Protection of lithium anodes by atomic layer deposition of metal oxides

Group: CoCooN

Promotors: Christophe Detavernier and Jolien Dendooven

Supervisors: Bo Zhao and Andreas Werbrouck

 

Challenge

Nowadays, lithium-ion batteries (LIBs) represent the most prominent form of electrical energy storage. They are present everywhere around us, from the battery in our smartphones up to the large-scale batteries in electric vehicles and in grid storage farms. However, since their invention (which was awarded the 2019 Nobel prize for chemistry), they have essentially not progressed much in terms of energy capacity and lifetime. At the same time, the continued electrification of our society demands greatly more efficient energy storage.

Driven by the search for more energy in the battery, pure metallic lithium is considered as a potential next-generation anode. Currently, the anode is constructed of graphite, which has a capacity of only 372mAh/g. Lithium is a promising substitute with a high theoretical capacity (3860 mAh/g, more than 10x that of graphite) and a very low potential (-3.04V vs. standard hydrogen electrode) to maximize cell voltage (and thus power). However, the extreme reactivity of a pure lithium surface can induce side reactions, reducing the performance and lifetime of batteries employing lithium metal as anodes. Moreover, during electrochemical cycling the lithium often forms dendrites, which can cause a short-circuit between the electrodes and result in cell failure. One promising solution to these issues is the application of thin protection layers to stabilize the lithium metal surface.

Goals

Protection of lithium anodes by atomic layer deposition of metal oxides

Selected metal oxides can offer high corrosion resistance, outstanding thermal stability, and favourable chemical inertness towards Li. Based on these merits, selected metal oxides are interesting candidates as the protective layer on the surface of lithium metal. Atomic layer deposition (ALD), which is based on self-limiting chemical reactions between  gaseous precursors and a solid surface, offers an ideal method for thin film preparation in view of the layer-by-layer growth mode and atomic-level control over the thickness.

In this project, ALD process will be developed for the deposition of oxide- or phosphate films on metallic Lithium substrates. These films will, amongst others, be characterised using X-ray based techniques such as fluorescence (XRF), diffraction (XRD), reflection (XRR) and x-ray photo-electron spectroscopy (XPS). The battery electrodes will be characterised functionally in a protected glovebox environment. Of course, the input of the student is valued and the research direction can be modified based on interesting proposals/discoveries.

In this way, this project gives the student a solid background in thin film deposition and characterisation, materials research and battery technology.