Synthesis and electrochemical characteristics of nanocoatings of lithiated tantalum oxide solid electrolyte

One of the most promising technologies for increasing the safety and durability of solid-state batteries (SSB) is nano-coating between electrodes and electrolytes. The paper presents the results of a detailed microscopic and electrochemical analysis of multilayer thin films. The investigated multilayer structures consist of a two-layer system of an amorphous Li-O layer and a Ta-O layer obtained by atomic-layer deposition on Si and steel substrate. The results show that the growth rate of the films is 0.21 nm/supercycle, which corresponds to the theoretical one under the given synthesis conditions. The X-ray diffraction pattern shows that the Li-O and Ta-O layers are X-ray amorphous with a small content of Ta2O5 nanocrystallites. The ratio of the Ta: O components in the films obtained was 1:4, which is close to the theoretical LiTaO3. However, no mixed oxides of the Li-Ta-O system were found, which indicates that the film is multilayered. Analysis of cyclic voltammograms showed no interaction with liquid electrolyte in the range of cathode potentials (4.3−3.0 V). In addition, the coatings do not significantly contribute to the electrochemical capacity so that they can be used as a functional layer between solid electrolytes and electrodes in SSB.