Nanoparticle dispersion in PEO polymeric solutions via plasma treatment for the production of electrospun lithium batteries separator

The use of electrospun mats is considered an innovative solution for the production of separators for lithium-ion batteries. Furthermore, the addition of oxide nanoparticles is known to be a suitable way to increase mechanical, thermal and electrical properties of the electrospun separators. Conventional techniques such as mechanical stirring, sonication, ball-milling and sol-gel methods have been investigated in the past in order to improve nanoparticle dispersion. This work is focused on a novel treatment, where an atmospheric pressure plasma is employed to treat the polymeric solution thus facilitating nanoparticle dispersion. Poly(ethylene oxide) (PEO) is dissolved in bidistilled water and fumed silica nanoparticles (average size = 7 nm) are added to the solution. The electrospinning solution, either before or after nanoparticle addition, is exposed to a plasma jet driven by high voltage nanosecond pulses. In addition, mechanical stirring is performed both on treated and reference samples. A very good particle dispersion in the electrospun fibers of plasma treated polymeric solutions is observed by means of transmission electron microscope. In particular, when a 3 minutes plasma treatment of the solution is followed by 10 minutes stirring of nanoparticles, an outstanding dispersion of fumed silica is obtained in the produced nanofibers.