This may be attributed to the partial
inhibition effect of Co3O4 addition on the polymer crystal formation.
Similar behavior was observed for systems with Fe3O4 on
PVDF [24] and TiO2 [4], -LiAlO2 [25], Sm2O3 [26], lithium salts
[27] and ceramic additives [28] on PEO-based electrolyte systems.
Also, there may be some complicated interactions between cobalt
and oxygen in Co3O4 and fluorine in PVDF which may induce structural
modifications in the polymer chain such as breaking of the
preformed crystals. This renders the polymer amorphous to some
extent, favoring the improvement in its conductivity [29].