• Minjauw, Matthias
• Detavernier, Christophe
• Kint, Jeroen
• Zhao, Bo
• Mattelaer, Felix

Abstract

Developing higher capacity electrode materials is a key challenge in battery advancement. Metal oxides undergoing conversion and/or alloying reactions offer high capacities, but suffer from volumetric changes and poor conductivities. However, combining several of these oxides can induce a synergistic effect, enhancing electrode characteristics. Using atomic layer deposition (ALD), carefully controlled model thin-film electrodes comprised of SnO2 and Fe2O3, and mixtures thereof are deposited to investigate length scales at which intermixing of the oxides is required to maximize this effect. ALD enables the synthesis of both intermixed structures and oxides where Fe, Sn, and O are mixed at the atomic scale and nanolaminated structures where Fe2O3 layer and SnO2 layers form a structure with well-defined interfaces. These model systems reduce the complexity of electrodes by eliminating the need for binders and additives and ensuring one-dimensional charge carrier diffusion. Using ALD enables us to study the influence of interfaces on electrode characteristics. It was found that intermixing of Fe2O3 and SnO2 at the atomic scale kinetically suppresses the alloying of Sn. In the nanolaminated superstructure, however, Sn alloying does take place, causing the well-defined interfaces to break down due to the volume changes brought about by alloying. As a consequence, the electrode capacity is rapidly fades, and thus, this structure type should be avoided. Here, the authors demonstrate that ALD is a unique tool with great potential for unraveling complex mechanisms in battery materials.

Topics

• impedance spectroscopy
• thin film
• one-dimensional
• atomic layer deposition