Graphite-Si@TiO2 Core-Shell Nanoparticles as Composite Anode for Li-Ion Batteries: Postcycling Analysis

The present work deals with the postcycling analysis of the graphite-based composite anodes, graphite reinforced with bare silicon nanoparticles (GrSi), and Si@TiO2 core-shell nanoparticles (GrCS), for lithium-ion batteries. The electrochemical behavior is recorded through galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) tests. The postcyclic analysis is done using material and structural characterization. The GrSi anode demonstrates a higher initial specific capacity but lower cyclic stability relative to the GrCS anode. The capacity retention for the GrSi anode is approximate to 57%, while for the GrCS anode it is approximate to 75%. After cycling, the EIS analysis indicates that GrSi anode exhibits higher resistance than GrCS anodes. The cross-sectional appearance of cycled anodes reveals minimal changes in the surface morphology of the GrCS anode, with a approximate to 75% thickness increase for the GrSi anode and approximate to 35% for the GrCS anode. The changed electrochemical behavior is attributed to the change in the composition of the solid-electrolyte interphase layer, as confirmed by X-ray photo spectroscopy, and minor loss in crystallinity of GrCS anode material, as confirmed by X-ray diffraction. The study provides insights into the mechanisms governing material degradation during the electrochemical processes in the composite anodes.