The results of measuring the charge-discharge characteristics of solid-state thin-film lithium-ion batteries with a nanocomposite anode based on a-Si(Al) solid solution are presented. The charging characteristics of batteries have a feature in the form of a step on the gentle branch of the curve. It has been suggested and substantiated that the appearance of the step is related to the gradual compensation and change of the a-Si(Al) hole conductivity to electronic one as the lithium concentration increases. As a result, the a-Si(Al)|Ti ohmic contact becomes rectifying, and the electrons participating in the Faraday process are forced to overcome the Schottky barrier. The potential growth required to maintain the galvanostatic charge regime appears as a step on the charge curve.

The results on measuring the impedance of a solid-state thin-film lithium-ion battery of the LiCoO2-LiPON-Si@O@Al electrochemical system in the temperature range from -20°С to 50°С are presented. A structural model is proposed and the parameters of its elements, providing the best fit for the experimental Nyquist diagrams, are calculated. It is shown that the main contribution to the internal resistance is made by the LiPON-LiCoO2 interface. Based on the temperature dependence of the LiPON solid electrolyte conductivity the activation energy of lithium is determined, which is in good agreement with the literature data.

The results of measuring the resistivity of thin-film structures Ti|Si@O@Al|Ti and Ti|LiCoO2|Ti by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) are presented. It was found that, according to the EIS data, the resistance of Ti|Si@O@Al|Ti is three orders of magnitude higher than the CV data, which is due to the nonohmic nature of the metal-semiconductor junction and the varistor effect. It is shown that the Ti-LiCoO2 contact is ohmic, while the nonlinearity of the CVC is well described by the varistor effect. The results obtained are of importance for the interpretation of the impedance spectra of thin-film solid-state lithium-ion batteries based on semiconductor materials.

The results on measuring the I-V characteristics of the metal-semiconductor transition within the Ti(200nm)|Si@O@Al(179nm)|Ti(203nm) test structure are presented. The basis of the Si@O@Al nanocomposite is a solid solution of Al in amorphous silicon a-Si(Al). The I–V of the test structure has a form characteristic of a reverse-biased ohmic contact between a metal and a p-type semiconductor, which implies that a-Si(Al) is a substitutional solid solution. It is shown that the I-V fits well the framework of the metal-semiconductor transition model and the varistor effect of the nanocomposite. Within the framework of the percolation model, it is shown that the I–V give values of the Si@O@Al resistivity, which are overestimated with respect to the resistance of the a-Si(Al) solid solution.