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Title of the thesis: High resolution morphological characterization of solid polymer electrolytes

Thesis defender: Monika Król 
Opponent: Professor Ting Xu, University of California, USA
Custos: Professor Janne Ruokolainen, Aalto University School of Science

The global transition towards renewable energy systems, together with the expansion of the electric vehicle market, is increasing the demand for safer and more efficient batteries than widely used lithium-ion technology. Conventional lithium-ion batteries contain a flammable liquid electrolyte, which raises safety concerns. One promising solution is to replace this liquid component with a solid alternative, creating what is known as the solid-state battery.
This doctoral thesis focuses on a specific class of such materials: block copolymer electrolytes (BCPEs). These materials are particularly interesting because they can self-organize into various well-defined structures. Block copolymers are made of chemically distinct polymer blocks jointed by covalent bond. During self-assembly, these blocks separate into different domains: one type forms ion-conducting pathways that allow lithium ions to move, while the other type forms a mechanically strong framework that provides structural support. However, the overall performance strongly depends on how this internal nanoscale morphology develops and how precisely it can be controlled during the material synthesis together with its processing. Advanced characterization methods, including transmission electron microscopy and small-angle X-ray scattering, were used to resolve nanoscale morphologies.

This work explored how key aspects of molecular design and processing influence the internal structure of BCPEs. Specifically, it investigated the effects of polymer topology, salt content together with processing methods - such as thermal treatment and the application of an electric field - on the formation and organization of self-assembled nanostructures.

These findings deepen the understanding of how molecular design and processing affect performance providing at the same time framework for developing safer, high-performance solid polymer electrolytes for the next-generation solid-state batteries.

Keywords: block copolymer, solid polymer electrolytes, self-assembly

Thesis available for public display 7 days prior to the defence at .