Development of Thin Glass-Ceramic Electrolytes Via a Sol-Gel Route

Due to their high energy densitites lithium-air and lithium-sulfur are the most promising battery technologies. Both systems inhibit substantial drawbacks, though. The dendrite formation on the lithium anode and subsequent shorting of the cell is still unsolved since the first market introduction of rechargeable lithium-batteries in the early 1990s. With common liquid electrolytes dendrite formation cannot reliably be prevented. However, solid electrolytes with a high shear modulus effectively inhibit this effect.^[1]

Solid NASICON-type electrolytes (e. g. Li_1+xAl_xTi_2-x (PO₄)₃, LATP) offer a high ionic conductivity at room temperature and a high anodic stability. The low stability against metallic lithium, due to the reduction of the transition metal (e. g. Ti⁴⁺), requires an intermediary layer.^[2] Additionally, a reliable concept for the integration of a  free standing and thick (> 50 µm) “electrolyte-sheet” has yet to be proven.

In our work, dense electrolyte layers with a thickness below 1 µm were prepared by sol-gel methods (Figure 1). It was intended that a wet chemical deposition of cathode material onto the sintered electrolyte should reduce the interface resistance and that the resistance could be further optimized by varying the deposition and sintering conditions. The electrolyte/electrode interface was analyzed by means of SEM and depth-profiling XPS. Temperature dependent XRD allows for the analysis of the sintering process in situ. The interface resistance was tested galvanostatically and by electrochemical impedance spectroscopy. Electrochemical tests on the electrolyte were performed with sputtered platinum electrodes. The (spectro) electrochemical characterization (Figure 2) of thin-film electrodes on TCO coated glass substrates was realized in specially designed test cells.

This poster presents the first results on the sol-gel deposited glass ceramics as electrolyte, thin film cathodes and the interface between both components. Future work will focus on the anode/electrolyte interface (Lithium/polymer/glass-ceramic) and finally a working solid-state cell.  

[1]   W. Xu, J. Wang, F. Ding, X. Chen, E. Nasybulin, Y. Zhang, J.-G. Zhang, Energy Environ. Sci. 2014.

[2]   P. Knauth, Solid State Ionics 2009, 180, 911–916.