One-Step Electrodeposition of Layer by Layer Architectural Si-Graphene Nanocomposite Anode of Lithium Ion Battery with Enhanced Cycle Performance

Abstract

One step electrodeposition is applied to prepare Si-Graphene (SiG) composites from Graphene(G)-SiCl 4 - [BMP]tf 2 N ionic liquid. The SiG composites have shown an alternate layer-structure of Si and graphene caused by alternate processes of Si reduction and graphene adsorption on the electrode, which is confirmed by the regular current pulsation in the chronoamperometric curves during the whole electrodeposition process. The SEM and TEM morphologies indicate that each layer is about 120 nm thickness for the SiG3 composites electrodeposited from the 0.1852 mol·l −1 Graphene(G)-SiCl 4 -[BMP]tf 2 N ionic liquid, in which Si particle size is about 80-110 nm closely stick on 4-5 layers of graphene with a molar ratio of Si and C of 4.57:1. SiG3 anode displays a specific capacity of 1378 mAh·g −1 at the initial cycle, and 1083 mAh·g −1 at the end of 400 cycle (retention of 78%) at 4 A·g −1 , as well as 988 mAh·g −1 at 8A·g −1 , showing a good cycle life and rate performance. The layer-structured SiG anode significantly improve the conductivity and electrochemical performances of Si anode. The research provides a feasibility for electrodeposition preparation of layer-structured materials, especially for semiconductor-based alloys, graphene-based alloys in large-scale. Lithium ions battery has attracted more and more attention as one of the most promising power sources in the electric vehicles and portable electronic devices.1 Silicon, with a much larger theoretical specific capacity of 4200 mAh·g −12 and superior safety characteristics 3,4 compared to the current graphite anode, has been regarded as the most promising next generation anode for lithium ions battery.5 However, some inherent drawbacks of Si anode such as a low electronic conductivity (≈10 −4 S m −1 ) 6 and a large volumetric change 2,7,8 during charging and discharging processes, have limited the electrochemical performances and the practical application of Si anodes in lithium ions battery.Extensive investigations show that nano-structured Si such as Si nanotubes 9-12 and nanowires [13][14][15][16][17] can improve the electrochemical performances of Si anodes. The Si nanotubes by reductive decomposition of silicon precursors in an alumina template followed by etching according to Cui 11 maintain 2878 mAh·g −1 at a 5C rate after 200 cycles. However, Si-based anodes are still needed to further enhance the cyclability and rate performances.Graphene (G), as reported, not only can increase the conductivity of Si anode 1,18,19 but also can accommodate the large volumetric change of Si anode during cycling 18,21 due to its excellent electrical conductivity and exceptionally large specific surface area.20 Yi and Ran 19 use H 2 to reduce SiO 2 and graphene oxide mixture at 950• C to prepare G/Si-C composite, and the capacity of this composite is about 1314 mAh·g −1 at a rate of 0.4 A·g −1 . And the charge transfer resistance of G/Si-C is reduced from 59.98 to 9.14 as the addition of graphene.Compared with the above methods, electrodeposition can simplify the produ...

Alternative Layered-Structure SiCu Composite Anodes for High-Capacity Lithium-Ion Batteries

“…Moreover, the specific capacity of SiCu-2.1 is 1038.2 mAh/g after 750 cycles. Compared with our previous work, 37 bare Si electrode delivers a relatively lower capacity of 970 mAh/g at the end of the 200th cycle. The results indicate that the introduction of Cu promotes Li + and electron transfer to enhance the cycling performance of Si.…”

“…−0.65 V to about −1.5 V and peaking at −1.2 V presents the reduction of Si 4+ to Si 2+ , then the B2 step peaking at −1.65 V was the reduction reaction of Si 2+ to Si 0 on Cu substrate, and B3 with the reduction current appearing at ca. −1.8 V corresponds the Si deposition process, which was caused by the reduction of Si 4+ to Si 0 element on the Si film. − The above different potentials of Si 4+ to Si are attributed to different working electrodes. The reduction potential of Si 4+ to Si shifts to a more positive value on the Cu electrode due to underpotential electrodeposition, while the reduction potential of Si 4+ to Si remains relatively negative on the Si electrode.…”

An Iron-Group Metal Boride/Boron-Doped Vertically Oriented Graphene as Efficient Catalyst for Overall Water Splitting in a Wide pH Range

“…Ultimately, the intrinsic interfacial interactions between BG could be totally shielded, leading to the vertical orientation of BG sheets with relatively independent units on electrodes. 34,[36][37][38][39] It is well known that, larger interactions between metals and functional groups of surfaces can increase the dispersive character of IMBs atoms. During this deposition process, dispersive Fe-Co-Ni-B nanoparticles were in situ nucleated and grown on the functional groups of BVG surface, leading to the formation of Fe-Co-Ni-B/BVG composite.…”

Acetylcholinesterase Biosensor Based on Gold Nanoparticles/Nitrogen−Doped Vertically Oriented Reduced Graphene Oxide Prepared by Single−Step Electrodeposition

“…We deduce that, during the simultaneous electrodeposition of the two components, each NRGO sheet was surrounded by AuCl 4 homogeneously and therefore NRGO would be entrained during the AuNPs deposition at around −0.25 V, and meanwhile the NRGO sheets that have various functional groups provided anchor sites for nucleation and growth of AuNPs at the NRGO surfaces. AuNPs would also be entrained during the NRGO deposition at around −1.2 V. 31,32,35 The formation of smaller AuNPs may be ascribed to the nitrogen atoms, which are homogeneously doped into the RGO by urea, that induce new nucleation and growth of Au atoms, leading to the formation of smaller AuNPs. This suggested that the AuNPs/NVRGO composite possessed the largest specific surface area.…”