Expanding insights into the mechanisms of polaronic and ionic conduction in oxide glass-(ceramics) POLAR-ION-GLASS
Electrically conducting oxide glasses are an important class of electrolyte/electrode materials whose application in modern electrochemical devices are growing rapidly. The type of conduction (polaronic, ionic or mixed polaronic-ionic) in these glasses depends on the composition, while the transport mechanism itself is strongly influenced by the interaction of charge carriers with the local structural environment and understanding it from a microscopic point of view poses a major challenge.
The overall aim of the project is to clarify the mechanisms of polaronic and ionic conduction in tungsten phosphate and molybdenum phosphate glasses and glass-ceramics with a special emphasis on their correlation to the structure.
The research contains three interconnected steps:
- identification of factors that govern polaronic conduction in binary tungsten/molybdenum phosphate glasses,
- investigation of the mixed conduction in tungsten/molybdenum phosphate glasses containing alkali oxides and
- study of the influence of crystallization on electrical transport in selected glasses from steps 1) and 2) in order to obtain highly conductive glass-ceramics with tuneable contributions of polaronic and ionic conduction.
The chosen phosphate glasses are especially attractive for application as cathodes in solid-state batteries because they can accommodate a considerable amounts of transition metal and alkali oxides, and hence exhibit high polaronic and ionic conductivity.
Detailed structural and electrical characterizations which are needed for resolving and relating processes of polaronic and ionic transport in these materials will be achieved using various advanced methods (Raman, MAS NMR and EPR spectroscopy, neutron and X-ray diffraction, impedance spectroscopy, DC measurements), while the numerical modelling of electrical conductivity using MIGRATION concept will give additional valuable insights into the elementary processes of polaronic and ionic motions.