Plasma enhanced atomic layer deposition of solid-state electrolyte Li-Ta-O for solid-state batteries

Abstract

Solid-state batteries (SSBs) are regarded as the next step in energy storage technology. One of the main problems in developing such batteries is developing and synthesizing solid-state electrolytes (SSE). The main factor that stops the introduction of SSBs into everyday life is the low ionic conductivity of Li ions in modern SSEs. Therefore, the primary purposes of the work are to establish the reasons for the manifestation of this inhibiting factor and to assess the possibility of using new materials for SSLIB. Solution these problems ultimately can give an impetus to the development and promotion of such type batteries. In this work, SSE was obtained by the atomic layer deposition (ALD) method, allowing the formation of homogeneous coatings with precision control of the thickness. ALD of LixTaOy thin films on silicon and stainless steel substrates using Ta(OEt)5 and LiOtBu was studied. The synthesis temperature was 300 °С, which is based on the previous research. Samples were synthesized with different ratios of Li:Ta = 1:2, 1:3, 1:7, and depending on the ratio of metals, the growth rate per supercycle varied from 0.21 to 0.46 nm. The film thickness was determined by spectral ellipsometry. A scanning electron microscopy was used to determine the conformity and morphology of the coatings. X-ray Photoelectron Spectroscopy was used to determine the elemental composition on the surface and in the bulk of SSE. According to X-ray diffraction, thin films are amorphous. Cyclic voltammetry has been used to study how thin films will respond to different voltages. The cathodic region cycling at various discharge currents (from 20 to 80 µA/cm2) presents a low capacity.