engleski

Nanostructured Silicon as Anode for Lithium-ion batteries

The enhancement in the morphology of anode materials leads to better capacitance properties. Nanostructure design is an effective way to improve battery cycling because nanostructures provide short diffusion length for Li+ ions and electrons with better resistance to fracture [1]. The most widely used anode is graphite whose lithiated compounds have stable phases up to the LiC6 stoichiometry corresponding to a theoretical specific capacity of 372 mAh / g [2]. In contrast, silicon possesses a very high theoretical capacity of 4200 mAh / g and can intercalate 4.4 Li into Si at high temperature to form Li15Si4 [3]. Silicon also features a working potential around 0.4 V vs. Li / Li+ which is safer than operating potential of graphite (0.05 V vs. Li / Li+). Although silicon possesses all of these advantages, silicon-based anodes suffer from huge volume expansion upon cycling (≈400%) causing electrode fracture and electrical isolation during repeated cycling [4]. Continuous volume changes cause the breaking-reformation of the solid electrolyte interphase (SEI) film which leads to the consumption of lithium-ions and electrolyte. There are two strategies to avoid this problem, first one is combining Si with different kinds of carbon materials such as amorphous carbon, conductive carbon black, carbon nanotubes and graphene and secondly, by designing nanoscale silicon with different structures. In the present work, we represent nanostructured composite anodes. Structural and microstructural changes in silicon nanomaterials were examined using several methods: X-ray powder diffraction combined with the results of Raman spectroscopy, FT-IR spectroscopy, UV-Vis spectrometry, Nitrogen adsorption measurements, and TEM analysis. Electrochemical performances were investigated by cyclic voltammetry and galvanostatic charge- discharge measurements.

silicon ; ball-milling ; chemical etching ; porosity ; anode ; battery ; electrochemical performance

nije evidentirano