All-solid-state batteries have been shown as an innovative candidate for next-gen lithium-ion batteries. Thin-film technologies offer an approach to solve several inherent challenges. To achieve a complete thin-film all-solid-state battery all components, especially electrodes and solid electrolytes have to be prepared in a suitable combination. In contrast to conventional liquid-solid electrolyte-electrode systems, additional requirements arise from the fact that electrochemically active interfaces have to be formed while preparing.

Using cost efficient and upscalable sol-gel processes 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 [1]. In previous work we presented a LATP solid electrolyte prepared by sol-gel methods on a current collector as substrate [2]. In a layer-by-layer setup (shown in Fig. 1) the substrate-anode system forms the underlying substrate for the electrolyte coating. Oxide-based electrodes indicate interfacial reactions in the presence of NASICON-type electrolytes at temperatures higher than 300 °C [3]. Therefore they turned out to be unstable in the coating-associated temperature treatment. Phosphate-based electrode materials provide a suitable approach.

This poster presents single- and multi-layer films a of phosphate-based anode material on conducting transparent oxides prepared by dip- and spin- coating method. The single- and multi-layer systems exhibited good electrochemical properties and appear suitable for the electrolyte coating process including the associated temperature treatment. Grazing incidence X-ray diffraction reveals no interface reaction and SEM investigation shows a good physical connection on the electrolyte-electrode interface. Furthermore, half-cell CV and cycling tests confirm a low charge transfer resistance at the interface. Future work will focus on the cathode/electrolyte interface and finally a working solid-state cell.

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

[2]   F. Frech et. al., Development of thin glass-ceramic electrolytes via a sol-gel route, Poster on IMLB 2014

[3]   A. Aboulaich et. al., Adv. Energy Mater. 2011, 1, 179–183