ma0c00466_si_001.pdf (457.79 kB)
Reversible Changes in the Grain Structure and Conductivity in a Block Copolymer Electrolyte
journal contribution
posted on 2020-07-02, 18:05 authored by Saheli Chakraborty, Xi Jiang, Zach J. Hoffman, Gurmukh K. Sethi, Chenhui Zhu, Nitash P. Balsara, Irune VillaluengaWe
study the phase behavior of a triblock organic–inorganic
hybrid copolymer, poly(polyhedral oligomeric silsesquioxane)-b-poly(ethylene oxide)-b-poly(polyhedral
oligomeric silsesquioxane) (POSS-PEO-POSS)/lithium bis(trifluoromethanesulfonyl)imide
(LiTFSI) salt mixture, as a function of temperature. The polymer exhibits
a lamellar morphology both in the neat state and in the presence of
salt. However, the average grain size increases substantially when
the electrolyte is heated above 113 °C. The grain structure of
this sample changes reversibly with temperature, that is, smaller
grains reappear when the electrolyte is cooled below 113 °C.
While annealing block copolymers at high temperatures often leads
to an increase in the grain size, this change is generally irreversible.
The reason for the reversible change in the grain structure of the
POSS-PEO-POSS/LiTFSI electrolyte is discussed. The ionic conductivity
of the electrolyte also exhibits reversible changes in this temperature
window. Knowledge of the grain structure is crucial for understanding
ion transport in nanostructured electrolytes.