Graphite-Si@TiO2 Core-Shell Nanoparticles as Composite Anode for Li-ion Batteries: Electrochemical Response

Abstract

This study focuses on optimizing composite anode through varying Si@TiO2 core–shell nanoparticles (core is silicon and shell is titania) percentages in graphite. Material characterization reveals the morphological transformation of graphite and silicon nanoparticles into composite anodes. Electrochemical tests, including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy, provide essential insights into the electrochemical behavior of these composites. In the cycling tests, graphite with 5% core–shell (GrCS5), graphite with 10% core–shell (GrCS10), and graphite with 15% core–shell (GrCS15) show initial discharge capacities of 568 mAh g−1, 675 mAh g−1, and 716 mAh g−1, retaining 76%, 75%, and 72% after 100 cycles, respectively. Conversely, the graphite with 10% bare silicon (GrSi10) composite, commencing with 728 mAh g−1, exhibits rapid degradation, retaining 54% after 100 cycles. Moreover, the EIS analysis reveals higher values of ohmic, SEI, and charge transfer resistances in GrSi10 compared to other composite anodes after 100 cycles. The examination of the lithium diffusion coefficient indicates that GrCS5 demonstrates superior lithium diffusion kinetics, displaying the highest coefficient among all composite anodes. The research objective is to identify the optimal composite anode composition through quadrant analysis, considering specific capacity and lithium diffusivity after 100 cycles. In conclusion, integrating Si@TiO2 core–shell nanoparticles in graphite anodes improves their performance, with GrCS10 demonstrating notable effectiveness.