Novel ceramic-polymer hybrid electrolytes for Li-ion solid state batteries: interrelation of interface structure and morphology with ion transport

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Solid state batteries based on Li-ion technology are promising candidates for high energy density, safe and stable storage devices. A major issue for the development of such batteries is the manufacture of suitable composite cathodes. Material- and processing solutions are required to provide the electrode with high electric conductivity in order to minimize ohmic losses as well as provide elasticity to compensate volume changes. Also, single-ion electrolytes are preferred to avoid polarization effects. This proposal aims to investigate novel inorganic-organic hybrid solid state electrolytes for use in solid state Li-ion batteries, mainly as catholyte in the composite cathode. Conceptionally, hybrid electrolytes can combine the advantages of crystalline electrolytes (high conductivity) with the advantages of polymer electrolytes (elasticity). A major challenge for such a concept is to provide high conductivity channels within the composite, related to bulk and interface properties of the two different component materials. Our approach is to combine polyelectrolytes with improved bulk properties and ceramic electrolyte particles with suitable morphology and surface chemistry to fabricate composites with high Li-ion conductivity and good mechanical properties. The surface chemistry of the ceramic electrolyte particles is thereby modified by ultra-thin coatings with the aim to improve the transport across (or along) ceramic-polymer interfaces. A major aim of the project is to establish the interrelation of interface structure and morphology with ion transport. In order to understand interface-related Li-ion transport phenomena, fundamental investigations towards interface formation and properties is performed by means of 2D model interfaces (layer stacks), which are characterized by surface science methods and electrochemical techniques.