Liquid crystal as ion conductor in solid polymer electrolytes for lithium metal batteries

Details

Supervisors

Gohy, Jean-François

Faculty

Faculté des sciences

Degree label

Master [120] en sciences chimiques, à finalité spécialisée: chimie de l'industrie

Abstract

The energy demand over the next years and decades will not stop increasing and a transition to new types of energy production will become an important challenge. Another obstacle that will be faced is the energy storage, and the current most promising solution is the development of lithium metal batteries. Those batteries are still not usable in their current state since some safety issues are faced. This thesis focuses on lithium metal batteries and more specifically solid polymer electrolytes for lithium metal batteries. Solid polymer electrolytes have the advantage to posses a good mechanical strength, with a resistance to flammability and a reduction of lithium dendrites formation. However, the ionic conductivity of solid polymer electrolytes is low at room temperature. The focus of this study is thus to try to improve the ionic conductivity of a peculiar solid polymer electrolyte. This is realized by adding liquid crystals to create a hybrid material with new properties, as the formation of channels improving the lithium-ion mobility inside the electrolyte. The objective is then to improve and facilitate the channel formation using photopolymerization with an electric field applied, by realizing polymerizations without solvent, hoping it would microphase-separate to create two distinct phases. This project began with the synthesis of the different monomers used for the solid polymer electrolyte, with thermal characterization of them. Photopolymerization with and without a 2 kV/mm electric field applied was performed to compare the interest of it, and electrochemical and structural characterization were realized to analyze the formed solid polymer electrolytes. The ionic conductivity of the solid polymer electrolyte synthetized did not exceed 10-6 S.cm-1 . Although the results were not as expected, there is still some room for improvement.