Study of the Structural Changes Undergone by Hybrid Nanostructured Si-CNTs Employed as an Anode Material in a Rechargeable Lithium-Ion Battery

Abstract

Silicon–carbon nanotube (Si-CNT) hybrid structures have been fabricated in a single step on Cu substrate by hot filament chemical vapor deposition (HFCVD). A mixture of straight chain saturated aliphatic polymer and Si nanoparticles was used as the seeding source. The material was analyzed by transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS), and the Si content in the Si-CNT was estimated to be ∼15% wt % by thermogravimetric analysis (TGA). Thereafter, the films were used for lithium-ion battery (LIB) anodes, whose cyclic voltammetry studies show redox peaks for Si and C consistent with lithium insertion/extraction, indicating good reversibility over extensive cycling. Electrochemical tests showed that Si-CNT electrodes can deliver an initial high discharge capacity of ∼700 mAh/g and a reversible capacity of ∼500 mAh/g over 520 cycles. After electrochemical cycling, the Si-CNTs were analyzed and compared to pristine material. The cycled films showed an increment of Si-CNT diameter and negligible cracks, formed due to high volumetric expansion of the silicon upon lithiation. Micro-Raman spectroscopy performed before electrochemical cycling established the presence of crystalline Si nanoparticles (<10 nm), and amorphous Si particles still bound to CNT after cycling. These results were confirmed by X-ray photoelectron spectroscopy (XPS). After cycling, the films showed good contact with the Cu substrate, and delamination was not observed by electrochemical impedance spectroscopy (EIS). The Si-CNT hybrid structure grown in a single step represents a promising anode material for a rechargeable LIB with high energy density and long cycling stability.

Silicon–Carbon Core–Shell Hollow Nanotubular Configuration High-Performance Lithium-Ion Anodes

“…In the present study, a hollow amorphous silicon nanotube structures (h-SiNTs) of different wall thicknesses (∼40−75 nm) has been synthesized by low-pressure chemical vapor deposition (LPCVD) of silicon on sacrificial MgO nanowire template, generated by a simple approach, followed by acid etching of the MgO template to obtain the hollow Si nanotubes (h-SiNTs). The wall thickness of h-SiNTs has been varied by controlling the deposition time (10,15, or 20 min) of LPCVD of Si on the MgO nanowire template. The wall thickness of the h-SiNTs increases with concomitant consolidation occurring with increasing time of deposition (∼45, ∼60, and ∼75 nm at 10, 15, and 20 min, respectively), which causes a reduction in specific surface area and improvement in areal loading density of h-SiNTs.…”

Research Progress of Silicon/Carbon Anode Materials for Lithium‐Ion Batteries: Structure Design and Synthesis Method

“…In preparation of Si/C anode materials, CVD can not only achieve uniform Si growth in carbon matrix or outside of CNT, [44,56,73,74] but also obtain amorphous carbon or CNT outside of Si [40,47,51,75–83] . Sometimes, both Si and carbon can be prepared by CVD [84–87,89] …”

“…[40,47,51,[75][76][77][78][79][80][81][82][83] Sometimes, both Si and carbon can be prepared by CVD. [84][85][86][87]89] Wilson et al [88] firstly obtained nano-dispersed Si in carbon using CVD and they found that the silicon was mainly located in the unorganized regions of the carbon without disturbing the organized regions. Zhang et al [40] synthesized a yolk-shellstructured carbon@void@silicon anode material.…”

A Facile, One-Step Synthesis of Silicon/Silicon Carbide/Carbon Nanotube Nanocomposite as a Cycling-Stable Anode for Lithium Ion Batteries

“…To address the issues, researchers have formed silicon into nano-scale particles [13,14,15], tubes [16,17], wires [18], and films [19] to help accommodate its volume expansion and contraction. For further improvement, the nano-scale Si is often embedded in a matrix, such as amorphous carbon [20,21,22], carbon nanotubes (CNTs) [23,24], or graphene [25], which not only accommodates the severe volume change, but also facilitates transporting electrons. CNTs hold great potential for constructing advanced Si-based anodes because of their high electrical conductivity, high aspect ratio, and high mechanical strength.…”