-80], interest in solvent-based LLC systems as ion conductors
has only recently emerged. The bulk of the research into the ionic conduc-
tivity of LLC materials has only been investigated within the last decade.
Somewhat unique approaches to testing the bulk conductivity of these ma-
terials are required due to the concentration dependent ordering of the LLC
systems as well as the solvent(s) utilized (water, methanol, etc.) in phase
formation. Methods have recently been developed to measure the ionic con-
ductivity of these materials in their respective LLC phases.
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