Facile conductive bridges formed between silicon nanoparticles inside hollow carbon nanofibers

Abstract

This paper reports on a simple and effective method for improving the electrochemical performance of silicon nanoparticle-core/carbon-shell (Si-core/C-shell) nanofibers. Instead of increasing the encapsulation amount of Si nanoparticles, additional conductive paths between the Si nanoparticles were formed by incorporating a small percentage of multi-walled carbon nanotubes (MWNTs) (e.g., 5 wt% with respect to Si) into the Si nanoparticle core. The electrical conductivity of a single Si-core/C-shell nanofiber was measured by a four-point probe using four nano-manipulators, which showed a more than five times increase according to MWNT addition. A galvanostatic charge-discharge test demonstrated that a small amount of MWNTs greatly improved the electrochemical performance of the Si-core/C-shell nanofibers (e.g., a 25.1% increase in the Li-ion storage capability) due to the enhanced participation of Si through the additional conductive paths formed between the Si nanoparticles.

Interfacially Induced Cascading Failure in Graphite‐Silicon Composite Anodes

“…As part of the comprehensive efforts, silicon (Si) has been considered as a potential candidate to replace the current anode material, graphite (372 mAh g −1 , LiC 6 ), because of its high capacity (3579 mAh g −1 , Li 15 Si 4 ), low environmental impacts, and low cost. Noteworthy advances have been made in addressing Si's instabilities through the design of nanostructured Si, functional conductive polymer binders for mitigating the mechanical degradation of Si, and electrolyte additives to form a more stable solid electrolyte interphase (SEI). However, the volume expansion of Si anode material, a consequence of the high lithiation degree of Si, continues to cause poor cycling stability associated with mechanical degradation and hinders the use of high‐capacity Si in commercial rechargeable LIBs …”

A Review of Recent Advancements in Electrospun Anode Materials to Improve Rechargeable Lithium Battery Performance

“…There are multiple studies on silicon core/carbon shell composite nanofiber anode materials, in which the amount of silicon is increased and the electrical contact is increased through the addition of carbon shells and auxiliary carbon additives, resulting in materials that have a specific capacity greater than 1000 mAh/g and stable cycling performances. Examples include the following: (i) silicon–CNT core/carbon shell composite nanofibers, shown in Figure 21 c,d [ 235 , 236 , 237 ]; (ii) carbon core/silicon medium/carbon shell composite nanofibers in Figure 21 e [ 238 ]; (iii) a silicon core with pyrolyzed carbon/carbon shell composite nanofibers in Figure 21 f,g [ 239 , 240 ]; and (iv) multi-channeled silicon core/carbon shell composite nanofibers in Figure 21 h [ 205 ]. In addition to structural optimization, the addition of an auxiliary anode material can help to improve the electrochemical performance of the silicon/carbon composite nanofibers.…”

“… Hollow carbon nanofiber anode materials containing silicon nanoparticles in void space. ( a ) Schematic diagram of structural change and solid electrolyte interphase growth on the raw silicon and the silicon contained in hollow carbon structure (reprinted with permission from [ 233 ]; copyright 2012 American Chemical Society) and coaxially electrospun silicon/carbon composite nanofibers: ( b ) silicon core/carbon shell composite nanofiber (reprinted with permission from [ 234 ]; copyright 2012 Elsevier), ( c ) silicon-carbon nanotube core/carbon shell composite nanofiber (reprinted with permission from [ 235 ]; copyright 2013 Royal Society of Chemistry), ( d ) silicon-carbon nanotube core/carbon shell composite nanofiber (reprinted with permission from [ 236 ]; copyright 2014 Royal Society of Chemistry), ( e ) carbon core/silicon medium/carbon shell composite nanofiber (reprinted with permission from [ 238 ]; copyright 2014 Royal Society of Chemistry), ( f ) silicon-carbon core/carbon shell composite nanofiber (reprinted with permission from [ 239 ]; copyright 2015 Royal Society of Chemistry), ( g ) silicon-carbon core/carbon shell composite nanofiber (reprinted with permission from [ 240 ]; copyright 2019 Elsevier), and ( h ) multi-channeled silicon core/carbon shell composite nanofiber (reprinted with permission from [ 205 ]; copyright 2014 Royal Society of Chemistry). …”

Preparation of hollow carbon submicro-fibers with controllable wall thicknesses from acrylonitrile copolymer

“…4 The HCSFs can be prepared by a template method 5 or coaxial electrospinning method. 6 The coaxial electrospinning of core/shell submicro-fibers and subsequent carbonization is an effective method for manufacturing HCSFs. 7 The core components, like polymethyl methacrylate, mineral oil and styrene- co -acrylonitrile copolymer, are decomposed and eliminated during the carbonization process.…”