RESUMEN
We present a temperature-controlled scanning probe microscopy characterisation of morphology and mechanical behaviour of conducting N,N'-cyclized pyrazolium salts. These salts are plastic crystals belonging to the pyrazolium trifluoromethanesulfonimide family. Going from a five-membered to a seven-membered ring, and adding a methyl group in alpha to either the five-membered or six-membered rings, allows modulation of the temperature of the phase transitions. Before and after the transitions, the materials' Young moduli, hardnesses and surface roughnesses change. We attribute these macroscopic modifications to specific states: brittle, elastoplastic and viscoplastic, corresponding to variations in the extent of the dislocations present in the crystal lattice planes of the compounds.
RESUMEN
Solid ionic conductors are actively sought for their potential application in electrochemical devices, particularly lithium batteries. We have found high ionic conductivity for a large variety of salts dissolved in the highly polar medium based on the plastic-crystal form of succinonitrile (N[triple bond]C[bond]CH(2)[bond]CH(2)[bond]C[triple bond]N). Its high diffusivity, plasticity and solvating power allowed the preparation of a large number of materials with high ionic conductivity, reaching values of 3 mS cm(-1) at 25 degrees C (two orders of magnitude above polymers). Their ease of preparation and processing allowed us to study the influence of the solute on ionic conduction within this medium. Comparisons revealed a dichotomy between plastic crystals and conventional polymer media. The usefulness of these new, easily processed electrolytes was asserted in electrochemical tests with lithium intercalation electrodes.