O. Bohnke et al., FAST-ION TRANSPORT IN NEW LITHIUM ELECTROLYTES GELLED WITH PMMA .1. INFLUENCE OF POLYMER CONCENTRATION, Solid state ionics, 66(1-2), 1993, pp. 97-104
Conductivities and viscosities of gel electrolytes made of poly(methyl
methacrylate) (PMMA)-LiClO4-propylene carbonate have been measured. In
this paper, the influence of the concentration of polymer in the gell
ed electrolytes is investigated. These gels are both anhydrous and lit
hium ionic conductors. It is found that ionic conductivity decreases w
ith increasing amount of polymer and lies in the range 5 x 10(-3) to 5
X 10(-5) S/cm at room temperature. On the other hand, the viscosity v
aries greatly from 8 x 10(-3) to 6 x 10(6) Pa.s leading to a solid adh
esive material. The thermal dependence of both conductivity and viscos
ity can be accurately described by a VTF expression. The experimental
results show that some change occurs in the conduction path of the gel
around 30-35 w/o of polymer. For low concentrations of PMMA, the gela
tinized electrolytes can be considered as a liquid electrolyte encaged
in a polymer matrix. On the other hand, for high concentrations, some
interactions may be created between the polymer chains and the conduc
ting electrolyte leading to both a decrease of conductivity and an inc
rease of the activation energy of conduction.