Graphene quantum dots modified nanoporous SiAl composite as an advanced anode for lithium storage

• Published in: Electrochimica acta Vol. 318; pp. 228 - 235
• Main Authors: Chen, Zizhong, Hou, Jiagang, Liu, Qiang, Zhou, Qiuxia, Liu, Hong, Xu, Caixia
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 20.09.2019; Elsevier BV
• Subjects: Aluminum; Anode; Anodes; Binary alloys; Electrode materials; Graphene; Graphene quantum dots; Lithium; Lithium ion batteries; Nanoporous; Quantum dots; Rechargeable batteries; SiAl; Silicon; Lithium ion batteries; Anode; Nanoporous; SiAl; Graphene quantum dots
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2019.06.071

Graphene quantum dots modified nanoporous SiAl (NP-SiAl/GQDs) composite was easily prepared by a facile dealloying followed by the encapsulation of graphene quantum dots. Nanoporous Si with part of Al residues was first fabricated through incomplete corrosion of binary Si5Al95 precursor alloy. GQDs were then used as the building units to enwrap the positively charged NP-SiAl on the basis of the electrostatic assembly. Owing to the combination of graphene quantum dots and embedded Al, NP-SiAl/GQDs displays dramatically boosted lithium storage performances with excellent reversible capacity, outstanding cyclability, as well as high rate capability. Especially, NP-SiAl/GQDs composite exhibits superior cycling stability with large reversible capacity of 1318.7 and 1005.5 mAh g−1 retained after 120 and 150 cycles under the rate of 200 and 1000 mA g−1, respectively. Moreover, it exhibits high reversible capacity even cycled at 3000 mA g−1. With the merits of facile preparation and exceptional performances, the as-prepared NP-SiAl/GQDs composite presents great application potential as next-generation anode material in lithium ion batteries. A cotton-like protective layer formed on the surface of NP-SiAl backbone was conveniently fabricated through selective dealloying of Si5Al95 binary alloy under mild conditions followed by a surface combination with graphene quantum dots. The as-prepared NP-SiAl/GQDs composite is composed of bimodal SiAl network skeleton and interconnected graphene quantum dots protective layer uniformly distributed on the surface. With the advantages of unique structure and excellent lithium storage performances, NP-SiAl/GQDs composite holds promising application potential as an anode material in LIBs. [Display omitted] 1.Graphene quantum dots modified nanoporous SiAl composite was easily fabricated.2.GQDs encapsulation greatly enhanced the lithium storage performances of NP-SiAl.3.NP-SiAl/GQDs composite shows superior reversible capacity and cycling stability.4.NP-SiAl/GQDs composite shows a high capacity of 749.3 mAh g−1 under 3 A g−1.