This title appears in the Scientific Report : 2014 

Review of physical properties of NASICON materials for use in sodium batteries
Guin, Marie
Tietz, Frank / Buchkremer, Hans Peter
Werkstoffsynthese und Herstellungsverfahren; IEK-1
Fachtagung Kraftwerk Batterie 2014, Münster (Germany), 2014-03-25 - 2014-03-26
Helmholtz Interdisciplinary Doctoral Training in Energy and Climate Research (HITEC)
Energy Storage
The environmental concerns about the use of fossil fuels and their resource constraints have led to a great interest in renewable energy sources and new electrical energy storage systems. One promising solution is the electrochemical storage of electricity in batteries. Among all rechargeable battery technologies, the Li-ion cells offer the largest energy density and output voltage. But recently, Na-ion batteries are back in the focus of interest due to the abundant availability of Na instead of the limited resources of Li. However, much work has to be done in the field of Na-ion in order to catch up with Li-ion technology. NASICON materials (sodium super ionic conductors) are a thoroughly-studied class of solid electrolytes for Na-ion batteries. In this study, their structure, compositional diversity and ionic conductivity are reviewed in order to correlate the lattice parameters and specific crystal structure data with the sodium mobility and the activation energy. For approximately 150 structures with the general formula Na1+x+yMxM’2-xSiyP3-yO12 (M and M’ di-, tri-, tetra- or pentavalent cations) an optimal size for M and M’ could be found and the impact on the conductivity of the amount of Na per formula unit could be pointed out. This understanding will be useful for the search of new and improved NASICON materials. An extensive study of the size of the structural bottleneck for the sodium conduction (formed by triangles of oxygen ions) has been made to validate the influence of this geometrical parameter on the sodium mobility.