Study of the Role of Void and Residual Silicon Dioxide on the Electrochemical Performance of Silicon Nanoparticles Encapsulated by Graphene

Silicon nanoparticles are used to enhance the anode specific capacity for the lithium-ion cell technology. Due to the mechanical deficiencies of silicon during lithiation and delithiation, one of the many strategies that have been proposed consists of enwrapping the silicon nanoparticles with graphe...

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Autores principales:	Dimitrios-Panagiotis Argyropoulos, George Zardalidis, Panagiotis Giotakos, Maria Daletou, Filippos Farmakis
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	silicon nanoparticles anode lithium-ion graphene void Chemistry QD1-999
Acceso en línea:	https://doaj.org/article/755a28d0aa704bedba5ba5974a801b48
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spelling	oai:doaj.org-article:755a28d0aa704bedba5ba5974a801b482021-11-25T18:30:27ZStudy of the Role of Void and Residual Silicon Dioxide on the Electrochemical Performance of Silicon Nanoparticles Encapsulated by Graphene10.3390/nano111128642079-4991https://doaj.org/article/755a28d0aa704bedba5ba5974a801b482021-10-01T00:00:00Zhttps://www.mdpi.com/2079-4991/11/11/2864https://doaj.org/toc/2079-4991Silicon nanoparticles are used to enhance the anode specific capacity for the lithium-ion cell technology. Due to the mechanical deficiencies of silicon during lithiation and delithiation, one of the many strategies that have been proposed consists of enwrapping the silicon nanoparticles with graphene and creating a void area between them so as to accommodate the large volume changes that occur in the silicon nanoparticle. This work aims to investigate the electrochemical performance and the associated kinetics of the hollow outer shell nanoparticles. To this end, we prepared hollow outer shell silicon nanoparticles (nps) enwrapped with graphene by using thermally grown silicon dioxide as a sacrificial layer, ball milling to enwrap silicon particles with graphene and hydro fluorine (HF) to etch the sacrificial SiO<sub>2</sub> layer. In addition, in order to offer a wider vision on the electrochemical behavior of the hollow outer shell Si nps, we also prepared all the possible in-between process stages of nps and corresponding electrodes (i.e., bare Si nps, bare Si nps enwrapped with graphene, Si/SiO<sub>2</sub> nps and Si/SiO<sub>2</sub> nps enwrapped with graphene). The morphology of all particles revealed the existence of graphene encapsulation, void, and a residual layer of silicon dioxide depending on the process of each nanoparticle. Corresponding electrodes were prepared and studied in half cell configurations by means of galvanostatic cycling, cyclic voltammetry and electrochemical impedance spectroscopy. It was observed that nanoparticles encapsulated with graphene demonstrated high specific capacity but limited cycle life. In contrast, nanoparticles with void and/or SiO<sub>2</sub> were able to deliver improved cycle life. It is suggested that the existence of the void and/or residual SiO<sub>2</sub> layer limits the formation of rich Li<sub>X</sub>Si alloys in the core silicon nanoparticle, providing higher mechanical stability during the lithiation and delithiation processes.Dimitrios-Panagiotis ArgyropoulosGeorge ZardalidisPanagiotis GiotakosMaria DaletouFilippos FarmakisMDPI AGarticlesilicon nanoparticlesanodelithium-iongraphenevoidChemistryQD1-999ENNanomaterials, Vol 11, Iss 2864, p 2864 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	silicon nanoparticles anode lithium-ion graphene void Chemistry QD1-999
spellingShingle	silicon nanoparticles anode lithium-ion graphene void Chemistry QD1-999 Dimitrios-Panagiotis Argyropoulos George Zardalidis Panagiotis Giotakos Maria Daletou Filippos Farmakis Study of the Role of Void and Residual Silicon Dioxide on the Electrochemical Performance of Silicon Nanoparticles Encapsulated by Graphene
description	Silicon nanoparticles are used to enhance the anode specific capacity for the lithium-ion cell technology. Due to the mechanical deficiencies of silicon during lithiation and delithiation, one of the many strategies that have been proposed consists of enwrapping the silicon nanoparticles with graphene and creating a void area between them so as to accommodate the large volume changes that occur in the silicon nanoparticle. This work aims to investigate the electrochemical performance and the associated kinetics of the hollow outer shell nanoparticles. To this end, we prepared hollow outer shell silicon nanoparticles (nps) enwrapped with graphene by using thermally grown silicon dioxide as a sacrificial layer, ball milling to enwrap silicon particles with graphene and hydro fluorine (HF) to etch the sacrificial SiO<sub>2</sub> layer. In addition, in order to offer a wider vision on the electrochemical behavior of the hollow outer shell Si nps, we also prepared all the possible in-between process stages of nps and corresponding electrodes (i.e., bare Si nps, bare Si nps enwrapped with graphene, Si/SiO<sub>2</sub> nps and Si/SiO<sub>2</sub> nps enwrapped with graphene). The morphology of all particles revealed the existence of graphene encapsulation, void, and a residual layer of silicon dioxide depending on the process of each nanoparticle. Corresponding electrodes were prepared and studied in half cell configurations by means of galvanostatic cycling, cyclic voltammetry and electrochemical impedance spectroscopy. It was observed that nanoparticles encapsulated with graphene demonstrated high specific capacity but limited cycle life. In contrast, nanoparticles with void and/or SiO<sub>2</sub> were able to deliver improved cycle life. It is suggested that the existence of the void and/or residual SiO<sub>2</sub> layer limits the formation of rich Li<sub>X</sub>Si alloys in the core silicon nanoparticle, providing higher mechanical stability during the lithiation and delithiation processes.
format	article
author	Dimitrios-Panagiotis Argyropoulos George Zardalidis Panagiotis Giotakos Maria Daletou Filippos Farmakis
author_facet	Dimitrios-Panagiotis Argyropoulos George Zardalidis Panagiotis Giotakos Maria Daletou Filippos Farmakis
author_sort	Dimitrios-Panagiotis Argyropoulos
title	Study of the Role of Void and Residual Silicon Dioxide on the Electrochemical Performance of Silicon Nanoparticles Encapsulated by Graphene
title_short	Study of the Role of Void and Residual Silicon Dioxide on the Electrochemical Performance of Silicon Nanoparticles Encapsulated by Graphene
title_full	Study of the Role of Void and Residual Silicon Dioxide on the Electrochemical Performance of Silicon Nanoparticles Encapsulated by Graphene
title_fullStr	Study of the Role of Void and Residual Silicon Dioxide on the Electrochemical Performance of Silicon Nanoparticles Encapsulated by Graphene
title_full_unstemmed	Study of the Role of Void and Residual Silicon Dioxide on the Electrochemical Performance of Silicon Nanoparticles Encapsulated by Graphene
title_sort	study of the role of void and residual silicon dioxide on the electrochemical performance of silicon nanoparticles encapsulated by graphene
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/755a28d0aa704bedba5ba5974a801b48
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Study of the Role of Void and Residual Silicon Dioxide on the Electrochemical Performance of Silicon Nanoparticles Encapsulated by Graphene

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