Atomic layer deposition (ALD) provides a promising route for depositing uniform thin-film electrodes for Li-ion batteries. In this work, bis(methylcyclopentadienyl) nickel(II) (Ni(MeCp) 2 ) and bis(cyclopentadienyl) nickel(II) (NiCp 2 ) were used as precursors for NiO ALD. Oxygen plasma was used as a counter-reactant. The films were studied by spectroscopic ellipsometry, scanning electron microscopy, atomic force microscopy, X-ray diffraction, X-ray reflectometry, and X-ray photoelectron spectroscopy. The results show that the optimal temperature for the deposition for NiCp 2 was 200-300 • C, but the optimal Ni(MeCp) 2 growth per ALD cycle was 0.011-0.012 nm for both precursors at 250-300 • C. The films deposited using NiCp 2 and oxygen plasma at 300 • C using optimal ALD condition consisted mainly of stoichiometric polycrystalline NiO with high density (6.6 g/cm 3 ) and low roughness (0.34 nm). However, the films contain carbon impurities. The NiO films (thickness 28-30 nm) deposited on stainless steel showed a specific capacity above 1300 mAh/g, which is significantly more than the theoretical capacity of bulk NiO (718 mAh/g) because it includes the capacity of the NiO film and the pseudo-capacity of the gel-like solid electrolyte interface film. The presence of pseudo-capacity and its increase during cycling is discussed based on a detailed analysis of cyclic voltammograms and charge-discharge curves (U(C)).NiO nanofilms are produced using various methods [12] such as thermal spraying, pulsed laser deposition, sol-gel, spin-coating, dip-coating, chemical vapor deposition, and atomic layer deposition (ALD). ALD is the most promising technology because it provides control over the thickness and purity of coatings with high precision, and can deposit uniform surface coatings on of complex shape and even porous and high aspect ratio substrates [13][14][15]. This method could be a crucial factor for transition from 2D to 3D solid-state batteries (SSB), which are structured on 3D substrates with high aspect ratio instead of planar substrates. It could increase the energy density of SSB with the same thickness of the electrode to maintain the required conductivity of the layers [16]. ALD is based on a realization of the sequence of chemical reactions between gaseous reagents and the surface species of the substrate, separated in time by purges with an inert gas to prevent uncontrolled reactions between the reactants and the reaction products. Because of the self-limiting nature, this method allows the deposition of films in a layer-by-layer fashion and the control of the thickness with high precision [13].When selecting the deposition conditions via ALD, it is necessary to consider the stability and reactivity of the precursors. Many precursors have been tested for ALD NiO so far, but the most frequently used are shown in Table 1: nickel(II) acetylacetonate (Ni(acac) 2 ), bis(2,2,6,6-tetramethylheptane-3,5dionate)nickel(II) (Ni(thd) 2 ), bis(cyclopentadienyl) nickel(II) (NiCp 2 ), and NiCp 2 -based compounds such as ...

Lithium nickelate (LiNiO2) and materials based on it are attractive positive electrode materials for lithium-ion batteries, owing to their large capacity. In this paper, the results of atomic layer deposition (ALD) of lithium–nickel–silicon oxide thin films using lithium hexamethyldisilazide (LiHMDS) and bis(cyclopentadienyl) nickel (II) (NiCp2) as precursors and remote oxygen plasma as a counter-reagent are reported. Two approaches were studied: ALD using supercycles and ALD of the multilayered structure of lithium oxide, lithium nickel oxide, and nickel oxides followed by annealing. The prepared films were studied by scanning electron microscopy, spectral ellipsometry, X-ray diffraction, X-ray reflectivity, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and selected-area electron diffraction. The pulse ratio of LiHMDS/Ni(Cp)2 precursors in one supercycle ranged from 1/1 to 1/10. Silicon was observed in the deposited films, and after annealing, crystalline Li2SiO3 and Li2Si2O5 were formed at 800 °C. Annealing of the multilayered sample caused the partial formation of LiNiO2. The obtained cathode materials possessed electrochemical activity comparable with the results for other thin-film cathodes.

The observed downsizing tendency of microelectronic devices leads to a higher demand in new types of miniaturized energy sources. Thin‐film Li‐ion batteries (LiBs) are promising candidates to fulfil this function. New materials and technologies should be investigated for customized production of miniaturized, high‐efficient solid‐state batteries. Herein, inkjet printing technology is considered as a promising one for the fabrication of LiBs. The modification of crystalline lattice of Li‐rich cathode material by aluminium, sodium, and potassium and their influence on power efficiency are studied in detail. Lithium‐manganese‐rich compounds are chosen as the most suitable composition of an active component for LiBs fabrication. The stable aqueous colloidal ink composition is synthesized and its rheological parameters are optimized for inkjet printing in terms of viscosity, surface tension, and contact angle. Protocols for inkjet printing for the fabrication of thin‐film cathodes with the thickness of less than 10 μm are reported. The good correlation of electrochemical properties such as average voltage, capacity, and energy between inkjet printed and conventionally fabricated electrodes confirms the feasibility of the suggested technological approach and selected cathode material composition.

Due to the demand for wearable and implantable microelectronic devices (MED), there is growing interest in the development of thin-film lithium-ion microbatteries (LiBs) with high-energy density. The high cost of production is an issue restraining thin-film LiBs’ wide application. Inkjet printing is a method of applying materials to the substrate surface: ink droplets formed on piezoelectric nozzles fall on the substrate, whereafter evaporation of the solvent thin layer of film is formed. The proposed technology can simplify the production of LiBs for MED and reduce their cost. The present work reports the results of inkjet printing 3D cathode development for LiBs. The 3D printed cathodes were produced using synthesized Li-rich cathode material (Li1.2+xMn0.54Ni0.13Co0.13O2, 0 < x < 0.05) which has a larger capacity (>250 mAh/g) in comparison with the materials used in modern lithium-ion cells. For LiB electrode printing, the non-aqueous solvent-based inks were used. The prepared cathode material was dispersed in N-methyl-2-pyrrolidone. The effect of various additives such as ethylene glycol, diethylene glycol, propylene glycol on the viscosity and stability of the ink was studied. Inkjet printing was performed with the use of a Dimatix Material Printer 2831. Substrate temperature, number of layers and other parameters were varied to determine the optimal printing conditions.