Abstract
Silicon and silicon nitride (Si3N4) are some of the most appealing candidates as anode materials for LIBs (Li-ion battery) due to their favorable characteristics: low cost, abundance of Si, and high theoretical capacity. However, these materials have their own set of challenges that need to be addressed for practical applications. A thin film consisting of silicon nitride-coated silicon on a copper current collector (Si3N4@Si@Cu) has been prepared in this work via RF magnetron sputtering (Radio Frequency magnetron sputtering). The anode material was characterized before and after cycling to assess the difference in appearance and composition using XRD (X-ray Powder Diffraction), XPS (X-ray Photoelectron Spectroscopy), SEM/EDX (Scanning Electron Microscopy/ Energy Dispersive X-Ray Analysis), and TEM (Transmission Electron Microscopy). The effect of the silicon nitride coating on the electrochemical performance of the anode material for LIBs was evaluated against Si@Cu film. It has been found that the Si3N4@Si@Cu anode achieved a higher capacity retention (90%) compared to Si@Cu (20%) after 50 cycles in a half-cell versus Li+/Li, indicating a significant improvement in electrochemical performance. In a full cell, the Si3N4@Si@Cu anode achieved excellent efficiency and acceptable specific capacities, which can be enhanced with further research.
Highlights
The findings showed that these anode materials have a more stable cycling compared to silicon anodes
The as-prepared films were characterized using a range of analytical techniques: X-ray diffractometry (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and Transmission electron microscopy (TEM)
The electrochemical performance of Si3 N4 @Si@Cu as the anode material in half cells was assessed against Li+ /Li using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge–discharge (GCD)
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Si offers a high specific capacity of about 4200 mAh/g based on the formation of Li22 Si4 at high temperatures [8,10,11], which is over 10 times greater than that of graphite This is due to the ability of silicon to form Li-rich alloys (i.e., Li15 Si4 , Li21 Si5 ) with lithium, as opposite to graphite where six carbon atoms bond with only one Li+ ion (LiC6 ) [6,12]. The separation of the active material caused by the cracks results in a low electrical conductivity and prevents the transport of Li+ ions [17], which was initially provided by the addition of conductive carbon materials This leads to capacity fading and anode failure due to loss of electrical contact over longterm cycling [8]. We have utilized thin film technology to improve the electrical conductivity of Si by sputtering a thin layer onto copper foil, along with the addition of silicon nitride (Si3 N4 ) on top of the Si layer to accommodate the volume changes during lithiation/delithiation processes
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