Electrochemical activity and SEI formation inhibition of Al in Ni–Al-O ALD thin films

Abstract

Thin-film solid-state lithium-ion batteries (SSLIBs) are promising power supplies for small-scale electronics, particularly for Internet of Things (IoT) devices, sensors, microchips, and others. Transition metal oxides have potential for application in SSLIBs due to their high theoretical capacity. In this work, films of mixed nickel and aluminum oxides (NAO) were obtained at a temperature of 300 ℃ by plasma-assisted atomic layer deposition (ALD). The growth rates of the films turned out to be higher than the expected ones calculated from the growth rates of monoxide films. The increase in the growth rates is presumably associated with the chemosorption of a larger number of reagent molecules on the film surface during the alternation of reagent pairs during the ALD. High growth per cycle values of alumina lead to higher aluminum content and lower density of NAO films. The phase composition of NAO 50/1 and 75/1 films corresponds to the cubic NiO (Fm-3 m) space group. NAO films have a uniform surface dotted with round and fragmented particles. The electrochemical properties of the obtained films were studied by the cyclic voltammetry and cyclic charge–discharge tests at discharge currents from 0.5 to 60C. With an 80-fold increase in the discharge current, the electrode capacity decreased by 30%. It was shown the presence of aluminum in certain concentrations slows down the growth of pseudocapacitance by 20–28% and does not significantly affect the Coulomb efficiency of the films obtained. © 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.