Understanding the Relationship of Nanostructure to Performance in Additive Free TiO2 Anodes for Lithium-Ion Batteries
In this study, we present the fabrication of TiO2 nanostructures using a single step gas phase method directly on the current collector. Aerosol Chemical Vapor Deposition (ACVD) process has been successfully used for single step synthesis of nanostructured TiO2 with different morphologies by controlling the aerosol dynamics in the process. One dimensional (columnar) single crystal TiO2 nanostructures and granular structures were synthesized on stainless steel substrates (current collector) by the ACVD process. The electrochemical performance of these nanostructures was tested in a half-cell assembly against Li/Li+.
Single crystalline columnar structures exhibited enhanced specific capacity compared to the polycrystalline granular structures for the same structure height (Figure 1). The difference in performance of the columnar structures and the granular structures widens with increasing charging rates indicating the sluggish diffusion kinetics in the granular structures. This reduced performance of the granular structures was attributed to the presence of grain boundaries and the different crystallographic orientation in the structures. Further the performance of the columnar and granular nanostructures depended on the height of the structures. Mass transfer characteristics of the different morphologies were studied using electrochemical impedance spectroscopy (EIS) and Galvanic Intermittent Titration Technique (GITT). Transport modelling of lithium in the nanostructure will be used to understand the correlation between the nanostructure and performance of the anodes.