Growth Parameters and Diffusion Barriers for Functional High-Voltage Thin-Film Batteries Based on Spinel LiNi_0.5Mn_1.5O₄ Cathodes

Abstract

Cobalt-free spinel LiNi0.5Mn1.5O4 is one of the most promising and environmentally friendly cathodes, based on its high specific theoretical capacity (147 mAh·g–1) and high electrochemical potential (4.7 V vs Li+/Li), as well as good electronic and Li-ion conductivities. In this work, we present the fabrication of LiNi0.5Mn1.5O4 thin-film cathodes deposited by the industrially scalable AC magnetron sputtering technique on functional and cost-effective stainless steel current collectors. This is the first step toward battery downscaling, envisioning the fabrication of compact microbatteries for low-power energy supply. The thin-film strategy is crucial also for solid electrolyte fabrication that will allow the integration of high-energy-density batteries while overcoming most of the current battery challenges. In this work, the effect of film thickness on the material’s electrochemical performance is discussed, correlating the observed structural and morphological evolution with the final electrochemical response. Moreover, the effect of iron diffusion from the current collector substrate into the cathode film is analyzed. The addition of a stable CrN barrier layer in between the substrate and the film is proposed to prevent Fe diffusion, with a direct positive influence on the electrochemical behavior. All in all, the obtained results will facilitate the practical implementation of LiNi0.5Mn1.5O4 thin films as high-voltage cathodes in functional cost-effective microbatteries.

Monolithic All-Solid-State High-Voltage Li-Metal Thin-Film Rechargeable Battery

“…The selected growth parameters are detailed in a previous work focused on the optimization of LNMO thin-films. 40 Under these conditions, an 8.91 nm min −1 deposition rate and a good film adhesion were achieved. The growth process lasted for 2 h, leading to the deposition of 1.07 ± 0.02 μm-thick films.…”

“…LNMO deposition was performed by a CemeCon MF-AC dual technology-based magnetron sputtering system on low-cost stainless-steel discs (316L, Hohsen Corp.) using a 12 mm circular mask. The selected growth parameters are detailed in a previous work focused on the optimization of LNMO thin-films . Under these conditions, an 8.91 nm min –1 deposition rate and a good film adhesion were achieved.…”

“…The structural and electrochemical properties of each electroactive component of the battery have been analyzed separately before the building up of the cell. The optimization of the cathode has been described in a previous work …”